Lenalidomide plus dexamethasone is more effective than high-dose dexamethasone alone in relapsed or refractory multiple myeloma. (ClinicalTrials.gov number, NCT00424047 [ClinicalTrials.gov].).

Promising new drugs are being evaluated for treatment of multiple myeloma (MM), but their impact should be measured against the expected outcome in patients failing current therapies. However, the natural history of relapsed disease in the current era remains unclear. We studied 286 patients with relapsed MM, who were refractory to bortezomib and were relapsed, refractory, or ineligible, to an IMiD (Immunomodulatory Drug), with measurable disease and ECOG PS of 0, 1 or 2. The date patients satisfied the entry criteria was defined as time zero (T0). The median age at diagnosis was 58 years and time from diagnosis to T0 was 3.3 years. Following T0, 213 (74%) patients had a treatment recorded with one or more regimens (median=1; range 0-8). The first regimen contained bortezomib in 55 (26%) patients and an IMiD in 70 (33%). A minor response or better was seen to at least one therapy after T0 in 94 patients (51%) including >=partial response in 69 (38%). The median overall survival and event free survival from T0 were 9 and 5 months respectively. This study confirms the poor outcome once patients become refractory to current treatments. The results provide context for interpreting ongoing trials of new drugs.

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Background:Despite recent advances, multiple myeloma (MM) remains incurable, and new treatment options are needed to continue to improve patient outcomes. This is the first randomized, phase 3 trial of an anti‐CD38 antibody in combination with pomalidomide (P) and dexamethasone (d) in RRMM.Aims:The primary objective of this phase 3 trial (NCT02990338) was to demonstrate progression free survival (PFS) improvement of isatuximab (Isa), a novel anti‐CD38 monoclonal antibody targeting a specific epitope, combined with Pd versus (vs) Pd in RRMM.Methods:Patients (pts) with RRMM who received ≥2 prior lines, including lenalidomide (len) and a proteasome inhibitor (PI), refractory to last therapy were enrolled. IsaPd arm received Isa 10 mg/kg IV weekly for first 4 weeks (wks), then every 2 wks. Both arms received approved schedules of pom and dex (4 mg PO days 1–21; 40 mg [20 mg if >75 yrs] PO or IV weekly) every 28 days until progression or unacceptable toxicity.Results:307 pts (154 IsaPd, 153 Pd) were randomized and analyzed (ITT). Patient characteristics were well balanced across arms. Median age: 67 (36–86) yrs; median prior lines of therapy: 3 (2–11); estimated GFR: <60 ml/min in 33.9% pts; 92.5% refractory to len, 75.9% to PI; and 19.5% pts had high‐risk cytogenetics. At median follow‐up of 11.6 months (mos), median PFS was 11.5 mos IsaPd vs 6.5 mos Pd; HR 0.596 (95% CI 0.44–0.81), P = 0.001. PFS benefit was consistent across all major subgroups. ORR (≥PR) was 60.4% IsaPd vs 35.3% Pd, P < 0.0001. VGPR rate or better was 31.8% IsaPd vs 8.5% Pd, and MRD negativity (NGS, 10−5) was seen in 5.2% IsaPd pts vs 0% Pd. At analysis date, overall survival (OS) was immature (99 events) but a trend to OS improvement in IsaPd (vs Pd) was observed (HR 0.687; 95% CI 0.461–1.023). Median treatment duration was 41 wks IsaPd vs 24 wks Pd; median Isa infusion (inf.) duration was 3.3 h at 1st inf. and 2.8 h at subsequent inf. Grade ≥3 AEs were observed in 86.8% IsaPd vs 70.5% Pd; 7.2% IsaPd and 12.8% Pd pts discontinued due to AEs; 7.9% IsaPd and 9.4% Pd pts died due to AEs. Inf. reactions were reported in 38.2% (2.6% grade 3–4) IsaPd. Grade ≥3 infections were seen in 42.8% IsaPd and 30.2% Pd, grade ≥3 neutropenia in 84.9% (febrile 11.8%) IsaPd and 70.1% (febrile 2.0%) Pd.Summary/Conclusion:Isatuximab in combination with pomalidomide and dexamethasone significantly improved PFS and ORR vs pomalidomide and dexamethasone, with a manageable safety profile. Isatuximab in combination with pomalidomide and dexamethasone is an important new treatment option for the management of RRMM.

