Recent clinical trials have demonstrated significant efficacy for pomalidomide-based combination regimens in patients with relapsed/refractory multiple myeloma, offering new treatment options for this challenging patient population.
The final overall survival analysis from the phase 3 OPTIMISMM trial (NCT01734928) has shown that combining pomalidomide (Pomalyst) with bortezomib (Velcade) and dexamethasone (PVd) yielded improved outcomes compared to bortezomib plus dexamethasone (Vd) alone in patients with lenalidomide-exposed relapsed/refractory multiple myeloma.
After a median follow-up of 64.5 months, the median overall survival was 35.6 months with PVd versus 31.6 months with Vd (HR, 0.94; 95% CI, 0.77-1.15; P = .5707). When accounting for subsequent therapies as a time-dependent covariate, researchers observed a statistically significant OS improvement with the addition of pomalidomide (HR, 0.76; 95% CI, 0.619-0.931; P = .008).
The progression-free survival benefit was particularly notable, with PVd extending median PFS to 11.7 months compared to 6.9 months with Vd alone (HR, 0.56; 95% CI, 0.46-0.68; P <.0001). This PFS advantage was consistent across clinically relevant subgroups, including patients with high-risk cytogenetics (HR, 0.59) and those previously treated with proteasome inhibitors (HR, 0.50).
"These results from OPTIMISMM are consistent with previous reports, showing improved outcomes with PVd versus Vd in patients with relapsed/refractory multiple myeloma who had received prior lenalidomide-based treatments, including patients with lenalidomide-refractory disease," noted lead study author Paul G. Richardson, MD, clinical program leader at Dana-Farber Cancer Institute and Professor of Medicine at Harvard Medical School.
Richardson emphasized that "these data reinforce that a switch in class of agent may not be necessary for patients who have become lenalidomide-refractory, although decisions should be made on an individual basis with consideration given to the patient's response to first-line lenalidomide."
Elotuzumab Plus PVd Shows Promise in Phase 2 Trial
In a complementary development, findings from a prospective phase 2 trial (NCT02718833) published in Blood Advances demonstrated that adding elotuzumab (Empliciti) to the PVd regimen (elo-PVd) exhibited efficacy and tolerability in patients with relapsed/refractory multiple myeloma who had received at least one prior line of therapy.
Among 48 patients treated with elo-PVd, the overall response rate was 56.3% (95% CI, 42.3%-69.3%). The response rate was particularly impressive in patients who had received only one prior line of therapy, reaching 73.7% (95% CI, 51.2%-88.2%), compared to 44.8% (95% CI, 28.4%-62.3%) in those with two or more prior lines.
The median progression-free survival in the overall population was 10.0 months (95% CI, 7.75-20.1) at a median follow-up of 36.8 months. For patients who had received only one prior line of therapy, the median PFS extended to 23.4 months (95% CI, 10.0-not reached).
"In this phase 2 trial of patients with relapsed/refractory disease with a median of 3 prior lines of therapy and prior treatment with lenalidomide and a proteasome inhibitor, we found that the combination of elo-PVd yielded an ORR of 56.3% and a median PFS of 10.0 months," reported Andrew J. Yee, MD, assistant professor of medicine at Harvard Medical School and clinical director of the Center for Multiple Myeloma at Massachusetts General Hospital.
Dr. Yee highlighted that "these response rates are notable given the extensive prior treatment history: 33% were previously exposed to pomalidomide, 29% to carfilzomib, and 29% to an anti-CD38 antibody; 13% of patients were penta-drug exposed."
Safety Profiles Consistent with Known Toxicities
Both regimens demonstrated manageable safety profiles consistent with the known toxicities of the individual agents.
In the OPTIMISMM trial, grade 3/4 treatment-emergent adverse effects occurred in 93.2% of patients in the PVd arm, with neutropenia (47.1%) being the most common. Serious adverse events were reported in 63.7% of PVd patients compared to 44.1% in the Vd arm.
The elo-PVd regimen's most common hematologic adverse events included neutrophil count decrease (60%; grade 3 or higher: 33%), anemia (60%, 10%), white blood cell decrease (54%, 19%), and platelet count decrease (48%, 15%). Non-hematologic adverse events included fatigue (75%, 2%), infections (75%, 33%), and upper respiratory infection (60%, 4%).
Notably, no infusion-related reactions were observed with elotuzumab in the phase 2 trial, though three grade 3 instances of rash occurred but were resolved with supportive measures.
Clinical Implications
These findings collectively support the sequencing of pomalidomide-based regimens immediately after lenalidomide treatment failure in patients with relapsed/refractory multiple myeloma. The data provide valuable insights for translating clinical trial results into real-world practice.
For patients who have become refractory to lenalidomide, these studies suggest that switching to a pomalidomide-based combination can provide meaningful clinical benefits without necessarily requiring a change in drug class. The addition of elotuzumab to the PVd regimen appears to further enhance efficacy, particularly in patients with fewer prior lines of therapy.
As multiple myeloma treatment continues to evolve, these pomalidomide-based combinations represent important additions to the therapeutic armamentarium for managing this challenging malignancy, especially for patients who have progressed on lenalidomide-containing regimens.
