Compass Therapeutics to Present Promising Phase 1 Clinical Data for CTX-8371 in Patients with Advanced Malignancies Treated in the Post-Checkpoint Inhibitor Setting at the 2026 ASCO Annual Meeting
Rhea-AI Summary
Compass Therapeutics (Nasdaq:CMPX) will present Phase 1 data for CTX-8371, a dual PD-1×PD-L1 bispecific antibody, in advanced malignancies post-checkpoint inhibition at the 2026 ASCO Annual Meeting.
Among 15 evaluable patients, three responses were reported, with a 33% ORR at higher doses and no dose-limiting toxicities.
AI-generated analysis. How Rhea-AI works. Not financial advice.
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News Market Reaction – CMPX
On the day this news was published, CMPX gained 7.25%, reflecting a notable positive market reaction. Argus tracked a peak move of +9.1% during that session. Our momentum scanner triggered 25 alerts that day, indicating elevated trading interest and price volatility. This price movement added approximately $26M to the company's valuation, bringing the market cap to $387.19M at that time.
Data tracked by StockTitan Argus on the day of publication.
Key Figures
Previous Clinical trial Reports
| Date | Event | Sentiment | 24h Move | Catalyst |
|---|---|---|---|---|
| Apr 27 | Phase 2/3 results | Positive | -64.4% | Tovecimig plus paclitaxel met primary and key secondary BTC endpoints. |
| Apr 24 | Topline preview | Positive | -64.4% | Company scheduled webcast to review COMPANION-002 topline endpoints. |
| Nov 04 | Preclinical data | Positive | +1.3% | Preclinical CTX-10726 data showed strong anti-tumor activity and IND timing. |
| Apr 01 | Phase 2/3 success | Positive | +17.9% | Tovecimig combo met primary ORR endpoint in BTC Phase 2/3 trial. |
24h Move is the share-price change in the day after each event; other market factors may also have contributed.
Clinical trial headlines for CMPX have produced highly variable reactions, with some positive data drawing sharp selloffs and others strong gains; the tag-specific average move of -27.4% underscores this volatility.
Recent clinical-trial news for Compass has centered on bispecific antibodies. In April 2025, tovecimig met its primary endpoint in biliary tract cancer and the stock rose 17.89%. A November 2025 preclinical CTX-10726 update saw a modest gain. However, detailed COMPANION-002 Phase 2/3 data and a related topline-announcement webcast in April 2026 coincided with steep -64.41% moves. Today’s CTX-8371 Phase 1 data adds another bispecific program to that developing clinical narrative.
Historical Comparison
In the past year, CMPX issued 4 clinical-trial updates averaging a -27.4% move, with both sharp rallies and steep selloffs. Today’s modest +4.42% reaction to early CTX-8371 data sits near the lower end of that volatility range.
Compass has progressed from tovecimig Phase 2/3 BTC success to additional detailed readouts, while advancing its bispecific pipeline with preclinical CTX-10726 data and now first-in-human CTX-8371 activity across multiple tumor types.
Regulatory & Risk Context
Key Terms
bispecific antibody medical
dose limiting toxicities medical
triple-negative breast cancer medical
Hodgkin lymphoma medical
non-small cell lung cancer medical
overall response rate medical
pseudo-progression medical
AI-generated analysis. How Rhea-AI works. Not financial advice.
- CTX-8371, a novel dual checkpoint blocker that simultaneously targets the programmed death receptor PD-1 and its ligand PD-L1, demonstrated promising monotherapy clinical activity in patients with advanced malignancies resistant to prior immune checkpoint inhibitors.
- Deep and durable responses were observed in patients with triple-negative breast cancer (TNBC), Hodgkin lymphoma (HL), and non-small cell lung cancer (NSCLC).
- CTX-8371 was generally well tolerated with no observed dose limiting toxicities (DLTs).
BOSTON, May 21, 2026 (GLOBE NEWSWIRE) -- Compass Therapeutics, Inc. (Nasdaq: CMPX), a clinical-stage, oncology-focused biopharmaceutical company developing proprietary antibody-based therapeutics to treat multiple human diseases, today announced 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) Annual Meeting, taking place May 29 – June 2, 2026, in Chicago, IL.
“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,” 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 https://www.compasstherapeutics.com/pipeline once the presentation has concluded.
About Compass Therapeutics
Compass Therapeutics, Inc. was founded in 2014 and is headquartered in Boston, MA. Compass is a clinical-stage, oncology-focused biopharmaceutical company discovering and developing proprietary antibody-based therapeutics to treat multiple diseases. The company’s scientific focus is on the relationship between angiogenesis, the immune system and tumor growth. Compass has a robust pipeline of novel product candidates designed to target multiple key biological pathways to drive an effective anti-tumor response, including angiogenesis modulation, immune activation within the tumor microenvironment, and reduction of tumor-driven immunosuppression. The company is advancing discovery candidates through clinical development to commercial-stage assets. For more information, visit www.compasstherapeutics.com.
Forward-Looking Statements
This press release contains forward-looking statements. Statements in this press release that are not purely historical are forward-looking statements. Such forward-looking statements include, among other things, references to Compass’s financial position to continue advancing its product candidates, expectations about cash runway, business and development plans, and statements regarding Compass’s product candidates, including their development and clinical trial milestones such as the expected trial design, timing of enrollment, patient dosing and data readouts, regulatory plans with respect to Compass’s product candidates and the therapeutic potential thereof. Actual results could differ from those projected in any forward-looking statements due to numerous factors. Such factors include, among others, Compass’s ability to raise the additional funding it will need to continue to pursue its business and product development plans, the inherent uncertainties associated with developing product candidates and operating as a development stage company, Compass’s ability to identify additional product candidates for development, Compass’s ability to develop, complete clinical trials for, obtain approvals for and commercialize any of its product candidates, competition in the industry in which Compass operates and market conditions. These forward-looking statements are made as of the date of this press release, and Compass assumes no obligation to update the forward-looking statements, or to update the reasons why actual results could differ from those projected in the forward-looking statements, except as required by law. Investors should consult all of the information set forth herein and should also refer to the risk factor disclosure set forth in the reports and other documents Compass files with the U.S. Securities and Exchange Commission (SEC) available at www.sec.gov, including without limitation Compass’s latest Annual Report on Form 10-K, Quarterly Report on Form 10-Q and subsequent filings with the SEC.
Investor Contact
ir@compasstherapeutics.com
Media Contact
Anna Gifford, Chief of Staff
media@compasstherapeutics.com
617-500-8099
