Oral MLN9708 Research Articles

Preclinical Activity of a New Proteasome Inhibitor, MLN9708, in Acute Myelogenous Leukemias Expressing NPM1 Mutated Protein

ABSTRACT: The nucleophosmin-1 (NPM1) mutation represents the most common genetic lesion (30-35%) in adult acute myeloid leukemia (AML) with the mutation resulting in the cytoplasmic delocalization of the NPM protein (NPMc+, most commonly mutation type A, c.860_863dupTCTG). Outside of conventional chemotherapy, treatment options for those with relapsed disease are extremely limited. We have previously discovered that leukemic cells expressing NPMc+ are preferentially sensitive to the cytotoxic effects of the first generation proteasome inhibitor, bortezomib, as result of the induction of superoxide in these cells (Huang M, et al., Leukemia, 2013). However, bortezomib has demonstrated only modest anti-leukemic activity as a single agent in early phase clinical trials that have included primarily heavily pretreated patients not stratified according to mutational genotype. In addition, the high incidence of clinically significant peripheral neuropathy in these studies led to early discontinuation of treatment. MLN9708 (Ixazomib) is a novel second generation proteasome inhibitor that is orally bioavailable and has shown promising activity and improved tolerability in early phase clinical trials in lymphoma and in multiple myeloma, where it is currently in a Phase III clinical trial. The efficacy of MLN9708 in relapsed patients with AML has not yet been examined. We have investigated the in vitro effects of MLN9708 on the cytotoxicity, generation of reactive oxygen species (ROS), and cellular glutathione in both cultured NPMc+ AML cell lines and primary leukemic samples. Cultured OCI-AML3 cells (human AML cell line featuring the NPMc+ mutation) were approximately 50-fold more sensitive to MLN9708 with a mean half inhibitory concentrations (IC50 ± SD) of 67 nM ± 1.83 nM at 24 hours than were an AML cell line (THP-1) expressing wild type NPM1. Knockdown of both NPM1/NPMc+ by inducible NPM1 shRNA expression significantly attenuated the MLN9708-mediated cytotoxicity, as determined by MTS colorimetric and flow cytometric apoptosis assays. As with bortezomib, MLN9708 treatment at 75 nM induced a 2.1-fold (p < 0.002) increase in superoxide-specific DHE (PE)-derived fluorescence as compared to controls. Pre-incubation of cells with 25 mM N-acetylcysteine, a ROS scavenger, dramatically reduced cytotoxicity, strongly implicating the generation of ROS in the mechanism of MLN9708-induced cytotoxicity. Knockdown of NPM1/ NPMc+ expression resulted in an increase of glutathione levels of 2.6-fold (p < 0.04) in untreated cells, and 2.3-fold (p < 0.005) and 2.9-fold (p < 0.004) after a 22 hour incubation with MLN9708 at pharmacologically achievable doses of 75 nM and 150 nM, respectively (Figure 1). In addition, a concomitant 4-fold reduction (p < 0.04) in the NADP+/NADPH ratio was observed in the NPM1/NPMc+ depleted OCI-AML3 cells. In vitro apoptosis assays of primary leukemic blasts isolated from five patients with relapsed NPMc+ AML showed an IC50 for MLN9708 ranging from 49.963-467.487nM (183.8 nM ± 176.8 nM). Based on these promising in vitro studies, a Phase 2 clinical trial of single-agent oral MLN9708 (clinicaltrials.gov identifier: NCT02030405) has been initiated for patients with relapsed or refractory NPMc+ AML.We conclude that the expression of NPMc+ renders AML cells more susceptible to MLN9708 toxicity and that this effect results at least in part from the generation of superoxide. Lower glutathione levels in NPMc+ expressing cells suggests an underlying defect in the antioxidant defense pathway. Demonstration of the sensitivity of NPMc+ AML cells to MLN9708 as a single agent may serve as a platform for the development of novel combination strategies with this drug.Acknowledgments: Research was facilitated by the ASH Clinical Research Training Institute and AACR/ASCO Clinical Cancer Research training program. J.S.G is funded by the Leukemia & Lymphoma Society Career Development Award and ASCO YIA award through a grant supported by Mr. Aaron Sasson. J.S.G. is further supported by the Stanford Hematology Fellowship Program. [Display omitted] DisclosuresOff Label Use: MLN9708 is an investigational compound by Millennium Pharmaceuticals, Inc. (MPI). Through an MTA we have secured the compound for in vitro analysis. This data has led to a clinical trial and drug for that study is supplied by MPI.. Medeiros:Agios: Consulting - Ad board Other.

