Pyxis Oncology, Inc. (Nasdaq: PYXS) announced updated results from its global Phase 1 monotherapy study of micvotabart pelidotin (MICVO) in patients with second-line and beyond recurrent/metastatic head and neck squamous cell carcinoma (R/M HNSCC) on September 9, 2026. The data cutoff date for the report is August 18, 2026.
The study evaluated MICVO at a dose of 5.4 mg/kg intravenously once every three weeks with a dose cap. In the efficacy-evaluable population of 33 patients, the confirmed objective response rate (cORR) was 36 percent (12/33), and the disease control rate (DCR) was 94 percent (31/33). Responders achieved their response by the first scan at six weeks in 75 percent of cases, and 83 percent of responders achieved more than a 50 percent reduction in tumor size from baseline.
Median progression-free survival (mPFS) was 6.2 months (95% CI: 4.8 - 8.8), and the 12-month overall survival (OS) probability was 79 percent (95% CI: 58.1, 90.3). Median overall survival has not yet been reached (NR). The company reported that clinical activity was observed across key subgroups, including human papillomavirus (HPV) status and prior treatment history.
Safety data was reported for 35 patients. No new safety signals were observed. The tolerability profile was consistent with other antibody-drug conjugates (ADCs) containing auristatin payloads. The most common treatment-related adverse events of interest included cutaneous events (48.6 percent), peripheral neuropathy (40.0 percent), and ocular events (28.6 percent). Peripheral neuropathy generally occurred after patients had received evidence of clinical benefit and after prolonged treatment duration.
Pyxis Oncology plans to initiate a pivotal Phase 3 study, named Headliner, in mid-2027. The randomized, open-label trial will enroll approximately 500 patients with second- or third-line R/M HNSCC who have progressed following platinum-based therapy and anti-PD-(L)1 therapy. The study will compare MICVO against investigators' choice of cetuximab, docetaxel, or methotrexate. The company also expects to report updated data from a combination study of MICVO and Merck's KEYTRUDA (pembrolizumab) in the fourth quarter of 2026.
