Belch, Andrew R.

Abstract Abstract 302 Background: Carfilzomib (CFZ) is a proteasome inhibitor with unique target selectivity and an irreversible binding mechanism that results in sustained proteasome inhibition. In preclinical studies, CFZ lacks non-proteasome off-target activities associated with bortezomib (BTZ) (Kapur et al, Blood 2008). This may account for observed differences in tolerability with CFZ (e.g. minimal neuropathy and myelosuppression), permitting consecutive day dosing and treatment over an extended period of time. We previously observed higher response rates in multiple myeloma (MM) patients without prior BTZ exposure (BTZ-naïve) compared to those with relapsed disease following BTZ therapy (BTZ-treated). Here we present updated data on the BTZ-naïve cohort from PX-171-004, an ongoing Phase 2 study of single-agent CFZ in MM patients with relapsed or refractory disease following 1–3 prior therapies. Methods: Patients with relapsed or refractory (e.g, < 25% response or disease progression during last treatment) MM were enrolled and stratified into two cohorts: BTZ-naïve and BTZ-treated. CFZ 20 mg/m2 IV was administered on Days 1, 2, 8, 9, 15 and 16 every 28 days, for up to 12 cycles. The primary endpoint was Overall Response Rate [≥ Partial Response (PR)] per International Uniform Response Criteria for Multiple Myeloma. Secondary endpoints included Clinical Benefit Response [CBR = ORR + Minor Reponse (MR)] and safety. Results: Fifty-seven BTZ-naive patients have been enrolled and 56 subjects have received at least one dose of CFZ. Prior therapies included alkylators (81%), stem cell transplant (SCT) (77%), thalidomide (THAL) (67%), lenalidomide (LEN) (42%), and anthracyclines (23%). Ten (18%) patients had received both LEN and THAL and 18 (32%) patients were refractory to their most recent regimen prior to study entry. At baseline, 30 (53%) patients had an ECOG score ≥ 1, 21 (37%) had neuropathy Grade ≥ 1, 12 (21%) had impaired renal function (CrCl < 60 mL/min) and 10 (18%) had diabetes. The mean time from diagnosis was 4 years (range 0.7–24). To date, the mean number of CFZ doses administered was 29.2 (∼5 four-week cycles; range 2–72 doses, 1–12 cycles). Fifty-one patients initiated therapy and were evaluable for response per protocol. The ORR was 45% (23/51 patients) and included 1 CR, 4 VGPR and 18 PR. An additional 9 (18%) patients had MR and 10 (20%) had stable disease (SD) for ≥ 6 weeks. The most common (>25%) adverse events (AEs) were fatigue (59%), nausea (41%), dyspnea (36%), and anemia (29%), and were primarily ≤ Grade 2. Grade 3/4 AEs occurring in ≥ 5% of patients were thrombocytopenia (9%), fatigue (9%), neutropenia (7%), lymphopenia (7%), anemia (5%), pneumonia (5%) and hyperglycemia (5%). One (1.7%) patient had febrile neutropenia. Dose modifications were rarely required. Peripheral neuropathy (PN) of any grade was infrequent (7 patients, 12%) with a single case of Grade 3 PN (2%) in a pt with a history of THAL-induced PN that lasted 41 days. The CFZ dose was reduced and the event resolved to Grade 1 while on CFZ and prior to study discontinuation. Of the12 patients with impaired renal function at baseline, none required dose modifications due to renal AE. Overall, 5 patients have completed the full 12-cycle protocol and another 5 (9%) have completed ≥ 9 cycles; 17 patients (30%) are continuing on study. Conclusions: The 45% ORR (CBR 63%) is noteworthy for a single-agent regimen in patients with tumor progression despite therapy with novel combinations. CFZ can be safely administered to patients with significant comorbidities (e.g. peripheral neuropathy, leukopenia, renal dysfunction, diabetes) when other anti-myeloma agents may not be well tolerated. Enrollment to PX-171-004 is continuing and, based on the safety profile, subjects are now permitted to dose escalate to 27 mg/m2. Disclosures: Wang: Proteolix: Honoraria, Research Funding. Off Label Use: testing testing. Siegel:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Jakubowiak:Millennium Pharmaceuticals, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Centocor Ortho Biotech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Exelixis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Bristol-Myers-Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Kukreti:Celgene: Honoraria. Bahlis:Celgene: Honoraria, Speakers Bureau; Ortho Biotech: Honoraria, Speakers Bureau. McDonagh:Proteolix: Research Funding. Belch:Ortho Biotech: Honoraria, Research Funding. Le:Proteolix, Inc.: Employment. Bennett:Proteolix: Employment. Kunkel:Proteolix: Consultancy, Employment. Kauffman:Proteolix, Inc.: Employment. Vij:Proteolix, Inc.: Consultancy, Research Funding.

