Allogene Therapeutics (ALLO) Risk Analysis

Previously, certain of our oncology product candidates utilized an anti-CD52 monoclonal antibody (ALLO-647) as part of a lymphodepletion regimen to be infused prior to infusing our product candidates. The anti-CD52 antibody may reduce the likelihood of a patient's immune system rejecting the engineered allogeneic T cells for a sufficient period of time to enable a window of persistence during which such engineered allogeneic T cells can actively target and destroy cancer cells. However, the antibody may not have the benefits that we anticipate and could have adverse effects. For instance, our lymphodepletion regimen, including using an anti-CD52 antibody, will cause immune suppression that can be of unpredictable depth and duration and that may be associated with an increased risk of infection, such as to common viral or bacterial or opportunistic pathogens, that may be unable to be cleared and ultimately lead to other SAEs or death. In the prior CALM and PALL trials, a commercially available monoclonal antibody, alemtuzumab, that binds CD52 was used. Alemtuzumab is known to have risk of causing certain adverse events. In 2020, within the context of a procedure based on Article 20 of Regulation 726/2204 (EMA Regulation), the EMA completed a pharmacovigilance review of alemtuzumab in the context of the treatment of multiple sclerosis following reports of immune-mediated conditions and problems affecting the heart and blood vessels, including fatal cases. The EMA recommended that alemtuzumab should not be used in patients with certain heart, circulation or bleeding disorders or in patients who have autoimmune disorders other than multiple sclerosis. The EMA also recommended that alemtuzumab only be given in a hospital with ready access to intensive care facilities and specialists who can manage serious adverse reactions. The previous use of our anti-CD52 antibody may result in the same or similar adverse events as alemtuzumab. To secure our own readily available source of anti-CD52 antibody, we were previously developing our own monoclonal anti-CD52 antibody, ALLO-647, which we used in certain of our clinical trials. ALLO-647 may cause SAEs that alemtuzumab may cause, including fatal adverse events, infusion related reactions, immune thrombocytopenia, glomerular nephropathies, thyroid disorders, autoimmune cytopenias, autoimmune hepatitis, hemophagocytic lymphohistiocytosis, acquired hemophilia, infections, stroke, and progressive multifocal leukoencephalopathy. For example, a patient death occurred in the discontinued FCA arm of our ALPHA3 trial. This Grade 5 SAE, which occurred on Day 54 post-infusion, involved fulminant hepatic failure caused by disseminated adenovirus infection, potentially worsened by acetaminophen toxicity. The depth of immunosuppression likely associated with ALLO-647 is believed to have increased susceptibility to this viral infection. In addition, we may explore various dosing strategies for lymphodepletion in our clinical trials, such as including varying doses of the chemotherapy agents and/or other agents or eliminating one or more of the agents, which may alter the risk of SAEs or have other undesirable outcomes such as a reduction of the efficacy of treatment. Additionally, our experimental lymphodepletion regimens may show different safety profiles when paired with different allogeneic CAR T product candidates such that regimens deemed safe with one CAR T product candidate may be determined to be associated with unacceptable toxicity when combined with another CAR T candidate or with the same candidate in a different patient population. If observed, these differences may require additional clinical exploration and may cause delays in the execution or termination of development campaigns. Refer to the section entitled "Business-Product Pipeline and Development Strategy" included in our Annual Report for information on safety events.

Under the Orphan Drug Act, the FDA may grant orphan designation to a drug or biologic intended to treat a rare disease or condition, defined as a disease or condition with a patient population of fewer than 200,000 in the United States, or a patient population greater than 200,000 in the United States when there is no reasonable expectation that the cost of developing and making available the drug or biologic in the United States will be recovered from sales in the United States for that drug or biologic. In order to obtain orphan drug designation, the request must be made before submitting a BLA. In the United States, orphan drug designation entitles a party to financial incentives such as opportunities for grant funding towards clinical trial costs, tax advantages, and user-fee waivers. After the FDA grants orphan drug designation, the generic identity of the drug and its potential orphan use are disclosed publicly by the FDA. Orphan drug designation does not convey any advantage in, or shorten the duration of, the regulatory review and approval process. If a product that has orphan drug designation subsequently receives the first FDA approval of that particular product for the disease for which it has such designation, the product is entitled to orphan product exclusivity, which means that the FDA may not approve any other applications, including a BLA, to market the same biologic (meaning, a product with the same principal molecular structural features) for the same indication for seven years, except in limited circumstances such as a showing of clinical superiority to the product with orphan drug exclusivity or if FDA finds that the holder of the orphan drug exclusivity has not shown that it can assure the availability of sufficient quantities of the orphan drug to meet the needs of patients with the disease or condition for which the drug was designated. As a result, even if one of our product candidates receives orphan exclusivity, the FDA can still approve other biologics that do not have the same principal molecular structural features for use in treating the same indication or disease or the same biologic for a different indication or disease during the exclusivity period. Furthermore, the FDA can waive orphan exclusivity if we are unable to manufacture sufficient supply of our product or if a subsequent applicant demonstrates clinical superiority over our product. The FDA granted orphan drug designation to ALLO-715 for the treatment of multiple myeloma. We plan to seek orphan drug designation for additional product candidates in specific orphan indications in which there is a medically plausible basis for the use of these products, but may never receive such designations. Some of our product candidates target indications that are not orphan indications. In addition, even with orphan drug designation, exclusive marketing rights in the United States may be limited if we seek approval for an indication broader than the orphan designated indication and may be lost if the FDA later determines that the request for designation was materially defective or if we are unable to assure sufficient quantities of the product to meet the needs of patients with the rare disease or condition, or if a subsequent applicant demonstrates clinical superiority over our products, if approved.

