A comparison of bortezomib, cyclophosphamide, and dexamethasone (Vel-CD) chemotherapy without and with thalidomide (Vel-CTD) for the treatment of relapsed or refractory multiple myeloma

Proteasome Inhibitors for the Treatment of Multiple Myeloma

Use of proteasome inhibitors (PIs) has been the therapeutic backbone of myeloma treatment over the past decade. Many PIs are being developed and evaluated in the preclinical and clinical setting. The first-in-class PI, bortezomib, was approved by the US food and drug administration in 2003. Carfilzomib is a next-generation PI, which selectively and irreversibly inhibits proteasome enzymatic activities in a dose-dependent manner. Ixazomib was the first oral PI to be developed and has a robust efficacy and favorable safety profile in patients with multiple myeloma. These PIs, together with other agents, including alkylators, immunomodulatory drugs, and monoclonal antibodies, have been incorporated into several regimens. This review summarizes the biological effects and the results of clinical trials investigating PI-based combination regimens and novel investigational inhibitors and discusses the future perspective in the treatment of multiple myeloma.

Phase II study of bortezomib, cyclophosphamide and dexamethasone as induction therapy in multiple myeloma: DSMM XI trial

We assessed the safety and efficacy of bortezomib, cyclophosphamide and dexamethasone (VCD) induction therapy in previously untreated multiple myeloma patients. A total of 414 patients received three 21-day cycles of VCD prior to autologous stem-cell transplantation (ASCT). Most common grade ≥3 adverse events were leucopenia (31·4%) and thrombocytopenia (6·8%). The overall response rate (ORR) by investigator-based assessment was 85·4%. Most patients (74%) underwent successful central laboratory-based molecular cytogenetic analysis. No clinically relevant differences in ORR post-induction were seen between patients with or without high-risk cytogenetic abnormalities (86·2% vs. 84·3%). Further follow-up data are available for 113 patients receiving ASCT who were included in a prospective consolidation trial (median follow-up, 55·5 months); median progression-free survival (PFS) was 35·3 months and median overall survival (OS) was not reached. In patients with high-risk versus standard-risk cytogenetics, median PFS was 19·9 vs. 43·6 months (P < 0·0001), and median OS was 54·7 months versus not reached (P = 0·0022). VCD is an effective and tolerable induction regimen; results suggest that VCD induces high response rates independently of cytogenetic risk status, but after long-term follow-up, cytogenetic high risk is associated with markedly reduced PFS and OS post-ASCT.

Pharmacokinetic study of bortezomib administered intravenously in Taiwanese patients with multiple myeloma

This phase 4, single-arm, non-randomized, open-label, post approval commitment study evaluated the pharmacokinetics and safety of bortezomib in Taiwanese patients with multiple myeloma. Patients (≥20 years) with measurable secretory multiple myeloma (serum monoclonal IgG ≥10, IgA/IgE ≥5, IgD ≥0.5 g/L, IgM present [regardless of level], and urine M protein of ≥200 mg/24 h) received intravenous bortezomib 1.3 mg/m² , twice weekly for 2 weeks, followed by a 10-day resting phase (days 12 to 21). Pharmacokinetics and safety were assessed at pre-specified time points. All enrolled patients (n = 18, men: 11; women: 7) completed the study. Mean (SD) C_max (maximum observed plasma concentration) on day 11 was 266 (77.5) ng/mL, approximately 60% higher compared with non-Asian patients receiving a similar bortezomib regimen but with overlapping ranges. Because of the protracted terminal phase, half-life (t_1/2 ), area under the plasma concentration-time curve from time 0 to infinity (AUC_∞ ), volume of distribution (V_z ), and systemic clearance were not assessable. All patients experienced treatment-emergent adverse events (TEAEs); 78% were drug-related. Most commonly reported TEAEs were thrombocytopenia (n = 11 [61%]), neutropenia (n = 9 [50%]), leukopenia (n = 6 [33%]), and diarrhoea (n = 6 [33%]); the most common serious adverse event was pneumonia (n = 2 [11%]). One patient had a dose reduction due to a TEAE of thrombocytopenia. Overall, bortezomib exposure (AUC) in Taiwanese patients (AUC_last [SD]: 230 [147] ng·h/mL) with twice weekly intravenous administration was comparable with non-Asian population (AUC_last [SD]: 241 [82] ng·h/mL). Bortezomib treatment was associated with manageable toxicity profile and did not limit the continuity of therapy.