Background:The pivotal FIRST trial, the largest study conducted in transplant‐ineligible (TNE) patients (pts) with newly diagnosed multiple myeloma (NDMM), examined lenalidomide plus low‐dose dexamethasone until disease progression (Rd continuous), Rd for 18 cycles (Rd18), and melphalan, prednisone, and thalidomide (MPT). The study, conducted in 18 countries in Europe, North America, and Asia Pacific, demonstrated that Rd continuous significantly improved progression‐free survival (PFS) vs MPT (median 26.0 vs 21.9 mos; HR, 0.69; 95% CI, 0.59‐0.79; P < .00001). PFS was similarly extended for Rd continuous vs Rd18 (median 21.0 mos; HR, 0.70; 95% CI, 0.60‐0.81). Furthermore, median overall survival (OS) was significantly longer with Rd continuous vs MPT (median 59.1 vs 49.1 mos; HR, 0.78; 95% CI, 0.67‐0.92; P = .0023). These results support the use of frontline oral, alkylator‐free continuous therapy for TNE NDMM pts and established Rd continuous as a standard of care as reflected by clinical guidelines in Canada, the US, and Europe.Aims:To report outcomes in the subset of patients from Canada and the US.MethodsPts with TNE NDMM were randomized 1:1:1 to Rd continuous (with lenalidomide given on days 1‐21 of 28‐day cycles until disease progression), Rd18 (with lenalidomide given on days 1‐21 of eighteen 28‐day cycles), or MPT (twelve 42‐day cycles). Rd18 and MPT were both 72 weeks in duration. Stratification factors included country and Rd continuous vs MPT was the primary comparison. The primary endpoint was PFS and secondary endpoints included OS, time to next therapy (TTNT) and safety. Time from randomization to second progression or death (PFS2) was an exploratory analysis. Response assessment used for PFS and PFS2 analysis was determined by investigators based on International Myeloma Working Group criteria. Data is presented as of the January 21, 2016 cutoff used for the final OS analysis.Results:A total of 312 pts from Canada (n = 252) and the US (n = 60) were enrolled (104 in each arm). Consistent with results from the intent‐to‐treat (ITT) analysis, the Canada/US subgroup also demonstrated a significant improvement in PFS with Rd continuous vs MPT (median 29.3 vs 20.2 mos; HR, 0.69; 95% CI, 0.49‐0.97; P = .03326) and an improvement vs Rd18 (median 21.9 mos; HR, 0.72; 95% CI, 0.51‐1.02; Table). Median OS was 56.9 vs 46.8 mos for Rd continuous vs MPT (HR, 0.77; 95% CI, 0.53‐1.11; P = .15346). Median PFS2 was longer for Rd continuous vs MPT (median 39.3 vs 35.1 mos; HR, 0.69; 95% CI 0.50‐0.95) as was TTNT (median 39.1 vs 24.6 mos; HR, 0.54; 95% CI, 0.37‐0.78). Additional details, including safety data, will be presented at the meeting.Summary/Conclusion:In the Canada/US subpopulation of pts from FIRST, Rd continuous extended median PFS by 9 mos vs MPT and > 7 mos vs Rd18. Rd continuous also delayed median TTNT > 14 mos and resulted in a longer PFS2 vs MPT, suggesting that the benefit from frontline Rd continuous is maintained at relapse. These results are consistent with that from the ITT population confirming the advantage of Rd continuous vs MPT in the Canada/US subgroup and supporting the role of Rd continuous as a standard of care for TNE pts with NDMM. The efficacy observed with Rd continuous raises the question on the role of immunostimulatory effects by the immunomodulatory agents in NDMM.image

SummaryVenous 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.

Key Points Thalidomide and prednisone maintenance after transplantation improves progression-free but not overall survival.

