23andMe Holding Co. announced the further expansion of the ongoing 23ME-00610 Phase 1/2a study to include an additional 30 patients with advanced neuroendocrine and ovarian cancers, above the original enrollment goals. The ongoing study has been enrolling the Phase 2a portion of the Phase 1/2a clinical trial evaluating the anti-CD200R1 monoclonal antibody since February 2023.

As previously presented at a scientific conference in November 2023, 23ME-00610 has an appropriate safety profile in the highest doses tested, and met pharmacodynamic biomarker and pharmacokinetic objectives, while not reaching a maximum tolerated dose in the Phase 1 study. The Phase 2a portion of the study is being conducted with the highest tested dose from the Phase 1, 1400 mg intravenously every 3 weeks. In order to characterize potential optimal dosing of 23ME-00610, and aligned with recent regulatory guidelines, 23andMe is utilizing this clinical trial to further characterize safety and efficacy of a second potentially efficacious dose of 600 mg intravenously every 3 weeks in these additional patients.

23ME-00610 is a high-affinity, fully humanized monoclonal antibody that is designed to bind to CD200R1 and prevent the interaction of CD200R1 with CD200. Preclinical data indicate that this mechanism has the potential to restore the ability for both T-cells and myeloid cells to kill cancer cells. The Phase 1/2a study is an open-label study to evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics, and clinical activity of 23ME-00610 monotherapy in patients with advanced solid malignancies who have progressed on all available standard therapies.

Clinical trials registry (clinicaltrials.gov): NCT05199272.