A little over a month after Seattle Genetics $SGEN snapped up the global rights to Immunomedics lead cancer drug IMMU-132 (sacituzumab govitecan) in a $2 billion deal, including $300 million in cash, the Morris Plains, NJ-based biotech detailed the data they plan to hustle to the FDA from its positive mid-stage study for triple-negative breast cancer.
While the study was a fairly small, single-arm probe of efficacy and safety, the two partners are planning the shortest route possible to see if they can get an accelerated approval while the therapy navigates a Phase III pivotal study.
Investigators in the study tracked a median overall survival rate of 16.6 months and a progression-free survival time of six months for the drug, which has the FDA’s breakthrough therapy designation for TNBC. Also, 30% of the 69 heavily pretreated patients in the single-arm study achieved an objective response — two complete and 19 partial.
“These results are very encouraging given the impressive clinical activity seen in a refractory setting, durability of responses, and the safety profile,” noted lead author Aditya Bardia, MD, MPH, attending physician at Massachusetts General Hospital Cancer Center. “The average PFS is about 3.5 months for standard agents, including cisplatin, capecitabine, nab-paclitaxel, and eribulin, as reported in earlier metastatic TNBC trials.”
Three out of four of the patients in the study who had previously been treated with a checkpoint — and failed — also achieved a partial response, a snapshot of possible combo potential the biotech plans to follow up on.
These data were laid out in the Journal of Clinical Oncology. And Immunomedics stock bumped up on the report, which follows earlier reports of the drug’s efficacy.
The drug is an antibody-drug conjugate, or armed antibody, designed for precise delivery of SN-38, the active metabolite of irinotecan. As such, it fits comfortably in Seattle Genetics sphere.
The drug didn’t kill anyone, but it’s not without safety issues. Thirty-nine percent of the patients suffered from neutropenia, with 7% experiencing febrile neutropenia and 13% afflicted by severe diarrhea.
Remarked Immunomedics CEO Cynthia L. Sullivan:
“We are working diligently with the FDA to make this valuable product candidate available to this group of patients as soon as possible. Blinded, independent radiological assessments are ongoing, and so far show a high concordance with local tomography findings.”
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