23andMe presents preliminary Phase 2 safety, efficacy data from Phase 1/2a trial

23andMe announced positive preliminary Phase 2 safety and efficacy data from its Phase 1/2a clinical trial covering two new patient cohorts from 23ME-00610, a first-in-class anti-CD200R1 antibody, at the European Society of Medical Oncology Congress 2024 in Barcelona, September 13-17. 23andMe Therapeutics presented posters summarizing results for 10 patients with clear-cell renal-cell carcinoma and for 13 patients with tumor mutational burden-high or microsatellite instability-high cancers. A third poster summarized data from 118 participants across the Phase 1/2a trial to evaluate high tumor expression of CD200 as a potential predictive biomarker of clinical benefit. These presentations supplement data for cohorts with neuroendocrine and ovarian cancer presented earlier this year at the 2024 American Society of Clinical Oncology Meeting. 23ME-00610 is a first-in-class IgG1 antibody designed to reverse immunosuppression by inhibiting binding of CD200R1 on immune cells with CD200 on tumor cells. In preclinical studies, this mechanism leads to restoration of T cell activity and killing of CD200-expressing tumor cells. The CD200R1 axis was recognized as a potentially significant checkpoint inhibition pathway through the identification of pleiotropic causal variants with opposing effect on risk for cancer and immune diseases, referred to by 23andMe Therapeutics as an immuno-oncology signature. Confirmed partial response in a patient with refractory ccRCC. 23ME-00610 monotherapy continues to demonstrate acceptable safety and tolerability, and achieves the prespecified targets for maximal pharmacology at 1400 mg dosed every three weeks. Higher tumor expression of CD200 may be associated with clinical benefit in some patient groups treated with 23ME-00610, warranting further exploration of this biomarker. In addition to CD200 expression, histology data suggest that immunosuppressed tumors may be more likely to exhibit disease control with 23ME-00610. Biopsied patients that had tumor shrinkage or prolonged stable disease with 23ME-00610 treatment tended to be less inflamed at baseline and have lower levels of immunosuppressive macrophages. Emerging data demonstrate the potential interaction of a tumor biomarker with host genetics, leveraging 23andMe developed polygenic risk scores.