We have received Regenerative Medicine Advanced Therapy (RMAT) designation for cema-cel, ALLO-316, and ALLO-715 and fast track designation for cema-cel, ALLO-316 and ALLO-329. There is no assurance that we will be able to obtain RMAT designation or fast track designation for any of our additional product candidates. RMAT designation and fast track designation do not change the FDA's standards for product approval, and there is no assurance that such designation will result in expedited review or approval or that the approved indication will not be narrower than the indication covered by the designation. Additionally, RMAT designation and fast track designation can be revoked if the criteria for eligibility cease to be met as clinical data emerges.

We may experience difficulties in patient enrollment in our clinical trials for a variety of reasons. For example, as we progress the ALPHA3, TRAVERSE and RESOLUTION trials, we may face enrollment challenges, including an unwillingness of sites or patients to participate, the exclusion of patients with certain disease characteristics or the ineligibility of patients that have received prior autologous CAR T therapies, which continue to gain adoption. The timely completion of clinical trials in accordance with their protocols depends, among other things, on our ability to enroll a sufficient number of patients. Because we anticipate a minority of the 1L patients we will test for MRD as part of screening for the ALPHA3 trial will be MRD positive, we will likely experience a very high screen failure rate, which will require screening a large number of patients to complete enrollment in the study. Because of the anticipated high screen failure rate, certain clinical trial sites may decline to participate in ALPHA3 or completion of enrollment may be significantly delayed. Future epidemics or pandemics may result in reduced enrollment and challenges to related clinical trial activities. The enrollment of patients may be more difficult, such as due to the perceptions of the safety of our product candidates, and will depend on many factors, including: - the patient eligibility criteria defined in the protocol;- the prevalence of any biomarker required for enrollment, such as MRD or CD70 expression;- the performance of the diagnostic tests used to determine eligibility for enrollment (e.g., MRD or CD70);- the size of the patient population required for analysis of the trial's primary endpoints;- the proximity of patients to study sites;- the design of the trial;- our ability to recruit clinical trial investigators with the appropriate competencies and experience and to activate, in a timely manner, the clinical trial sites with which they are associated and that have access to eligible patients;- our ability to obtain and maintain patient consents;- the competition from approved products in the same or other lines of therapy and/or disease indications and from product candidates in other clinical trials; and - the risk that patients enrolled in clinical trials will drop out of the trials before the infusion of our product candidates or trial completion. Since we only need to conduct a limited number of manufacturing runs to generate clinical supply, the diversity of our supply is limited during clinical trials. As a result, some patients may have antibodies to certain donor specific antigens at titers that could negatively impact the activity of our product candidates and which would render the patients ineligible for treatment. Furthermore, cellular mechanisms of allogeneic tissue rejection may limit the efficacy of our products. In addition, we have introduced an in vitro companion diagnostic (IVD) assay in the TRAVERSE trial to screen for patients with CD70+ tumors and are utilizing an MRD assay in the ALPHA3 trial to screen for patients who are MRD positive, both of which are restricting the number of patients eligible for the trials. Development and research use of an experimental diagnostic assay or test, such as that we are using to determine CD70 expression on tumor tissue of potential participants in the TRAVERSE trial or to identify MRD positive patients in the ALPHA3 trial, may influence results of the study in expected or unexpected ways. For example, emerging safety and efficacy outcomes could lead us to impose, tighten or expand "cutoff" values of CD70 expression to determine enrollment eligibility for TRAVERSE. Assay performance or necessary changes we or our partners make to the assay(s) during development may reduce the pace of enrollment or may lead to alterations in the expected benefit risk profile as compared to results collected prior to the change. In addition, our use of such assays may add complexity to initiating or expanding clinical trials outside the United States, including because the assay may be subject to regulation as an in vitro diagnostic medical device in certain jurisdictions and may require regulatory review, authorization, clearance or approval, or additional country-specific validation or operational requirements, before it can be used for patient selection. Any delays or inability to obtain such regulatory authorization, clearance or approval, or to meet local requirements, could delay trial initiation, site activation, patient screening or enrollment in those jurisdictions.The diagnostic assay itself may not perform as expected due to identifiable or obscure factors. It is also possible that we may not be aware of such underperformance of the assay which could lead to incorrect conclusions. This could, in turn, impact enrollment and interpretation of the clinical trial results. Our clinical trials will also compete with other clinical trials for product candidates that are in the same therapeutic areas as our product candidates, and this competition will reduce the number and types of patients available to us because some patients who might have opted to enroll in our trials may instead opt to enroll in a trial being conducted by one of our competitors. For example, our collaboration with Foresight Diagnostics is nonexclusive. As a result, there is a risk that Foresight Diagnostics might work with our competitors to enable a competing clinical trial involving the same MRD positive patient population that we plan to enroll in ALPHA3, which