Lenalidomide Maintenance Stalls Myeloma in Trio of Clinical Trials

Older Patients Ineligible for Transplant

Dr. Antonio Palumbo of the University of Turin, Italy, and his coinvestigators from the Multiple Myeloma-015 (MM-015) trial also explored continuous lenalidomide, but in a population of 459 patients aged 65 years and older who were not eligible for stem cell transplantation.

Patients were randomized to three groups: One group received induction therapy with melphalan, prednisone, and lenalidomide followed by lenalidomide maintenance (MPR-R); the second received MPR followed by placebo maintenance; and the third received only melphalan and prednisone (MP) followed by placebo. Investigators reported that about two-thirds of patients completed their induction regimens.

Median progression-free survival, the primary end point, was significantly longer in the group that received lenalidomide maintenance (31 months) than in the groups that received MPR with placebo (14 months) or MP without any lenalidomide in the induction and maintenance phases (13 months).

In a landmark analysis that looked at progression-free survival from the start of maintenance therapy, the median reached 26 months with lenalidomide vs. 7 months with placebo, with a hazard ratio of 0.34 for MPR-R vs. MPR (P less than .001).

Greater benefit was seen in patients 65-75 years of age, with median progression-free survival of 31 months with MPR-R, 15 months with MPR, and 12 months with MP. In patients over age 75, the medians were 19 months, 12 months, and 15 months, respectively.

Median overall survival at 3 years was not significantly different, reaching 70% with MPR-R, 62% with MPR, and 66% with MP.

"Altogether, these results confirm the benefits of maintenance therapy with respect to progression-free survival. The influence on overall survival remains unclear," concluded Dr. Palumbo and his coauthors (N. Engl. J. Med. 2012;366:1759-69).

Secondary Malignancies

In all three studies lenalidomide was associated with higher rates of secondary primary cancers.

• The rate was 8% in the lenalidomide group vs. 3% in the placebo group in the CALGB study.

• The IFM investigators calculated the incidence as 3.1 per 100 patient-years in their lenalidomide group vs. 1.2 per 100 patient-years with placebo (P = .002).

• In the MM-015 study, the 3-year rate was 7% with MPR-R, 7% with MPR, and 3% with MP. The increased risk was "mainly confined to acute myeloid leukemia or myelodysplastic syndromes, and is observed when lenalidomide is given with or after melphalan," the investigators wrote.

Other Adverse Events

Hematologic toxicity dominated the adverse event reports from all three studies.

• In the CALBG trial, grade 3 and 4 hematologic side effects were significantly more common with lenalidomide maintenance, as were grade 3 nonhematologic events. The most pronounced was neutropenia in 45% of the lenalidomide group vs. 15% of the placebo group (P less than .001).

• The IFM investigators also reported that grade 3 or 4 hematologic events were more frequent with lenalidomide than with placebo (58% vs. 23%, P less than .001), as were thromboembolic events (6% vs. 2%, P = .01).

• Similarly, the MM-015 group found that the most frequent adverse events were hematologic, with grade 4 neutropenia occurring in 35% of patients given lenalidomide. Nonhematologic events, including deep vein thrombosis, occurred at low rates, however, according to Dr. Palumbo and his coauthors. "Lenalidomide maintenance was associated with little evidence of cumulative toxic effects," they said.

How the safety profiles will influence adoption of lenalidomide maintenance is uncertain. "A major concern during maintenance therapy is toxicity that limits long-term use and the ability to receive future treatment after disease progression or that results in life-threatening disorders," noted Dr. McCarthy and his coauthors.

The National Cancer Institute supported the CALGB trial. Celgene, maker of lenalidomide, provided support for the IFM and MM-015 studies. The IFM trial also received support from the Programme Hospitalier de Recherche Clinique and the Swiss Group for Clinical Cancer Research (SAKK). Disclosure forms filed by individual investigators are posted at https://www.nejm.org.