FDA accepts BLA filing for Sanofi's rival to J&J's Darzalex 

The FDA has accepted Sanofi’s filing for approval of its Darzalex rival in relapsed/refractory multiple myeloma. Sanofi will learn whether the FDA will approve anti-CD38 antibody isatuximab by the end of April 2020. 

Isatuximab impressed at the American Society of Clinical Oncology's (ASCO's) annual meeting last month with phase 3 data linking its addition to pomalidomide and dexamethasone to a 40% reduction in the risk of disease progression. The data established isatuximab as a legitimate rival to Johnson & Johnson’s Darzalex, particularly as Sanofi’s drug has a shorter infusion time and lower rate of infusion-related reactions.

Sanofi could gain the chance to challenge J&J in the U.S. next year. The FDA recently accepted a filing for approval of the drug, setting a PDUFA date of April 30. The FDA action comes shortly after its European counterpart accepted a filing for approval in its jurisdiction.

Winning approval would set Sanofi up to eat away at J&J’s blockbuster franchise and turn isatuximab, which it developed with ImmunoGen, into the poster child for its efforts to rely more heavily on its own R&D teams. Analysts at Jefferies expect global sales of isatuximab to peak at $1 billion. 

Darzalex sales fell short of analyst expectations at points during 2018, but the drug has nonetheless made a fast start. Sales topped $2 billion last year and, boosted by first-quarter sales of $629 million, are on track to grow again in 2019. Those figures show the opportunity available to isatuximab is far bigger than its sales forecast suggests, but some analysts doubt it will take a big slice of the market. 

“Whilst feedback suggests we cannot yet say if one is superior to the other, or how/if they could be cycled, we feel that Darzalex's entrenched position is unlikely to be threatened on data to-date, particularly given a subcutaneous formulation [of Darzalex] could be approved during 2020,” analysts at Jefferies wrote in a note to investors following the publication of data at ASCO last month.

The subcutaneous formulation could negate isatuximab’s current advantages over Darzalex. A phase 3 trial of the subcutaneous version found it was noninferior to the approved intravenous formulation. The infusion time of the subcutaneous version is five minutes compared to up to seven hours for the intravenous formulation, and the phase 3 linked it to a far lower rate of infusion-related reactions.

Neither J&J nor Sanofi is standing still. Sanofi is running phase 3 trials designed to show isatuximab is effective in a wider range of multiple myeloma patients. J&J, which has already won approval in some newly diagnosed patients, is continuing to work to improve and expand use of Darzalex, while also keeping tabs on a potential successor through an agreement with Genmab.