MacroGenics Announces Positive Interim Results for MGC026 in SCCHN

ROCKVILLE, MD, Oct. 23, 2026 /CourierPR/ -- MacroGenics, Inc., a clinical-stage biopharmaceutical company focused on developing innovative antibody-based therapeutics for cancer, announced positive interim Phase 1 results for its B7-H3-directed antibody-drug conjugate, MGC026, at the European Society for Medical Oncology (ESMO) 2026 Congress in Madrid, Spain. The company presented these findings, which demonstrate durable activity across multiple solid tumors, supporting the potential for MGC026 in front-line metastatic squamous cell carcinoma of the head and neck (SCCHN) in combination with pembrolizumab.

As of September 1, 2026, 85 patients had been treated across the dose-escalation and dose-expansion cohorts. MGC026 demonstrated a manageable safety and tolerability profile, with no treatment-related discontinuations in SCCHN patients. Grade ≥3 treatment-related adverse events (TRAEs) occurred in 51% of patients, with the most common being neutropenia (27%) and anemia (25%). No cases of interstitial lung disease, pneumonitis, or ocular toxicity were observed.

In the 32-patient dose-escalation portion, patients with advanced and metastatic solid tumors received MGC026 at doses ranging from 1 mg/kg to 9 mg/kg administered every three weeks (Q3W) and had received a median of four prior lines of systemic therapy (range 1-8). Pharmacokinetic analyses supported the selection of the 7.5 mg/kg Q3W regimen for continued evaluation.

Among 17 response-evaluable patients representing 10 different tumor types who received MGC026 at doses of at least 6 mg/kg in dose escalation, the confirmed objective response rate was 29% (5/17), and the disease control rate was 65% (11/17). Responses were durable, with a median duration of response (mDOR) of 10.2 months. These findings highlight the potential of MGC026 to deliver meaningful and durable clinical benefit in patients with advanced solid tumors that were refractory to prior treatments.

The company is evaluating MGC026 in an ongoing Simon's 2-stage tumor-specific expansion cohort in recurrent/metastatic SCCHN. This study is designed to enroll 40 patients treated at a dose of 7.5 mg/kg Q3W. The interim results reported here are based on a September 1, 2026, data cutoff and include 27 patients evaluable for safety and 22 patients evaluable for response. Patients were heavily pretreated, with 46% of the response-evaluable participants having received three prior lines of systemic therapy and 41% having received four or more prior lines (median was 3 prior lines [range 1-7]). MGC026 demonstrated encouraging antitumor activity in these SCCHN patients, achieving a best overall response rate of 27% (6/22), including four confirmed and two unconfirmed partial responses (PRs), and a disease control rate of 64% (14/22). Activity appeared higher among patients with HPV-positive disease, with five of the responses observed (5/16) in this population.

MGC026 demonstrated a manageable safety profile in this heavily pretreated and difficult-to-treat SCCHN population. No TRAEs led to treatment discontinuation, and no cases of interstitial lung disease, pneumonitis, or ocular toxicity were observed. Grade ≥3 TRAEs occurred in 48% of patients. The only two Grade ≥3 TRAEs observed in ≥10% of participants were anemia (30%) and neutropenia (26%). The TRAEs observed in Stage 1 were well managed and reversible. Many of the patients who experienced hematologic toxicities had previously received platinum- and/or taxane-based chemotherapy.

MacroGenics believes the emerging profile of MGC026 supports evaluation in earlier-line treatment settings, where the molecule’s orthogonal mechanism of action and non-overlapping toxicity profile may potentially complement immune checkpoint inhibition. The company plans to initiate an expansion cohort in early 2027 evaluating MGC026 in combination with pembrolizumab in front-line patients with PD-L1 positive (CPS ≥1) recurrent or metastatic SCCHN.

The company expects to provide updated data in mid-2027.