BioAtla, Inc. announced expanded data at an upcoming presentation entitled, ?Phase 1 study of evalstotug (BA3071), an anti-CTLA-4 Conditionally Active Biologic, in combination with nivolumab in advanced solid tumors?, demonstrating confirmed responses with a potentially differentiated tolerability profile with the Company?s novel, conditionally active anti-CTLA-4 agent, evalstotug, in combination with anti-PD-1 therapy. The poster will be presented at the upcoming 2024 American Society of Clinical Oncology (ASCO) Annual Meeting at the McCormick Place Convention Center in Chicago, Illinois on Saturday, June 1, 2024. A Phase 1 dose-escalation study evaluated evalstotug (7 mg ?

1 g Q3W) in combination with nivolumab (240 mg), conducted in 21 patients: Data cut of March 29, 2024 unless otherwise specified. Patients received a median of 3 prior lines of systemic therapy. All patients had experienced failure of anti?PD-1 therapy.

Patients treated with 350 mg evalstotug received more doses (mean, 7.2) compared with reported ipilimumab or tremelimumab dosing; no dose reductions occurred. Three patients have tolerated their first 1-gram evalstotug infusion; clearing the DLT observation period is anticipated by early June. Population PK modeling suggests that 1 g flat dose will enable over 98% of patients to maintain Cmin levels greater than EC50 throughout treatment potentially driving clinical benefit.

Evalstotug was generally well-tolerated with relatively low incidence and severity of immune-mediated AEs: Four patients experienced Grade 3 related treatment-emergent AEs, No Grade 4 or 5 related TEAEs were observed, No Grade 4 or 5 related TEAEs were observed, Only two treatment related discontinuations. Evalstotug demonstrated clinical benefit in heavily pre-treated patients (data cut as of April 30, 2024): Responses in three of eight patients who received evalstotug 350mg. One confirmed complete response in cervical carcinoma, One confirmed partial response in gastroesophageal carcinoma and One unconfirmed partial response in cutaneous melanoma patient who was dose escalated and who remains on therapy.

Disease control rate of 52%: Three patients (two with cutaneous melanoma, one with metastatic small cell lung cancer) remained without progression for greater than 1 year (69 weeks) and One uveal melanoma patient without progression for 9.8 months. Evalstotug, is a CAB anti-CTLA-4 antibody that is being developed as an immuno-oncology agent with the goal of delivering efficacy at least comparable to the approved anti-CTLA-4 antibodies, but with lower toxicities due to the CAB's tumor microenvironment-restricted activity. This may enable safer anti-CTLA-4 antibody combination therapies, such as with anti-PD-1 antibody checkpoint inhibitors, and potentially broaden the patient population tolerant to combination therapy and deliver greater efficacy.

Like the company?s other CAB candidates, this Phase 2 clinical asset is designed to be conditionally and reversibly active in the tumor microenvironment. Evalstotug is being developed as a potential therapeutic for several solid tumor indications that are known to be responsive to CTLA-4 treatment in combination with a PD-1 blocking agent.