Twice-Weekly Oral MLN9708 (Ixazomib Citrate), An Investigational Proteasome Inhibitor, In Combination With Lenalidomide (Len) and Dexamethasone (Dex) In Patients (Pts) With Newly Diagnosed Multiple Myeloma (MM): Final Phase 1 Results and Phase 2 Data

Twice-Weekly Oral MLN9708 (Ixazomib Citrate), An Investigational Proteasome Inhibitor, In Combination With Lenalidomide (Len) and Dexamethasone (Dex) In Patients (Pts) With Newly Diagnosed Multiple Myeloma (MM): Final Phase 1 Results and Phase 2 Data

Phase II Study Of The Combination Of MLN 9708 With Lenalidomide As Maintenance Therapy Post Autologous Stem Cell Transplant In Patients With Multiple Myeloma

Phase II Study Of The Combination Of MLN 9708 With Lenalidomide As Maintenance Therapy Post Autologous Stem Cell Transplant In Patients With Multiple Myeloma

Weekly MLN9708, an investigational oral proteasome inhibitor (PI), in relapsed/refractory multiple myeloma (MM): Results from a phase I study after full enrollment.

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.

A Phase 1/2 Study of Weekly MLN9708, an Investigational Oral Proteasome Inhibitor, in Combination with Lenalidomide and Dexamethasone in Patients with Previously Untreated Multiple Myeloma (MM)

A Phase 1/2 Study of Weekly MLN9708, an Investigational Oral Proteasome Inhibitor, in Combination with Lenalidomide and Dexamethasone in Patients with Previously Untreated Multiple Myeloma (MM)

Results of a Phase 1 Dose-Escalation Study of Once-Weekly MLN9708, an Investigational Proteasome Inhibitor, in Patients with Relapsed/Refractory Lymphoma

AbstractAbstract 3646 Background:The validity of proteasome inhibition as an effective therapeutic approach in lymphoma has been demonstrated by the first-in-class proteasome inhibitor bortezomib. MLN9708 is a reversible, orally bioavailable, specific investigational 20S proteasome inhibitor that immediately hydrolyzes in vivo to MLN2238, the biologically active form. In mouse models of lymphoma, MLN2238 was associated with greater tumor proteasome inhibition and enhanced antitumor activity versus bortezomib (Lee et al., Clin Cancer Res 2011). The primary objectives of this study of intravenous (IV) MLN9708 in patients with relapsed/refractory lymphoma (NCT00893464) were to determine the safety and maximum tolerated dose (MTD) of once-weekly MLN9708; secondary objectives included characterization of pharmacokinetics (PK) and pharmacodynamics, and assessment of preliminary antitumor activity. Methods:Patients aged ≥18 years with measurable relapsed/refractory lymphoma who had failed ≥2 prior lines of therapies received IV MLN9708 on days 1, 8, and 15 of 28-day cycles until disease progression or unacceptable toxicity. Dose doubling proceeded from a starting dose of 0.125 mg/m2 with 1 patient per dose up to 1.0 mg/m2. Dose escalation then occurred in 26–40% increments using a standard 3+3 scheme based on occurrence of dose-limiting toxicities (DLTs) in cycle 1. Adverse events (AEs) were graded using NCI CTCAE v3.0. Blood samples were collected at multiple time points on days 1 and 15 of cycle 1, and day 1 of cycle 2 for PK analyses. Response was assessed using IWG criteria. Results:At data cut-off (June 29, 2012), 26 patients (16 male) had been enrolled: 1 each at 0.125, 0.25, 0.5 and 1 mg/m2, 4 at 1.4 mg/m2, 7 at 1.76 mg/m2, 6 at 2.34 mg/m2, and 5 at 3.11 mg/m2. Median age was 56.5 years (range 23–78). Median number of prior therapies was 5 (range 1–12); 31% had prior radiation therapy, 23% had a prior stem cell transplant. Eight patients had Ann Arbor stage IV, 3 had stage III, 6 had stage II, and 2 had stage I; staging was unknown in 4 patients and not applicable in 3. Histologies included follicular lymphoma (FL; n=8), diffuse large B-cell lymphoma (n=6), peripheral T-cell lymphoma (PTCL; n=4), mycosis fungoides (n=2), Hodgkin lymphoma (n=3), and others (n=3). Patients have received a median of 2 cycles of MLN9708 (range 1–29). Four DLTs were reported: 1 grade 4 neutropenia at 1.76 mg/m2, 1 grade 3 neutropenia at 2.34 mg/m2, and 2 grade 3 acute pre-renal failure due to GI toxicities and dehydration at 3.11 mg/m2. The MTD has been determined as 2.34 mg/m2. All patients experienced drug-related AEs, including fatigue (n=12), diarrhea (n=10), nausea, vomiting (each n=8), thrombocytopenia (n=6), pyrexia, neutropenia, decreased appetite, and headache (each n=5). Twelve patients (46%) had drug-related grade ≥3 AEs, including neutropenia (n=4), thrombocytopenia, and diarrhea (each n=3). Three patients discontinued due to AEs of drug-related grade 3 neutropenia (2.34 mg/m2), drug-related grade 3 asthenia and grade 3 acute pre-renal failure, and unrelated grade 3 thrombocytopenia (both 3.11 mg/m2). Three patients reported drug-related serious AEs. Four patients reported drug-related peripheral neuropathy, all were grade 1 or 2. There was 1 on-study death due to respiratory failure, considered unrelated to MLN9708. PK analyses showed a dose-proportional increase in plasma exposure with increasing dose from 0.5 to 2.34 mg/m2 and a terminal half-life of 5.5–9 days after multiple dosing. There was a dose-dependent increase in maximal whole blood 20S proteasome inhibition. Of 22 response-evaluable patients (as of August 7, 2012), one achieved a complete response (CR; FL at 1.76 mg/m2, initial partial response [PR] at cycle 4, improved to CR at cycle 20, ongoing at cycle 24), and 3 achieved a PR (1 FL at 1.4 mg/m2, achieved at cycle 10, ongoing at cycle 30; 1 FL at 3.11 mg/m2, recently achieved at cycle 2 and ongoing at cycle 3; 1 PTCL at 2.34 mg/m2, achieved at cycle 4 but progressed at cycle 8). A further 4 patients had stable disease of ≥ 4 cycles. Conclusions:These phase 1 data suggest that once-weekly IV MLN9708 is generally well tolerated, with infrequent peripheral neuropathy, and shows signs of clinical activity in heavily pretreated relapsed/refractory lymphoma patients, particularly FL patients. Enrollment continues at the MTD; phase 2 studies with oral MLN9708 are planned. Disclosures:Off Label Use: Use of the investigational agent MLN9708, an oral proteasome inhibitor, in the treatment of relapsed and/or refractory lymphoma. Chang:Genentech: Research Funding; Celgene: Research Funding. Rifkin:Millennium Pharmaceuticals, Inc./Takeda: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; ONYX: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; INCYTE: Speakers Bureau; Amgen: Speakers Bureau. Hui:Millennium Pharmaceuticals, Inc.: Employment. Yu:Millennium Pharmaceuticals, Inc.: Employment. Gupta:Millennium Pharmaceuticals, Inc.: Employment. Di Bacco:Millennium Pharmaceuticals, Inc: Employment. Shou:Millennium Pharmaceuticals, Inc: Employment. Martin:Millennium Pharmaceuticals, Inc.: Speakers Bureau.

