Compass Therapeutics to Present Phase 1 Data for CTX-471, Showing Anti-Tumor Activity in Resistant Patients, at ASCO 2024

Compass Therapeutics, Inc. has announced promising results from their Phase 1 clinical trial investigating CTX-471, a novel anti-CD137 agonist antibody, in patients with metastatic or locally advanced malignancies who had progressed on PD-1 or PD-L1 inhibitors. The study, which was presented at a recent conference, evaluated the efficacy and safety of CTX-471 as a monotherapy.

CTX-471 targets the co-stimulatory receptor CD137 and has shown considerable promise in combating tumors. The trial consisted of two parts: a Dose Escalation phase, where doses ranged from 0.1–1.2 mg/kg biweekly, and a Dose Expansion phase, focusing on 0.3 and 0.6 mg/kg doses. The primary goal was to assess the safety and tolerability of CTX-471, while secondary goals included pharmacokinetics, immunogenicity, and clinical activity.

The trial's results were promising, particularly for patients who had limited options after failing previous treatments. Five clinical responses were reported among patients who had previously received checkpoint inhibitors. Notably, a patient with small-cell lung cancer (SCLC) achieved a durable partial response (PR) for three years before converting to a complete response (CR), as confirmed by a PET scan. Additionally, partial responses were observed in three out of eleven patients with melanoma and one out of four patients with mesothelioma.

Safety data indicated that CTX-471 was generally well tolerated. The most significant dose-limiting toxicity was thrombocytopenia, which was observed in two cases but resolved to normal levels. Liver toxicity was rare, with an incidence of only 6.3%, and most adverse events were low-grade (Grades 1 or 2).

Dr. Thomas Schuetz, Co-founder and President of R&D at Compass, expressed excitement over the trial's findings. He highlighted the differentiated safety profile of CTX-471 compared to other CD137-targeted agents and underscored the importance of the clinical responses observed in patients with refractory cancers.

The poster presentation included data from 19 patients in the dose escalation phase and 60 in the expansion phase. Among the patients with SCLC, one achieved a complete response confirmed by PET scan. Moreover, four additional partial responses were observed in patients with melanoma and mesothelioma.

CTX-471's potential to treat advanced malignancies with limited treatment options was emphasized. The data suggested that the antibody could serve as an effective treatment for patients who have exhausted other options.

CTX-471 is a fully human monoclonal antibody that activates a novel epitope of CD137, a receptor involved in immune response regulation. The antibody is currently in Phase 1b clinical trials, targeting solid tumors that have progressed despite prior treatment with PD-1 or PD-L1 inhibitors. Preliminary results have shown partial responses in melanoma, SCLC, and mesothelioma, with the antibody being generally well tolerated.

Compass Therapeutics, headquartered in Boston, Massachusetts, focuses on developing antibody-based therapeutics for oncology. The company's research explores the intersection of angiogenesis, the immune system, and tumor growth. Their pipeline includes candidates designed to target multiple biological pathways essential for an effective anti-tumor response. Compass aims to advance these candidates through clinical development, both as standalone therapies and in combination with other treatments.

Overall, the CTX-471 trial has provided promising data, suggesting that this novel antibody could become a valuable tool in the fight against advanced cancers. Further research and clinical trials will be necessary to confirm these findings and potentially bring this treatment to market.