Once-weekly (70 mg/m2 ) vs twice-weekly (56 mg/m2 ) dosing of carfilzomib in patients with relapsed or refractory multiple myeloma: A post hoc analysis of the ENDEAVOR, A.R.R.O.W., and CHAMPION-1 trials.

Combination of carfilzomib with dexamethasone (Kd) is approved for use in relapsed and/or refractory multiple myeloma (RRMM), with carfilzomib administered twice weekly at 56 mg/m2 (Kd56 BIW) or once weekly at 70 mg/m2 (Kd70 QW). Post hoc cross-trial comparisons were performed to compare efficacy and safety profiles of Kd70 QW vs Kd56 BIW dosing schedules using data from three trials of patients with RRMM: A.R.R.O.W., CHAMPION-1, and ENDEAVOR. To select for comparable patient populations, side-by-side efficacy and safety comparisons were performed in subgroups of patients with 2-3 prior lines of therapy who were not refractory to bortezomib. The overall response rate (ORR) was 69.9% (95% confidence interval [CI], 61.7-77.2) for Kd70 QW and 72.4% (95% CI, 65.9-78.2) for Kd56 BIW. Median progression-free survival (PFS) was 12.1 months (95% CI, 8.4-14.3) for Kd70 QW and 14.5 months (95% CI, 10.2-not evaluable) for Kd56 BIW. Frequency of grade ≥ 3 adverse events (AEs) was 67.6% for Kd70 QW and 85.3% for Kd56 BIW. Regression analyses (adjusting for prognostic factors) of all patients in the trials who received Kd70 QW vs Kd56 BIW estimated a PFS hazard ratio of 0.91 (95% CI, 0.69-1.19; P = .47) and an ORR odds ratio of 1.12 (95% CI, 0.74-1.69; P = .61). These results suggest that Kd70 QW has a comparable efficacy profile compared with Kd56 BIW and represents a convenient and well-tolerated treatment for patients with RRMM.

Thalidomide-prednisone maintenance following autologous stem cell transplant for multiple myeloma: effect on thrombin generation and procoagulant markers in NCIC CTG MY.10.

Venous thromboembolism (VTE) has an increased incidence in patients with multiple myeloma (MM), especially during chemotherapy. Mechanisms including upregulation of procoagulant factors, such as factor VIII, have been postulated. The National Cancer Institute of Canada Clinical Trials Group MY.10 phase III clinical trial compared thalidomide-prednisone to observation for 332 patients with MM post-autologous stem cell transplantation (ASCT), with a primary endpoint of overall survival and various secondary endpoints including the incidence of VTE. One hundred and fifty-three patients had biomarker data, including D-dimer, factor VIII and thrombin anti-thrombin (TAT) levels collected post-ASCT at baseline and 2 months after intervention investigating in-vivo thrombin generation. Differences between the time-points included a significant reduction over time in D-dimer, factor VIII and TAT levels in the observation group and sustained elevation of D-dimer, significant increase in factor VIII and reduction in TAT levels in the thalidomide-prednisone group. Eight VTE events were reported in this subset of study patients, all in the thalidomide-prednisone arm, with a trend to increase in D-dimer levels over time in those patients with VTE. This study provides physiological and clinical evidence for an increased risk of VTE associated with thalidomide-prednisone maintenance therapy post-ASCT for MM.

D(T)PACE as salvage therapy for aggressive or refractory multiple myeloma.

Dexamethasone ± thalidomide with infusion of cisplatin, doxorubicin, cyclophosphamide, and etoposide [D(T)PACE] is generally reserved as salvage therapy for aggressive multiple myeloma (MM) or plasma cell leukaemia (PCL) resistant to conventional therapies. The efficacy and durability of this potentially toxic regimen in this setting is unclear. We identified 75 patients who received D(T)PACE for relapsed/refractory MM at two tertiary care centres: Princess Margaret Hospital, Toronto and Mayo Clinic Arizona. At time of D(T)PACE, 16 patients had PCL and three patients had leptomeningeal disease. Patients were heavily pretreated (median three prior regimens, range 1-12; prior autologous stem cell transplant [ASCT] 33%). Overall response rate was 49% (very-good partial response 16%, partial response 33%) with stable disease in an additional 36%. Median progression-free survival (PFS) was 5·5 months (95% confidence interval [CI]:4·3-9·8); overall survival (OS) 14·0 months (95% CI:8·7-19·3). Thirty-five patients proceeded to ASCT or clinical trial, with median PFS for this subset of 13·4 months (95% CI:7·7-20·1) and OS 20·5 months (95% CI:14·8-63·8). D(T)PACE is an effective salvage therapy for heavily pretreated MM patients. Although the overall response rate of 49% in this poor prognosis cohort is reasonable, the PFS is short, suggesting the best role for D(T)PACE is in bridging to definitive therapy, such as transplantation.

IMWG consensus on maintenance therapy in multiple myeloma.

Maintaining results of successful induction therapy is an important goal in multiple myeloma. Here, members of the International Myeloma Working Group review the relevant data. Thalidomide maintenance therapy after autologous stem cell transplantation improved the quality of response and increased progression-free survival (PFS) significantly in all 6 studies and overall survival (OS) in 3 of them. In elderly patients, 2 trials showed a significant prolongation of PFS, but no improvement in OS. A meta-analysis revealed a significant risk reduction for PFS/event-free survival and death. The role of thalidomide maintenance after melphalan, prednisone, and thalidomide is not well established. Two trials with lenalidomide maintenance treatment after autologous stem cell transplantation and one study after conventional melphalan, prednisone, and lenalidomide induction therapy showed a significant risk reduction for PFS and an increase in OS in one of the transplant trials. Maintenance therapy with single-agent bortezomib or in combination with thalidomide or prednisone has been studied. One trial revealed a significantly increased OS with a bortezomib-based induction and bortezomib maintenance therapy compared with conventional induction and thalidomide maintenance treatment. Maintenance treatment can be associated with significant side effects, and none of the drugs evaluated is approved for maintenance therapy. Treatment decisions for individual patients must balance potential benefits and risks carefully, as a widely agreed-on standard is not established.

Bortezomib therapy response is independent of cytogenetic abnormalities in relapsed/refractory multiple myeloma.

Myeloma patients with unfavorable molecular cytogenetics have a poor prognosis irrespective of treatment with conventional chemotherapy or autologous stem cell transplant. To investigate whether bortezomib, a new proteasome inhibitor, is active in relapsed/refractory myeloma patients with genetic risk factors, we evaluated the outcome of 65 patients and correlated the clinical response with 13q deletion, translocations t(11;14) and t(4;14) and CKS1B amplification as detected by interphase cytoplasmic fluorescence in situ hybridization (cIg-FISH). Thirty-seven of 61 (61%) evaluable patients had an objective response to bortezomib with median progression free (PFS) and overall survivals (OS) of 9.5 and 15.1 months, respectively. Of 43 cases with evaluable bone marrows, cIg-FISH determination of del(13q), t(4;14), t(11;14) and CKS1B amplification was done on 40, 41, 41 and 37 cases and the frequency of their detection was 35%, 15%, 15%, and 32%, respectively. There was no statistically significant difference in response to bortezomib for patients with or without 13q deletion (77% versus 50%), t(4;14) (67% versus 56%), t(11;4) (33% versus 62%), or CKS1B amplification (67% versus 57%). Furthermore, there was no statistically significant difference in PFS or OS following bortezomib therapy between patients with or without these molecular cytogenetic abnormalities. Our data suggest that, in this pilot study, bortezomib is an effective salvage therapy for refractory/relapsed myeloma, irrespective of genetic risk factors.