would reduce the number of patients who are available to participate in ALPHA3, and potentially delay completion of ALPHA3. Since the number of qualified clinical investigators is limited, some of our clinical trial sites are also being used by some of our competitors, which may reduce the number of patients who are available for our clinical trials in that clinical trial site. As our clinical trials require conditioning patients with chemotherapy, including agents such as cyclophosphamide and fludarabine, and physicians use other drugs prophylactically or to manage adverse events, our ability to enroll may be impacted by the shortage of such agents or drugs. For instance, the FDA has reported a shortage of fludarabine and any failure or delays by us or by our clinical trial sites to obtain sufficient quantities of fludarabine may delay our ability to enroll and treat patients in our clinical trials. Moreover, because our product candidates represent a departure from more commonly used methods for treating cancer and autoimmune diseases, potential patients and their doctors may be inclined to use conventional therapies, such as chemotherapy, monoclonal antibodies, hematopoietic cell transplantation as well as autologous CAR T cell therapies for treating cancer or hydroxychloroquine, NSAIDs, immunosuppressants, corticosteroids, or other biologics for treating autoimmune diseases, rather than enroll patients in our clinical trial, including if our product candidates have or are perceived to have additional safety or efficacy risks or if using our product candidates may affect insurance coverage of conventional therapies. For instance, the development of autologous CAR T cell therapies continues to rapidly advance, including into earlier lines of treatment of LBCL and treatment of relapsed/refractory (R/R) multiple myeloma, as described under the section entitled "Business-Competition" included in our Annual Report. We also may experience risks associated with a new class of therapies, bispecific antibodies, which have been approved for multiple myeloma and LBCL. The compelling results and related approvals may impact our ability to enroll patients in our clinical trials. Moreover, patients eligible for allogeneic CAR T cell therapies but ineligible for autologous CAR T cell therapies due to aggressive cancer and inability to wait for autologous CAR T cell therapies may be at greater risk for complications and death from therapy or may experience a reduction in efficacy as compared to patients who are well enough and whose disease is sufficiently slow growing as to be eligible for autologous CAR T cell therapy. Delays in patient enrollment may result in increased costs or may affect the timing or outcome of our clinical trials, which could prevent completion of these trials and adversely affect our ability to advance the development of our product candidates.

We have concentrated our research, development and manufacturing efforts on our engineered allogeneic CAR T cell therapy and our future success depends on the successful development of this therapeutic approach. We are in the early stages of developing our platform and we have experienced significant development challenges, such as with the prior clinical hold by the FDA, and there can be no assurance that any development problems we have now or experience in the future will not cause significant delays or unanticipated costs, or that such development problems can be overcome. We may also experience regulatory, operational, or technical challenges or delays when we seek to transition to commercial manufacturing, which may prevent us from commercializing our products, if approved, on a timely or profitable basis, if at all. In addition, since we are in the early stages of clinical development, we do not know all the doses to be evaluated in pivotal trials or, if approved, commercially. Finding a suitable dose for our cell therapy product candidates may delay our anticipated clinical development timelines. These unknowns and other emerging findings from our clinical trials may result in protocol amendments, which may result in additional costs and may also delay our anticipated clinical development timelines. For example, our decision to terminate the FCA arm (fludarabine, cyclophosphamide, and ALLO-647) in our ALPHA3 trial resulted in a protocol amendment that has resulted in additional costs and could delay our anticipated clinical development timeline. In addition, our expectations with regard to our scalability and costs of manufacturing may vary significantly as we develop our product candidates and understand these critical factors. We are also advancing product candidates against unexplored targets and with new technology. For example, ALLO-316 targets CD70, and ALLO-329 targets CD19 and CD70. As a dual-targeting CAR T product candidate, ALLO-329 may demonstrate limited ability to target and eliminate cells, including both B and T lymphocytes, that express one or both targets. Additionally, there may be unexpected toxicity, such as severe or prolonged immunosuppression or hyperinflammation, arising from targeting both CD19 and CD70 simultaneously. Since CD70 is found on activated T and other immune cells, ALLO-316 and ALLO-329 may also cause fratricide resulting in the loss of ALLO-316 or ALLO-329 cells, either during the manufacturing process or after the cells are administered to patients, or may deplete host T or other immune cells. In addition, we are developing next-generation allogeneic CAR T technologies such as our proprietary Dagger platform technology, which is incorporated into ALLO-316 and ALLO-329. Dagger is designed to eliminate activated host T cells that may otherwise mediate rejection of infused allogeneic CAR T cells and thereby reduce or potentially eliminate the need for standard lymphodepletion. This approach is novel and remains unproven. Dagger technology may not function as intended, may fail to meaningfully reduce or eliminate the need for lymphodepleting chemotherapy, or may not improve expansion, persistence or clinical outcomes of our product candidates. In addition, the mechanism of eliminating activated host immune cells may introduce additional safety risks, including unintended immune effects or toxicities, which could limit