PharmAbcine's PMC-309 Gets Safety Nod in Initial Phase 1a/b Trial for Advanced Solid Tumors

PharmAbcine Inc., a clinical-stage biotechnology company specializing in next-generation antibody therapeutics, has announced a significant milestone for its PMC-309 program. The company's VISTA-targeting immuno-oncology drug, PMC-309, has received safety approval for its first dose cohort (0.2mg/kg) during its ongoing Phase 1a/b clinical trial in Australia. The trial targets patients with advanced or metastatic solid tumors. Moreover, the second dose cohort (0.5mg/kg) is currently in progress.

The first dose of PMC-309 was administered in January 2024, receiving safety clearance by April 2024. The second dose, administered at 0.5mg/kg, has already been given to two patients, with a third patient scheduled for treatment soon. PMC-309 is an IgG1 monoclonal antibody designed to bind specifically to VISTA on immunosuppressive cells. Its efficacy is highlighted by its strong binding affinity at various pH levels within the tumor microenvironment (TME). By inhibiting VISTA, PMC-309 activates T cells, monocytes, and promotes the proliferation of M1 macrophages, contributing to its anti-cancer effects.

The open-label Phase 1a/b clinical trial includes a total of 67 patients and is divided into two phases: Phase 1a and Phase 1b. Phase 1a involves both monotherapy with PMC-309 and combination therapy with KEYTRUDA® (pembrolizumab), aiming to determine the maximum tolerated dose (MTD) and the recommended Phase 2 dose (RP2D). Phase 1b will then assess the safety and tolerability of PMC-309, both as a monotherapy and in combination with KEYTRUDA®, at the RP2D. This trial is being carried out across four institutions in Australia.

Dr. Jin-San Yoo, CEO of PharmAbcine Australia Pty, emphasized the importance of next-generation immuno-oncology drugs. He noted that while first-generation immuno-oncology drugs have benefitted many patients over the past decade, some have developed resistance or have succumbed to the disease. Dr. Yoo expressed optimism about the gradual verification of PMC-309’s safety and efficacy through higher dose cohorts. The company is also preparing for the combination trial of PMC-309 with KEYTRUDA® in partnership with MSD.

PMC-309 represents a novel approach as it is an anti-VISTA-antagonizing IgG in pan pH conditions, targeting MDSC (myeloid-derived suppressor cells) and M2 macrophages that play crucial roles in maintaining an immunosuppressive TME. The Phase 1a part of the trial is already underway in multiple centers in Australia, and a Phase 1b trial combining PMC-309 with pembrolizumab is planned.

PharmAbcine's pipeline also includes other promising assets. Olinvacimab, the company's leading asset, is in a Phase 2 trial in combination with MSD's pembrolizumab for mTNBC patients in Australia. This follows encouraging results from a Phase 1b trial. Another notable asset is PMC-403, a TIE2-activating antibody aimed at stabilizing pathological blood vessels, currently in a Phase 1 trial for neovascular AMD patients in Korea.

PharmAbcine continues to develop innovative treatments to address cancer and other vascular-related unmet medical needs. The company is committed to providing new therapeutic options for patients, particularly those who have not benefitted from first-generation immuno-oncology drugs.