On May 21, 2026 Compass Therapeutics, Inc. (Nasdaq: CMPX), a clinical-stage, oncology-focused biopharmaceutical company developing proprietary antibody-based therapeutics to treat multiple human diseases, reported a poster presentation of data from the Phase 1 study of CTX-8371, a novel PD-1×PD-L1 bispecific antibody, in patients with advanced malignancies treated in the post-checkpoint inhibitor setting will be presented at the 2026 American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting, taking place May 29 – June 2, 2026, in Chicago, IL.
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"We are pleased to share the initial clinical data from the dose escalation portion of our ongoing Phase 1 study of CTX-8371 in patients with advanced malignancies treated in the post-checkpoint inhibitor setting at ASCO (Free ASCO Whitepaper)," said Thomas Schuetz, MD, PhD, CEO of Compass and Vice Chairman of the Board of Directors. "Based on the deep, confirmed, and durable responses observed in patients with NSCLC, TNBC and HL, as well as the favorable safety profile, we have initiated cohort expansions in patients with these three malignancies and anticipate reporting additional data in the fourth quarter of 2026."
Details of the presentation are as follows:
Title: Phase 1 Dose Escalation of CTX-8371, a novel PD-1×PD-L1 bispecific antibody, in patients with advanced malignancies post checkpoint inhibition
Presenter: Judy S Wang, MD; Florida Cancer Specialists/Sarah Cannon Research Institute- Sarasota, Sarasota, FL
Date & Time: May 30, 2026 at 1:30-4:30 pm CT
Session: Developmental Therapeutics—Immunotherapy
Abstract number: 2629
Poster Board: 419
Location: McCormick Place Convention Center, Hall A
Data highlights from the poster presentation include:
15 patients completed the dose-limiting toxicity (DLT) evaluation period and had at least one post-baseline disease assessment in the dose escalation cohort of the Phase 1, open-label, first-in-human study evaluating CTX-8371 in patients with metastatic or locally advanced malignancies.
There were three responses: one patient with TNBC achieved > 90% reduction in target tumor lesions, one patient with HL achieved a partial metabolic response, and one patient with NSCLC achieved complete resolution of target lesions after initial pseudo-progression.
At the two highest dose levels (3.0 and 10.0 mg/kg), the overall response rate (ORR) was 33% (2 of 6 evaluable patients). The responses at the two highest dose levels were significantly durable: 10.5+ months for TNBC and 7.5+ months HL. Both of these patients remain on study with continuing durability.
CTX-8371 was well tolerated with no DLTs. All treatment-related adverse events (AEs) were mild Grade 1 or Grade 2, with the exception of one asymptomatic Grade 3 lipase increase.
A copy of the presentation materials can be accessed on the Compass website at View Source once the presentation has concluded.
(Press release, Compass Therapeutics, MAY 21, 2026, View Source [SID1234665988])