Arcellx took a risk by including more patients with a tougher, more aggressive form of multiple myeloma in an early-stage trial for its CAR-T med. But it doesn’t matter, because “any way you slice” it, the small biotech seems to have put up strong enough data to rival the market-leading therapy by Johnson & Johnson and Legend Biotech.
Maryland-based Arcellx presented the latest on CART-ddBCMA, its BCMA-specific CAR-modified T-cell therapy for multiple myeloma, at the 2022 American Society of Clinical Oncology (ASCO) annual meeting in Chicago on Friday.
The data comes from a phase 1 study of patients with relapsed or refractory multiple myeloma, including 31 eligible for an efficacy and safety analysis who had at least three prior lines of treatment. Out of these patients, 21 had “poor prognostic factors,” including extramedullary disease, which means cancer that has spread to form tumors outside the bone marrow in the soft tissues of the body.
The CAR-T therapy had a 100% overall response rate after a median follow-up of 12.1 months, and 71% of those patients achieved a complete response or better. Complete response in multiple myeloma means minimal disease is detected based on biomarker testing.
On safety, the CAR-T therapy was well tolerated, but cases of cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome (ICANS) did crop up in trial patients. Arcellx did not offer specific safety data, but did say that the cases of cytokine syndrom were mild and only one patient developed a grade 3 ICANS event.
The data “continues to impress” analysts from SVB Securities, who compared Arcellx’s therapy to J&J and Legend’s Carvykti, which was approved in February to treat multiple myeloma after four previous therapies.
“Pretty much any way you slice the updated data, CART-ddBCMA’s efficacy outcomes are in line with the class leader, cilta-cel (Carvykti)—best response, [minimal residual disease] negativity, and measures of durability,” SVB Securities wrote in a Monday note.
Arcellx managed all this even with a higher proportion of patients with extramedullary disease in its trial compared to J&J and Legend's. That type of multiple myeloma is difficult to treat, according to SVB Securities. CART-ddBCMA may also have an advantage when it comes to manufacturing, as Arcellx’s proprietary D-domain binder technology, which uses novel synthetic proteins designed to bind to specific therapeutic targets, could help with scale-up and provide a wider window for product release, the firm said.
Shares of Arcellx were trading up 23% Monday afternoon to $16.23, compared to a prior close of $13.09.
Up next for Arcellx is another data update at the American Society for Hematology in December. The company aims to move the therapy into a phase 2 pivotal trial by the end of 2022, according to its end-of-year earnings report presented in March. SVB Securities is also awaiting details on how CART-ddBCMA will be manufactured, either in-house or through outsourcing.
All three of these pieces will need to come together for Arcellx to shake off the big question facing the small biotech: How will you launch a competing therapy against the J&J machine? SVB Securities points out that Carvykti has a notable head start and a massive investment will be required to develop and scale a commercial CAR-T like CART-ddBCMA.
J&J and Legend also featured Carvykti at ASCO, with a new round of data showing the CAR-T therapy sustained an effect in heavily pretreated multiple myeloma patients and shrank tumors when given earlier in a population.