A phase I trial of panobinostat with ipilimumab in advanced melanoma.

Abstract

9547 Background: Immune checkpoint blockade is standard therapy for advanced melanoma (MEL), yet not all patients (pts) benefit. Panobinostat (PAN), a pan inhibitor of class I, II, and IV histone deacetylases (HDAC) is immunomodulatory, decreases tumor associated inhibitory cytokines and inhibition of effector T-cells. This dose finding study aimed to determine the safety and efficacy of escalating doses of PAN combined with ipilimumab (IPI) in advanced MEL. Methods: Eligible pts with unresectable stage 3/4 MEL, up to 3 prior lines of therapy, and adequate laboratory values were treated with oral PAN 5mg thrice weekly (TIW) plus IPI at 3mg/kg IV every 3 weeks X 4 doses, followed by maintenance PAN until progression or intolerance. Using a modified Ji design, PAN dose escalation by 5mg was planned in 3-12 pt cohorts up to a maximum dose of 20mg TIW, without intra-pt dose escalation. Dose limiting toxicity (DLT) was assessed up to day 84 from start of therapy. Results: Seventeen pts (M/F: 13/4), median age 66 yrs (48, 80) were treated with a median of 4 cycles of IPI (1,4). Of 6 pts treated at PAN 5mg TIW, there was one DLT (G3 hydronephrosis). Eleven pts received PAN 10mg TIW; of 9 evaluable for DLT, there were 3 DLTs (G3 rash, G3 diarrhea, G4 thrombocytopenia) preventing further dose escalation. Other G3 toxicities included anemia, hypophysitis, diarrhea, fatigue (all n = 2); rash, colitis, nausea, dehydration, dizziness, hypotension, ↑ lipase, ↓ sodium, & ↑ glucose (all n = 1). Three pts had previous anti-PD1 therapy. The response rate was 12% (2 PRs) with 35% stable disease. One pt remains on PAN > 24m since start of therapy. Median progression free- and overall survival was 2.23m (95% CI,1.57, 5.8) and 20.97m (95% CI, 8.97, NR) respectively. Biomarker analysis from peripheral blood and limited tumor biopsies pre-and on treatment examining immunoregulatory markers, including EOMES promoter acetylation in T-cells from PAN are ongoing. Conclusions: At tolerated doses, PAN does not appear to increase response to standard IPI in advanced MEL. Biomarker analyses will inform if immunomodulation by PAM improves efficacy of IPI. Combinations with selective HDAC inhibitors may be more appropriate for future study. Supported by grant P50 CA168536, Moffitt Skin Cancer SPORE. Clinical trial information: NCT02032810.