dosing, delay development or prevent successful clinical advancement of product candidates incorporating this technology. CAR T administration and/or the lymphodepletion that is required before administration of CAR T cells, may increase the risk of prolonged blood cell count suppression (cytopenia) or other adverse events including infections or inflammatory conditions such as cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), and/or immune effector cell-associated hemophagocytic lymphohistiocytosis-like syndrome (IEC-HS), which can be life-threatening and results in death. These events have been observed in our clinical trials and have resulted in pausing enrollment or requiring protocol amendments. For example, in our ongoing ALLO-316 TRAVERSE trial, we implemented risk mitigation measures for IEC-HS, which delayed and increased the cost of conducting the clinical trial. In our ALPHA3 trial, we are advancing cema-cel for the treatment of patients with LBCL who have completed standard first line therapy and have attained a remission, but who still test positive for minimal residual disease (MRD). On April 13, 2026, we announced results from the planned interim futility analysis of the first 24 randomized patients to the two ongoing arms in ALPHA3. Although we believe these interim MRD and safety results are encouraging, they are based on a limited number of patients and may not be predictive of future results or demonstrate that ALPHA3 will meet its primary endpoint. Likewise, although we believe this early experience supports the potential for cema-cel to be administered in a broader range of treatment settings than autologous CAR T therapies, these data remain limited and may not be predictive of future outpatient or community-based administration. As part of this trial, under Investigational Device Exemption (IDE), we are using an investigational assay developed by Foresight Diagnostics, known as the ClarityTM MRD assay, to determine if a patient is MRD positive. The ClarityTM MRD assay represents a novel approach to detecting the presence of minimal disease and the design of our trial is based on certain assumptions regarding the performance of the MRD assay, including assumptions regarding the anticipated MRD+ rate being consistent with published data. There is a risk that the assay may not function as intended and that the assay may not be sufficiently sensitive to detect the presence of low levels of MRD or sufficiently specific to avoid unacceptable rates of false positives. There is also a risk that the MRD+ rate observed in ALPHA3 may be lower than the previously reported rates as a result of the patient population screened, availability of sufficient patient test material, the performance of the test, and other factors that differ from previously reported rates. In addition, there are logistical risks with distributing diagnostic test kits to clinical trial sites, and collecting and sending patient samples to Foresight Diagnostics for testing, and there is a risk that the MRD assay will not be timely performed on the patient samples. Such logistical and timing risks are enhanced as we look to expand the ALPHA3 trial to clinical trial sites outside of the United States. If the MRD assay does not function as intended (e.g., false negatives/positives, or the MRD+ rate is lower than expected), or if the MRD assay is not timely performed on patient samples, it could negatively impact the rate of enrollment, the clinical results of, or the feasibility of the ALPHA3 trial, or negatively impact the market opportunity for cema-cel. In addition, we are reliant on Foresight Diagnostics to perform MRD testing. A delay or failure by Foresight Diagnostics to perform MRD testing may negatively impact our ability to conduct the ALPHA3 trial as planned, or prevent us from conducting the ALPHA3 trial. The clinical study requirements of the FDA, European Medicines Agency (EMA) and other comparable foreign regulatory authorities and the criteria these regulators use to determine the safety and efficacy of a product candidate are determined according to the type, complexity, novelty and intended use and market of the potential products. The regulatory approval process for novel product candidates such as ours can be more complex and consequently more expensive and take longer than for other, better known or extensively studied pharmaceutical or other product candidates. For example, the regulatory approval process for cema-cel based on our ALPHA3 trial is more complex because the regulatory agencies may require us to pair the approval of cema-cel with a companion diagnostic test. Approvals by the European Commission and FDA for existing autologous CAR T therapies, such as Kymriah and Yescarta, may not be indicative of what these regulators may require for approval of our therapies. Also, the use of healthy donor material in our allogeneic CAR T product candidates may create product variability challenges for us, and we do not yet fully understand the impact of donor variability on clinical outcomes. More generally, approvals by any regulatory agency may not be indicative of what any other regulatory agency may require for approval or what such regulatory agencies may require for approval in connection with new product candidates. Moreover, our product candidates may not perform successfully in clinical trials or may be associated with adverse events that distinguish them from the autologous CAR T therapies that have previously been approved. For instance, allogeneic product candidates may result in graft-versus-host disease (GvHD) or chromosomal abnormalities not experienced with autologous products. Additionally, any Phase 2 trial results, such as in the ALPHA3 trial, may not be representative of Phase 1 results, which were based on limited patients and a patient population in an advanced stage of LBCL, and such Phase 2 trial results may not be accepted by the FDA as pivotal and sufficient for cema-cel approval, requiring us to open additional trials to establish that cema-cel is safe and effective. Even if we collect promising initial clinical data of our product candidates, longer-term data may reveal new adverse events or responses that are not durable. Unexpected clinical outcomes would significantly impact our business.