MLN9708, a Novel, Investigational Oral Proteasome Inhibitor, in Patients with Relapsed or Refractory Light-Chain Amyloidosis (AL): Results of a Phase 1 Study

Abstract 731 Background: Treatment with bortezomib achieves high hematologic response rates and rapid and durable responses in AL patients (pts), providing the rationale for proteasome inhibition in this population. MLN9708 is an investigational, oral, potent, reversible, and specific 20S proteasome inhibitor (PI). In preclinical studies, MLN9708 has shown improved antitumor activity compared to bortezomib in a range of xenograft models. This phase 1 study (NCT01318902) assessed weekly doses of oral MLN9708 in pts with relapsed or refractory AL. Methods: Pts aged ≥18 years with relapsed or refractory AL after ≥1 prior therapy, cardiac biomarker stage I/II disease, and measurable major organ (heart/kidney) involvement, received increasing doses of oral MLN9708 (standard 3+3 dose escalation fixed doses of 4.0 and 5.5 mg), on days 1, 8, and 15 of 28-day cycles for up to 12 cycles. Pts with no major hematologic response ( Results: At data cut-off (June 29, 2012) 16 pts had been enrolled and received ≥1 MLN9708 dose (safety population). The median age was 66.5 years (range 54–78) and 7 were male. Median number of prior therapies was 3 (range 1–7); 10 received prior transplant, 7 received prior bortezomib. Major organ involvement, defined by standard criteria, included heart, kidney, or both in 7/5/4 pts, respectively, with a median of 2 (range 1–5) involved organ systems, and Mayo cardiac biomarker risk stage was I, II, III in 6, 9, 1 pts. Five pts were treated in the 5.5 mg cohort and 11 pts were treated in the 4.0 mg (n=6 dose escalation; n=5 dose expansion) cohorts. Of the 11 pts treated at 4.0 mg, 4 were PI-naive, 7 were PI-exposed. Pts received a median of 3 cycles (range 1–12); 5 pts received ≥5 cycles, and 8 pts remain on treatment. Dex was added in 4 pts (2 in each MLN9708 dose level). There were no on-study deaths. Pts discontinued due to disease progression (n=5), AE, withdrawal by pt, or unsatisfactory response (each n=1); 2 pts completed planned 1 year of therapy. One pt in the 4.0 mg cohort experienced a DLT of grade 3 thrombocytopenia. Two pts in the 5.5 mg dose cohort experienced DLTs: grade 3 diarrhea in 1 pt, and renal failure, respiratory failure (both grade 2), and cardiac arrest (grade 4) in another pt. The MTD was determined as 4.0 mg. AEs were reported in 14 pts. The most common drug-related AEs included nausea (n=5), diarrhea and thrombocytopenia (each n=4), abdominal pain and fatigue (each n=3). Grade ≥3 AEs (any cause) reported in >1 pt were thrombocytopenia (n=4), dyspnea (n=3), maculo-papular rash, dehydration, and abdominal pain (each n=2); all were grade 3. Preliminary response data are shown in the table. At data cut-off, one responder had progressed, and the median duration of hematologic response was 7.4 months (range 1.3–11.5+); 2 pts had cardiac organ response. Preliminary PK data showed that MLN9708 was rapidly absorbed, with a median Tmax of 1 hr (range 0.5–6). MLN9708 day 15 plasma Cmax was 73.6 ± 40.2 ng/mL (mean ± SD) and AUC0–168was 1250 ±530 ng*hr/mL (n=8 at 4.0 mg dose cohort). MLN9708 PK parameter values in this study appear similar to other MLN9708 studies in myeloma pts. Conclusions: These data suggest weekly oral administration of MLN9708 is feasible in pts with relapsed or refractory AL. The MLN9708 MTD was determined as 4.0 mg. Assessment is ongoing, with preliminary evidence of hematologic responses noted. A phase 3 study of MLN9708 plus dex versus physician9s choice of treatment is planned (NCT01659658). Disclosures: Merlini:Millennium Pharmaceuticals, Inc.: Consultancy. Off Label Use: Use of the investigational agent MLN9708, an oral proteasome inhibitor, in the treatment of