(Reuters) -The U.S. Food and Drug Administration's staff on Wednesday raised concerns that it was unclear if Johnson & Johnson (NYSE:JNJ) and Bristol Myers (NYSE:BMY) Squibb's cancer cell therapies would benefit blood cancer patients when given as early treatments.
The staff reviewers pointed to a pattern of early deaths in late-stage trials of the two therapies, saying that it raised uncertainty about how effective the treatments were in extending the time patients live after receiving treatment.
The comments were made in briefing documents prepared ahead of a meeting of the FDA's independent advisers scheduled for Friday, which is being closely watched by investors to understand the regulator's view on CAR-T therapies after recent safety concerns over the treatments.
The therapies - J&J's Carvykti and Bristol Myers' Abecma - are approved by the FDA to treat patients with multiple myeloma who have received at least four prior lines of treatment.
The companies are seeking approval for Carvykti and Abecma as a second and third line of treatment, respectively, which could expand their use to a larger subset of patients who are less sick than those treated with multiple therapies.
In late-stage studies, both the treatments helped extend the time patients live before their disease begins to worsen. The advisory panel on Friday is expected to focus on overall survival data, the FDA's gold standard for cancer treatments.
Data for Carvykti did not clearly establish a favorable benefit-risk profile for its use as an earlier treatment, the FDA staff said.
Roughly 8% of those who received Carvykti died before their cancer worsened in the trial, higher than the 2% who received standard of care.
Even if additional overall survival data from Abecma is statistically significant, it is unlikely to overcome the risk of early deaths, reviewers said.
About 8% patients who received Abecma died before their disease progressed, higher than the 3% of patients who received standard of care therapy in the trial.
J&J partners with Legend Biotech for Carvykti, while 2seventy bio is Bristol's partner for Abecma.