A Gilead cancer drug whose developments have essentially been halted not only failed to improve survival odds for blood cancer patients but also came with worrying safety risks — including a higher number of deaths in one trial — according to detailed data from two Phase 3 studies.
The drug, magrolimab, was the centerpiece of Gilead’s $4.9 billion buyout of the biotech Forty Seven in 2020. But it has run into repeated setbacks, and earlier this year the company stopped patient enrollment in solid tumor trials with the drug, and halted trials in blood cancer.
Gilead had revealed some details of the trials and the safety signals it uncovered, but the data unveiled Friday at the European Hematology Association meeting contained more details from the studies. In one Phase 3 trial, dubbed ENHANCE, over 500 patients with high-risk myelodysplastic syndromes — a precursor disease to acute myeloid leukemia — received either magrolimab and standard treatment, or placebo plus standard treatment.
Patients in the magrolimab arm appeared to die sooner than those not getting the drug, by about three months, though those results weren’t statistically significant (p=0.13).
The drug showed high rates of side effects, as well: 42.6% of patients in the magrolimab arm experienced anemia compared to 21.2% in the placebo arm. And 24% of patients in the experimental group discontinued the study, twice the rate of the placebo group.
A second study, known as ENHANCE-3, enrolled a group of 378 acute myeloid leukemia patients who weren’t eligible for intensive chemotherapy. In this study, patients received either magrolimab or placebo on top of azacitidine and Venclexta.
Patients who received magrolimab in this trial survived a median of 11.7 months compared to 10.4 months for the placebo group — a difference that was not statistically significant.
However, there were 10 more deaths in the magrolimab arm than in the comparator arm (68 vs. 58), including a higher rate of fatal adverse events and fatal infections in the magrolimab arm, as well as a higher incidence of grade 3+ anemia.
Gilead has also been facing scrutiny as of late over its purchase of Immunomedics for $20 billion after Trodelvy, an antibody-drug conjugate key to that buyout, failed Phase 3 trials in lung cancer and bladder cancer. The company’s shares are down 22% since the beginning of the year.