First HARNESS-1 Patient Safely Treated with RC220

• First patient treated safely with RC220 and osimertinib
• No dose-limiting toxicities reported
• One additional patient to be treated before dose escalation

Race Oncology Ltd announced that the Safety Review Committee (SRC) has reviewed the safety data from the first patient in the HARNESS-1 trial, who was treated with RC220 at 50 mg/m2 plus osimertinib 80 mg daily. The SRC found no dose-limiting toxicities or treatment-related safety concerns during the safety observation period. However, the patient reported Grade 2 colitis symptoms after the observation period, which is under investigation. As a precaution, the SRC recommended treating one additional patient at the same dose before escalating to 100 mg/m2. Enrollment for the next patient is underway, with the next SRC review expected in 6-8 weeks.

The HARNESS-1 trial will continue with the next patient enrollment and safety review, with the next update expected in 6-8 weeks.