PharmaMar has filed (PDF) for FDA approval of lurbinectedin in relapsed small cell lung cancer. The filing tees PharmaMar up to become the first company to win approval for a new chemical entity in the disease in more than 20 years.
Lurbinectedin is designed to cause cell death by inhibiting activated transcription and inducing DNA double-strand breaks. Through this mechanism, PharmaMar thinks lurbinectedin can improve the prospects of small cell lung cancer patients who have progressed after receiving platinum-containing therapy.
PharmaMar ran a phase 2 clinical trial to generate data to back up that hypothesis. In the 105-subject small cell lung cancer cohort, PharmaMar linked lurbinectedin to a 35% response rate. Of the eight patients previously treated with immuno-oncology drugs, five responded.
The study also generated data on the duration of those responses. The median duration of response clocked in at 5.3 months, and the median overall survival was 10.8 months. One in 10 patients had ongoing responses 12 months into the trial.
PharmaMar achieved the best results in a subset of patients with chemotherapy-free intervals of more than 90 days, which it classed as having sensitive disease. In that subgroup, the response rate was 47%, as compared to 21% in patients with shorter chemotherapy-free intervals. The responses in the sensitive disease subgroup were longer, too.
The data are now with the FDA for review. PharmaMar thinks it has a shot at bringing lurbinectedin to market in the U.S. in the second half of next year. If PharmaMar achieves that goal, lurbinectedin will become the first new chemical entity approved in the indication since Hycamtin in the 1990s.
That fact paints a slightly misleading picture of the extent of innovation in the indication. In recent years, Bristol-Myers Squibb and Merck have won approval for Opdivo and Keytruda, respectively, in the indication, giving patients the option of receiving checkpoint inhibitors.
Opdivo and Keytruda came to market in the indication on the strength of response rates that fell short of the 35% achieved by lurbinectedin, although the unreliability of cross-trial comparisons makes the significance of that difference unclear. PharmaMar also has early evidence that lurbinectedin works in patients previously treated with immuno-oncology agents.