relapsed or refractory light-chain amyloidosis. Sanchorawala:Celgene: Research Funding; Millennium Pharmaceuticals, Inc.: Research Funding; Onyx: Research Funding. Zonder:Celgene: Research Funding; Millennium Pharmaceuticals, Inc: Consultancy, Research Funding. Kukreti:Roche: Consultancy, Honoraria; Celgene: Honoraria; Janssen: Honoraria. Schonland:Celgene: Honoraria, Research Funding; Janssen: Honoraria. Dispenzieri:Janssen Research & Development: Research Funding; Millennium Pharmaceuticals, Inc.: Research Funding; Celgene: Research Funding. Cohen:Celgene: Honoraria, Membership on an entity9s Board of Directors or advisory committees; Bristol-Meyers Squibb: Honoraria, Membership on an entity9s Board of Directors or advisory committees; Onyx: Honoraria, Membership on an entity9s Board of Directors or advisory committees. Berg:Millennium Pharmaceuticals, Inc.: Employment. Liu:Millennium Pharmaceuticals, Inc.: Employment. Di Bacco:Millennium Pharmaceuticals, Inc.: Employment. Gupta:Millennium Pharmaceuticals, Inc.: Employment. Hui:Millennium Pharmaceuticals, Inc.: Employment. Comenzo:Millennium Pharmaceuticals, Inc.: Consultancy, Membership on an entity9s Board of Directors or advisory committees, Research Funding.

Weekly dosing of the investigational oral proteasome inhibitor MLN9708 in patients (pts) with relapsed/refractory multiple myeloma (MM): A phase I study.

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.

Oral weekly MLN9708, an investigational proteasome inhibitor, in combination with lenalidomide and dexamethasone in patients (pts) with previously untreated multiple myeloma (MM): A phase I/II study.

8033 Background: MLN9708 is an oral, reversible 20S proteasome inhibitor. The feasibility of combining a proteasome inhibitor with an immunomodulatory drug and a steroid in previously untreated MM has been demonstrated with the RVD regimen. This is the first study of MLN9708 in combination with lenalidomide and dexamethasone (NCT01217957). Here we report the phase (Ph) 1 MTD and preliminary Ph 2 results. Methods: Pts with previously untreated MM, aged ≥18 yrs with measurable disease received oral MLN9708 (phase 1: 1.68–3.95 mg/m2) days 1, 8, and 15, lenalidomide 25 mg days 1–21, and dexamethasone 40 mg days 1, 8, 15, and 22, for up to twelve 28-day cycles. Primary objectives were determination of safety, MTD, and recommended phase 2 dose (RP2D) (Ph 1), and CR+VGPR rate (Ph 2). Results: At data cut-off (Dec 1, 2011), 29 pts had been enrolled (15 Ph 1, 14 Ph 2). Median age was 64 yrs (range 40–82); 69% ISS stage II/III. In Ph 1, the MLN9708 MTD was determined as 2.97 mg/m2 and the RP2D as 2.23 mg/m2; for Ph 2, the RP2D was converted to a 4.0 mg fixed dose based on population PK results. Ph 1 pts have received a median of 6 treatment cycles (range 1–11), 8 received ≥6 cycles; 6 stopped to receive ASCT, 7 are ongoing. Ph 2 pts received a median of 1 (range 1–2), all are ongoing. Grade ≥3 hematologic toxicity was reversible and included anemia (n=2) and thrombocytopenia (n=1). Grade ≥3 nonhematologic toxicity included erythematous rash, syncope, and vomiting (2 pts each). All-grade drug-related peripheral neuropathy was seen in 6 pts (21%), including grade 2 with pain in 2 (both Ph 1 at doses above the MTD). Two pts discontinued due to AE; there were 5 pts who had serious drug-related AE (all Ph 1). Of 19 response-evaluable pts (Ph 1 + Ph 2), all achieved ≥PR, including 5 CR (1 sCR), 4 VGPR, and 10 PR; all remain in response with duration of confirmed response of up to 9.5 months. Of 4 response-evaluable Ph 2 pts, 1 has achieved VGPR and 3 PR to date. Conclusions: Oral MLN9708 plus lenalidomide and dexamethasone appears well tolerated with manageable toxicity. These data show antitumor activity at the RP2D in pts with previously untreated MM, with ≥PR in all pts to date.

