A Phase I Trial Of Anti-KIR Monoclonal Antibody IPH2101 and Lenalidomide For Multiple Myeloma

Multiple myeloma (MM) remains an essentially incurable plasma cell malignancy. MM utilizes specific immunoevasive strategies to avoid natural killer (NK) cell immune surveillance and cytotoxicity. Immunomodulatory agents such as lenalidomide (LEN) may exert indirect anti-MM efficacy via expansion and activation of NK cells. However, these favorable effects may be diminished when LEN is co-administered with high doses of dexamethasone (DEX). IPH2101 is a monoclonal anti-inhibitory KIR antibody which prevents negative signaling in NK cells and enhances NK cell recognition and killing of MM cells. A single-agent, phase I study of IPH2101 demonstrated full KIR blockade with encouraging safety and tolerability, and 34% of heavily pre-treated patients achieved disease stabilization (Blood 2012;120:4324-33). Preclinical data demonstrate that LEN and IPH2101 exert anti-MM effects via complementary NK-cell immunomodulatory mechanisms (Blood 2011;118:6397-91). Herein, data are presented from the first clinical experience with IPH2101 and LEN in combination in patients with MM.

A 3+3 phase I dose-escalation trial was conducted. Patients (age 18-80) with measurable, progressive MM were enrolled having received one or two prior lines of therapy. Prior LEN exposure was permitted unless resistance or intolerance was observed. Patients must have had ECOG performance status ≤ 2, creatinine clearance ≥ 60 ml/min, platelets ≥ 75,000/uL (or ≥ 30,000/uL if > 50% bone marrow plasma cells), absolute neutrophil count ≥ 1,000/uL, bilirubin < 1.5 ULN, and ALT / AST < 3 ULN. Patients must have adhered to standard prescribing guidelines for LEN. Three dose levels included: IPH2101 0.2mg/kg IV q 28 days + LEN 10 mg PO days 1-21; IPH2101 0.2 mg/kg + LEN 25 mg, and IPH2101 1mg/kg + LEN 25 mg for 4 cycles. Responding patients were allowed to receive 4 additional cycles. Patients completing all 8 cycles were maintained on LEN thereafter. No administration of DEX or other systemic corticosteroids was permitted. Dose reductions of LEN were permitted per prescribing information. The primary objective was to determine the safety and tolerability of IPH2101 + LEN, the secondary objectives included pharmacokinetics (PK) and pharmacodynamics (PD) of IPH2101 and biologic correlates with LEN as well as to determine clinical activity by standard IMWG uniform response criteria.

15 patients (10 M, 5 F, median age 60) were enrolled, 8 in first relapse and 9 in second relapse. 9 had prior LEN exposure. Cohorts 1 and 3 were expanded to n=6 patients respectively due to occurrence of possible dose-limiting toxicity. In both cases, a patient experienced a similar, apparent infusion reaction on cycle 1, day 1, characterized by fever, chills, cytokine release, and leucopenia. Events resolved with supportive care and both patients continued on trial without recurrence. The protocol was amended to include premedication with anti-histamine and acetaminophen,and no further infusion reactions were observed. Most other observed adverse events were of low grade and generally investigator-attributed as possibly or probably related to LEN. IPH2101 PD were not affected by co-administration of LEN. Full KIR occupancy was achieved in cohort 3 across the dosing interval. Five patients achieved a response (2 VGPR, 3 PR) with a median duration of 15+ months (3-26+).

The combination of IPH2101 + LEN appears to be a safe and well tolerated, and steroid-free combination in MM patients. Infusion reactions have not been observed since the addition of premedication prior to IPH2101 dosing. IPH2101 PD do not appear to be altered by co-administration of LEN, and full KIR blockade over the dosing interval has been achieved. Although the study is small, response rate and response duration are encouraging. These findings support further investigation of antiKIR therapy with LEN as the first, steroid-sparing, dual immunotherapy for MM.

Benson:Innate Pharma: Research Funding. Off Label Use: Lenalidomide without concomitant dexamethasone. Zerbib:Innate Pharma: Employment. Andre:Innate Pharma: Employment. Caligiuri:Innate Pharma: Membership on an entity’s Board of Directors or advisory committees.