HUTCHMED doses first patient in Phase I/IIa trial of HMPL-A580 in advanced solid tumors

HUTCHMED has dosed the first patient in a Phase I/IIa clinical trial of HMPL-A580, an antibody-targeted therapy conjugate (ATTC) designed to deliver a PI3K/PIKK inhibitor payload via an anti-EGFR antibody, in patients with unresectable, advanced, or metastatic solid tumors. The first dose was administered on March 4, 2026, in a multicenter, open-label study running across sites in China and the United States (source; AllSci trial listing). HMPL-A580 is the second clinical candidate from HUTCHMED's next-generation ATTC platform, which conjugates proprietary small-molecule inhibitor payloads to monoclonal antibodies using cleavable linkers. No licensing partners have been disclosed; HUTCHMED retains full rights.

The trial consists of two parts. In the dose-escalation phase, patients receive intravenous HMPL-A580 at predefined dose levels to establish maximum tolerated dose and a recommended expansion dose. The subsequent Phase IIa expansion and optimization part will characterize safety, tolerability, and preliminary anti-tumor activity in selected solid tumor types. Primary endpoints include safety, pharmacokinetics, and immunogenicity, with efficacy as a secondary measure. The trial is registered as NCT07396584; enrolment numbers and estimated completion dates have not been publicly specified.

Research context

The rationale for HMPL-A580 rests on a well-documented biological intersection. The PI3K/AKT/mTOR (PAM) pathway is among the most frequently altered signaling cascades in solid tumors, driving proliferation, survival, and therapeutic resistance. Yet PI3K inhibitors developed as systemic oral agents — alpelisib (Novartis), copanlisib (Bayer), and others — have been constrained by on-target toxicities including hyperglycemia, rash, and hepatotoxicity that limit dosing intensity and duration. Feedback loops that reactivate the pathway upon single-node inhibition further erode efficacy. Separately, anti-EGFR antibodies such as cetuximab and panitumumab show activity only in select populations (RAS wild-type colorectal cancer, head and neck squamous cell carcinoma) and face resistance frequently mediated by downstream PAM pathway activation through PIK3CA mutations or PTEN loss. By conjugating a PI3K/PIKK inhibitor to an anti-EGFR antibody, HMPL-A580 is designed to concentrate payload delivery within EGFR-expressing tumor cells, potentially widening the therapeutic index while simultaneously blocking receptor-level and downstream pathway signaling. HUTCHMED states that preclinical data demonstrate synergy between PAM pathway inhibition and anti-EGFR activity, though these data have not yet been presented publicly.

Current standard of care for EGFR-expressing solid tumors varies by tumor type but includes EGFR tyrosine kinase inhibitors such as osimertinib (AstraZeneca) in EGFR-mutant NSCLC, anti-EGFR antibodies in colorectal and head and neck cancers, and checkpoint inhibitors across multiple indications. Recent approvals have reshaped the landscape: amivantamab plus lazertinib (Janssen) gained approval for first-line EGFR-mutant NSCLC, while capivasertib (AstraZeneca) and inavolisib (Roche) were approved for PAM pathway-altered HR+/HER2- breast cancer. Despite these advances, patients who progress through available therapies — particularly those with resistance driven by PAM pathway reactivation — have limited options. No approved agent simultaneously targets EGFR and the intracellular PI3K pathway through a single conjugate molecule, leaving a gap that HMPL-A580 is designed to address.

The competitive field pursuing PAM pathway inhibition in solid tumors is active. Relay Therapeutics is advancing RLY-2608, a mutant-selective PI3Kα inhibitor, in a Phase II pivotal study in PIK3CA-mutated breast cancer. Eli Lilly is developing two mutant-selective PI3Kα inhibitors — LOXO-783 (lilzenisertib) and STX-478, acquired through its purchase of Scorpion Therapeutics — both in Phase I/II. Taiho Oncology's TOS-358, a dual mutant-selective PI3Kα and mTORC1 inhibitor in Phase I/Ib, attempts to address feedback reactivation by targeting two pathway nodes simultaneously. Celcuity and Pfizer are running gedatolisib, a dual pan-PI3K/mTOR inhibitor, in a Phase III breast cancer trial. These programs all deliver their payloads systemically as oral small molecules. HMPL-A580's conjugate format represents a divergent strategy — using antibody-directed delivery to restrict pathway inhibition to tumor cells rather than relying on isoform selectivity or mutant specificity to achieve tolerability. Merck and Kelun-Biotech are separately developing MK-2870, an anti-EGFR ADC carrying a cytotoxic payload, in Phase I/II for solid tumors. That program shares the EGFR-targeting antibody approach but uses a conventional cytotoxic warhead rather than a targeted therapy payload, making HMPL-A580's non-cytotoxic ATTC design distinct in the EGFR-directed conjugate space. Whether antibody-mediated delivery of a pathway inhibitor can achieve sufficient intratumoral concentrations to outperform systemic mutant-selective inhibitors — without introducing new liabilities related to the antibody component — remains the central translational question this trial will begin to answer.

---

Spot something wrong? Report an issue with this article