Embattled Immunomedics has some good news to report on its lead antibody-drug conjugate (ADC) program with a preliminary study showing IMMU-132 has activity in small cell lung cancer (SCLC).
The data could add another possible indication for IMMU-132, which according to Immunomedics is on course for an accelerated approval later this year for triple-negative breast cancer but will need to be backed up by further studies.
The small trial of IMMU-132—also known as sacituzumab govitecan—involved 53 patients with advanced metastatic SCLC who had already been heavily treated with conventional chemotherapy but whose disease was still progressing. All told, out of 49 evaluable patients there were 7 partial responses and 21 people in whom the disease stabilized, according to the AACR abstract.
It says that equated to an overall response rate of 14% and this "compares well" to topotecan, which was the last drug to be approved for second-line treatment after platinum chemotherapy for SCLC two decades ago.
Overall, 60% of patients showed tumor shrinkage from baseline measurements, and median progression-free survival (PFS) came in at 3.7 months, with median overall survival of 7.5 months. Immunomedics isn't talking up the data just yet, but CEO Cynthia Sullivan said the data suggest the drug "may gain a role in the therapy of both chemo-sensitive and chemo-resistant SCLC patients, both before or after topotecan treatment" if further studies are positive.
Jhanelle Gray, M.D. of H. Lee Moffitt Cancer Center and Research Institute in Tampa, Florida—who presented the data this week at the American Association of Cancer Research (AACR) meeting in Washington D.C.—said that the results are "encouraging" and important since SCLC is "still a lethal disease, especially in the population that is chemo-resistant to first-line therapy."
The new results come at a torrid time for Immunomedics. In February, the biotech signed a $2 billion development and licensing deal with Seattle Genetics for IMMU-132, including a hefty $250 million upfront, only to have it placed on hold last month after a shareholder revolt. Disgruntled investors—led by activist investor venBio—eventually forced through changes to the biotech's board of directors.
The increasingly acrimonious battle centers on IMMU-132, with venBio pushing to keep the drug in-house and calling the Seattle Genetics agreement "a rushed deal that does not deliver fair value to shareholders."