Phase Ib/II study of durvalumab and guadecitabine in advanced kidney cancer Big Ten Cancer Research Consortium BTCRC GU16-043.
Authors: Zakharia Yousef , Singer Eric A. , Ross Ryan , Joshi Monika , Abern Michael , Garje Rohan , Park Joseph J. , Kryczek Ilona , Zou Weiping , Alva Ajjai Shivaram 
Published: March 2021

328 Background: Anti-PD1/PDL1 immune checkpoint inhibition (CPI) is active in advanced clear cell RCC, but not all patients benefit. Preclinical studies with the combination of hypomethylating agents and CPI resulted in reversal of immune evasion and tumor regression. We examined the combination of the hypomethylating agent guadecitabine (subcutaneously on Days 1-5), with the anti-PDL1 antibody durvalumab (intravenously at flat dose of 1500 mg on Day 8) in 28 day cycles in advanced RCC in a single arm trial. Methods: In the phase Ib portion (n=6; presented previously), guadecitabine dosing of 45 mg/m2/day was selected as maximum tolerated dose. For the phase II portion of Cohort 1 (36 pts with no prior CPIs), eligible patients had metastatic RCC with clear cell component, ECOG PS of 0-1, and measurable disease by RECIST 1.1. We present pooled efficacy and toxicity data for the 42 CPI-naive pts from the phase Ib and phase II portions. An exploratory Cohort 2 (N=16) consisting of CPI-refractory pts is enrolling. Results: Of the 42 pts, 71% were men, median age was 67 years, ECOG PS was 0 in 57%, IMDC risk group was intermediate in 83% and poor in 17%, and histology was mixed in 21%. At a median follow-up of 20.1 m, best RECIST 1.1 response was PR in 9 pts (22%); SD in 25 pts (61%); PD in 7 pts (17%); and non-evaluable in 1 pt. Response categories were identical by irRECIST. Clinical benefit defined as either PR or SD ≥6 months was seen in 66%. Median OS had not been reached and median PFS was 17 m. Treatment was generally well tolerated with asymptomatic neutropenia the most frequent AE attributed to guadecitabine (38.1%), and asymptomatic lipase elevation the most common AE from durvalumab (11.9%). Grade 4 AEs were noted in 50.0% pts, grade 3 59.5%. Immune-mediated AEs were generally mild (all ≤ grade 3), included pruritus (14.3%), rash (14.3%), asymptomatic amylase or lipase elevations (16.7%), hypothyroidism (11.9%), diarrhea (16.7%), dyspnea (16.7%), pneumonitis (4.8%), myalgia (4.8%), and transaminitis (9.6%). Laboratory peripheral blood profiling (done at baseline, C1D8, C2D8) was associated on univariate unadjusted analysis at baseline with response in two major PBMC subsets - MDSCs (negative) and ILCs (positive). Further functional analysis revealed that increased expression of IL-22 in both CD4 and CD8 positive T cells positively correlated with response. Associations were noted for toxicity with IL-22 expressed by CD8-CD4- T cells, and CTLs T-bet level. Baseline archival tumor tissue next generation sequencing results will be presented. Conclusions: Guadecitabine in combination with durvalumab was well tolerated and had reasonable activity in first-line advanced ccRCC. MDSCs and regulatory T lymphocytes decreased in responders, increased Th17 subpopulations of T cells were associated with immune-mediated toxicities. Further study of this combination in CPI-refractory RCC pts is ongoing. Clinical trial information: NCT03308396 .