Berenson, James R.

e19505 Background: CFZ combined with dexamethasone is approved to treat pts with RRMM, with CFZ given once-weekly at 70 mg/m2 (Kd70 QW) or twice-weekly at 56 mg/m2 (Kd56 BIW). No randomized trials have directly compared Kd70 QW with Kd56 BIW. We performed a post hoc comparison between pts who received Kd56 BIW in the ENDEAVOR trial and pts who received Kd70 QW in the A.R.R.O.W. or CHAMPION-1 trials. Methods: Data were analyzed from 3 trials of CFZ in RRMM: A.R.R.O.W. (240 pts in Kd70 QW arm; 2–3 prior therapies and refractory to most recent therapy), CHAMPION-1 (104 pts received Kd70 QW; 1–3 prior therapies), and ENDEAVOR (464 pts in Kd56 BIW arm; 1–3 prior therapies). Pts who received Kd70 QW in A.R.R.O.W. and CHAMPION-1 were pooled and compared with pts who received Kd56 BIW in ENDEAVOR. As study populations slightly varied among the 3 trials, an analysis of safety and efficacy was performed in a subgroup of pts who received 2–3 prior therapy lines and were not refractory to bortezomib (BTZ). Also, we performed regression analyses (controlling for age, ISS stage, BTZ and lenalidomide refractory status, and number of prior regimens) among all pts in the trials who received Kd70 QW or Kd56 BIW. Results: Among BTZ non-refractory pts with 2–3 lines of prior therapy, median progression-free survival (PFS) was 12.1 months (95% CI 8.4–14.3) for Kd70 QW (n = 146) and 14.5 months (95% CI 10.2–NE) for Kd56 BIW (n = 217), and the overall response rate (ORR) was 69.9% (95% CI 61.7–77.2) for Kd70 QW and 72.4% (95% CI 65.9–78.2) for Kd56 BIW. The rate of grade ≥3 adverse events (Kd70 QW vs Kd56 BIW) was 67.6% and 85.3%; among adverse events of interest, the grade ≥3 rate was 1.4% and 5.1% for cardiac failure, 3.4% and 6.0% for renal failure, and 5.5% and 15.7% for hypertension. Kd70 QW represents a convenient and well-tolerated treatment modality for pts with RRMM. In a Cox proportional hazards model, the hazard ratio for PFS (Kd70 QW vs Kd56 BIW) was 0.91 (95% CI 0.69–1.19), and in a logistic regression model the odds ratio for ORR (Kd70 QW vs Kd56 BIW) was 1.12 (95% CI 0.74–1.69). Conclusions: This post hoc analysis suggests that once-weekly Kd70 has a comparable benefit-risk profile to twice-weekly Kd56. Clinical trial information: NCT02412878, NCT01677858, NCT01568866.

8020 Background: BCMA (B-cell maturation antigen) is a TNF receptor family member found on normal and malignant B-cells, including multiple myeloma (MM). It plays a role in proliferation and antiapoptotic pathways. Levels of serum (s)BMCA are elevated in patients (pts) with plasma cell disorders (PCD) and increase with each stage of disease: healthy donor< MGUS<SMM< active untreated MM. The purpose of this study was to test whether sBCMA levels predict progression of MGUS or SMM to MM. Methods: There were 3 cohorts in this retrospective study: MGUS progressing to MM (n=42); MGUS not progressing to MM (n=49); SMM progressing to MM (n=32). sBCMA levels were measured using an ELISA-based assay with a polyclonal anti-BCMA antibody from R&D Systems (Minneapolis, MN). The Kruskal-Wallis analysis was used to assess differences. The relationships between sBCMA and both time to progression and overall survival were also