Pilot trial of ibrutinib plus nivolumab in patients (pts) with metastatic renal cell cancer (mRCC): Results from a dose-finding cohort.

Abstract

600 Background: Immune checkpoint inhibitor therapy (CPI) has transformed the management of pts with mRCC, with a fraction experiencing durable tumor responses. However, most eventually develop disease progression after either an initial response to CPI or while on CPI. Newer agents that modulate immune response can possibly potentiate CPI therapy. The ITK/ETK/BTK inhibitor ibrutinib has been reported to inhibit myeloid derived suppressor cells in preclinical models and to potentiate CPI. We conducted an investigator-initiated pilot trial of ibrutinib plus the PD1 inhibitor nivolumab in mRCC pts, particularly in those previously exposed to CPI. Here we report initial safety and efficacy results from the dose-finding cohort. Methods: Pts with mRCC of any histologic subtype and who have completed at least one line of prior systemic therapy including prior CPI were eligible. Pts must have acceptable end-organ function and Zubrod PS of 0-2. Treatment consisted of nivolumab 240 mg IV q2 weeks plus ibrutinib 560 mg (dose level 0) or 420 mg (dose level -1) orally once daily. Cycle length was 28 days. Dose limiting toxicity (DLT) was defined as any Grade(Gr) 3+ adverse event (AE) attributable to therapy. Results: As of 9/18/17, 12 pts have been enrolled, six to each dose level. Patient characteristics: Mean age = 62 years (range 44-78); Male sex = 7 (58%); White race = 9 (75%); Prior CPI = 11 (92%). Three pts experienced one DLT each in dose level 0 (all Gr3): elevated lipase, hypoalbuminemia, & nausea. Only 1 DLT has been seen thus far in dose level -1 (Gr3 infection). The most common Gr3+ AEs include anemia (n = 5), ALT elevation (4), AST elevation (3), nausea (3), hypoalbuminemia (2), esophagitis, infection, lipase increase, and vomiting (1 each). Two pts with prior CPI had partial tumor response (1 confirmed, 1 unconfirmed). Conclusions: Ibrutinib at a dose of 420mg orally once daily in combination with nivolumab 240mg IV q 2 weeks appears feasible and tolerable in mRCC patients. No unique immune-related AEs have been seen thus far. Anti-tumor activity was seen in 2 pts previously exposed to PD1-targeted therapy. Further evaluation of this combination is warranted. (Supported by Pharmacyclics and UCDCCC). Clinical trial information: NCT02899078.