Phase I study of twice-weekly dosing of the investigational oral proteasome inhibitor MLN9708 in patients (pts) with relapsed and/or refractory multiple myeloma (MM).

8017 Background: MLN9708 is the first oral proteasome inhibitor to enter clinical investigation in MM. This study (NCT00932698) assessed safety, MTD, and response rate with twice-weekly oral MLN9708 in pts with relapsed and/or refractory MM, and characterized plasma pharmacokinetics (PK) and blood pharmacodynamics. Methods: Pts aged ≥18 yrs with measurable MM received MLN9708 on d 1, 4, 8, and 11 of 21-d cycles. In the dose-escalation phase, pts required ≥2 prior therapies (including bortezomib, thalidomide/lenalidomide, and corticosteroids). At the MTD (2.0 mg/m2), pts were enrolled to relapsed and refractory [RR], bortezomib-relapsed [VR], proteasome-inhibitor [PI] naïve, and carfilzomib [CZ] expansion cohorts. Results: 57 pts (53% M) were enrolled, 37 to the expansion cohorts (16 RR, 14 VR, 6 PI naïve, 1 CZ). Median age was 65 yrs (range 50-86). Median number of prior lines of therapy was 4 (range 1-28); 88%, 84%, 61%, and 5% had prior bortezomib, lenalidomide, thalidomide, and carfilzomib, respectively. Pts have received a median of 3 cycles (range 1-24) to date (data cut-off Dec 1, 2011); 7 (12%) have received ≥13 cycles. Drug-related AEs were seen in 89% of pts, including fatigue (46%), thrombocytopenia (40%), and nausea (30%); 63% had drug-related grade ≥3 AEs, including thrombocytopenia (33%), neutropenia (14%), fatigue (9%), and rash (7%). Only 6 (11%) pts had drug-related peripheral neuropathy (PN; no grade ≥3). 7 pts discontinued due to AEs. 2 pts died on study, due to PD and an unrelated cardiac disorder. Of 46 response-evaluable pts, 6 have achieved ≥PR, with 1 sCR (PI naïve cohort) and 5 PRs (2 in dose-escalation, 1 in RR, 2 in VR cohorts), and 1 VR pt has achieved MR, with duration of disease control of up to 18.6 mo. PK analyses showed MLN2238 (biologically active hydrolysis product) has linear plasma PK (0.8-2.23 mg/m2), Tmax of 0.5-1.25 hr, and terminal half-life of 4-6 d. A dose-dependent increase in whole blood 20S proteasome inhibition was observed. Conclusions: Current data suggest MLN9708 has clinical activity in heavily pretreated MM pts, with durable responses/disease control, and is generally well tolerated with infrequent low-grade PN.

Phase 1/2 Study of Oral MLN9708, A Novel, Investigational Proteasome Inhibitor, in Combination with Lenalidomide and Dexamethasone in Patients with Previously Untreated Multiple Myeloma (MM)

