MacroGenics posts Phase 1 update on B7-H3 ADC MGC026 ahead of ESMO 2026

MacroGenics announced on July 23, 2026 a clinical update on its ongoing Phase 1 study of MGC026, a novel B7-H3-directed antibody-drug conjugate incorporating a topoisomerase I inhibitor-based linker-payload, in patients with advanced solid tumors.¹ The company plans to present dose escalation and preliminary tumor-specific cohort results at the ESMO 2026 Congress, taking place October 23-27, 2026, in Madrid, Spain.¹

Dose escalation tested MGC026 from 1 mg/kg to 9 mg/kg every three weeks and finished in the fourth quarter of 2025, with 7.5 mg/kg q3W now being studied in four tumor-specific cohorts covering recurrent or metastatic SCCHN, endometrial cancer, melanoma, and soft tissue sarcoma.¹ The trial is running at sites in the United States, Australia and the United Kingdom.¹

The SCCHN cohort uses a Simon's two-stage design targeting 40 patients, and MacroGenics is now enrolling Stage 2 after the cohort met its pre-specified Stage 1 response threshold.¹ Enrollment in the other three cohorts continues as planned.¹ As of July 8, 2026, 74 patients had been enrolled across dose escalation and cohort expansion, with no reported cases of interstitial lung disease or ocular toxicity and evidence of anti-tumor activity observed across several indications.¹

At ESMO, the MGC026 data will be presented as poster 1020P by lead author Rachel E. Sanborn, M.D., on Friday, October 23, 2026, from 15:15 to 16:00 CEST.¹ MacroGenics will also present a phase 2 poster on lorigerlimab in advanced gynecologic cancers, titled "LINNET," numbered 1278P, led by Amir Jazaeri, M.D., on Monday, October 26, 2026, from 12:00 to 12:45 CEST.¹

MGC026 uses Synaffix's ADC technology and the SYNtecan E topoisomerase I inhibitor-based linker-payload, a cleavable exatecan-based payload conjugated at a drug-to-antibody ratio of 4.¹