High dose interleukin-2 and response in 944 patients with metastatic renal cell cancer (RCC): Data from the PROCLAIM registry.

Abstract

624 Background: High dose interleukin-2 (HD IL2) has traditionally been dosed every 8 hours for a maximum of 14 doses each cycle. We evaluated whether alternate dosing schedules and dose intensity affected achievement of complete response (CR) or partial response (PR) in the PROCLAIM registry. Methods: Patients with metastatic RCC were enrolled retrospectively and prospectively into the PROCLAIM registry to collect outcome data. Statistical methods for comparisons were done using Fisher’s and Chi Square tests. Results: From 2006-2017 the registry included 944 RCC patients; 257 (27%) women, 676 (72%) men. 844 (89%) were white. Histologic distribution: 624 (66%) clear cell, 93 (10%) medullary, 79 (8%) collecting duct, 78 (8%) chromophobe and 70 (7%) papillary. 207 (22%) had prior therapy with VEGF/mTOR. Best response was 51 (5.4%) CR and 169 (17.9%) PR; 263 (28%) progressive disease. 13 (1.4%) patients received q12 hour dosing while 830 (88%) received q8 hour dosing. 608 (64%) received 600 KIU/kg and 67 (7%) received 720 KIU/kg. Median # of doses in cycle 1 was 10 for CR and PR patients at 600 KIU/kg and 9 for those with stable or progressive disease. In the 720 KIU/kg group median #doses was 11 for CR, 8 for PR, and 7 for stable or progressive disease. In cycle 2 median doses received was 7.16 for patients with CR, 7.02 for PR and 6.76 for stable disease. Median dose intensity is similar at these two dose levels. Associations with achievement of CR/PR are summarized in the Table. Conclusions: There is no difference in response rate based on dosing schedule but the small number of subjects dosed q12 hours limits interpretation. Good performance patients possess the best opportunity for benefit from HD IL2. There is a trend for response with higher median # doses. Further studies of alternate dosing schedules are warranted. Clinical trial information: NCT01415167. [Table: see text]