On July 23, 2026 MacroGenics, Inc. (NASDAQ: MGNX), a clinical-stage biopharmaceutical company focused on developing innovative antibody-based therapeutics for the treatment of cancer, reported an update on the ongoing Phase 1 study evaluating MGC026, a novel B7-H3-directed antibody-drug conjugate (ADC), incorporating a topoisomerase I inhibitor-based linker-payload, in patients with advanced solid tumors. MacroGenics plans to present dose escalation and preliminary tumor-specific cohort results at the European Society for Medical Oncology (ESMO) (Free ESMO Whitepaper) 2026 Congress, taking place October 23-27, 2026, in Madrid, Spain.

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The dose escalation portion of the study evaluated MGC026 at doses ranging from 1 mg/kg to 9 mg/kg administered every three weeks (q3W) and was completed in the fourth quarter of 2025. A dose of 7.5 mg/kg q3W is being further evaluated in four tumor-specific cohorts: recurrent or metastatic SCCHN, endometrial cancer, melanoma, and soft tissue sarcoma. The study is active at clinical sites in the United States, Australia and the United Kingdom.
The SCCHN cohort employs a Simon’s two-stage design, with a planned enrollment target of 40 patients.

MacroGenics is currently enrolling SCCHN patients in Stage 2 after meeting the pre-specified response threshold in Stage 1. Enrollment in the other three cohorts continues as planned. As of July 8, 2026, a total of 74 patients had been enrolled across the dose escalation and ongoing cohort expansion portions of the study. As of this date, there were no cases of interstitial lung disease or ocular toxicity reported, and evidence of anti-tumor activity was observed across several indications.

"We look forward to sharing the data at ESMO (Free ESMO Whitepaper) and believe this presentation represents an important opportunity to demonstrate the potential of MGC026 as we continue its clinical development," said Eric Risser, President and Chief Executive Officer of MacroGenics.

ESMO 2026 Poster Presentations

•Title: Phase 1, first-in-human study of MGC026, a B7-H3–targeted antibody-drug conjugate (ADC) in advanced solid tumors
•Presentation Number: 1020P
•Lead Author: Rachel E. Sanborn, M.D.
•Date: Friday, October 23, 2026
•Time: 15:15 – 16:00 CEST
The Company also plans to present the following poster on lorigerlimab, an investigational, bispecific DART molecule that targets PD-1 and CTLA-4:
•Title: LINNET: A phase 2 study to evaluate lorigerlimab in participants (pts) with advanced gynecologic cancers
•Presentation Number: 1278P
•Lead Author: Amir Jazaeri, M.D.
•Date: Monday, October 26, 2026
•Time: 12:00 – 12:45 CEST

About MGC026

MGC026 is an investigational antibody-drug conjugate (ADC) targeting B7-H3, a protein with expression across the tumor microenvironment, including on tumor cells, tumor-associated stroma, and tumor-associated vasculature. MGC026 incorporates Synaffix’s proprietary ADC technology and the SYNtecan E topoisomerase I inhibitor-based linker-payload, which consists of a cleavable, exatecan-based cytotoxic payload conjugated at a drug-to-antibody ratio (DAR) of 4. MGC026 is designed to deliver this potent payload selectively to B7-H3-expressing tumors and is being developed for patients with advanced solid tumors. The ongoing Phase 1 study of MGC026 is an open-label clinical trial evaluating the safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary antitumor activity of MGC026 in patients with advanced solid tumors. Additional information about the study is available at www.clinicaltrials.gov using the identifier NCT0624270.

(Press release, MacroGenics, JUL 23, 2026, View Source [SID1234669394])