FDA puts Gilead's $225M BCMA CAR-T on hold over patient death, delaying potential rival to J&J, BMS

Gilead Sciences' $225 million bet on Arcellx’s CAR-T cell therapy has hit turbulence. Months after the biotech closed the deal, the FDA has put a phase 2 trial of the anti-BCMA therapy on hold in response to the death of a patient. 

Working through its Kite cell therapy unit, Gilead paid $225 million upfront and invested $100 million in Arcellx for the right to co-develop and co-commercialize the candidate late last year. The deal established Gilead as a potential rival to Johnson & Johnson and Legend Biotech, the developers of Carvykti, and to Bristol Myers Squibb and 2seventy bio, the partners behind Abecma.

Arcellx is trailing its rivals and now faces a delay that may see it slip further behind the front-runners. The FDA hit the pivotal iMMagine-1 study with a clinical hold in response to a patient death. Arcellx “believes limitations on bridging therapy are a contributing factor” to the death. 

Having reached that conclusion, the biotech is working with the FDA “to amend the protocol to expand options for patients that are consistent with current clinical practice.” In the interim, Arcellx can continue to dose patients who have already undergone lymphodepletion. 

Arcellx CEO Rami Elghandour expanded on the next steps in a statement, saying expansion of bridging therapy regimens is consistent with clinical practice and in the best interest of patients. The CEO added that Arcellx continues “to evaluate other potential improvements” to the trial and that the “drug product release characteristics” from iMMagine-1 are consistent with the earlier phase 1 study.

Enrollment was in line with Arcellx’s expectations before the FDA pumped the brakes on the program. ClinicalTrials.gov puts the primary completion of the 110-subject study at May 2024, with full completion penciled in for one year after that.

Any delay to the launch of Arcellx’s anti-BCMA CAR-T will give Bristol Myers and J&J more time to work through the challenges that have held back their launches, establish strong positions in the market and  potentially move into earlier lines of therapy. Sales of Abecma hit (PDF) $147 million in the first quarter of the year, with Carvykti trailing (PDF) at $72 million. 

Arcellx argues its use of a novel binding domain and 100% phase 1 response rate suggest it may have a best-in-class therapy and, with the backing of Gilead’s Kite, it has a partner that is well versed in making and selling CAR-Ts.