Clinical and immune correlate results from a phase 1b study of the histone deacetylase inhibitor mocetinostat with ipilimumab and nivolumab in unresectable stage III/IV melanoma

• Published in: Melanoma research Vol. 32; no. 5; p. 324
• Main Authors: Weber, Jeffrey S, Levinson, Benjamin A, Laino, Andressa S, Pavlick, Anna C, Woods, David M
• Format: Journal Article
• Language: English
• Published: England 01.10.2022
• Subjects: Antineoplastic Combined Chemotherapy Protocols - therapeutic use; Benzamides; Histone Deacetylase Inhibitors - adverse effects; Humans; Ipilimumab - pharmacology; Ipilimumab - therapeutic use; Leukocytes, Mononuclear - pathology; Melanoma - pathology; Melanoma, Cutaneous Malignant; Nivolumab - pharmacology; Nivolumab - therapeutic use; Pyrimidines; Skin Neoplasms - pathology
• ISSN: 1473-5636
• DOI: 10.1097/CMR.0000000000000818

Checkpoint immunotherapies (CPIs) have improved outcomes for metastatic melanoma patients, with objective response rates to combination ipilimumab and nivolumab of ~58%. Preclinical data suggest that histone deacetylase (HDAC) inhibition enhances antitumor immune activity and may augment CPI. In a phase Ib open-label pilot trial (NCT03565406), patients with therapy-naive metastatic melanoma were treated with the class I/IV HDAC inhibitor mocetinostat orally three times a week in combination with nivolumab and ipilimumab every 3 weeks for 12 weeks followed by 12-week maintenance cycles of nivolumab every 2 weeks and mocetinostat at the same dose and schedule as induction. The endpoints of the trial were safety, definition of a recommended phase 2 dose, preliminary assessment of response, and correlative marker determination. Patient PBMC and serum samples collected at baseline and on-treatment were assessed by flow cytometry and Luminex assays for immune correlates. Ten patients were treated: nine with 70-mg and one with 50-mg mocetinostat. In the 70-mg cohort, eight patients had objective responses. The patient in the 50-mg cohort had an early progression of disease. All patients had grade 2 or higher toxicities, and six had grades 3 and 4 toxicities. Patient PBMC showed significant decreases in myeloid-derived suppressor cells and trends towards reduced anti-inflammatory monocyte phenotypes. Patient serum showed significant upregulation of granzyme A and TNF and trends towards increased granzyme B and IFNγ. Collectively, combining CPI and mocetinostat had favorable response rates but with high levels of toxicity. Assessment of immune correlates supports a shift away from immunosuppressive phenotypes towards enhanced immune responses.