Phase 1 study of selinexor plus carfilzomib and dexamethasone for the treatment of relapsed/refractory multiple myeloma

Selinexor, an oral Selective Inhibitor of Nuclear Export, targets Exportin 1 (XPO1, also termed CRM1). Non-clinical studies support combining selinexor with proteasome inhibitors (PIs) and corticosteroids to overcome resistance in relapsed/refractory multiple myeloma (RRMM). We conducted a phase I dose-escalation trial of twice-weekly selinexor in combination with carfilzomib and dexamethasone (SKd) to determine maximum tolerated dose in patients with RRMM (N = 21), with an expansion cohort to assess activity in carfilzomib-refractory disease and identify a recommended phase II dose (RP2D). During dose escalation, there was one dose-limiting toxicity (cardiac failure). The RP2D of twice-weekly SKd was selinexor 60 mg, carfilzomib 20/27 mg/m² and dexamethasone 20 mg. The most common grade 3/4 treatment-emergent adverse events included thrombocytopenia (71%), anaemia (33%), lymphopenia (33%), neutropenia (33%) and infections (24%). Rates of ≥minimal response, ≥partial response and very good partial response were 71%, 48% and 14%, respectively; similar response outcomes were observed for dual-class refractory (PI and immunomodulatory drug)/quad-exposed (carfilzomib, bortezomib, lenalidomide and pomalidomide) patients (n = 17), and patients refractory to carfilzomib in last line of therapy (n = 13). Median progression-free survival was 3·7 months, and overall survival was 22·4 months in the overall population. SKd was tolerable and re-established disease control in RRMM patients, including carfilzomib-refractory patients. Registered at ClinicalTrials.gov (NCT02199665)     

Overall survival of relapsed and refractory multiple myeloma patients after adjusting for crossover in the MM‐003 trial for pomalidomide plus low‐dose dexamethasone

In the phase III MM‐003 trial, pomalidomide plus low‐dose dexamethasone (POM+LoDEX) improved overall survival (OS) versus high‐dose dexamethasone (HiDEX) in 455 patients with relapsed and refractory multiple myeloma (RRMM) after treatment with bortezomib and lenalidomide. Here, a two‐stage Weibull method was used to adjust for the crossover of patients in the HiDEX arm to pomalidomide‐based therapy. The adjusted difference in median OS between patients in the POM+LoDEX and HiDEX arms was 7·0 months (12·7 vs. 5·7 months, respectively). These findings provide important evidence for understanding the clinical efficacy of pomalidomide on OS benefits seen in RRMM patients.     

Pomalidomide plus low-dose dexamethasone in relapsed refractory multiple myeloma after lenalidomide treatment failure

Patients with relapsed/refractory multiple myeloma (RRMM) for whom the benefits of lenalidomide have been exhausted in early treatment lines need effective therapies. In cohort A of the phase 2 MM-014 trial, we examined the safety and efficacy of pomalidomide plus low-dose dexamethasone immediately after lenalidomide-based treatment failure in patients with RRMM and two prior lines of therapy. Pomalidomide 4 mg was given on days 1 to 21 of 28-day cycles. Dexamethasone 40 mg (20 mg for patients aged >75 years) was given on days 1, 8, 15 and 22 of 28-day cycles. The primary endpoint was overall response rate (ORR), and secondary endpoints included progression-free survival (PFS), overall survival (OS) and safety. The intention-to-treat population comprised 56 patients; all received prior lenalidomide (87·5% lenalidomide refractory) and 39 (69·6%) received prior bortezomib. ORR was 32·1% (28·2% in the prior-bortezomib subgroup). Median PFS was 12·2 months (7·9 months in the prior-bortezomib subgroup). Median OS was 41·7 months (38·6 months in the prior-bortezomib subgroup). The most common grade 3/4 treatment-emergent adverse events were anaemia (25·0%), pneumonia (14·3%) and fatigue (14·3%). These findings support earlier sequencing of pomalidomide-based therapy in lenalidomide-pretreated patients with RRMM, including those who have become refractory to lenalidomide. Trial registration: www.ClinicalTrials.gov identifier NCT01946477.     

