WALTHAM, Mass. — Mythic Therapeutics has unveiled encouraging early-stage results from its Phase 1 KisMET-01 study of MYTX-011, a novel cMET-targeting antibody-drug conjugate (ADC), during a presentation at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting. The investigational therapy is being tested in patients with previously treated, locally advanced or metastatic non-small cell lung cancer (NSCLC).
MYTX-011 is designed with a pH-sensitive mechanism that enables it to more selectively deliver its cancer-fighting payload across varying levels of cMET expression, a receptor commonly implicated in cancer progression. According to the company, this innovative engineering may reduce toxicity and increase the number of patients who can benefit from ADC-based treatment.
Preliminary data from the trial showed encouraging signs of anti-tumor activity across all levels of cMET expression and various tumor types. Among patients with cMET-low tumors, the overall response rate (ORR) was 36%. In those with cMET-high tumors, the ORR reached 39%. The therapy was especially effective in patients whose tumors harbored EGFR mutations and high or intermediate cMET expression, with a 50% response rate observed in that subgroup. Some responses lasted as long as 8.9 months, and most responding patients remained on therapy.
The findings were drawn from 66 patients who received efficacious dose levels (≥4.0 mg/kg) of MYTX-011 every three weeks. These patients had undergone a median of three prior treatment regimens, with some having received as many as ten. Nearly half had previously been treated with taxanes. The data also showed that responses occurred regardless of EGFR mutation status or past taxane use.
At the 12-week mark, 80% of patients experienced disease control, while 52% maintained that control at 24 weeks. Among patients with squamous cell histology and low cMET levels, all four evaluable individuals derived clinical benefit, including one partial response and three instances of stable disease.
MYTX-011 also showed favorable pharmacokinetics and maintained stability. The safety profile was consistent with earlier results. Common treatment-related side effects included blurred vision, keratopathy, keratitis, nausea, peripheral neuropathy, fatigue, and elevated AST levels. More severe adverse events, including blurred vision, keratopathy, neutropenia, and keratitis, occurred more frequently at doses of 5.8 mg/kg or higher. Four patients discontinued treatment due to eye-related effects, three of whom had been on the higher dose.
Based on the safety and efficacy data, Mythic selected a 5.0 mg/kg dosing schedule with a 2-on, 1-off regimen as the recommended Phase 2 dose. This will be evaluated alongside a 4.0 mg/kg schedule in the next part of the study.
Dr. George Eliades, President and CEO of Mythic Therapeutics, emphasized the significance of the early results, stating that the data highlight the potential of pH-dependent ADCs to broaden access to effective cancer therapies. He noted the strong anti-tumor activity and tolerability support the case for MYTX-011 as a potential new standard of care for patients who have exhausted other treatment options.
Dr. Rebecca Heist of Massachusetts General Hospital Cancer Center added that the early efficacy and durability of responses, along with the manageable safety profile, make MYTX-011 a compelling candidate for continued development. Additional findings from the ongoing expansion phase of the study are expected to be shared at a future medical meeting.
