(Bloomberg) — An experimental therapy from Bluebird Bio Inc. and Bristol-Myers Squibb Co. benefited more than 80% of patients nearing death from an advanced form of blood cancer in a pivotal study, clearing a hurdle in its path to U.S. approval.A single high-dose infusion of the personalized medicine known as bb2121 generated a response in 44 of 54 patients with multiple myeloma, including 19 who had a complete response, the companies said in a statement Friday. Patients went a median of 11.3 months before the cancer progressed, topping expectations that it needed to stop the disease for at least six months to gain approval from the U.S. Food and Drug Administration.Bluebird shares briefly jumped in late trading on Friday before surrendering most of their gains. The recently-issued CVR given in connection with the closing of Bristol-Myers’ deal with Celgene, known by the ticker BMY-R, rose 8.3%.The companies divulged the findings on the eve of the American Society of Hematology’s annual meeting in Orlando, Florida, where GlaxoSmithKline Plc., Regeneron Pharmaceuticals Inc. and Bristol’s own Celgene unit will present data on competing approaches. Cambridge, Massachusetts-based Bluebird and New York-based Bristol-Myers are scheduled to give an update on their next-generation therapy, bb21217, on Monday, while hotly anticipated results from competitor Johnson & Johnson’s Nanjing Legend Biotech-partnered therapy will take the spotlight that morning.The depth and the durability of the data “puts us in very good stead around any of the antibodies as well as other gene therapies,” Bluebird Chief Executive Officer Nick Leschly said. “We feel quite good about it, and that’s why we’re sprinting toward submission and driving toward earlier lines of therapy.”Positive results from the study, dubbed KarMMa, could lead to the first approval of the approach called CAR-T for patients with multiple myeloma, a deadly form of cancer found in white blood cells, wrote Raju Prasad, an analyst at William Blair, in a note. A response rate greater than 80% that can hold off the disease for at least 11 months would be well-received by doctors who might otherwise be wary of potential high costs and an aggressive approach, said Yaron Werber, an analyst at Cowen & Co.The approach known as CAR-T is already approved for a hard-to-treat form of pediatric leukemia and diffuse large B cell lymphoma, both blood cancers that are much less common than the multiple myeloma, which is diagnosed in about 30,000 Americans each year. Bluebird and Bristol’s therapy involves removing infection-fighting T cells from the blood, altering them to recognize a protein known as BCMA that is found in multiple myeloma cells, then putting them back into the patient to kill the cancer.(Updates with stock-price movement in third paragraph)\–With assistance from Tatiana Darie.To contact the reporters on this story: Bailey Lipschultz in New York at [email protected];Michelle Fay Cortez in Minneapolis at [email protected] contact the editors responsible for this story: Catherine Larkin at [email protected], Mark Schoifet, Timothy AnnettFor more articles like this, please visit us at bloomberg.com©2019 Bloomberg L.P.