SummaryCarfilzomib is a next‐generation proteasome inhibitor that selectively and irreversibly binds to its target. In clinical studies, carfilzomib has shown efficacy in patients with relapsed and/or refractory multiple myeloma (MM) and has demonstrated a tolerable safety profile. In this phase 2, open‐label, multicentre clinical trial, 35 patients with relapsed and/or refractory MM following 1–3 prior therapies, including at least one bortezomib‐based regimen, received carfilzomib 20 mg/m2 in a twice‐weekly, consecutive‐day dosing schedule for ≤12 monthly cycles. The best overall response rate (ORR) was 17·1% and the clinical benefit response rate (ORR + minimal response) was 31·4%. The median duration of response was >10·6 months and the median time to progression was 4·6 months. The most common adverse events were fatigue (62·9%), nausea (60·0%), and vomiting (42·9%). No exacerbation of baseline peripheral neuropathy was observed. Single‐agent carfilzomib was generally well tolerated for up to 12 treatment cycles and showed activity in patients with relapsed and/or refractory MM who had received prior treatment with bortezomib. These data, combined with an acceptable toxicity profile, support the potential use of carfilzomib in patients with relapsed and/or refractory MM and warrant continued investigation of carfilzomib as single agent or in combination with other agents.

Abstract Carfilzomib is a selective proteasome inhibitor that binds irreversibly to its target. In phase 1 studies, carfilzomib elicited promising responses and an acceptable toxicity profile in patients with relapsed and/or refractory multiple myeloma (R/R MM). In the present phase 2, multicenter, open-label study, 129 bortezomib-naive patients with R/R MM (median of 2 prior therapies) were separated into Cohort 1, scheduled to receive intravenous carfilzomib 20 mg/m2 for all treatment cycles, and Cohort 2, scheduled to receive 20 mg/m2 for cycle 1 and then 27 mg/m2 for all subsequent cycles. The primary end point was an overall response rate (≥ partial response) of 42.4% in Cohort 1 and 52.2% in Cohort 2. The clinical benefit response (overall response rate + minimal response) was 59.3% and 64.2% in Cohorts 1 and 2, respectively. Median duration of response was 13.1 months and not reached, and median time to progression was 8.3 months and not reached, respectively. The most common treatment-emergent adverse events were fatigue (62.0%) and nausea (48.8%). Single-agent carfilzomib elicited a low incidence of peripheral neuropathy—17.1% overall (1 grade 3; no grade 4)—in these pretreated bortezomib-naive patients. The results of the present study support the use of carfilzomib in R/R MM patients. This trial is registered at www.clinicaltrials.gov as NCT00530816.

AbstractMultiple myeloma (MM) is a B-lineage malignancy characterized by diverse genetic subtypes and clinical outcomes. The recurrent immunoglobulin heavy chain (IgH) switch translocation, t(4;14)(p16;q32), is associated with poor outcome, though the mechanism is unclear. Quantitative reverse-transcription–polymerase chain reaction (RT-PCR) for proposed target genes on a panel of myeloma cell lines and purified plasma cells showed that only transcripts originating from the WHSC1/MMSET/NSD2 gene are uniformly dysregulated in all t(4;14)POS patients. The different transcripts detected, multiple myeloma SET domain containing protein (MMSET I), MMSET II, Exon 4a/MMSET III, and response element II binding protein (RE-IIBP), are produced by alternative splicing and alternative transcription initiation events. Translation of the various transcripts, including those from major breakpoint region 4-2 (MB4-2) and MB4-3 breakpoint variants, was confirmed by transient transfection and immunoblotting. Green fluorescent protein (GFP)–tagged MMSET I and II, corresponding to proteins expressed in MB4-1 patients, localized to the nucleus but not nucleoli, whereas the MB4-2 and MB4-3 proteins concentrate in nucleoli. Cloning and localization of the Exon 4a/MMSET III splice variant, which contains the protein segment lost in the MB4-2 variant, identified a novel protein domain that prevents nucleolar localization. Kinetic studies using photobleaching suggest that the breakpoint variants are functionally distinct from wild-type proteins. In contrast, RE-IIBP is universally dysregulated and also potentially functional in all t(4;14)POS patients irrespective of fibroblast growth factor receptor 3 (FGFR3) expression or breakpoint type.