Sonnet announces results of biodistribution studies using FHAB technology

Sonnet BioTherapeutics Holdings announced data from two radiolabeling studies that validate the tumor targeting attributes associated with albumin binding by the FHAB technology. Sonnet performed two independent in vivo proof-of-concept studies to show the biodistribution of interleukin-FHAB molecules to the tumor microenvironment, using labs with expertise in radiolabeling biologics and in vivo biodistribution analysis. The labs employed different radiolabeling methodologies for mIL-12 and mIL12-FHAB, either with or without a polyhistidine tag. The two studies were completed using the B16F10 mouse melanoma model for measuring the accumulation of radiolabeled product and tumor volume inhibition over various time points. The key findings from both studies indicated that mIL12-FHAB had significantly higher tumor accumulation, 2.5-4.7 times higher on average at the longer time points, and increased retention when compared to mIL-12. Accumulation was demonstrated in tumors compared to normal mice, and was transient in liver, kidney, and other organs, as expected. Importantly, radiolabeled mIL12-FHAB also demonstrated measurable accumulation in the draining lymph nodes. Overall, these findings have important implications for therapeutic applications of any mono-or bi-functional molecules demonstrating enhanced tumor targeting and accumulation, as well as the potential for improved efficacy that could lead to a variety of drug candidates. Sonnet previously compared three constructs, the FHAB, an anti-TGF-beta scFv, and an anti-TGF-beta-FHAB fusion protein, to evaluate the generic potential for in vivo accumulation and retention in tumors by FHAB-albumin complexes using a 4T1 tumor-bearing mouse model, which has tumors that over-express TGF-beta. Accumulation and retention profiles were characterized over a 24-hour period by Western blot analysis of tumor extracts taken at 30 minutes, then at 4-, 12-, and 24-hours after dosing of each construct. The comparative data showed that the FHAB domain exhibited superior accumulation and retention in the tumor at all time points. In contrast, the anti-TGF-beta molecule, which lacked the FHAB domain, exhibited a rapid decline in abundance at 4 hours and was not detectable at 12 or 24 hours, thus exhibiting poor accumulation and retention in the tumor. By comparison, fusion of the FHAB domain to anti-TGF-beta, which created the anti-TGF-beta-FHAB fusion protein, restored the accumulation and retention profile in the tumor extracts tested at all time points, thus proving that the FHAB-albumin complex is driving anti-TGF-beta into the tumor, while the anti-TGF-beta molecule without FHAB did not. In summary, these early findings highlighted the importance of the FHAB domain’s binding to albumin, which in turn facilitated the targeted delivery and retention of various fusion constructs within the tumor tissue, making FHAB a promising technology for the innovation of biologic therapeutics.