Assessing the BCMA scene
Why it’s too soon to call bluebird’s bb2121 the winning BCMA CAR at ASH 2017
Differences in patient populations and a dearth of clinical outcome data mean it’s too soon to declare bluebird bio Inc.’s anti-BCMA chimeric antigen receptor therapy the leader of the pack of CARs that presented clinical data in multiple myeloma at the American Society of Hematology meeting.
While the CAR data do hint at unprecedented benefits for targeting BCMA, they don’t shut antibody-drug conjugates (ADCs) and other anti-BCMA modalities out of the fold; these will likely still have a place in the arsenal for MM patients unable to access or tolerate CAR T regimens.
BCMA (TNF receptor superfamily member 17; TNFRSF17; CD269) has emerged as the next hot target in CAR T therapies. At least 10 BCMA-targeted CAR T cell therapies are in the clinic to treat multiple myeloma. Of those, six reported clinical data at ASH, which ran Dec. 9-12 in Atlanta (see “New Targets for CAR Ts”).
If approved for MM, BCMA-targeted CARs would address a more prevalent cancer than the indications of currently approved CAR therapies, acute lymphoblastic leukemia (ALL) and diffuse large B cell lymphoma (DLBCL). The National Cancer Institute estimates 30,280 new cases of myeloma will have been diagnosed in the U.S. in 2017, compared to 5,970 cases of acute lymphoblastic leukemia (ALL). NCI estimates 72,240 new non-Hodgkin’s lymphoma (NHL) cases will be diagnosed, of which 31% (about 22,000) tend to be DLBCL.
BCMA promotes plasma cell survival and plays a role in growth and survival of myeloma cells. Its expression is limited to B cells in later stages of development and it is almost universally present on myeloma cells.
Going into ASH, expectations for anti-BCMA therapies were high in part because of a June presentation at the American Society of Clinical Oncology meeting where Nanjing Legend Biotech Co. Ltd. reported that all 19 evaluable patients (100%) responded in the first phase of the Phase I/II LEGEND-2 study of LCAR-B38M to treat relapsed or refractory MM.
Nanjing Legend is a subsidiary of Genscript Biotech Corp.
“There are some innate differences in these studies that make that comparison unfair at this moment.”