Our business and future success depends on our ability to advance clinical development, obtain regulatory approval of, and then successfully commercialize, our lead product candidates. Because cema-cel, ALLO-316, and ALLO-715, products designed for use in patients with cancer, and ALLO-329, designed for use in patients with autoimmune disease, are or will be among the first allogeneic products to be evaluated in the clinic, the failure of any such product candidates, or the failure of other allogeneic CAR T cell therapies, including for reasons due to safety, efficacy or durability, may impede our ability to develop our product candidates, and significantly influence physicians' and regulators' opinions in regard to the viability of our entire pipeline of allogeneic CAR T cell therapies. For instance, all of our clinical trials were previously put on clinical hold due to an observation in the phase 1 portion of the ALPHA2 trial. While the clinical hold has been resolved, we could be subject to a clinical hold in the future due to unexpected observations, adverse patient outcomes or other issues. All of our product candidates, including our lead product candidates, will require additional clinical and non-clinical development, regulatory review and approval in multiple jurisdictions, substantial investment, access to sufficient commercial manufacturing capacity and significant marketing efforts before we can generate any revenue from product sales. In addition, because our other product candidates are based on similar technology as our lead product candidates, if any of the lead product candidates encounters additional safety issues, efficacy problems, manufacturing problems, developmental delays, regulatory issues or other problems, our development plans and business would be significantly harmed. We cannot predict the likelihood, nature or extent of government regulation that may arise from future legislation or administrative action, either in the U.S. or abroad. The policies of the FDA, the competent authorities of the European Union Member States (EU Member States), the EMA, the European Commission and other comparable regulatory authorities responsible for clinical trials may change and additional government regulations may be enacted. For instance, the regulatory landscape related to clinical trials in the European Union recently evolved. The European Union Clinical Trials Regulation (CTR), which was adopted in April 2014 and repeals the European Union Clinical Trials Directive, became applicable on January 31, 2022. The CTR allows sponsors to make a single submission to both the competent authority and an ethics committee in each EU Member State, leading to a single decision for each EU Member State. The assessment procedure for the authorization of clinical trials has been harmonized as well, including a joint assessment by all EU Member States concerned, and a separate assessment by each EU Member State with respect to specific requirements related to its own territory, including ethics rules. Each EU Member State's decision is communicated to the sponsor via the centralized European Union portal. Once the clinical trial is approved, clinical study development may proceed. The CTR foresees a three-year transition period. The extent to which ongoing and new clinical trials will be governed by the CTR varies. The CTR will apply to clinical trials from an earlier date if the related clinical trial application was made on the basis of the CTR or if the clinical trial has already transitioned to the CTR framework before January 31, 2025. Compliance with the CTR requirements by us and our third-party service providers, such as CROs, may impact our developments plans. As we work toward expanding ALPHA3 into additional jurisdictions, including the European Union, we may face additional regulatory, operational, site activation, privacy, data transfer, vendor coordination, import/export, pharmacovigilance and clinical-trial execution requirements. Any delays, additional data requests, country-specific requirements or other issues encountered in connection with these activities could delay site activation, patient screening or enrollment, and could increase costs or adversely affect the timing or conduct of ALPHA3.

Future undesirable or unacceptable side effects caused by our product candidates could cause us or regulatory authorities to interrupt, delay or halt clinical trials and could result in a more restrictive label or the delay or denial of regulatory approval by the FDA or other comparable foreign regulatory authorities. Results of our clinical trials could reveal a high and unacceptable severity and prevalence of side effects or unexpected characteristics. Approved autologous CAR T therapies and those under development have shown frequent rates of CRS, neurotoxicity including ICANS, serious infections, prolonged cytopenia and hypogammaglobulinemia, hemophagocytic lymphohistiocytosis/macrophage activation syndrome (HLH/MAS), immune effector cell-associated HLH-like syndrome (IEC-HS) and adverse events have resulted in the death of patients. We have observed certain of these adverse events for our allogeneic CAR T product candidates. Other adverse events could also emerge in autologous CAR T therapies over time. For instance, patients who received an autologous anti-BCMA CAR T cell therapy have experienced neurocognitive and hypokinetic movement disorder with features of Parkinson's disease that emerged months after treatment and may have been due to BCMA expression within the brain. Our anti-BCMA product candidates have the risk of causing similar adverse events. In January 2024 the FDA sent letters to all companies with approved autologous CAR T therapies requesting them to add a black box warning on the label of their autologous CAR T therapies. The FDA is requiring label updates to include a black box warning that T-cell malignancies may occur following treatment with BCMA- and CD19-directed genetically modified autologous T-cell immunotherapies. The required warnings are specific to autologous therapies. Such T-cell malignancies have been observed in approximately 1 patient for every 1,000 patients treated with autologous therapies. Because our allogeneic therapies are based on similar technology, until we have treated more patients, there is a risk that we may find similar T-cell malignancies following treatment with our allogeneic CAR T product candidates. If such malignancies are observed, regulatory authorities, such as the FDA, may require a similar black box warning or other safety-related labeling statements on our products' label, if approved, which could prevent us from achieving or maintaining market acceptance and adversely affect our business, financial condition, results of operations and prospects. Our allogeneic CAR T cell product candidates may also cause unique adverse events related to the differences between the donor and patients, such as GvHD or infusion reactions. In addition, we utilize a lymphodepletion regimen that caused serious adverse events. For instance, because some regimens are expected to cause a deep and sometimes prolonged immune suppression, patients will have an increased risk of infection that may be unable to be cleared by the patient and ultimately lead to other serious adverse events or death. For example, a patient death occurred in