Ifinatamab Deruxtecan Shows Promise in Treating Small Cell Lung Cancer

Key Insights

• Interim Phase 2 trial results indicate that ifinatamab deruxtecan (I-DXd) demonstrates notable activity against small cell lung cancer (SCLC).
• The 12 mg/kg dose of I-DXd achieved an objective response rate (ORR) of approximately 55% in SCLC patients, while the 8 mg/kg dose showed an ORR of ~26%.
• Median overall survival reached 11.8 months with the 12 mg/kg dose and 9.4 months with the 8 mg/kg dose, with preliminary intracranial responses also observed.

Merck and Daiichi Sankyo announced encouraging interim findings from their Phase 2 IDeate-Lung01 trial, evaluating ifinatamab deruxtecan (I-DXd) in patients with extensive-stage small cell lung cancer (SCLC). The antibody-drug conjugate (ADC) demonstrated clinically meaningful activity, offering a potential new treatment option for this aggressive cancer.

The data, with an April 25 cutoff, revealed that I-DXd at a 12 mg/kg dose resulted in a confirmed objective response rate (ORR) of approximately 55%. The 8 mg/kg dose achieved an ORR of around 26%. The study included heavily pre-treated patients who had undergone a median of two prior lines of therapy, with over 75% having received immunotherapy.

Efficacy and Survival Outcomes

Detailed results indicated that the 12 mg/kg dose led to 23 partial responses, while the 8 mg/kg dose resulted in one complete response and 11 partial responses. With median follow-up durations of 15.3 months and 14.6 months for the 12 mg/kg and 8 mg/kg groups, respectively, the median overall survival (OS) was 11.8 months and 9.4 months.

Intracranial Response

The companies also reported preliminary responses in patients with brain lesions, a common and challenging manifestation of SCLC. Intracranial ORRs reached 50.0% and 66.7% across the two dose groups, suggesting potential for I-DXd to address central nervous system involvement.

Safety Profile

Regarding safety, 17% of patients in the 12 mg/kg dose group and 6.5% in the 8 mg/kg dose group discontinued treatment due to adverse events. This highlights the importance of careful monitoring and management of potential side effects.

Dose Selection and Future Directions

Based on these findings, Merck and Daiichi Sankyo have chosen the 12 mg/kg dose for the dose expansion phase of the trial. This decision reflects a balance between efficacy and tolerability observed in the study. The data was presented at the World Conference on Lung Cancer in San Diego, California. These results suggest that I-DXd could represent a valuable addition to the treatment landscape for SCLC, particularly in patients who have progressed on prior therapies.