SummaryThere is a significant unmet need in effective therapy for relapsed myeloma patients once they become refractory to bortezomib and lenalidomide. While data from the front line setting suggest bendamustine is superior to melphalan, there is no information defining optimal bendamustine dose in multiply-treated patients. We report a multi-centre randomized two-stage phase 2 trial simultaneously assessing deliverability and activity of two doses of bendamustine (60 mg/m 2 vs. 100 mg/m 2 ) days 1 and 8, thalidomide (100 mg) days 1-21 and low dose dexamethasone (20 mg) days 1, 8, 15 and 22 of a 28-d cycle. Ninety-four relapsing patients were treated on trial, with a median three prior treatment lines. A pre-planned interim deliverability and activity assessment led to closure of the 100 mg/m 2 arm due to excess cytopenias, and led to amendment of entry criteria for cytopenias. Non-haematological toxicities including thromboembolism and neurotoxicity were infrequent. In the 60 mg/m 2 arm, treatment was deliverable in 61Á1% subjects and the partial response rate was 46Á3% in the study eligible population, with 7Á5 months progression-free survival. This study demonstrates bendamustine at 60 mg/m 2 twice per month with thalidomide and dexamethasone is deliverable for repeated cycles in heavily pretreated myeloma patients and has substantial clinical activity.

IntroductionMultiple myeloma (MM) is a plasma cell tumour with over 5800 new cases each year in the UK. The introduction of biological therapies has improved outcomes for the majority of patients with MM, but in approximately 20% of patients the tumour is characterised by genetic changes which confer a significantly poorer prognosis, generally termed high-risk (HR) MM. It is important to diagnose these genetic changes early and identify more effective first-line treatment options for these patients.Methods and analysisThe Myeloma UK nine OPTIMUM trial (MUKnine) evaluates novel treatment strategies for patients with HRMM. Patients with suspected or newly diagnosed MM, fit for intensive therapy, are offered participation in a tumour genetic screening protocol (MUKnine a), with primary endpoint proportion of patients with molecular screening performed within 8 weeks. Patients identified as molecularly HR are invited into the phase II, single-arm, multicentre trial (MUKnine b) investigating an intensive treatment schedule comprising bortezomib, lenalidomide, daratumumab, low-dose cyclophosphamide and dexamethasone, with single high-dose melphalan and autologous stem cell transplantation (ASCT) followed by combination consolidation and maintenance therapy. MUKnine b primary endpoints are minimal residual disease (MRD) at day 100 post-ASCT and progression-free survival. Secondary endpoints include response, safety and quality of life. The trial uses a Bayesian decision rule to determine if this treatment strategy is sufficiently active for further study. Patients identified as not having HR disease receive standard treatment and are followed up in a cohort study. Exploratory studies include longitudinal whole-body diffusion-weighted MRI for imaging MRD testing.Ethics and disseminationEthics approval London South East Research Ethics Committee (Ref: 17/LO/0022, 17/LO/0023). Results of studies will be submitted for publication in a peer-reviewed journal.Trial registration numberISRCTN16847817, May 2017; Pre-results.

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BackgroundMultiple 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.MethodsMUK 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.DiscussionThe 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 registrationThe trial is registered under ISRCTN17354232, December 2012.

Background: Early phase trials are essential in drug development, determining