Mature adipocytes in bone marrow protect myeloma cells against chemotherapy through autophagy activation

A major problem in patients with multiple myeloma is chemotherapy resistance, which develops in myeloma cells upon interaction with bone marrow stromal cells. However, few studies have determined the role of bone marrow adipocytes, a major component of stromal cells in the bone marrow, in myeloma chemotherapy resistance. We reveal that mature human adipocytes activate autophagy and upregulate the expression of autophagic proteins, thereby suppressing chemotherapy-induced caspase cleavage and apoptosis in myeloma cells. We found that adipocytes secreted known and novel adipokines, such as leptin and adipsin. The addition of these adipokines enhanced the expression of autophagic proteins and reduced apoptosis in myeloma cells. In vivo studies further demonstrated the importance of bone marrow-derived adipocytes in the reduced response of myeloma cells to chemotherapy. Our findings suggest that adipocytes, adipocyte-secreted adipokines, and adipocyte-activated autophagy are novel targets for combatting chemotherapy resistance and enhancing treatment efficacy in myeloma patients.

The MUK five protocol: a phase II randomised, controlled, parallel group, multi-centre trial of carfilzomib, cyclophosphamide and dexamethasone (CCD) vs. cyclophosphamide, bortezomib (Velcade) and dexamethasone (CVD) for first relapse and primary refractory multiple myeloma

Background

Multiple myeloma is a plasma cell tumour with an annual incidence in the UK of approximately 40–50 per million i.e. about 4500 new cases per annum. The triple combination cyclophosphamide, bortezomib (Velcade®) and dexamethasone (CVD) is an effective regimen at relapse and has emerged in recent years as the standard therapy at first relapse in the UK. Carfilzomib has good activity as a single agent in the relapsed setting, and it is expected that efficacy will be improved when used in combination with dexamethasone and cyclophosphamide.

Methods

MUK Five is a phase II open label, randomised, controlled, parallel group, multi-centre trial that will compare the activity of carfilzomib, cyclophosphamide and dexamethasone (CCD) with that of CVD, given over an equivalent treatment period (24 weeks), in participants with multiple myeloma at first relapse, or refractory to no more than 1 line of treatment. In addition, the study also aims to assess the utility of a maintenance schedule of carfilzomib in these participants. The primary objective of the trial is to assess whether CCD provides non-inferior activity in terms of ≥ VGPR rates at 24 weeks, and whether the addition of maintenance treatment with carfilzomib to CCD provides superior activity in terms of progression-free survival, as compared to CCD with no maintenance. Secondary objectives include comparing toxicity profiles, further summarizing and comparing the activity of the different treatment arms and analysis of the effect of each treatment arm on minimal residual disease status.

Discussion

The development of carfilzomib offers the opportunity to further explore the anti-tumour efficacy of proteasome inhibition and, based on the available evidence, it is important and timely to obtain data on the activity, toxicity and tolerability of this drug. In contrast to ongoing phase III trials, this phase II trial has a unique subset of participants diagnosed with multiple myeloma at first relapse or refractory to no more than 1 line of treatment and will also evaluate the utility of maintenance with carfilzomib for up to 18 months and investigate minimal residual disease status to provide information on depth of response and the prognostic impact thereof.

Trial registration

The trial is registered under ISRCTN17354232, December 2012.

Clinical outcome of bortezomib retreatment in patients with relapsed or refractory multiple myeloma

This retrospective study investigated the clinical efficacy and safety of bortezomib retreatment in patients with relapsed or refractory multiple myeloma (MM). A total of 30 patients who relapsed or progressed after ≥6 months since the last dose of their previous bortezomib therapy were included in this study. During the median 6 cycles (range: 2-12) of bortezomib retreatment, 10 (33.3%), 2 (6.7%), and 6 (20.0%) patients achieved complete response, very good partial response, and partial response, respectively. Grade 3 or 4 neutropenia (47.0%), thrombocytopenia (43.0%), anemia (10.0%), and peripheral sensory neuropathy (3.0%) were observed. The median time to progression, progression-free survival, and overall survival were 5.8 months (95% CI: 2.6-9.0), 5.5 months (95% CI: 4.2-6.8), and 13.4 months (95% CI: 6.1-20.7), respectively. Patients who received bortezomib retreatment ≥12 months from initial last therapy had a 1-year OS rate of 65.8% (95% CI: 43.5-88.1) while patients receiving retreatment after 6-12 months interval had a 1-year OS rate of 41.7% (95% CI: 13.9-69.5) (P = 0.038). In conclusion, this study demonstrates that retreatment with bortezomib is an effective strategy for patients with MM who relapsed at a long interval after initial bortezomib therapy.

