Akari Therapeutics announces abstract on PH1 mechanism-of-action data

Akari Therapeutics (AKTX) announced its abstract highlighting immune mechanism-of-action data for its novel ADC payload, PH1. The abstract is now available on the 40th Annual SITC Meeting website, and the Company will present the abstract in oral and poster presentations at the SITC Annual Meeting being held November 5-9, 2025 in National Harbor, MD. Utilizing its innovative ADC payload platform, Akari is advancing a new class of immuno-oncology ADCs built on the platform of a novel PH1 payload, a spliceosome modulator that has a unique preclinical efficacy and safety profile with the potential to address unmet need for oncology patients singly or in combination with checkpoint inhibitors. In this work, Akari investigates the mechanism behind preclinical colon tumor regressions induced by a Trastuzumab PH1 ADC with/without anti-PD-1 and contrasts that against a first-in-class ADC with a microtubule inhibitor payload. A higher rate of complete regressions in the PH1 ADC combination vs comparator ADC combination is attributed to an immune response stimulated by neoantigen, activation of antigen-presenting cells, B, and T-cells, and a mechanistic synergy between the PH1 payload and the checkpoint inhibitor. Interestingly, while neither single agent induced gamma-delta T cells, a kind of T-cell that is not limited by low neoantigen expression in tumors or low numbers of antigen-presenting cells, the PH1 ADC together with anti-PD-1 agent expanded this tumor-killing T-cell population.