Expanded safety experience with lenalidomide plus dexamethasone in relapsed or refractory multiple myeloma

Lenalidomide gained Food and Drug Administration (FDA) approval for treatment of patients with relapsed or refractory multiple myeloma (MM) in combination with dexamethasone in June 2006. In April 2005, the FDA and patient advocacy groups requested an expanded access programme to both provide lenalidomide to patients likely to benefit and obtain additional safety information. Relapsed/refractory MM patients received lenalidomide 25 mg/d (days 1–21) and dexamethasone 40 mg/d (days 1–4, 9–12, and 17–20 of cycles 1–4; days 1–4 only from cycle 5 onwards), in 4-week cycles until disease progression, study drug discontinuation, or lenalidomide approval. Of the 1438 patients enrolled, ∼60% were male, median age was 64 years, and 61·7% had Durie-Salmon stage III disease. Median time on study was 15·4 weeks (range: 0·1–49·1) and median dose was 25 mg. The most common adverse events (AEs) were haematological (49%), gastrointestinal (59%), and fatigue (55%). The most common grade ≥3 AEs were haematological (45%), fatigue (10%), and pneumonia (7%). The most common serious AEs were pneumonia (8%), pyrexia (4%), and deep-vein thrombosis (3%). Primary cause of death was disease progression (10%). Safety data confirmed known AEs of lenalidomide plus dexamethasone therapy in patients with relapsed/refractory MM.     

Synergistic anti‐myeloma activity of the proteasome inhibitor marizomib and the IMiD® immunomodulatory drug pomalidomide

The proteasome inhibitor bortezomib is an effective therapy for the treatment of relapsed and refractory multiple myeloma (RRMM); however, prolonged treatment can be associated with toxicity, peripheral neuropathy and drug resistance. Our earlier studies showed that the novel proteasome inhibitor marizomib is distinct from bortezomib in its chemical structure, mechanisms of action and effects on proteasomal activities, and that it can overcome bortezomib resistance. Pomalidomide, like lenalidomide, has potent immunomodulatory activity and has been approved by the US Food and Drug Administration for the treatment of RRMM. Here, we demonstrate that combining low concentrations of marizomib with pomalidomide induces synergistic anti‐MM activity. Marizomib plus pomalidomide‐induced apoptosis is associated with: (i) activation of caspase‐8, caspase‐9, caspase‐3 and PARP cleavage, (ii) downregulation of cereblon (CRBN), IRF4, MYC and MCL1, and (iii) suppression of chymotrypsin‐like, caspase‐like, and trypsin‐like proteasome activities. CRBN‐siRNA attenuates marizomib plus pomalidomide‐induced MM cells death. Furthermore, marizomib plus pomalidomide inhibits the migration of MM cells and tumour‐associated angiogenesis, as well as overcomes cytoprotective effects of bone marrow microenvironment. In human MM xenograft model studies, the combination of marizomib and pomalidomide is well tolerated, inhibits tumour growth and prolongs survival. These preclinical studies provide the rationale for on‐going clinical trials of combined marizomib and pomalidomide to improve outcome in patients with RRMM.     

Elotuzumab in combination with thalidomide and low‐dose dexamethasone: a phase 2 single‐arm safety study in patients with relapsed/refractory multiple myeloma