Weekly intravenous bortezomib is effective and well tolerated in relapsed/refractory myeloma

OBJECTIVES

Bortezomib is an effective antimyeloma therapy, but clinical benefits can be limited by neurotoxicity. In newly diagnosed, older patients, modification of the biweekly dosing schedule to weekly regimens improves tolerability whilst maintaining efficacy. There is less information on the efficacy and tolerability of weekly bortezomib regimens in the relapsed/refractory setting. Here, we report our experience of weekly intravenous bortezomib in clinical practice in relapsed/refractory patients.

METHODS

We analysed fifty-two patients who received weekly bortezomib for relapsed/refractory MM.

RESULTS

Thirty-one per cent of patients received bortezomib beyond first relapse. Almost all (94%) also received steroids and 48% also received an alkylator. The median cumulative dose was 22.6 mg/m(2) , and median length of treatment was 164 d. Three patients reported grade 2 sensory neuropathy, and one reported grade 3 motor neuropathy. There were no grade 4 neurotoxicities. Eighty-three per cent achieved a PR or greater, and the median PFS for the whole group was 13 months. One-year PFS and OS were 53% (95% CI 39-66.6%) and 78% (95% CI 66.7-89.6%), respectively.

CONCLUSIONS

Weekly intravenous bortezomib when used in combination with steroids ± alkylator is effective in relapsed/refractory MM, producing outcomes comparable with biweekly regimens and with lower rates of peripheral neuropathy.

Efficacy of bortezomib as first-line treatment for patients with multiple myeloma

Recent years have seen a dramatic change in the approach towards diagnosing and treating Multiple Myeloma. Newer and more target specific approach to treatment has prolonged the survival for patients with multiple myeloma. The proteasome inhibitors make an important class of anti-myeloma drugs that disrupts the proteolytic machinery of the tumor cells preferentially, enhancing their susceptibility to apoptosis. Bortezomib, in particular has shown significant clinical efficacy in myeloma treatment. It is the most commonly used proteasome inhibitor and has been tested to be effective in prolonging the overall survival in several trials. Its combinations with cyclophosphamide and dexamethasone are the treatment of choice for standard risk patients following the mSMART guidelines. The success with its lower dosage in elderly and its proven efficacious subcutaneous usage makes Bortezomib a useful agent for maximizing patient compliance and minimizing therapy related toxicity and costs. This review discusses several trials where Bortezomib has been used as a single/combination agent for front-line treatment of multiple myeloma.

A prospective, international phase 2 study of bortezomib retreatment in patients with relapsed multiple myeloma

Multiple myeloma (MM) typically follows a relapsing course with many patients requiring multiple therapies. This single-arm phase 2 study prospectively evaluated the efficacy and safety of bortezomib retreatment in MM patients who had relapsed after achieving at least a partial response (≥ PR) to prior bortezomib-based therapy. Patients aged ≥ 18 years, with measurable, secretory MM, who relapsed ≥ 6 months after prior bortezomib treatment were eligible. Patients received up to eight cycles of bortezomib (± dexamethasone). The primary endpoint was best confirmed response at retreatment; secondary endpoints included duration of response (DOR), time to progression (TTP), and safety. Adverse events (AEs) were graded by National Cancer Institute Common Terminology Criteria for Adverse Events version 3.0. A total of 130 patients (median of two prior lines of therapy) were enrolled and received retreatment. At retreatment, 28% and 72% of patients received bortezomib and bortezomib-dexamethasone, respectively. Overall response rate was 40%. In patients who achieved ≥ PR, median DOR and TTP were 6.5 and 8.4 months, respectively. Thrombocytopenia was the most common grade ≥ 3 AE (35%). Forty percent of patients experienced neuropathy events, which improved and resolved in a median of 1.5 and 8.9 months, respectively. In conclusion, bortezomib retreatment was effective and tolerable in relapsed MM patients, with no evidence of cumulative toxicities.