By Bill Berkrot
(Reuters) - More than half of patients with advanced multiple myeloma who had run out of therapeutic options remained in complete remission after receiving bluebird bio Inc's experimental gene-modifying immunotherapy in a small, early stage study, according to updated data released on Sunday.
Of 18 patients who received a therapeutic dose of bb2121, all but one responded to the treatment, a 94 percent response rate, while 56 percent remained in remission with a median follow-up of 40 weeks after treatment.
Researchers, who reported the data at the American Society of Hematology meeting in Atlanta, said the initial response to the treatment was very quick and that many of the patients continued to improve over time.
Patients in the Phase I dose-escalation study had received seven prior treatment regimens, including regimens with the newest multiple myeloma drugs, such as Johnson & Johnson's Darzalex, and had undergone at least one stem cell transplant before receiving bb2121, which is being co-developed with Celgene Corp.
"Some of these patients were going to hospice until they got this," said Dr. Jesus Berdeja, the study's lead investigator.
"This is unheard of, something that we haven't seen with any drugs approved for myeloma in this type of population. The excitement among all the myeloma providers is crazy," said Berdeja, director of myeloma research at the Sarah Cannon Center for Blood Cancer in Nashville.
bb2121 belongs to a potentially revolutionary new type of one-time treatment called CAR-T therapy that involves genetic manipulation of a patient's immune system. A patient's own disease-fighting T-cells are harvested and genetically reengineered to target specific proteins on cancer cells before being replaced so they can circulate seeking out and attacking the cancer, possibly for years.
The first two CAR-T therapies from Novartis and Gilead Sciences, through its acquisition of Kite Pharma, were approved earlier this year for other blood cancers.
Three patients who received what proved to be sub-optimal doses of cells early in the bb2121 study died. Of the 18 who received higher doses, four patients have now experienced disease progression, while 14 continue to respond, researchers reported.
The treatment was very well tolerated for a CAR-T product, Berdeja said.
Only two patients experienced serious cytokine release syndrome with no reports of serious brain toxicity, both common side effects of CAR-T treatment. The most serious side effect was neutropenia, or very low white blood cell count, researchers said.
While this was a small Phase I study, the results were considered so impressive that Celgene plans to begin enrolling patients this month for a larger, potentially pivotal trial that could position bb2121 to become the third approved CAR-T.
"They're hitting it so far out of the park that they're not wasting any time," Berdeja said.
(Reporting by Bill Berkrot; Editing by Nick Zieminski)