the FCA arm (fludarabine, cyclophosphamide, and ALLO-647) of our ALPHA3 trial. This Grade 5 SAE, which occurred on Day 54 post-infusion, involved fulminant hepatic failure caused by disseminated adenovirus infection, potentially worsened by acetaminophen toxicity. The depth of immunosuppression, which has been attributed in part to the use of ALLO-647, is believed to have increased susceptibility to this viral infection. Although the FCA arm of our ALPHA3 trial and all uses of ALLO-647 have been discontinued, our lymphodepletion regimen has caused such adverse events and may also cause prolonged cytopenia and aplastic anemia. We have previously explored and may in the future explore various dosing strategies for lymphodepletion in our clinical trials, such as including varying doses of the chemotherapy agents and/or other components, or eliminating one or more of the agents, which may alter the risk of SAEs or have other undesirable outcomes such as a reduction of the efficacy of treatment. In our and Servier's clinical trials of allogeneic CAR T product candidates, the most common severe or life-threatening adverse events resulted from CRS, serious infections, febrile neutropenia, prolonged cytopenia including prolonged pancytopenia, haemophagocytic lymphohistiocytosis, hypokalemia, multiple organ dysfunction syndrome, neutropenic sepsis and aplastic anemia. As reported, patients have died from adverse events and future patients may also experience toxicity resulting in death. For additional safety data, please see the section entitled "Business-Product Pipeline and Development Strategy" included in our Annual Report. As we treat and re-treat more patients with our product candidates in our clinical trials, new less common side effects may also emerge or increased incidence of previously observed side effects may occur. There is a risk that the FDA or other comparable foreign regulatory authorities may not agree that sufficient mitigating procedures are included in our protocols to address such side effects, and FDA or other comparable foreign regulatory authorities may impose a clinical hold as it evaluates risks associated with such side effects and/or as we work with the agency to implement protocol amendments to appropriately manage such side effects. For instance, we observed a chromosomal abnormality that led to a previous clinical hold on our clinical trials. While our investigation concluded that the chromosomal abnormality had no clinical significance and was unrelated to our manufacturing process, our manufacturing processes include gene engineering by using viral vectors and genomic nucleases that may in the future cause insertion, deletion, or chromosomal translocation that may result in allogeneic CAR T cells to proliferate uncontrollably and adverse events. We may also combine the use of our product candidates with other investigational or approved therapies that may cause separate adverse events or events related to the combination. If unacceptable toxicities arise in the development of our product candidates, we could suspend or terminate a development program, a trial or certain arms of a trial, or the FDA or comparable foreign regulatory authorities could order us to cease clinical trials or deny approval of our product candidates for any or all targeted indications. For example, as a result of the Grade 5 SAE in the ALPHA3 trial described above, we have terminated the FCA arm of the ALPHA3 trial, and the trial is now moving forward as a two arm trial under which patients will be randomized equally (1:1) into either the FC lymphodepletion arm or standard-of-care observation. Additionally, we have terminated all further development of ALLO-647. Any data safety monitoring board may also suspend or terminate a clinical trial at any time on various grounds, including a finding that the research patients are being exposed to an unacceptable health risk, including risks inferred from other unrelated immunotherapy trials. Treatment-related side effects could also affect patient recruitment or the ability of enrolled subjects to complete the trial or result in potential product liability claims. In addition, these side effects may not be appropriately recognized or managed by the treating medical staff, as toxicities resulting from T cell therapy are not normally encountered in the general patient population and by medical personnel. We have trained and expect to have to train medical personnel using CAR T cell product candidates to understand the side effect profile of our product candidates for both our clinical trials and upon any commercialization of any of our product candidates. Inadequate training in recognizing or managing the potential side effects of our product candidates could result in patient deaths. Any of these occurrences may harm our business, financial condition and prospects significantly.

Before obtaining regulatory approvals for the commercial sale of our product candidates, we must demonstrate through lengthy, complex and expensive preclinical testing and clinical trials that our product candidates are both safe and effective for use in each target indication. Clinical testing is expensive and can take many years to complete, and its outcome is inherently uncertain. Failure can occur at any time during the clinical trial process. The results of preclinical studies and early clinical trials of our product candidates may not be predictive of the results of later-stage clinical trials, including in any post-approval studies. There is typically an extremely high rate of attrition from the failure of product candidates proceeding through clinical trials. Product candidates in later stages of clinical trials may fail to show the desired safety and efficacy profile despite having progressed through preclinical studies and initial clinical trials. A number of companies in the biopharmaceutical industry have suffered significant setbacks in advanced clinical trials due to lack of efficacy, insufficient durability of efficacy or unacceptable safety issues, notwithstanding promising results in earlier trials. Most product candidates that commence clinical trials are never approved as products. In addition, for any trials that may be completed, we cannot guarantee that the FDA or comparable foreign regulatory authorities will interpret the results as we do, and more trials could be required before we submit our product candidates for approval. For example, the FDA may determine that results from our Phase 2 ALPHA3 trial are not sufficient to establish that cema-cel is safe and effective, and the FDA may require additional trials. Additionally, although the EMA has previously granted Marketing Authorizations for products even when their clinical development programs did not involve any European sites, the regulatory landscape for CAR T products continues to evolve, and the EMA may require us to conduct clinical trials in the EU in order to obtain approval. To the extent that the results of the trials are not satisfactory to the FDA or comparable foreign regulatory authorities for support of a marketing application, approval of our product candidates may be significantly delayed, or we may be required to expend significant additional resources, which may not be available to us, to conduct additional trials in support of potential approval of our product candidates.