High-dose dexamethasone (Dex) remains a standard therapy for relapsed or refractory MM. Lenalidomide is a novel, orally administered, immunomodulatory drug (IMiD) that has single-agent activity against MM and additive effects when combined with Dex. In this phase 3, multicenter, randomized, double-blind trial, 351 patients with relapsed or refractory MM were enrolled from clinical centers in Europe, Israel, and Australia. Patients were treated with Dex 40 mg daily on days 1–4, 9–12, and 17–20 every 28 days and were randomized to receive either lenalidomide 25 mg daily orally on days 1–21 every 28 days or placebo. Beginning at cycle 5, the dose intensity of Dex was reduced to 40 mg daily on days 1–4 only every 28 days. Patients resistant to Dex were excluded. Patients were stratified with respect to B2M (≤ 2.5 vs. &gt; 2.5 mg/mL), prior stem cell transplant (none vs. ≥1), and number of prior regimens (1 vs &gt; 1). A pre-planned interim analysis of time to progression (TTP; primary endpoint), response (Blade criteria), and safety data was performed by an independent Data Monitoring Committee (IDMC) when at least half the number of disease progressions required for full statistical power had occurred (50% information). The treatment arms were well balanced for prognostic features. With a study duration of 18 months, the median TTP for patients treated with the combination of lenalidomide plus Dex was 13.3 months compared to 5.1 months for patients treated with Dex and placebo (p &lt; 0.000001). The overall response rate was greater in patients who received lenalidomide plus Dex than in patients who were given Dex alone (58% vs. 22%; p &lt; 0.001). Grade 3 or 4 neutropenia adverse events were reported more frequently in patients given combination therapy than in patients treated Dex alone (16.5% vs. 1.2%), however grade 3 or 4 infections were reported with similar frequencies between treatment groups. Thromboembolic events occurred in 8.5% of patients in the lenalidomide/Dex group and in 4.5% of patients in the Dex alone group. Otherwise, the safety profile of lenalidomide/Dex was similar to that of Dex alone. Conclusion: Combination lenalidomide/Dex is a relatively well-tolerated and active oral regimen for patients with relapsed or refractory MM. The difference in TTP between the 2 arms surpassed the pre-specified O’Brien-Fleming boundary for superior efficacy (p &lt; 0.0015) and the IDMC recommended the data be released to all study participants. Prophylactic antithrombotic therapy should be considered for patients undergoing treatment with lenalidomide/Dex. These data support further evaluation of this combination in previously untreated patients with MM.

One of the differences between acute myeloblastic leukemia (AML) and acute lymphoblastic leukemia (ALL) is their sensitivity to vincristine. Although vincristine plays an important role in chemotherapeutic regimens for ALL, it does not possess clinically significant activity in AML. Horseradish peroxidase, a heme-centered peroxidase, oxidatively degrades Vinca derivatives and thereby abrogates their cytotoxic activity. This finding suggested that myeloperoxidase (MPO), a heme- centered peroxidase characteristically found in AML and not in ALL, might also degrade vincristine. We first examined the effects of MPO on vincristine in a cell-free system and demonstrated that this enzyme is capable of catalyzing vincristine's oxidative breakdown. We also observed that vincristine is more rapidly degraded in tissue culture by MPO-positive HL-60 cells than by a MPO-negative HL-60 subclone. The degree of MPO activity in these cell lines correlated in a positive manner with their degree of resistance to vincristine's cytotoxic activity. Moreover, the differential resistance to vincristine observed between these cell lines could be increased by increasing the concentration of H2O2 available to the enzyme. These data support the hypothesis that MPO-mediated oxidation of vincristine accounts in part for this drug's lack of activity in AML.

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