Phase 1 Dose-Escalation Study of MLN4924, a Novel NAE Inhibitor, in Patients with Multiple Myeloma and Non-Hodgkin Lymphoma.

MLN4924 is a first-in-class small molecule inhibitor of NEDD8-activating enzyme (NAE), an essential component of the NEDD8 conjugation pathway in the ubiquitin-proteasome system. Inhibition of NAE with MLN4924 prevents conjugation of NEDD8 to the Cullin Ring Ligases (CRLs). This subsequently prevents ubiquitination and proteasomal degradation of CRL substrates, which include proteins involved in cell cycle regulation (p27), signal transduction (pIκBá), DNA replication (Cdt-1), stress response (Nrf-2), and other processes important to tumor cell growth and survival. MLN4924 has demonstrated potent antitumor activity in vitro against multiple myeloma (MM) and non-Hodgkin lymphoma (NHL) cell lines as well as in mouse xenograft models of NHL. This phase 1 dose-escalation study is the first investigation of MLN4924 in MM or NHL patients (pts). The primary objectives were to determine the maximum tolerated dose (MTD) and safety profile of MLN4924, describe the pharmacokinetics (PK) and pharmacodynamics (PD) in blood (inhibition of NEDD8-Cullin levels in peripheral blood mononuclear cells [PBMCs]; Nrf-2 target gene transcription in whole blood), and investigate PD effects in skin (Cdt-1, Nrf-2 accumulation).

Pts aged ≥18 yrs with relapsed and/or refractory MM or NHL after ≥2 prior lines of therapy were eligible. Pts received escalating doses of MLN4924 by IV infusion on days 1, 2, 8, and 9 of 21-day cycles; once the MTD for this schedule was reached, MTDs for other schedules will be investigated. MTD determination was based on an adaptive approach using a Bayesian continual reassessment method, with the MTD defined as the dose level closest to that predicted to result in a dose-limiting toxicity (DLT) rate of 25%. DLT was defined as: grade 4 neutropenia or thrombocytopenia for >7 days; grade 3 neutropenia with fever/infection or thrombocytopenia with bleeding; grade ≥3 non-hematologic toxicity except arthralgia/myalgia, brief fatigue, or fever without neutropenia; and grade ≥2 MLN4924-related toxicities requiring dose reduction/discontinuation. For PD analysis, PBMCs and whole blood were isolated at screening, baseline, and following MLN4924 administration; skin biopsies for Cdt-1 and Nrf-2 assays were performed at baseline and after the second dose.

Among 22 pts enrolled to date, median age was 65 years, 13 were male, 14 had MM, and 8 had NHL (4 FL, 1 MCL, 1 DLBCL, 1 B-cell CLL/SLL, 1 transformed CLL). All MM pts had received prior autologous SCT, and 13, 9, and 9 had prior bortezomib, lenalidomide, and thalidomide, respectively. Seven NHL pts had received prior autologous SCT, 1 had a prior allogeneic SCT, and 8 had prior rituximab. Pts received MLN4924 at 6 dose levels: 25 (n=3), 50 (n=2), 65 (n=3), 83 (n=2), 110 (n=9), and 147 mg/m² (n=3). Of the 15 (68% of the 22 enrolled) pts who received all 4 scheduled doses or had a DLT in cycle 1 (DLT-evaluable pts), 4 experienced a DLT: 1 grade 4 febrile neutropenia at 65 mg/m²; 1 grade 3 liver function tests at 110 mg/m², and 1 grade 4 muscle cramps and 1 grade 2 myalgia that was considered dose limiting at 147 mg/m². Thus, the MTD for this schedule was determined to be 110 mg/m². The most common adverse events (AEs, NCI CTCAE v3.0) included fatigue, nausea, myalgia, and elevated liver enzymes. With the exception of the grade 4 neutropenia seen at 65 mg/m², myelosuppression was limited. No infusion-related reactions were noted. Elevated CRP levels appeared transient in most cases. There have been no treatment-related deaths; 1 MM pt died due to progressive disease. MLN4924 displayed a multiexponential PK profile with a half life of 4–9 hours, relatively low PK variability, and approximately dose-proportional increases in total plasma exposure over the 25–147 mg/m² dose range. NEDD8-Cullin levels in PBMCs were inhibited and Nrf-2 target gene transcripts in whole blood were higher vs baseline after MLN4924 administration, indicative of NAE inhibition. Cdt-1 and Nrf-2 levels in skin increased above baseline following the second dose of MLN4924, indicative of NAE inhibition in peripheral tissue. The 110 mg/m² dose level is being expanded to more fully characterize safety, PK, and PD in MM and NHL. Subsequent pts will be enrolled to receive MLN4924 on 2 other schedules.

This early analysis provides evidence of PD inhibition of NAE activity by MLN4924 in blood and skin, and supports continued investigation of MLN4924.

Shah:Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Elan: Consultancy; Millennium Pharmaceuticals, Inc.: 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. Off Label Use: MLN4924 is not approved for the treatment of multiple myeloma or non-Hodgkin lymphoma.. Jakubowiak:Bristol-Myers-Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; 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. Berger:Millennium Pharmaceuticals, Inc.: Employment. Mulligan:Millennium Pharmaceuticals, Inc.: Employment. Petruzzelli:Pfizer: Equity Ownership; Millennium Pharmaceuticals, Inc.: Employment; Amgen: Equity Ownership. Pickard:Millennium Pharmaceuticals, Inc.: Employment. Smith:Millennium Pharmaceuticals, Inc.: Employment. Venkatakrishnan:Millennium Pharmaceuticals, Inc.: Employment. Lonial:Novartis: Consultancy; Gloucester: Research Funding; BMS: Consultancy; Millennium Pharmaceuticals, Inc.: Consultancy, Research Funding; Celgene: Consultancy.