Photo courtesy of ASH
ORLANDO, FL—Adding the oral proteasome inhibitor ixazomib to treatment with lenalidomide and dexamethasone can prolong progression-free survival (PFS) in patients with relapsed and/or refractory multiple myeloma (MM), according to interim results of the phase 3 TOURMALINE-MM1 trial.
It is not yet clear if the 3-drug combination can prolong overall survival when compared to treatment with lenalidomide and dexamethasone.
However, researchers believe the triplet shows promise and could become a new standard of care for relapsed/refractory MM.
Philippe Moreau, MD, of the University of Nantes in France, discussed this possibility while presenting results from TOURMALINE-MM1 at the 2015 ASH Annual Meeting (abstract 727*). The study was sponsored by Millennium Pharmaceuticals, Inc.
The trial included 722 MM patients enrolled at 147 centers in 26 countries. Patients were randomized to receive ixazomib, lenalidomide, and dexamethasone (IRd, n=360) or placebo, lenalidomide, and dexamethasone (Rd, n=362).
Baseline patient characteristics were similar between the arms. The median age was 66 in both arms (overall range, 30-91), and nearly 60% of patients in both arms were male.
Fifty percent of patients in the IRd arm and 47% in the Rd arm had an ECOG performance status of 0. Forty-three percent and 45%, respectively, had a status of 1, and 5% and 7%, respectively, had a status of 2.
Eighty-seven percent and 88%, respectively, had an ISS stage of I or II. Fifty-five percent of patients in the IRd arm had standard-risk cytogenetics, as did 60% in the Rd arm.
Fifty-nine percent of patients in both arms had received 1 prior line of therapy, and 41% in both arms had 2 or 3 prior lines.
Response and survival
“Ixazomib, when combined with len-dex . . . , was associated with a significant and meaningful improvement in progression-free survival, improved time to progression, and [higher] response rate as well,” Dr Moreau said.
At a median follow-up of about 15 months, the median PFS was 20.6 months in the IRd arm and 14.7 months in the Rd arm. The hazard ratio was 0.742 (P=0.012).
Dr Moreau said the PFS benefit was consistent across pre-specified subgroups. So the benefit was present regardless of age, ISS stage, cytogenetic risk, number of prior therapies, prior exposure to a proteasome inhibitor, prior immunomodulatory therapy, whether the patient was refractory to his last therapy, and whether the patient had relapsed or refractory disease.
Dr Moreau also pointed out that, in the IRd arm, the median PFS in high-risk patients was similar to that in the overall patient population and in patients with standard-risk cytogenetics. This suggests ixazomib may overcome the negative impact of cytogenetic alterations.
Whether IRd confers an overall survival benefit is not clear, as those data are not yet mature. At a median follow-up of about 23 months, the median overall survival was not reached in either treatment arm.
The researchers conducted a non-inferential PFS analysis at the same time point (23 months) and found the median PFS was 20 months in the IRd arm and 15.9 months in the Rd arm. The hazard ratio was 0.82.
As for other efficacy endpoints, the overall response rate was 78.3% in the IRd arm and 71.5% in the Rd arm (P=0.035). The rates of complete response were 11.7% and 6.6%, respectively (P=0.019). And the rates of very good partial response or greater were 48.1% and 39%, respectively (P=0.014).
The median time to response was 1.1 months in the IRd arm and 1.9 months in the Rd arm. The median duration of response was 20.5 months and 15 months, respectively. And the median time to progression was 21.4 months and 15.7 months, respectively.
At a median follow-up of about 23 months, patients had received a median of 17 cycles of IRd and a median of 15 cycles of Rd.
The incidence of any adverse event (AE) was 98% in the IRd arm and 99% in the Rd arm. The incidence of grade 3 or higher AEs was 74% and 69%, respectively. The incidence of serious AEs was 47% and 49%, respectively.
The incidence of AEs resulting in discontinuation was 17% and 14%, respectively. And the incidence of on-study deaths (occurring within 30 days of the last dose) was 4% and 6%, respectively.
Common AEs in the IRd and Rd arms, respectively, were diarrhea (45% vs 39%), constipation (35% vs 26%), nausea (29% vs 22%), vomiting (23% vs 12%), rash (36% vs 23%), back pain (24% vs 17%), upper respiratory tract infection (23% vs 19%), thrombocytopenia (31% vs 16%), peripheral neuropathy (27% vs 22%), peripheral edema (28% vs 20%), thromboembolism (8% vs 11%), and neutropenia (33% vs 31%).
“Ixazomib is adding limited toxicity to lenalidomide and dex, with a very low rate of peripheral neuropathy and no cardiovascular or renal adverse signals,” Dr Moreau said.
“This all-oral triplet regimen may become one of the new standards of care in the relapsed setting. [It has] a very safe profile, [is] a very effective combination, [and is] simple and convenient.”
*Data in the abstract differ from the presentation.