MADRID – A four-drug induction regimen induced quicker and deeper remissions than sequential triplet regimens in patients with newly diagnosed multiple myeloma.
In addition, fast, deep remissions may lead to improved progression-free survival (PFS) following autologous stem cell transplantation (ASCT), said investigators from a U.K. Medical Research Council study.
In the phase 3 randomized, parallel group Myeloma XI study, very good partial responses (VGPR) or better were seen following induction in 79.5% of patients assigned to the quadruplet (KCRD) of carfilzomib (Kyprolis), cyclophosphamide, lenalidomide (Revlimid), and dexamethasone, compared with 60.8% for those assigned to cyclophosphamide, lenalidomide, and dexamethasone (CRD) and 52.8% for those assigned to cyclophosphamide, thalidomide, and dexamethasone (CTD), said Charlotte Pawlyn, MD, PhD, at the annual congress of the European Hematology Association.
“In our study, we see a very much deeper response after initial induction with the quadruplet regimen, compared with triplet regimens,” Dr. Pawlyn of the Institute of Cancer Research, London, said in an interview.
Medical Research Council investigators showed in the Myeloma IX study that among patients who had a less than VGPR to an immunomodulator-based triplet regimen such as CRD, a triplet regimen including the proteasome inhibitor bortezomib (Velcade) could improve both pre- and post-transplant response rates, and that the improved responses translated into improved PFS.
For the Myeloma XI study, the investigators employed the same response-adapted approach to compare outcomes following induction with the proteasome inhibitor–containing KCRD regimen and the lenalidomide- or thalidomide-based regimens.
Nancy B. Baron
Dr. Charlotte Pawlyn
They chose carfilzomib as the proteasome-inhibitor backbone of the quadruplet because of its selective, irreversible target binding, lower incidence of peripheral neuropathy (compared with bortezomib), and efficacy in both the frontline and relapsed/refractory setting, she said.
Asked why the comparator regimens did not contain a proteasome inhibitor, Dr. Pawlyn said that while the current standard for induction therapy in the United Kingdom is bortezomib, thalidomide, and dexamethasone, CTD was the standard of care at the time of study planning and initial enrollment.
The trial was open to all patients in the United Kingdom of all ages with newly diagnosed symptomatic multiple myeloma, with pathways for both transplant-eligible and transplant-ineligible patients. The only main exclusion criteria were for patients with dialysis-dependent renal failure and for those who had a prior or concurrent malignancy.
A total of 1,021 patients were assigned to each of the CTD and CRD cohorts, and 526 patients were assigned to the KCRD cohort. The cohorts were well balanced by sex, age, World Health Organization performance score, and other parameters.
Patients randomized to either CTD or CRD were assessed for response after a minimum of four induction cycles, with treatment continued until best response. Those with a VGPR or better went on to ASCT, while those with a partial response were randomized to either a second induction with cyclophosphamide, bortezomib, and dexamethasone (CVD) or no CVD, and then proceeded to transplant. Patients with stable disease or disease progression in either of these arms went on to CVD prior to ASCT.
In the KCRD arm, all patients went from induction to transplant. Following ASCT, patients were randomized to either observation or lenalidomide maintenance.
A higher proportion of patients assigned to KCRD completed the minimum of four induction cycles, and few patients in any trial arm had to stop induction therapy because of adverse events. Dose modifications were required in 63.9% of patients on KCRD, 56.3% of patients on CRD, and 82.2% of patients on CTD.
There was no significant cardiac signal seen in the study, and no difference in the incidence of venous thromboembolic events among the treatment arms.
As noted before, rates of VGPR or better after initial induction were highest in the KCRD arm, at 79.5%, compared with 60% for CRD, and 52.8% for CTD.
“The KCRD quadruplet achieved the highest speed and depth of response,” Dr. Pawlyn said.
The pattern of responses was similar across all cytogenetic risk groups, she added.
A higher proportion of patients treated with KCRD went on to ASCT, and the pattern of deeper responses among patients who underwent induction with KCRD persisted, with 92.1% of patients having a post-transplant VGPR or better, compared with 81.8% for CRD and 77.0% for CTD (statistical significance not shown).
Again, the pattern of responses post-transplant was similar across cytogenetic risk groups.
The investigators anticipate receiving PFS results from the Myeloma XI study in the third or fourth quarter of 2017.
The study was sponsored by the University of Leeds (England), with support from the U.K. National Cancer Research Institute, Cancer Research UK, and Myeloma UK, and collaboration with Celgene, Merck Sharp & Dohme, and Amgen. Dr. Pawlyn disclosed travel support from Celgene and Janssen, and honoraria from Celgene and Takeda.