Exceptional responders to abexinostat (ABX) plus pazopanib (PAZ) in pretreated renal cell carcinoma (RCC) and other solid tumors: Long-term follow-up of a phase 1b study

Autor: Nela Pawlowska, Phu Lam, Kathleen Comerford, Scott Thomas, Rahul Aggarwal, Daphne Bautista, Pamela N. Munster, Susan Calabrese, Jennifer A. Grabowsky
Rok vydání: 2019
Předmět:
Zdroj: Journal of Clinical Oncology. 37:3022-3022
ISSN: 1527-7755
0732-183X
0359-2472
Popis: 3022 Background: We previously reported the initial phase 1b study results of PAZ + ABX, a potent pan-HDAC inhibitor, demonstrating acceptable toxicity profile and encouraging anti-tumor activity (Aggarwal et al. JCO 2017). We report the long-term follow up of exceptional responders and additional correlative analyses associated with clinical outcomes. Methods: Key efficacy endpoints included objective response rate and duration of response. Peripheral blood histone acetylation, HDAC expression, and plasma VEGF levels were analyzed and associated with clinical outcomes. Results: 51 pts (RCC subset; N = 22) were enrolled between June 2012 and October 2015. 10 pts (20%) had experienced disease progression on prior PAZ; 59% had received any prior VEGF-targeting therapy. 9 evaluable pts (18%) (N = 6 RCC; 2 thyroid; 1 mesothelioma) achieved partial tumor response (PR), of which 6 had prior progression on VEGF-targeting therapy. 7/10 (70%) of pts with prior disease progression on PAZ monotherapy had reduction in tumor burden on study. The median duration of response was 9.1 months (range 1.2 to 70+), and clinical benefit rate (PR or stable disease > 6 months) was 33%. Five treatment-refractory pts achieved durable PRs lasting for > 2 years duration, and one previously PAZ-refractory patient with RCC remains on treatment with ongoing PR for > 6 years. Higher HDAC2 expression was associated with prolonged progression-free survival (median PFS 5.9 vs. 3.5 months, log-rank p = 0.02). Induction of histone acetylation on ABX lead-in treatment was associated with subsequent time to progression (p = 0.002). On-treatment plasma VEGF levels were inversely correlated with PBMC histone acetylation (p = 0.02). Conclusions: Markedly durable responses with PAZ + ABX are achievable, including in pts with PAZ- and VEGF-refractory RCC and other solid tumor malignancies. Host factors including HDAC expression and acetylation status may identify those most likely to benefit. A randomized phase 3 study is underway of PAZ + ABX as a first- or second-line therapy in pts with locally advanced or metastatic RCC (RENAVIV; NCT03592472). Clinical trial information: NCT01543763.
Databáze: OpenAIRE