To date, no CAR T therapy has been approved for use as part of a first-line consolidation treatment for patients with LBCL, and the regulatory and commercial landscape remains uncertain. Because there is no precedent for regulatory approval of a CAR T therapy in this treatment paradigm, we may face unexpected challenges in generating sufficient clinical data to support an approval, and regulatory authorities may impose additional requirements or take longer than anticipated to evaluate our data. Additionally, the standard of care for first-line treatment in LBCL is well-established, and physicians and patients may be reluctant to adopt CAR T therapy in this setting due to concerns over safety, efficacy, cost, or logistical challenges associated with administration. If our product candidate does not demonstrate compelling clinical benefit over existing treatments or fails to gain market acceptance, we may not achieve the commercial success necessary to sustain our business. Furthermore, payors and reimbursement authorities may be unwilling to provide coverage for CAR T therapy as a first-line consolidation treatment, particularly if they perceive it as too costly compared to existing alternatives. Even if we obtain regulatory approval, lack of adequate reimbursement could limit patient access and materially impact our ability to generate revenue. The success of our clinical trial and potential approval in this setting is also dependent on factors outside of our control, such as evolving treatment paradigms, competitive developments, and changes in clinical practice. If we are unable to successfully develop, obtain approval for, and commercialize our CAR T therapy in this novel setting, our business, financial condition, and results of operations could be adversely affected.

Data from clinical trials that we may complete are subject to the risk that one or more of the clinical outcomes may materially change as patient enrollment continues and more patient data becomes available. Phase 1 results are preliminary in nature and should not be viewed as predictive of ultimate success. It is possible that such results will not continue or may not be repeated in any clinical trial of our product candidates. For instance, our Phase 2 ALPHA3 trial design is based in part on Phase 1 data from a limited number of patients treated with various doses of ALLO-501 or cema-cel manufactured using the Alloy process. Results from the larger Phase 2 ALPHA3 trial, which we anticipate will only include cema-cel manufactured internally at CF1, but may ultimately also include cema-cel manufactured at a contract manufacturer, may not be consistent with the Phase 1 results. Furthermore, because ALPHA3 will include a different patient population versus our Phase 1 ALPHA2 trial, i.e., patients having MRD after front-line treatment versus patients with radiographically measurable disease after a minimum of two prior lines of treatment, it is possible that cema-cel may behave differently in terms of expansion, persistence and the ability to eradicate residual disease. In addition, our experience with our CD19 and BCMA programs indicates that manufacturing can impact clinical outcomes. The manufacturing runs we have completed and tested in the clinic are limited across our product candidates and any manufacturing variability that impacts clinical outcomes would significantly harm our business and prospects. We may also fail to develop any optimized manufacturing processes for any of our programs. Ultimately, if we cannot manufacture our product candidates with consistent and reproducible product characteristics, our ability to develop and commercialize any product candidate would be significantly impacted. Phase 1 trials of novel products also commonly include a dose exploration phase during which adverse effects of treatment may emerge at higher doses that are new, unexpected, or occur at higher-than-expected frequencies or severity and may limit our ability to develop such products in one or more target indications or patient populations. Similarly, in dose expansion phase, we may discover that adverse effects, either known or novel, may negatively impact the emerging overall benefit-risk profile of our product candidates and may lead to the discontinuation or other significant alteration to the development plan. Preliminary data also remain subject to audit and verification procedures that may result in the final data being materially different from the preliminary data we previously published. As a result, initial, interim and preliminary data should be viewed with caution until the final data are available. Adverse differences between preliminary or interim data and final data could significantly harm our business prospects. We have reported initial observations from early dose levels in our Phase 1 RESOLUTION trial of ALLO-329, including observations regarding clinical activity and tolerability. These observations are preliminary, are based on a small number of patients across different autoimmune indications, dose levels and lymphodepletion approaches, and may not be predictive of future results. As dose escalation continues and additional patients are treated and followed, we may observe different or less favorable safety, tolerability, biomarker or clinical activity results, and we may not identify a dose or lymphodepletion regimen that supports further development. Any unfavorable or inconclusive data from RESOLUTION could delay or prevent further development of ALLO-329 and materially adversely affect our business.

We plan to submit investigational new drug (IND) applications or IND amendments and equivalent foreign applications for current and potentially new product candidates or indications in the future. We cannot be sure that submission of an IND or IND amendment or an equivalent foreign application will result in the FDA or other comparable foreign regulatory authorities allowing testing and clinical trials to begin on our anticipated timelines, if at all, or that, once begun, issues will not arise that suspend or terminate such clinical trials. The manufacturing of allogeneic CAR T cell therapy remains an emerging and evolving field. Accordingly, we expect Chemistry, Manufacturing and Controls (CMC) related topics,including product specification, will be a focus of IND reviews, which may delay the clearance of INDs or IND amendments, and we may face internal or third-party resource constraints in preparing responses and supporting CMC-related submissions. For instance, if we introduce changes to the manufacturing of our product candidates, regulatory authorities may require additional studies or clinical data to support the changes, which could delay our clinical trial timelines. Additionally, even if such regulatory authorities agree with the design and implementation of the clinical trials set forth in an IND, IND amendment or clinical trial application, we cannot guarantee that such regulatory authorities will not change their requirements in the future.