assessed using Cox proportional hazard models. Results: The highest values of sBCMA were seen among pts with more advanced PCD (Table). The lowest baseline levels were seen in pts with MGUS who did not progress; the change of sBCMA over time was lowest in the MGUS non-progressors. ROC analysis identified a cutoff of 74.4 ng/mL to be predictive of progression at 5 years. This cut-point was associated with a risk ratio of progression of 5.8 (95%CI 3.2, 11.3) for all comers, a risk ratio of death for all comers of 2.5 (95%CI 1.5, 4.2), and a risk ratio of death for MGUS pts of 3.3 (95%CI 1.9, 5.7). Conclusions: Serum BCMA levels were predictive of diagnosis, progression and death among pts with MGUS or SMM. Limitations of the current study are that only a minority of pts had baseline bone marrow exams or serum FLCs to place sBCMA risk in the context of other previously described risk factors. Serum FLC is now being determined on all patients. [Table: see text]

7525 Background: New prognostic markers in chronic lymphocytic leukemia (CLL) are in demand. Different groups have developed models which combine multiple prognostic markers into a single index to classify CLL patients (pts). The CLL-International Prognostic Index (CLL-IPI) combines five parameters: age, clinical stage, TP53 status, IGHV mutational status, and serum β2 microglobulin levels. B-cell maturation antigen (BCMA) is a cell membrane receptor expressed exclusively on late stage B-cells and plasma cells with elevated serum (s) levels found in B-cell malignancies, such as multiple myeloma (MM). In MM, sBCMA levels can be used to monitor disease status and predict overall survival (OS). To further evaluate this biomarker in other hematologic malignancies, we studied it in CLL. Methods: Untreated (UNTX) CLL pts seen and consented at Mayo Clinic were identified. sBCMA levels were measured on stored sera of 331 UNTX CLL pts using an ELISA-based assay with a polyclonal anti-BCMA antibody from R&D Systems (Minneapolis, MN). The Mann-Whitney analysis was used to assess differences between CLL pts and healthy controls. The relationships between sBCMA and both time to first treatment (TFT) and OS were also assessed using Cox Regression models with an optimal sBCMA cutoff of 40.9 ng/mL. Results: The median age of pts was 61 years, and 71% were male. The distribution of CLL-IPI risk groups was as follows: 135 (41%) Low; 114 (34%) Intermediate; 67 (20%) High; 15 (5%) Very High. The median level of sBCMA in CLL pts (48.6 ng/mL) was higher (P <0.0001) than those of healthy controls (n = 104; 36.03 ng/mL). In CLL pts, sBCMA is significant in univariable analyses of TFT (HR 2.9 (95%CI, 2.0-4.2); P < 0.0001) and OS (HR 2.5 (95%CI, 1.5-4.0); P < 0.0003), and remains significant when adjusting for sex and CLL-IPI factors (HR 2.3 (95%CI, 1.6-3.3), P < 0.0001; HR 1.9 (95%CI 1.1-3.1), P = 0.01, respectively). Conclusions: sBCMA is elevated in CLL pts compared to healthy controls. After adjusting for CLL-IPI and sex, sBCMA levels provided independent prognostic value in predicting TFT and OS in this cohort. Measuring sBCMA with a readily accessible ELISA-based test, provides incremental value over the current CLL-IPI model in predicting prognosis of CLL.

