Median follow up was 44 months in the new update, about 2 additional years past the earlier report.
As in the earlier analysis, adding the anti-CD38 antibody to carfilzomib and dexamethasone brought substantial benefits, including a median progression free survival (PFS) of 35.7 months versus 19.2 months with placebo, as well as a higher rates of complete response (CR, 44.1% vs. 28.5%), minimal residual disease (MRD) negativity (33.5% vs. 15.4%), and MRD negativity CR (26.3% vs. 12.2%).
Although overall survival data are not yet mature, the probability of being alive at 42 months was 66.3% with isatuximab add-on versus 54.5% with placebo.
Investigators led by Thomas G. Martin, MD, director of the University of California, San Francisco, myeloma program, noted that median PFS of nearly 3 years “is the longest PFS reported to date with a PI-based regimen in the relapsed MM [multiple myeloma] setting.” The updated results further support the combination “as a standard of care treatment for patients with relapsed MM.”
Overall, the trial adds “another effective triplet in the treatment of patients with” relapsed/refractory MM, Sergio A. Giralt, MD, head of the division of hematologic malignancies at Memorial Sloan Kettering Cancer Center, New York, said when asked for comment. The study was published May 9 in Blood Cancer Journal.
Safety similar to interim analysis
IKEMA randomized 179 patients to isatuximab add-on and 123 to placebo. Patients had relapsed/refractory MM with one to three prior treatment lines. Isatuximab was dosed at10 mg/kg IV in the open-label trial, weekly in the first cycle then biweekly.
The PFS benefit held across various subgroups, including the elderly and others with poor prognoses.
In their write-up, the investigators acknowledged isatuximab’s rival anti-CD38 antibody, daratumumab (Darzalex), which is also approved in the United States for use in combination with carfilzomib and dexamethasone for relapsed/refractory MM after one to three treatment lines.
“Although inter-trial evaluations should be interpreted with caution,” they noted that PFS in the latest analysis of daratumumab’s CANDOR trial in combination with carfilzomib and dexamethasone was shorter than in IKEMA, 28.6 months versus 15.2 months with placebo.
Like efficacy, safety in latest update of IKEMA was similar to that of the interim analysis. However, while there was no difference in the incidence of all-cause serious treatment-emergent adverse events (TEAEs) in the earlier report, the incidence was higher with isatuximab than placebo in the newest findings (70.1% vs. 59.8%).
The investigators said the difference was likely because patients in the isatuximab arm stayed on treatment longer, a median of 94 weeks versus 61.9 weeks in the placebo arm, making adverse events more likely.
The most common, nonhematologic TEAEs were infusion reactions (45.8% in the isatuximab arm vs. 3.3% in the placebo group), diarrhea (39.5% vs. 32%), hypertension (37.9% vs 35.2%), upper respiratory tract infection (37.3% vs 27%), and fatigue (31.6% vs 20.5%).
Grade 3 or higher pneumonia occurred in 18.6% patients in the isatuximab arm versus 12.3% in the placebo group. The incidence of skin cancer was 6.2% with isatuximab versus 3.3%. The incidence of treatment-emergent fatal events remained similar between study arms, 5.6% with isatuximab versus 4.9% with placebo.
The study was funded by Sanofi, maker of isatuximab. Investigators included two Sanofi employees. Others reported a range of ties to the company, including Dr. Martin, who reported research funding and sitting on a Sanofi steering committee.