Racura Oncology has reported a positive step forward in its HARNESS-1 Phase 1a/b study of RC220 in lung cancer.
The HARNESS‑1 trial is evaluating RC220, Racura’s proprietary formulation of bisantrene, in combination with osimertinib for adults with EGFR‑mutant non‑small cell lung cancer.
The patient received RC220 at 50 mg/m2 alongside osimertinib 80 mg daily. During the formal safety observation period, no dose‑limiting toxicities or treatment‑related safety concerns were identified. In the week after that observation window ended, the patient reported moderate symptoms consistent with colitis, and clinical investigations into the cause are ongoing.
The Safety Review Committee (SRC) review concluded that, while the colitis was not considered a dose‑limiting toxicity, prudence calls for one more patient to be treated at the same RC220 dose with 80 mg osimertinib before advancing to the planned 100 mg/m2 dose.
Racura said two patients are currently awaiting an open slot and enrolment of the next patient is now underway. The SRC is expected to reconvene in 6 to 8 weeks to review safety data from the second patient.
Racura’s chief executive, Dr Daniel Tillett, said, “We are encouraged by the SRC’s review and welcome its support for the HARNESS-1 trial to continue. The absence of dose-limiting toxicities or treatment-related safety concerns during the safety observation period is an important early signal, and enrolment of the next patient is underway. We understand and fully support the SRC’s careful approach to patient safety. Treating an extra patient at 50 mg/m2 will allow a new patient needing urgent additional treatment to access the trial as soon as possible.”
Racura noted that colitis has not been observed in the medical literature among the more than 1,500 patients previously treated with bisantrene, but pointed out that serious colitis has been reported in some cases associated with osimertinib therapy. Because the HARNESS‑1 protocol follows an accelerated titration model, the first three dose levels are single‑patient cohorts that would only expand to three patients if a dose‑limiting toxicity occurs. The SRC’s precautionary step aims to balance patient safety with timely progression of the trial.