8514 Background: MLN9708 is an investigational, orally bioavailable, potent, reversible, specific inhibitor of the 20S proteasome that has demonstrated antitumor activity in in vivo models of MM. We report safety, activity and pharmacokinetics (PK) of weekly oral MLN9708 in a phase 1 trial in patients (pts) with relapsed and/or refractory MM after full enrollment (NCT00963820). Methods: Pts received MLN9708 (days 1, 8, 15; 28-day cycles) at 0.24–3.95 mg/m2 (dose-escalation phase) and at the MTD, 2.97 mg/m2, in relapsed and refractory (RR), bortezomib (btz)-relapsed, PI-naïve, and prior carfilzomib (CZ) expansion cohorts. Adverse events (AEs) were graded by NCI-CTCAE v3.0. Response was assessed by IMWG uniform criteria. Results: 60 pts (33 male, median age 64 yrs [40–79]) were enrolled, 32 in the dose-escalation phase and 31 to the expansion cohorts (11 RR, 10 btz-relapsed, 6 PI-naïve, 4 CZ; 2 RR and 1 btz-relapsed pts included from MTD dose-escalation cohort). Median time from MM diagnosis was 4.9 yrs (1.5–18.8). Median number of prior regimens was 6 (2–18), including btz, lenalidomide, thalidomide, and CZ in 83%, 95%, 52%, and 13%, respectively; 76% were refractory to last therapy (17% btz-refractory). At data cut-off (Nov 29, 2012) pts had received a median of 2 cycles (1–11); 5 pts remained on treatment. All-grade/grade ≥3 drug-related AEs were seen in 83%/52% of pts; common drug-related grade ≥3 AEs were thrombocytopenia (33%), diarrhea, neutropenia (17%), decreased appetite, fatigue, and lymphopenia (8%). 6 pts (10%) had drug-related PN (no grade ≥3). 5 pts discontinued due to drug-related AEs; 1 pt died on study due to an unrelated AE. By investigator assessment in 41 evaluable pts, responses included1 VGPR, 5 PR, 1 MR, and 15 with SD. MLN9708 was rapidly absorbed, with a terminal half-life of 4–12 days (supporting weekly dosing) and a proportional increase in plasma AUC with dose (0.8–3.95 mg/m2). PK data were similar across expansion cohorts. Conclusions: Current data suggest weekly oral MLN9708 is generally well tolerated with infrequent PN, and shows activity in this heavily pretreated population with prior exposure to immunomodulatory drugs and btz. Clinical trial information: NCT00963820.

8034 Background: Phase 1 studies are evaluating IV and oral dosing of the reversible proteasome inhibitor MLN9708 in multiple tumor types. We report the safety, MTD, pharmacokinetics (PK), pharmacodynamics, and preliminary responses with weekly oral MLN9708 in pts with relapsed/refractory MM (NCT00963820). Methods: Pts aged ≥18 yrs received MLN9708 on d 1, 8, and 15 of 28-d cycles. In the dose-escalation phase, pts required ≥2 prior therapies (including bortezomib, thalidomide/lenalidomide, and corticosteroids). At the MTD, pts were to be enrolled to relapsed and refractory (RR), bortezomib-relapsed (VR), proteasome inhibitor (PI) naïve, and carfilzomib (CZ) expansion cohorts. Results: 36 pts have been enrolled to date (data cut-off: Dec 1, 2011), 32 in the dose-escalation phase (0.24–3.95 mg/m2) and 8 to expansion cohorts (2 RR, 5 VR, 1 PI naïve; RR and VR cohorts each include 2 pts from MTD dose-escalation cohort). Median age was 64.5 yrs (range 40–79), 53% were male, and median number of prior lines of therapy was 3.5 (range 1-13), including 92%, 92%, 56%, and 8% who had prior bortezomib, lenalidomide, thalidomide, and carfilzomib, respectively. Pts have received a median of 2 cycles (range 1–11); 5 pts remain on treatment. Among 24 DLT-evaluable pts, 3 DLTs were seen: 2 at 3.95 mg/m2 (1 grade 3 rash, 1 grade 3 GI AEs) and 1 at 2.97 mg/m2 (grade 3 GI AEs). The MTD was determined as 2.97 mg/m2. Overall, 69% of pts had drug-related AEs, and 28% had related grade ≥3 AEs, including thrombocytopenia (17%), diarrhea (11%), nausea, neutropenia, and fatigue (each 8%). Only 3 (8%) pts had drug-related peripheral neuropathy (PN; no grade ≥3). 2 pts discontinued due to AEs. In 18 response-evaluable pts, 1 had a VGPR at 3.95 mg/m2, 1 had a PR at 2.97 mg/m2, and 8 have achieved SD durable for up to 9.5 mos. PK analyses showed linear plasma PK (0.8–3.95 mg/m2), Tmax of 0.5-2 hr, and terminal half-life of 7 d for MLN2238 (biologically active hydrolysis product). There was a trend for a dose-dependent increase in whole blood 20S proteasome inhibition. Conclusions: Current data suggest weekly oral MLN9708 is generally well tolerated with infrequent PN, and shows early signs of antitumor activity.