Abstract 479 Background:MLN9708 is an investigational, oral, potent, reversible, and specific 20S proteasome inhibitor, which immediately hydrolyzes to MLN2238, the biologically active dipeptidyl leucine boronic acid. In preclinical studies, MLN2238 has shown faster proteasome dissociation and greater tissue penetration than bortezomib. Current phase 1 data indicate that oral administration of single-agent MLN9708 was generally well tolerated, with no grade ≥3 peripheral neuropathy, and showed signs of antitumor activity in some patients with relapsed and/or refractory MM. Bortezomib in combination with lenalidomide and dexamethasone demonstrated a 100% partial response or better (≥PR) rate in patients with previously untreated MM, providing the rationale for evaluating oral MLN9708 in place of bortezomib in this combination. Here we report phase 1 data from the first combination study of MLN9708 (ClinicalTrials.gov: NCT01217957). Methods:Primary phase 1 objectives were to determine the safety, tolerability, and maximum tolerated dose (MTD) of weekly MLN9708 in combination with lenalidomide and dexamethasone; secondary objectives included characterization of the pharmacokinetic (PK)/pharmacodynamic (PD) profile of MLN9708, assessment of PK interaction and response. Adults aged ≥18 years with ECOG performance status of 0 to 2, and adequate renal, hepatic, and hematologic function were eligible. Patients with grade ≥2 peripheral neuropathy or prior/concurrent deep vein thrombosis (DVT)/pulmonary embolism were excluded. Patients received oral MLN9708 weekly on days 1, 8, and 15, lenalidomide 25 mg on days 1–21, and dexamethasone 40 mg on days 1, 8, 15, and 22, for up to twelve 28-day cycles. Patients received thromboprophylaxis with aspirin or low molecular weight heparin. Transplant-eligible patients could undergo stem cell transplant after six cycles. MLN9708 dose escalation, from a starting dose of 1.68 mg/m2, followed a 3+3 scheme based on the occurrence of dose-limiting toxicities (DLTs) in cycle 1. Adverse events (AEs) were evaluated according to NCI-CTCAE v4.0. Response was assessed according to modified EBMT criteria. Results:At data cut-off (June 29, 2011), 10 patients have been enrolled and treated: three each at 1.68, 2.23, and 2.97 mg/m2 and one at 3.95 mg/m2; median age was 66 years (range 59–77). Patients completed a median of 3 cycles (range 1–6), with three having received 6 cycles; treatment is ongoing in six patients. A DLT of grade 3 fainting was observed in a patient treated at 3.95 mg/m2. The MTD has not yet been reached; the current cohort is receiving 3.95 mg/m2. Drug-related AEs included rash in four patients (two maculopapular, two erythematous); vomiting and fatigue in three patients each; and diarrhea, constipation, and nausea in two patients each. Grade 1 treatment-related peripheral neuropathy was reported in one patient. Serious AEs were seen in four patients: one at 3.95 mg/m2 (DLT of grade 3 fainting), one at 2.23 mg/m2 (grade 3 DVT) unrelated to MLN9708, and two unrelated at 1.68 mg/m2 (grade 3 hypotension; grade 3 gastrointestinal hemorrhage resulting in discontinuation). Two patients required lenalidomide dose reductions to 15 mg due to erythematous rash; no dose reductions were required for MLN9708 or dexamethasone. There were no on-study deaths. Of nine response-evaluable patients, all nine achieved ≥PR, including three very good PR (VGPR) and one complete response. Time to response was rapid; all responders achieved a ≥50% decrease in M-protein in cycle 1, and best response was reached by the end of cycle 4. No patient has progressed to date. One patient with confirmed VGPR discontinued at cycle 6 to undergo stem cell transplant. Conclusions:MLN9708 administered weekly in combination with lenalidomide and dexamethasone appears to be generally well tolerated in previously untreated MM patients at the MLN9708 dose levels studied, with evidence of antitumor activity in the dose-escalation cohorts. Evaluation continues to determine the MTD of MLN9708 in this combination. Updated results, PK data, assessment of PK interaction, and PD data will be presented. Disclosures:Off Label Use: Use of the investigational agent MLN9708 for the treatment of previously untreated multiple myeloma. Richardson:Johnson & Johnson: Membership on an entity’s Board of Directors or advisory committees; Celgene: Membership on an entity’s Board of Directors or advisory committees; Millennium Pharmaceuticals, Inc.: Membership on an entity’s Board of Directors or advisory committees. Lonial:Millennium Pharmaceuticals, Inc.: Consultancy; Celgene: Consultancy; Novartis: Consultancy; BMS: Consultancy; Onyx: Consultancy; Merck: Consultancy. Niesvizky:Celgene: Consultancy, Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding, Speakers Bureau; Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding, Speakers Bureau; Onyx: Research Funding. Hui:Millennium Pharmaceuticals, Inc.: Employment. Berg:Millennium Pharmaceuticals, Inc.: Employment. Gupta:Millennium Pharmaceuticals, Inc.: Employment. Liu:Millennium Pharmaceuticals, Inc.: Employment. Di Bacco:Millennium Pharmaceuticals, Inc.: Employment. Kumar:Merck: Consultancy, Honoraria; Celgene: Consultancy, Research Funding; Millennium Pharmaceuticals, Inc.: Research Funding; Genzyme: Research Funding; Novartis: Research Funding.