Elotuzumab is an immunostimulatory, humanized immunoglobulin G1 monoclonal antibody that selectively targets and kills signalling lymphocytic activation molecule family member 7–expressing myeloma cells. We evaluated the safety and tolerability of elotuzumab 10 mg/kg combined with thalidomide 50–200 mg and dexamethasone 40 mg (with/without cyclophosphamide 50 mg) in patients with relapsed/refractory multiple myeloma (RRMM). The primary endpoint was the proportion of grade ≥3 non‐haematological adverse events (AEs); other endpoints included the number of dose reductions/discontinuations and efficacy. Forty patients were treated, who had a median of three previous therapies, including bortezomib (98%) and lenalidomide (73%). Grade ≥3 non‐haematological AEs were reported in 63% of patients, most commonly asthenia (35%) and peripheral oedema (25%). Six (15%) patients had an infusion reaction. Twenty‐six (65%) patients had ≥1 dose reduction/discontinuation due to an AE, none related to elotuzumab. Overall response rate was 38%; median progression‐free survival was 3·9 months. Median overall survival was 16·3 months and the 1‐year survival rate was 63%. Minimal incremental toxicity was observed with addition of elotuzumab to thalidomide/dexamethasone with or without cyclophosphamide, and efficacy data suggest clinical benefit in a highly pre‐treated population. Elotuzumab combined with thalidomide may provide an additional treatment option for patients with RRMM.     

A systematic review of phase II trials of thalidomide/dexamethasone combination therapy in patients with relapsed or refractory multiple myeloma

Thalidomide monotherapy in relapsed/refractory multiple myeloma (MM) has a response rate of 30%. The combination of thalidomide with dexamethasone (Thal/Dex) is expected to improve responses, but it is unknown if the combination increases the rate of adverse events. Here, we conducted a systematic review of studies evaluating Thal/Dex in relapsed/refractory MM. Twelve studies were included, comprising 451 patients. The response rate (CR and PR) was 46% (95% CI 42-51%). Therapy-related toxicity was comparable to thalidomide monotherapy and included somnolence (26%, 95% CI 22-31%), constipation (37%, 95% CI 32-42%) and peripheral neuropathy (27%, 95% CI 23-32%). Only venous thromboembolism appeared to occur more often with Thal/Dex (5%, 95% CI 3-8%). Thus, using Thal/Dex results in an improved response rate in relapsed/refractory MM, with a toxicity rate comparable to thalidomide monotherapy.     

Lenalidomide,bendamustine and prednisolone exhibits a favourable safety and efficacy profile in relapsed or refractory multiple myeloma: final results of a phase 1 clinical trial OSHO – #077

This phase 1 dose finding study tested a combination of lenalidomide, bendamustine and prednisolone (RBP) in 21 patients in five cohorts with advanced multiple relasped/refractory myeloma (MM) to determine the maximum tolerable dose (MTD) of the combination. The first cohort received a starting dose of lenalidomide 10 mg/d, days 1–21, bendamustine 60 mg/m²/d, days 1–2, and prednisolone 100 mg/d, days 1–4. Dose escalation was done in cohorts of three to six patients with lenalidomide dose increasing to 15, 20 and 25 mg, and after reaching 25 mg/d, bendamustine was increased to 75 mg/m². A total of 21 patients were enrolled and all completed at least two cycles. Two patients developed dose‐limiting haemotoxicity: one patient on lenalidomide 25 mg/d and bendamustine 60 mg/m² and another patient at the highest dose level (lenalidomide 25 mg/d and bendamustine 75 mg/m²). The MTD was not reached. Sixteen patients (76%) responded after at least two cycles of RBP with one stringent complete response (CR), one near CR, five very good partial response and nine partial response. After a median observation time of 16 months, progression‐free survival at 18 months was 48% and overall survival was 64%. In conclusion, RBP with lenalidomide 25 mg/d, days 1–21 and bendamustine 75 mg/m² days 1–2 is well tolerated in patients with relapsed/refractory MM.     