Clinical testing is expensive, time consuming and subject to uncertainty. We cannot guarantee that any clinical studies will be conducted as planned or completed on schedule, if at all. Even if our trials begin as planned, issues may arise that could suspend or terminate such clinical trials or a portion thereof. A failure of one or more clinical studies can occur at any stage of testing, and our future clinical studies may not be successful. Events that may prevent successful or timely completion of clinical development include: - inability to generate sufficient preclinical, toxicology or other in vivo or in vitro data to support the initiation of clinical studies;- delays in sufficiently developing, characterizing, controlling or optimizing a manufacturing process suitable for clinical trials, including the validation and deployment of release assays;- difficulty sourcing healthy donor material of sufficient quality and in sufficient quantity to meet our development needs;- delays in developing, obtaining regulatory approval for, or implementing suitable assays for screening patients for eligibility for trials with respect to certain product candidates;- the number of patients who consent to be screened for the ALPHA3 trial may be lower than we expect given the current well-established medical practice of frontline therapy for LBCL and the history of slow patient recruitment in other frontline LBCL trials;- the screen failure rate for clinical trials of our product candidates may be higher than we anticipate, requiring us to screen larger numbers of patients than originally planned. For example, the number of patients who have MRD at the end of front-line treatment in ALPHA3 may be lower than we expect requiring more patients to be screened;- delays in reaching a consensus with regulatory agencies on study design;- delays in reaching agreement on acceptable terms with prospective CROs and clinical study sites, the terms of which can be subject to extensive negotiation and may vary significantly among different CROs and clinical study sites;- delays in obtaining required IRB approval or approval of other ancillary regulatory committees at each clinical study site;- imposition of a temporary or permanent clinical hold by regulatory agencies for a number of reasons, including after review of an IND application or amendment, or equivalent application or amendment; as a result of a new safety finding that presents uncertain or unreasonable risk to clinical trial participants; a negative finding from an inspection of our or our collaborator's clinical study operations or our study sites; developments on trials conducted by competitors for related technology that raises FDA or other comparable foreign regulatory authority concerns about risk to patients of the technology broadly; or if the FDA or other comparable foreign regulatory authorities find that the investigational protocol or plan is clearly deficient to meet its stated objectives;- delays in recruiting suitable patients to participate in our clinical studies;- delays in activating clinical trial sites;- delays in obtaining the necessary regulatory approvals to expand clinical trials to countries outside the United States, including approvals relating to any required companion diagnostic;- difficulty collaborating with patient groups and investigators;- failure by our CROs, other third parties or us to adhere to clinical study requirements;- failure to perform in accordance with the FDA's good clinical practices (GCP) requirements or equivalent regulatory guidelines in other countries;- delays or failures in the transfer of manufacturing processes to any CDMO or our own manufacturing facility or any other development or commercialization partner for the manufacture of product candidates;- delays in having patients complete participation in a study or return for post-treatment follow-up;- patients dropping out of a study;- occurrence of adverse events associated with the product candidate that are viewed to outweigh its potential benefits;- changes in regulatory requirements and guidance that require amending or submitting new clinical protocols;- changes in the standard of care on which a clinical development plan was based, which may require new or additional trials;- the cost of clinical studies of our product candidates being greater than we anticipate;- clinical studies of our product candidates producing negative or inconclusive results, which may result in our deciding, or regulators requiring us, to conduct additional clinical studies or abandon product development programs;- delays or failure to secure supply agreements with suitable raw material suppliers, or any failures by suppliers to meet our quantity or quality requirements for necessary raw materials;- shortage, interruption, or failure to secure commercially available and/or investigational drug products that are required to conduct clinical trials with our allogeneic CAR T product candidates; and - delays in manufacturing, testing, releasing, validating, or importing/exporting sufficient stable quantities of our product candidates for use in clinical studies or the inability to do any of the foregoing. Tariffs and other trade restrictions, as well as a pandemic or epidemic may also increase the risk of certain of the events described above and delay our development timelines. Any inability to successfully complete preclinical and clinical development could result in additional costs to us or impair our ability to generate revenue. In addition, if we make manufacturing or formulation changes to our product candidates, we will be required to meet certain regulatory conditions, such as establishing comparability with the product candidates manufactured prior to such changes, and our inability to meet such conditions would result in investment of additional resources, a delay in our manufacturing of such product candidate and an extension of our clinical trial timelines. Clinical study delays could also shorten any periods during which our products have patent protection and may allow our competitors to bring products to market before we do, which could impair our ability to successfully commercialize our product candidates and may harm our business and results of operations. Our clinical trials may also be delayed because of the availability of drugs required to be used under our protocols. For example, in some of our clinical trials, the study participants receive commercially available drugs for lymphodepletion before our allogeneic CAR T product candidates are administered, and receive other drugs to prevent infections and manage the treatment emergent adverse events. Shortage or lack of availability of these commercially available drugs that are necessary to conduct our clinical trials may cause delays in our clinical trials.