Randomized Phase 2 Trial of Lirilumab (anti-KIR monoclonal antibody, mAb) As Maintenance Treatment in Elderly Patients (pts) with Acute Myeloid Leukemia (AML): Results of the Effikir Trial
Authors: Vey Norbert , Dumas Pierre-Yves , Recher Christian , Gastaud Lauris , Lioure Bruno , Bulabois Claude-Eric , Pautas Cecile , Marolleau Jean-Pierre , Leprêtre Stéphane , Raffoux Emmanuel , Thomas Xavier , Hicheri Yosr , Bonmati Caroline , Quesnel Bruno , Rousselot Philippe , Castaigne Sylvie , Jourdan Eric , Malfuson Jean Valère , Guillerm Gaelle , Bouhris Jean Henri , Ojeda Mario , Hunault Mathilde , Ifrah Norbert , Gardin Claude , Delannoy Andre , Beautier Lucile , Paturel Carine , Andre Pascale , Zerbib Robert , Preudhomme Claude , Toubert Antoine , Dulphy Nicolas , Olive Daniel , Pigneux Arnaud , Dombret Herve 
Published: April 2021

Abstract
Background
Inhibitory Killer Immunoglobulin-like Receptors (KIR) negatively regulate Natural Killer (NK) cell-mediated killing of HLA class I-expressing tumors. Lack of KIR-HLA class I interactions has been associated with antitumor efficacy and increased survival in patients (pts) with AML in CR after haploidentical stem cell transplantation from KIR-mismatched donors(Ruggeri, Blood 2007). IPH2101, a fully human mAb designed to enhance antitumor effects of NK cells by blocking the major inhibitory HLA-C-specific KIR can be safely administered in elderly pts with AML (Vey, Blood 2012). Lirilumab is a 2nd generation anti-KIR mAb currently evaluated in multiple indications and combinations with encouraging preliminary results in combination with nivolumab in pts with squamous cell carcinoma of the head and neck (Leidner, SITC 2016). Here we report the results of a phase 2 trial with lirilumab as single agent in the maintenance therapy of elderly pts with AML in first CR. The objectives of this randomized phase 2 study were to determine if lirilumab could improve leukemia free survival (LFS) and to assess two dose schedules predicted from the phase 1 dose-escalation trial (Vey, ASCO 2015) to be associated with either continuous (CONT) or intermittent (INT) full KIR occupancy.
Methods
EFFIKIR was a randomized double-blind 3-arm placebo controlled trial (NCT01687387). Eligible pts were: aged 60 to 80 yrs, diagnosed with non-APL AML, in CR1 following standard induction (1 to 2 cycles) and consolidation (1 to 2 cycles) and had: ECOG performance status of 0-1, adequate hematologic, liver and renal function. Pts were randomly allocated to receive placebo or lirilumab given at either 0.1 mg/kg q 12 weeks (INT) or 1mg/kg q 4 weeks (CONT) according to a minimization algorithm adjusting for center, primary vs. secondary AML, number of consolidation cycles (1 vs. 2) and cytogenetics. Pts were to receive up to 2 yrs of therapy. The primary endpoint was LFS by independent central review.
Results
Between November 2012 and July 2014, 153 pts were randomized and 152 pts were treated; Pts characteristics are depicted in Table 1. All had received 7+3 induction therapy. Most pts (81%) received 2 cycles of consolidation prior to inclusion. Consolidation chemotherapy consisted of intermediate-dose single agent cytarabine (IDAC) in 53%, and 5+1 in 47% of the pts, according to the recommendations of the ALFA and FILO cooperative groups, respectively. Median time since diagnosis was 4.9 months (mo) [2.8-15.5]. Median time between CR or the last consolidation and randomization were 3.3 [1.1-5.9] and 1.5 mo [0.3-3.5], respectively. The 3 arms were well balanced apart from a slight trend in favor of the placebo arm for lower age, better ECOG, and use of IDAC as consolidation.
In March 2015, based upon DSMB recommendation, treatment of pts in CONT was discontinued in light of an excess of early relapses. Mean number of treatment cycles administered was 14.7, 8.8 and 13.8 in the INT, CONT and placebo arms respectively and only 6 pts had one cycle postponed in the lirilumab arms. Major reasons for study discontinuation were relapse (63%) and adverse events (AE) (10%).
AE rate was analyzed by taking into account the exposure across pts in each arm. Slightly more AE rate of G1-G2 asthenia, diarrhea and pruritus was observed in CONT arm. Occurrence of hematological disorders did not differ between the 3 arms. 17 pts (11%) experienced second primary malignancies across the 3 arms.
PK/PD results were in line with the model predictions: transient full KIR occupancy lasting 7-28 days for the majority of the INT arm pts and permanent full occupancy in the CONT arm. Lirilumab is not significantly immunogenic and does not induce major modifications in peripheral blood NK and T cell subsets.
With a median follow-up of 36.6 mo [33.4; 38.2], 108 pts experienced relapses and 2 pts died before relapse. LFS results are presented in Table 2.
Conclusions
Single agent lirilumab administered for up to 24 cycles was well tolerated. Lirilumab did not result in a statistically significant improvement of LFS in the challenging setting of maintenance in AML in elderly pts. Immune-pharmacological studies will be presented. Potential hypotheses relevant for AML and lirilumab monotherapy (e.g. dosage/schedule optimization, partial desensitization by continuous KIR blockade leading to an impaired immunosurveillance by NK cells) for the non-significant trends will be discussed.

Disclosures
Recher: Novartis, Celgene, Jazz, Sunesis, Amgen: Consultancy; Celgene, Sunesis, Amgen, Novartis: Research Funding. Pautas: Pfizer: Honoraria. Rousselot: Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Sunesis: Honoraria; Incyte: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Research Funding; BMS: Research Funding. Castaigne: Pfizer: Honoraria, Research Funding. Jourdan: NOVARTIS: Consultancy, Honoraria. Gardin: Sunesis: Honoraria; AbbVie: Honoraria; Celgene: Honoraria. Delannoy: Innate Pharma: Honoraria. Beautier: Innate Pharma: Employment, Equity Ownership. Paturel: Innate Pharma: Employment, Equity Ownership. Andre: Innate Pharma: Employment, Equity Ownership. Zerbib: Innate Pharma: Employment, Equity Ownership. Dulphy: Celgene: Research Funding; Innate Pharma: Research Funding; Celyad: Consultancy, Membership on an entity's Board of Directors or advisory committees. Olive: Imcheck Therapeutics: Other: Cofunder; GSK: Research Funding; Innate Pharma: Research Funding. Pigneux: Pfizer: Membership on an entity's Board of Directors or advisory committees; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy; MSD: Consultancy, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Sunesis: Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees; Biogaran: Consultancy, Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees. Dombret: Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travels, Accommodations, Research Funding, Speakers Bureau; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travels, Accommodations, Research Funding, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Jazz Pharma.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Kite Pharma.: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Agios: Honoraria, Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sunesis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Karyopharm: Honoraria, Membership on an entity's Board of Directors or advisory committees; Astellas: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Cellectis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Menarini: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Chugai/Roche: Consultancy.