Weekly Dosing of the Investigational Oral Proteasome Inhibitor MLN9708 in Patients with Relapsed and/or Refractory Multiple Myeloma: Results From a Phase 1 Dose-Escalation Study

Weekly Dosing of the Investigational Oral Proteasome Inhibitor MLN9708 in Patients with Relapsed and/or Refractory Multiple Myeloma: Results From a Phase 1 Dose-Escalation Study

Investigational Agent MLN9708, An Oral Proteasome Inhibitor, in Patients (Pts) with Relapsed and/or Refractory Multiple Myeloma (MM): Results From the Expansion Cohorts of a Phase 1 Dose-Escalation Study

Abstract 301 Background: The investigational agent MLN9708 is the first oral proteasome inhibitor (PI) to enter clinical investigation in MM pts. MLN9708 has shown antitumor activity in solid tumor and hematologic malignancy xenograft models, including in vivo models of MM. The primary objectives of this study (NCT00932698) were to determine safety/tolerability, maximum tolerated dose (MTD), and recommended phase 2 dose of oral MLN9708 in pts with relapsed and/or refractory MM. Secondary objectives included evaluation of response rate and characterization of pharmacokinetics (PK, of MLN2238, the biologically active hydrolysis product) and pharmacodynamics (20S proteasome inhibition in blood). Methods: Pts aged ≥18 years with measurable disease and no grade ≥2 peripheral neuropathy (PN) were eligible. For the dose-escalation phase (3+3 design), pts required ≥2 prior therapies, which must have included bortezomib, thalidomide or lenalidomide, and corticosteroids. Pts could have received other PIs. At the MTD, pts were enrolled to four expansion cohorts: relapsed and refractory cohort (progressive disease [PD] on therapy or Results: As of June 29 2011, 53 pts have been enrolled (53% male). Median age was 66 years (range 50–86), median time since initial MM diagnosis was 4.6 years (range 1.1–24.3), and median number of prior therapies was 4 (range 1–28); 55% of pts had received stem cell transplant, 92%, 80%, 56%, and 4% had prior bortezomib, lenalidomide, thalidomide, and carfilzomib, respectively, and 47% were refractory to last therapy, including 28% who were bortezomib-refractory. During dose escalation, 27 pts received MLN9708 0.24–2.23 mg/m2; the MTD was determined as 2.0 mg/m2. To date, 32 pts have been enrolled to the expansion cohorts (including 6 from the dose-escalation phase): 17, 11, and 4 to the relapsed and refractory, bortezomib-relapsed, and PI-naive cohorts, respectively. Overall, pts have received a median of 3 cycles (range 1–17), with 6 (11%) receiving ≥12 cycles. At data cut-off, 58% of pts had discontinued, mainly due to PD (36%). Safety profiles appeared similar between dose-escalation and expansion cohorts. Overall, 87% of pts experienced drug-related AEs, the most common being fatigue (45%), thrombocytopenia (30%), nausea (26%), diarrhea (25%), vomiting, and rash (each 23%). Only four (8%) pts had drug-related PN (three grade 1, one grade 2); all had grade 1 PN (n=3) or paresthesias (n=1) at baseline. Overall, 58% had grade ≥3 AEs, 21% had dose reductions, and 6% discontinued due to AEs (thrombocytopenia, arthralgia, hypoxia). Two pts died on study due to PD and a cardiac disorder, considered unrelated. To date, of 36 evaluable pts, six have achieved minimal response or better, including two with partial responses (in the 1.2 and 2.23 mg/m2 cohorts), with duration of disease control of up to 11.3 months; all 6 pts remain in response. Another 22 pts have achieved stable disease, which also proved durable with stabilization for up to 9.9 months. MLN9708 was rapidly absorbed with MLN2238 Tmax of 0.5–1.25 hours and terminal half-life of approximately 4–5 days after multiple MLN9708 dosing. MLN2238 plasma exposure appeared to increase proportionally with increasing MLN9708 dose from 0.8–2.23 mg/m2. Maximal 20S proteasome inhibition in blood was immediate and dose-dependent. Conclusions: Current data suggest that single-agent MLN9708 may result in clinical activity in heavily pretreated relapsed and/or refractory MM pts, including durable disease control, and is generally well tolerated, with infrequent PN. Updated information for all cohorts, plus data from an analysis of candidate biomarkers of responsiveness to treatment with MLN9708, will be presented. Disclosures: Richardson:Millennium Pharmaceuticals, Inc.: Consultancy; Celgene: Consultancy; Johnson & Johnson: Consultancy. Off Label Use: Use of the investigational agent MLN9708, an oral proteasome inhibitor, in the treatment of relapsed and/or refractory multiple myeloma. Baz:Celgene: Consultancy, Research Funding; Millennium Pharmaceuticals, Inc.: Research Funding; Orthobiotech: Research Funding. Wang:Millennium Pharmaceuticals, Inc.: Research Funding. Jakubowiak:Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity9s Board of Directors or advisory committees; Onyx Pharmaceuticals: Consultancy, Membership on an entity9s Board of Directors or advisory committees; Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria, Membership on an entity9s Board of Directors or advisory committees, Speakers Bureau; Celgene: Consultancy, Honoraria, Speakers Bureau; Ortho Biotech: Consultancy, Honoraria, Membership on an entity9s Board of Directors or advisory committees, Speakers Bureau; Exelixis: Consultancy, Honoraria. 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. Lonial:Millennium Pharmaceuticals, Inc.: Consultancy; Celgene: Consultancy; Novartis: Consultancy; Bristol-Myers Squibb: Consultancy; Onyx: Consultancy; Merck: Consultancy.

