- Karyopharm got the go-ahead on Thursday to continue several studies of its lead candidate less than a few weeks after regulators placed them on partial clinical hold — an update that indicated problems with the trials were administrative in nature.
- The clinical-stage company is testing the drug, selinexor, as a treatment for a variety of blood cancers and solid tumors. With the Food and Drug Administration's Division of Hematology Products lifting the partial hold on the blood cancer investigations, Karyopharm can push forward with four mid- and late-stage studies evaluating selinexor in patients with multiple myeloma and diffuse large B-cell lymphoma.
- The partial holds stemmed from an adverse events list missing from the investigator's brochure and informed consent forms used in the selinexor trials, according to a March 10 statement from Karyopharm. While the hematoligical malignancies trials can recommence, the company is still waiting to hear whether the hold on its solid tumor trials will also be rescinded.
Karyopharm said it submitted the additional information by March 10, at which point the FDA had up to 30 days to decide if the amended investigator's brochure was adequate. The agency's quick decision to end the clinical hold well before that deadline bodes well for the drugmaker.
"Though the hold was related to administrative issues, we believe it did create some uncertainty, and the rapid resolution should help remove the overhang and ensure that key ongoing studies are not disrupted," Jefferies analyst Brian Abrahams said in a March 30 investor note.
Shareholders echoed Abraham's conclusion. Karyopharm stock was up about 3% to $12.31 per share in Thursday morning trading. Conversely, shares fell more than 10% when the company announced the partial holds.
The FDA's decision is another high along selinexor's rollercoaster journey through clinical development.
On the more positive end, the drug has notched victories in diseases such multiple myeloma. Topline results from the Phase 2 STORM testing selinexor in combination with dexamethasone in patients with quad- or penta-refractory multiple myeloma showed overall response rates (ORR) of 20.8% and 20%, respectively. The Phase 1b/2 STOMP trial found, in a similar patient population, those receiving the combination therapy had an ORR of about 70%.
Conversely, a Data Safety Monitoring Board determined through an interim analysis that the Phase 2 SOPRA study evaluating the drug as a monotherapy in patients with relapsed or refractory acute myeloid leukemia was unlikely to provide a benefit to overall survival. That verdict sent shares plummeting more than 16% on March 3.
Karyopharm CEO Michael Kauffman said in a March 30 statemen he expects a ruling on the solid tumor trials to come soon. So far, the company has tested selinexor in more than 1,900 patients.
"The Karyopharm team worked diligently to update and submit the required documents to the FDA, which allowed the hematology divison to expeditiously remove the partial clinical hold," he said. "Patient enrollment is again underway in our hematologic oncology studies. Our previously disclosed enrollment rates and timelines for both ongoing and planned trials are not expected to be materially impacted."