FDA Fast-Tracks Novel Cancer Drug for Extensive-Stage Small Cell Lung Cancer

The U.S. Food and Drug Administration (FDA) has granted Breakthrough Therapy Designation to ifinatamab deruxtecan (I-DXd), a new investigational drug, for the treatment of adult patients with extensive-stage small cell lung cancer (ES-SCLC). This designation is a significant step forward for a patient population that has very few effective treatment options, especially after their disease has progressed on or after chemotherapy.

What is I-DXd and How Does It Work?

I-DXd is a type of targeted therapy called an antibody-drug conjugate (ADC). It’s a “first-in-class” medicine that targets a protein called B7-H3, which is often overexpressed in various types of cancer, including SCLC. The overexpression of B7-H3 is linked to a poor prognosis, making it an ideal target for this new drug.

The ADC is engineered to deliver a potent chemotherapy payload directly to cancer cells that have the B7-H3 protein. This allows the drug to selectively attack tumor cells while minimizing harm to healthy cells, which can reduce the severe side effects often associated with traditional chemotherapy.

Basis for the FDA Designation

The breakthrough designation was based on promising results from two clinical trials: the Phase 2 IDeate-Lung01 trial and the Phase 1/2 IDeate-PanTumor-01 trial.

IDeate-Lung01 Trial: This global, multicenter trial evaluated the safety and efficacy of I-DXd in ES-SCLC patients who had already been treated with chemotherapy. Interim analysis showed clinically meaningful responses, with an objective response rate (ORR) of 54.8% at the 12 mg/kg dose. The median progression-free survival (PFS) was 5.5 months, and overall survival (OS) was 11.8 months.
IDeate-PanTumor-01 Trial: This trial was a first-in-human study that evaluated the drug’s safety and efficacy across a range of advanced solid tumors. The findings from this trial supported the results seen in the IDeate-Lung01 study, providing a strong basis for the FDA’s decision.

According to Dr. Ken Takeshita of Daiichi Sankyo, this designation underscores the urgent need for new therapies for ES-SCLC. The companies are moving with a sense of urgency to advance the drug through the final stages of regulatory review, with the goal of bringing this novel therapy to patients as soon as possible.