ORLANDO – While the benefit of daratumumab added to lenalidomide, bortezomib, and dexamethasone (D-RVd) continues to improve with longer follow-up of the GRIFFIN trial, even early adopters may want to wait for additional data before declaring the combination a first-line standard for transplant-eligible multiple myeloma, according to an investigator on the trial.
D-RVd has significantly improved both response rates and depth of response, compared with RVd alone,, of Levine Cancer Institute, Atrium Health, Charlotte, N.C., reported at the annual meeting of the American Society of Hematology.
Additionally, rates of response and minimal residual disease (MRD) negativity with D-RVd have increased with longer follow-up beyond posttransplant consolidation, in the ongoing randomized phase 2 trial, Dr. Voorhees said.
“Those of you that are early adopters have good ammunition based on this result, but I would argue that we do need to confirm that the increased MRD-negative rate that we’re seeing translates into a sustained improvement in MRD negativity,” said Dr. Voorhees while presenting the updated results.
Most importantly, it needs to be confirmed that improved depth of response with D-RVd translates into an improvement in progression-free survival, not only in GRIFFIN, he said, but in PERSEUS, a large, randomized European phase 3 trial of subcutaneous daratumumab plus RVd versus RVd alone.
In the GRIFFIN trial, a total of 207 patients with transplant-eligible newly diagnosed multiple myeloma were randomized to intravenous daratumumab plus RVd versus RVd alone, with a primary endpoint of stringent complete response (sCR) by the end of consolidation.
Primary findings, presented in September at the 17th International Myeloma Workshop (IMW) meeting in Boston, indicated an sCR of 42.4% for D-RVd versus 32.0% for RVd at a median follow-up of 13.5 months, a difference that Dr. Voorhees said was statistically significant as defined by the protocol (1-sided P = .068), with an odds ratio of 1.57 (95% confidence interval, 0.87-2.82) in favor of the D-RVd arm.
With longer follow-up data, which Dr. Voorhees reported at ASH, the responses have “deepened over time” in both arms of the study, though he said the daratumumab arm continues to perform better. The sCR with 22.1 months of follow-up was 62.6% for D-RVd versus 45.4% for RVd.
The rates of MRD negativity at this clinical cutoff were 51.0% versus 20.4% for the D-RVd and RVd arms, respectively (P less than .0001), while the 24-month PFS rates were 95.8% for D-RVd and 89.8% for RVd. “Suffice it to say that both groups of patients are doing incredibly well at 2 years,” Dr. Voorhees said.
Rates of grade 3 and 4 neutropenia and thrombocytopenia were higher in the D-RVd arm, and there were more infections, though this was largely driven by an increased incidence of grade 1 or 2 upper respiratory tract infections, according to Dr. Voorhees.
Daratumumab did not impact time to engraftment, with a median CD34+ cell yield of 8.2 x 106 cells/kg for D-RVd and 9.4 x 106 cells/kg for RVd, a difference that Dr. Voorhees said was “not of clinical significance.”
Dr. Voorhees reported disclosures related to Takeda, Oncopeptides, Novartis, GSK, Janssen, Celgene, BMS, Adaptive Biotechnologies, Amgen, and TeneBio.
SOURCE: Voorhees PM et al. ASH 2019, .