Bortezomib plus dexamethasone is highly effective in relapsed and refractory myeloma patients but responses are short‐lived

Objectives: Bortezomib has proven to be effective as single agent in myeloma patients. Aim of this study was to evaluate the efficacy and toxicity of bortezomib in combination with dexamethasone in a cohort of multiple myeloma (MM) relapsed/refractory patients treated in a single center. Patients and Methods: In this single center study, 70 patients were treated with bortezomib alone (9) or in combination with dexamethasone (61). Results: Forty‐one patients (59%) achieved at least a partial response (PR), including 7% complete response (CR), 36% very good partial response (VGPR) reaching the best response within four cycles. The duration of response was significantly longer for patients achieving CR/VGPR than for those achieving PR (7.3 vs. 3.8 months, P = 0.03). Likewise, time to progression, time to alternative treatment, and treatment free interval were significantly better for patients obtaining CR/VGPR (6.8, 9.4, 6.5 months respectively) as compared with PR (4.9, 6.3, 2 months respectively). The only dose‐limiting toxicity was peripheral neuropathy (PN), which occurred in 38/70 patients (55%) and was of grade 3–4 in 12 (17%). PN led to a dose reduction or treatment discontinuation in 17 (24%) patients. Complete resolution or improvement of PN occurred in 29/38 (76%) after a median time of 100 d (range: 17–202). Conclusions: Bortezomib in combination with dexamethasone is highly effective in relapsed/refractory MM producing an impressive rate of CR/VGPR, but responses are short‐lived.     

Ibrutinib alone or with dexamethasone for relapsed or relapsed and refractory multiple myeloma: phase 2 trial results

Novel therapies with unique new targets are needed for patients who are relapsed/refractory to current treatments for multiple myeloma. Ibrutinib is a first‐in‐class, once‐daily, oral covalent inhibitor of Bruton tyrosine kinase, which is overexpressed in the myeloma stem cell population. This study examined various doses of ibrutinib ± low‐dose dexamethasone in patients who received ≥2 prior lines of therapy, including an immunomodulatory agent. Daily ibrutinib ± weekly dexamethasone 40 mg was assessed in 4 cohorts using a Simon 2‐stage design. The primary objective was clinical benefit rate (CBR; ≥minimal response); secondary objectives included safety. Patients (n = 92) received a median of 4 prior regimens. Ibrutinib + dexamethasone produced the highest CBR (28%) in Cohort 4 (840 mg + dexamethasone; n = 43), with median duration of 9·2 months (range, 3·0–14·7). Progression‐free survival was 4·6 months (range, 0·4–17·3). Grade 3–4 haematological adverse events included anaemia (16%), thrombocytopenia (11%), and neutropenia (2%); grade 3–4 non‐haematological adverse events included pneumonia (7%), syncope (3%) and urinary tract infection (3%). Ibrutinib + dexamethasone produced notable responses in this heavily pre‐treated population. The encouraging efficacy, coupled with the favourable safety and tolerability profile of ibrutinib, supports its further evaluation as part of combination treatment.     

Phase 2 study of all-oral ixazomib,cyclophosphamide and low-dose dexamethasone for relapsed/refractory multiple myeloma

There is a need for efficacious, convenient treatments with long-term tolerability for patients with relapsed/refractory multiple myeloma (RRMM). This phase 2 study evaluated the all-oral combination of ixazomib, cyclophosphamide and dexamethasone (ICd). Patients with RRMM received ixazomib 4 mg and cyclophosphamide 300 mg/m² on days 1, 8 and 15, and dexamethasone 40 mg on days 1, 8, 15 and 22 in 28-day cycles. The primary endpoint was overall response rate (ORR). Seventy-eight patients were enrolled (median age 63·5 years). At data cut-off, patients had received a median of 12 treatment cycles; 31% remained on treatment. ORR was 48% [16% very good partial response or better (≥VGPR)]. ORR was 64% and 32% in patients aged ≥65 and <65 years (25% and 16% ≥VGPR), respectively. At a median follow-up of 15·2 months, median progression-free survival (PFS) was 14·2 months, with a trend towards better PFS in patients aged ≥65 years vs. <65 years (median 18·7 months vs. 12·0 months; hazard ratio 0·62, P = 0·14). ICd was well tolerated. The most common treatment-emergent adverse events were diarrhoea (33%), nausea (24%), upper respiratory tract infection (24%), and thrombocytopenia (22%); 10 patients (13%) had peripheral neuropathy (one grade 3). This study is registered at ClinicalTrials.gov (NCT02046070).