Pyxis Oncology Reports Promising Phase 1 Results for Novel ADC MICVO in Head and Neck Cancer
核心洞察
Pyxis Oncology announced positive preliminary Phase 1 data for micvotabart pelidotin (MICVO (搜索)), showing a 46% objective response rate as monotherapy in heavily pretreated recurrent/metastatic head and neck squamous cell carcinoma (搜索) patients.
The novel antibody-drug conjugate demonstrated even stronger efficacy when combined with pembrolizumab, achieving a 71% response rate and 100% disease control rate in first and second-line patients.
MICVO (搜索) targets extradomain-B of fibronectin (搜索) in the tumor extracellular matrix and has received FDA Fast Track Designation, with pivotal study plans expected in 2026.
Pyxis Oncology announced promising preliminary Phase 1 clinical data for micvotabart pelidotin (MICVO (搜索)), a first-in-concept antibody-drug conjugate targeting extradomain-B of fibronectin (搜索) (EDB+FN (搜索)) in the tumor extracellular matrix. The data, presented on December 18, 2025, showed encouraging efficacy signals both as monotherapy and in combination with pembrolizumab in patients with recurrent/metastatic head and neck squamous cell carcinoma (搜索) (R/M HNSCC (搜索)).
Monotherapy Results Show Activity in Heavily Pretreated Patients
In the Phase 1 monotherapy study, 18 patients with R/M HNSCC (搜索) received MICVO (搜索) at 5.4 mg/kg intravenously every three weeks. Among 13 evaluable patients, the confirmed objective response rate reached 46% (6/13), including one complete response by RECIST v1.1 criteria. The disease control rate was 92% (12/13), with 12 patients demonstrating significant tumor regression or tumor control.
The patient population represented a heavily pretreated cohort with a median of three prior lines of therapy. All patients (100%) had received prior platinum-based therapy and checkpoint inhibitor therapy, while 67% had prior taxane therapy and 50% had prior EGFR (搜索) targeting therapy.
"The preliminary data for MICVO (搜索) as monotherapy and in combination with pembrolizumab add to the growing body of evidence supporting MICVO's therapeutic potential and highlight its agility as a novel potential treatment option across the recurrent/metastatic head and neck squamous cell carcinoma (搜索) landscape," said Lara S. Sullivan, M.D., President, Chief Executive Officer and Chief Medical Officer of Pyxis Oncology.
Responses were observed across both study arms: 60% confirmed ORR in post-platinum and anti-PD(L)-1 (搜索) experienced patients (Arm 1, N=5) and 25% confirmed ORR in post-EGFRi and/or anti-PD(L)-1 experienced patients (Arm 2, N=4). Confirmed responses occurred in patients with HPV-positive, HPV-negative, and HPV-not applicable tumors.
Combination Therapy Demonstrates Enhanced Efficacy
The Phase 1/2 combination study evaluated MICVO (搜索) with pembrolizumab in seven R/M HNSCC (搜索) patients at doses of 3.6 mg/kg and 4.4 mg/kg of MICVO plus 200 mg pembrolizumab every three weeks. The combination achieved a confirmed overall response rate of 71% (5/7) and a disease control rate of 100% (7/7), with all seven patients demonstrating significant tumor regression.
Responses occurred across a range of PD(L)-1 (搜索) CPS scores (CPS ≥1 to CPS >20) and were observed even in patients who had disease progression following prior checkpoint inhibitor treatment. All patients treated to date were HPV-positive, with enrollment of HPV-negative and HPV-not applicable patients anticipated as additional global clinical trial sites are activated.
Safety Profile and Dosing Optimization
MICVO (搜索) demonstrated a generally manageable safety profile in both studies. In the monotherapy cohort, treatment-related adverse events (TRAEs) were observed in 89% (16/18) of patients, with Grade ≥3 TRAEs occurring in 56% (10/18) of patients. TRAEs leading to treatment discontinuation occurred in 28% (5/18) of patients, all of whom had "high bodyweight" defined as at least 10% above adjusted-ideal bodyweight.
No Grade 4 ADC payload TRAEs of interest were observed in the monotherapy study, and no Grade 5 events occurred. The company plans to implement Adjusted Ideal Bodyweight (AIBW) dosing in ongoing and future clinical studies, which has demonstrated improved tolerability without sacrificing activity in clinical studies of other ADCs.
In the combination study, TRAEs were observed in 86% (6/7) of patients with no Grade 3 or Grade 4 ADC payload TRAEs of interest observed. No TRAEs led to treatment discontinuation, and no overlapping toxicities between MICVO (搜索) and pembrolizumab were observed to date.
Novel Mechanism Addresses Unmet Medical Need
MICVO (搜索) represents a unique approach to cancer treatment by targeting EDB+FN (搜索), a non-cellular structural component of the tumor extracellular matrix that is selectively overexpressed in the tumor microenvironment of solid tumors (搜索) and largely absent from normal adult tissues. The drug is designed to treat solid tumors through a three-pronged mechanism: direct tumor cell killing, bystander effect, and immunogenic cell death.
"The current paradigm for treatment of recurrent/metastatic head and neck squamous cell carcinoma (搜索) offers limited options and therapeutic mechanisms for our patients, so we are particularly pleased to observe a novel mechanism providing emerging evidence of such compelling benefit-risk profile," said Glenn J. Hanna, M.D., Director, Center for Cancer Therapeutic Innovation and Center for Salivary and Rare Head and Neck Cancers at Dana-Farber Cancer Institute.
Regulatory Progress and Future Development
MICVO (搜索) has received Fast Track Designation from the U.S. Food and Drug Administration for the treatment of adult patients with R/M HNSCC (搜索) whose disease has progressed following treatment with platinum-based chemotherapy and an anti-PD(L)-1 (搜索) therapy. Pyxis Oncology has received FDA alignment on the clinical trial design for a planned pivotal monotherapy study in second-line and beyond R/M HNSCC.
The company plans to present updated data from the ongoing Phase 1 monotherapy study in mid-2026, expected to include additional patients and initial durability data. Updated data from the Phase 1/2 combination study, including in first-line/second-line and beyond R/M HNSCC (搜索) and other tumor types, is expected in the second half of 2026.
Pyxis Oncology is currently evaluating the path forward to pivotal studies for MICVO (搜索) as both monotherapy and in combination with pembrolizumab, with additional details expected in 2026. The company's current cash runway, bolstered by an $11 million payment from the sale of royalty rights to Enzeshu (搜索), is expected to fund operations through data milestones and into the fourth quarter of 2026.