Clinical Pharmacokinetics of Intravenous and Oral MLN9708, An Investigational Proteasome Inhibitor: An Analysis of Data From Four Phase 1 Monotherapy Studies

AbstractAbstract 1813 Background:Investigational agent MLN9708, a modified dipeptidyl boronic acid, is a potent, reversible and specific inhibitor of the 20S proteasome being evaluated in phase 1 trials of patients with hematologic malignancies and solid tumors. Preliminary plasma pharmacokinetic (PK) data for MLN9708 administered intravenously (IV) and orally (PO) are reported. Both routes of administration are being studied using a twice-weekly schedule (Days 1, 4, 8, and 11 of a 21-day treatment cycle) and a weekly schedule (Days 1, 8, and 15 of a 28-day treatment cycle). MLN9708 completely hydrolyzes to the pharmacologically active boronic acid MLN2238 in aqueous solutions. Methods:Preliminary PK data from four ongoing phase 1 dose-escalation studies with MLN9708 have been analyzed: two studies investigating IV administration (C16001, n=27; C16002, n=7) and two studies of the oral formulation (C16003, n=9; C16004, n=5). In all studies blood samples were collected following the first and final dose of MLN9708 administered in Cycle 1, and trough samples were collected throughout Cycle 1 and at the start of Cycle 2. MLN9708 PK samples were analyzed for MLN2238 plasma and urine concentrations using LCMS/MS with LLOQ of 0.5 ng/mL for plasma samples. Data were analyzed using noncompartmental and compartmental modeling approaches. Plasma exposure parameters (Cmax, Tmax, AUC0-t, and t1/2) were estimated using WinNonlin software v5.2. Results:Following bolus IV administration of MLN9708, MLN2238 showed multi-exponential plasma disposition, characterized by a rapid initial disposition phase (t1/2 of <0.25 hr), an intermediate disposition phase, and a terminal disposition phase with t1/2 of >4 days. For twice-weekly dosing, the Day 1 and Day 11 extrapolated immediate post-IV bolus plasma concentration of MLN2238 (C0) was roughly dose proportional over the dose range (0.125 to 2.34 mg/m2). In contrast, both the Day 1 and Day 11 dosing interval plasma concentration-time AUCs showed dose proportional increases only over the higher dose range (1 to 2.34 mg/m2). There was approximately 3–4 fold accumulation of MLN2238 by Day 11 on the twice-weekly schedule. For weekly IV dosing of MLN9708, only lower dose levels have been studied to date (0.125 to 1.4 mg/m2) but the PK behavior appears to be similar to that for twice-weekly dosing, with the exception that MLN2238 accumulates to a lesser degree (approximately 2-fold). Following oral administration of MLN9708 capsules, there was rapid absorption of MLN2238 (Tmax approximately 1 hr). At the doses studied to date (0.24 to 1.2 mg/m2) for twice-weekly and weekly dosing of MLN9708, systemic exposures achieved with oral dosing were similar to those achieved with IV dosing on the same schedule, indicating that the oral bioavailability of MLN2238 is substantial. Conclusions:MLN9708 (measured as MLN2238) shows approximately dose linear PK over the higher range of doses tested (1 to 2.34 mg/m2). Current data suggest that oral MLN9708 is rapidly absorbed and is substantially bioavailable. Acknowledgment:We thank all study investigators, study managers, and study enrollees participating in studies C16001 (advanced nonhematologic malignancies), C16002 (lymphoma), C16003 (multiple myeloma), and C16004 (multiple myeloma) for providing PK data for analysis. Disclosures:Gupta:Millennium Pharmaceuticals, Inc.: Employment. Off Label Use: Investigational agent in clinical development for the treatment of solid tumors and hematologic malignancies. Liu:Millennium Pharmaceuticals, Inc.: Employment. Berg:Millennium Pharmaceuticals, Inc.: Employment; Takeda, Inc.: Equity Ownership; Sanofi-Aventis: Equity Ownership; Pfizer: Equity Ownership. Kalebic:Millennium Pharmaceuticals, Inc.: Employment. Gomez-Navarro:Millennium Pharmaceuticals, Inc.: Employment, Equity Ownership.