First-in-human first-in-class phase I trial of murlentamab, an anti-Mullerian-hormone receptor II (AMHRII) monoclonal antibody acting through tumor-associated macrophage (TAM) engagement, as single agent and in combination with carboplatin (C) and paclitaxel (P) in AMHRII-expressing advanced/metastatic gynecological cancer patients (pts)
Résumé
2521 Background: Membranous expression of AMHRII is found in ~70% of gynecological tumors. Murlentamab (M) binds with high affinity both AMHRII (at cell membrane) and CD16 (on macrophage, via its low fucose Fc). M reprograms TAMs, restoring their antitumoral functions (phagocytosis) resulting in cytotoxic T cell reactivation. Methods: Pts with advanced/metastatic AMHRII-expressing ovarian, cervical or endometrial cancer with measurable disease and performance status ≤ 1 received M as single agent (SA) in 8 dose escalating and 2 expansion cohorts. Combination with CP was studied in 2 escalating cohorts. Safety, recommended dose determination, antitumor activity, pharmacodynamics (PD) effects (circulating immune cells and tumor microenvironment (TME) from paired biopsies) were assessed. Results: 68 heavily pretreated (median 4 prior lines) pts received M for 0.5 to 11 months (mo) (59 pts M SA and 9 pts M + CP). No dose limiting toxicity was reported. Most common toxicity was G1-2 asthenia (29 %). Eight pts (12%) had G ≥ 3 reversible toxicities (asthenia, nausea/vomiting, anorexia, arthralgia). No antidrug antibody was detected. One partial response (PR) was achieved with M SA in a granulosa pt. In CP combination, 4/9 pts (44%) responded to treatment (1 Complete Response and 3 PRs). Overall, 22/67 (33%) pts were progression-free at 4 mos. Among 17 pts treated ≥ 6 mos, 6/9 (67%) granulosa pts with M SA and 4/5 (80%) endometrium and cervix with CP combination had a longer PFS than under previous regimen. PD blood assessment of 25 pts treated with M SA showed an increase in classical monocytes, and T cells and neutrophils activation. Changes in TME under M will be presented. Conclusions: Murlentamab was very well tolerated, demonstrated immune PD effects and showed hints of antitumor activity. These results together with its innovative immunological mode of action support development of M in AMHRII-expressing cancers, in combination with chemotherapy or other immune oncology drugs. Clinical trial information: NCT02978755.