A Phase 1b/2 Study of the Anti-CD47 Antibody Magrolimab with Cetuximab in Patients with Colorectal Cancer and Other Solid Tumors.

Background: Chemotherapy plus epidermal growth factor receptor (EGFR) inhibitors, such as cetuximab, is standard therapy for KRAS wild-type (KRASwt) colorectal cancer (CRC); however, responses are infrequent. Magrolimab is a monoclonal antibody targeting CD47, an antiphagocytic signal overexpressed in solid tumors (STs).

Objective: This open-label, multicenter phase 1b/2 study (NCT02953782) aimed to determine the recommended phase 2 dose (RP2D) and evaluate the safety, tolerability, and efficacy of magrolimab + cetuximab in patients with advanced CRC or other STs.

Methods: A total of 78 patients were enrolled at eight study sites in the USA. In phase 1b, patients with advanced STs received weekly maintenance doses of magrolimab at 10-45 mg/kg and cetuximab at 200-250 mg/m2 following 3 + 3 dose-escalation. In phase 2, patients with anti-EGFR-refractory CRC received magrolimab + cetuximab at RP2Ds. Primary endpoints were dose-limiting toxicities, adverse events, and objective response rate (ORR; phase 2).

Results: The maximum tolerated dose was not reached in phase 1b. Two RP2Ds were explored in phase 2: magrolimab at 30 or 45 mg/kg plus cetuximab at 250 mg/m2. Most common treatment-related adverse events (TRAEs) were dermatitis acneiform (35.9%), infusion-related reactions (33.3%), dry skin (32.1%), fatigue (32.1%), and headache (29.5%). Most common grade ≥ 3 TRAEs were anemia (11.5%), increased blood bilirubin (9.0%), and decreased lymphocyte count (9.0%). Discontinuation of any study treatment owing to TRAEs occurred in 3.8% of patients. No deaths occurred due to TRAEs. In phase 2, ORR was 6.3% and 0% in the KRASwt and KRASmt CRC cohorts, respectively; disease control rate was 50.0% and 38.1%, and median overall survival was 9.5 and 7.6 months, respectively.

Conclusions: These results indicate tolerability and potential antitumor activity when combining anti-CD47 therapy and cetuximab in heavily pretreated patients with CRC.