Abstract Combination of carfilzomib with dexamethasone (Kd) is approved for use in relapsed and/or refractory multiple myeloma (RRMM), with carfilzomib administered twice weekly at 56 mg/m 2 (Kd56 BIW) or once weekly at 70 mg/m 2 (Kd70 QW). Post hoc cross‐trial comparisons were performed to compare efficacy and safety profiles of Kd70 QW vs Kd56 BIW dosing schedules using data from three trials of patients with RRMM: A.R.R.O.W., CHAMPION‐1, and ENDEAVOR. To select for comparable patient populations, side‐by‐side efficacy and safety comparisons were performed in subgroups of patients with 2‐3 prior lines of therapy who were not refractory to bortezomib. The overall response rate (ORR) was 69.9% (95% confidence interval [CI], 61.7‐77.2) for Kd70 QW and 72.4% (95% CI, 65.9‐78.2) for Kd56 BIW. Median progression‐free survival (PFS) was 12.1 months (95% CI, 8.4‐14.3) for Kd70 QW and 14.5 months (95% CI, 10.2—not evaluable) for Kd56 BIW. Frequency of grade ≥ 3 adverse events (AEs) was 67.6% for Kd70 QW and 85.3% for Kd56 BIW. Regression analyses (adjusting for prognostic factors) of all patients in the trials who received Kd70 QW vs Kd56 BIW estimated a PFS hazard ratio of 0.91 (95% CI, 0.69‐1.19; P = .47) and an ORR odds ratio of 1.12 (95% CI, 0.74‐1.69; P = .61). These results suggest that Kd70 QW has a comparable efficacy profile compared with Kd56 BIW and represents a convenient and well‐tolerated treatment for patients with RRMM.

Abstract Abstract 816 Background: Proteasome inhibition is a very effective therapeutic strategy in multiple myeloma (MM). The investigational agent MLN9708 is an oral, specific, reversible inhibitor of the 20S proteasome that has shown antitumor activity in solid tumor and hematologic malignancy xenograft models. Phase 1 trials are evaluating both intravenous and oral formulations using different dosing schedules in a variety of tumor types. Here we report the findings from the dose-escalation portion of a phase 1 trial of once-weekly, orally administered MLN9708 in patients with relapsed and/or refractory MM (NCT00963820). Methods: The primary objectives were to determine the maximum tolerated dose (MTD) and the safety/tolerability of MLN9708. Secondary objectives included determination of response rate, and characterization of the pharmacokinetics (PK, of MLN2238, the biologically active hydrolysis product) and pharmacodynamics (PD, 20S proteasome inhibition in blood) of once-weekly oral MLN9708. Patients with MM who had received ≥2 prior therapies, which must have included bortezomib, thalidomide or lenalidomide, and corticosteroids, were eligible. Treatment consisted of MLN9708 administered orally on days 1, 8, and 15 of a 28-day cycle. Dose-escalation proceeded from 0.24 mg/m2 using a standard 3+3 schema based on dose-limiting toxicities (DLTs) occurring in cycle 1. Adverse events (AEs) were graded by NCI-CTCAE v3. Response was assessed by modified EBMT/IMWG criteria. Blood samples were collected after dosing on days 1 and 15 of cycle 1 for PK and PD analyses; parameters were calculated using noncompartmental methods (WinNonlin software v5.3). Results: A total of 28 patients have been enrolled to date (data cut-off: June 29, 2011), including 3 each at dose levels of 0.24, 0.48, 0.80, and 1.20, 4 at 1.68, 3 at 2.23, 4 at 2.97, and 5 at 3.95 mg/m2. The median age was 63.5 years (range 40–76); 54% were male. The median number of prior regimens was 5 (range 2–15), and median time from diagnosis was 4.6 years. Nineteen (68%) patients had prior stem cell transplant, and 16 (59%) were refractory to their last prior therapy, including 7 (26%) to bortezomib and 11 (41%) to lenalidomide or thalidomide. The MTD has not been reached; the current cohort is receiving 3.95 mg/m2. No DLTs have been observed among 21 DLT-evaluable patients. Patients have received a median of 2 treatment cycles (range 1–11; mean 2.8). Four patients remain on treatment; discontinuation was mainly due to progressive disease (71%). All 28 patients are evaluable for toxicity; 26 (93%) experienced at least one AE, including 22 (79%) who experienced at least one drug-related AE. Drug-related AEs occurring in >20% of patients included fatigue (39%), thrombocytopenia (36%), nausea (32%), and diarrhea (29%). Two (7%) patients had drug-related peripheral neuropathy (PN, both grade 2); both had grade 1 PN at baseline. Ten (36%) patients experienced grade ≥3 AEs, 4 (14%) had AEs resulting in MLN9708 dose reductions, and 3 (11%) discontinued due to AEs. No on-study deaths have occurred. In 16 response-evaluable patients, one partial response has been seen, in a patient treated at 2.97 mg/m2 (who had three prior lines of therapy, thalidomide–dexamethasone, lenalidomide–dexamethasone –perifosine, and bortezomib–dexamethasone, to which the patient responded and relapsed); duration of response is 3.7 months, and the patient remains in response at cycle 8. A further five patients had a best response of stable disease, durable for up to 9.5 months. PK analyses showed that MLN9708 was rapidly absorbed, with MLN2238 Tmax of 0.5–2.0 hours and a terminal half-life after multiple dosing of approximately 7 days based on limited data (n=5). MLN2238 exposure appeared to increase proportionally with increasing MLN9708 dose over the range 0.8–2.97 mg/m2. Maximal 20S proteasome inhibition in blood was immediate and dose-dependent. Conclusions: Current data suggest that MLN9708 on a once-weekly schedule is generally well tolerated and has early signs of anti-tumor activity in this heavily pre-treated population with prior exposure to lenalidomide/thalidomide and bortezomib. To date, toxicity has been manageable, and no significant neuropathy signal has been observed. Updated data will be presented, with the MTD anticipated to be reached. Data from an analysis of candidate biomarkers of responsiveness to treatment with MLN9708 will also be presented. Disclosures: Kumar: Merck: Consultancy, Honoraria; Celgene: Consultancy, Research Funding; Millennium Pharmaceuticals, Inc.: Research Funding; Genzyme: Research Funding; Novartis: Research Funding. Off Label Use: Use of the investigational agent MLN9708, an oral proteasome inhibitor, in the treatment of relapsed and/or refractory multiple myeloma. Bensinger:Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria, Research Funding; Onyx Pharmaceuticals: Consultancy, Honoraria, Research Funding; Array: Research Funding; AstraZeneca: Research Funding; Genentech: Research Funding. Reeder:Celgene: Institutional research funding; Millennium Pharmaceuticals, Inc.: Institutional research funding; Novartis: Institutional research funding. Zimmerman:Novartis: Expert witness; Celgene: Honoraria, Speakers Bureau; Millennium Pharmaceuticals, Inc: Honoraria, Speakers Bureau. Berenson:Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau; Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria, Research Funding, Speakers Bureau; Onyx Pharmaceuticals: Consultancy, Honoraria, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; Medtronic: Consultancy, Honoraria, Research Funding, Speakers Bureau; Merck: Research Funding; Genentech: Research Funding. Berg:Millennium Pharmaceuticals, Inc.: Employment. Liu:Millennium Pharmaceuticals, Inc.: Employment. Gupta:Millennium Pharmaceuticals, Inc.: Employment. Di Bacco:Millennium Pharmaceuticals, Inc.: Employment. Hui:Millennium Pharmaceuticals, Inc.: Employment. Niesvizky:Millennium Pharmaceuticals, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Onyx Pharmaceuticals: Research Funding.

Abstract Background: Peripheral neuropathy (PN) is associated with multiple myeloma (MM) and often worsened with thalidomide (THAL) and vincristine (VCR) therapy. Bortezomib (BTZ) is a proteasome inhibitor approved for the treatment of MM that has been also shown to cause PN. An increased risk of BTZ-induced PN has been associated with the presence of both PN and diabetes mellitus (DM) before treatment. However, the incidence and characteristics of BTZ-induced PN among MM patients (pts) retreated with another BTZ-containing regimen is unknown. We analyzed the incidence, severity and risk factors for PN after treatment of MM pts with a second BTZ-containing regimen. Methods: Retrospective chart analysis. MM pts that had progressed from at least one prior BTZ-containing regimen and had received treatment with another BTZ-containing regimen were eligible. Pts had to have experienced PN during the course of the first BTZ regimen and could not have received therapy with THAL or VCR. The protocol was later amended to allow inclusion of pts without PN during their first BTZ treatment and those who had received THAL or VCR. Statistical significance was assessed using Fisher’s or McNemar’s tests as appropriate. The relationship between comorbidities, prior THAL or VCR treatment and PN grade after BTZ treatment and re-treatment was analyzed using a multivariate logistics regression model. All statistical analyses were two-sided and were performed at the 0.05 level of significance. Results: As of July 3, 2014, 83 pts have been accrued to the retrospective analysis, and 58 chart reviews have been completed. The median age of pts included in the analysis was 64 years (range: 31-84 years); 57% of the pts were male and 69% were Caucasian. Pts had received a median of 2 prior regimens (range: 2-10); 43% of the pts had received prior regimens containing THAL and 15% of those had also received therapy with VCR. Prior to the protocol amendment, the eligibility criteria required pts to have experienced PN after the first BTZ treatment; therefore, most pts included in this analysis (88%) had PN.During their first BTZ treatment, the most severe grade of PN experienced by the majority of the pts was grade 1 (N=34), followed by grade 2 (N=13) and grade 3 (N=4). A comparison of the symptoms assessed when pts had their most severe grade of PN during this treatment and the severity reported at its onset showed that PN worsened in only 16% of pts. Nearly half (48%) of pts showed no change in PN whereas symptoms improved or resolved in 15% and 9% of the pts, respectively. During treatment with the second BTZ-containing regimen, a comparable proportion of pts (N=44; 76%) reported having experienced PN. Among those experiencing PN upon re-treatment, the most severe grade of PN experienced by the majority of the pts (N=29) was also grade 1, followed by grade 2 (N=12) and grade 3 (N=3). During the second BTZ treatment, a comparison of the symptoms that pts had when PN was at its worst and those recorded at its onset demonstrated that PN worsened in only 7% of the pts. PN showed no change in 47%, improved in 15%, or resolved in 7% of the pts.Interestingly, 17% of the pts (N=10) who had reported PN while receiving their first BTZ-containing regimen did not report this complication during their second BTZ treatment, while 7% of the pts (N=4) experienced PN only upon re-exposure. There was no association between the incidence of PN during the first BTZ treatment and its incidence during re-treatment (p=0.1213) or between the severity of PN (defined as worsening vs. not worsening) after first BTZ treatment and its severity after BTZ re-exposure (p=0.1306). Fifty-four percent of the pts presented with comorbidities, including DM (26%), hypertension (HTN, 22%) and peripheral vascular disease (PVD, 13%). There were no associations between PN grade after BTZ treatment and prior THAL or VCR exposure (p=0.5569) or between PN grade and comorbidities (DM, p=0.6657; HTN, p=0.9966; PVD, p=0.9966). Similar results were found for BTZ re-exposure (THAL or VCR, p=0.8672; DM, p=0.4137; HTN, p=0.2033; PVD, p=0.9954). Conclusions: Results from this retrospective study show that the severity and incidence of PN did not change with a second BTZ-containing regimen. Comorbidities or prior therapy with other PN-inducing agents such as THAL or VCR did not significantly increase the risk of PN after BTZ re-treatment. Enrollment into the study continues and updated results will be presented at the meeting. Disclosures Berenson: Millennium: Consultancy, Honoraria, Research Funding, Speakers Bureau. Tabbara:Millennium: Speakers Bureau. Lutzky:Millennium: Speakers Bureau. Ailawadhi:Millennium: Consultancy. Moezi:Millennium: Speakers Bureau.

Key Points Weekly oral proteasome inhibitor ixazomib appears generally well tolerated with manageable toxicity, limited grade 1/2 neuropathy. Data show that more than 25% of 30 evaluable relapsed/refractory myeloma patients who received the MTD had clinically meaningful responses.