Phase I Study of Stereotactic Body Radiotherapy plus Nivolumab and Urelumab or Cabiralizumab in Advanced Solid Tumors.

PURPOSE: CD137 agonism and CSF1R blockade augment stereotactic body radiotherapy (SBRT) and anti-programmed death-1 in preclinical models. We evaluated the safety and efficacy of SBRT with nivolumab+urelumab (CD137 agonist) or nivolumab+cabiralizumab (CSF1R inhibitor). PATIENTS AND METHODS: This phase I clinical trial enrolled patients with advanced solid tumors that had progressed on standard therapies. SBRT was delivered to 1-4 metastases with nivolumab+urelumab or nivolumab+cabiralizumab given concurrently and following SBRT. Dose-limiting toxicity (DLT) was the primary endpoint with anatomic location-specific SBRT doses deemed safe if ≤33% DLT frequency was observed. Secondary endpoints included RECISTv1.1 response, progression-free survival (PFS), overall survival (OS), and molecular correlative studies. RESULTS: Sixty patients were enrolled, and median follow-up for living patients is 13.8 months. Of these, 23 (38%) received SBRT+nivolumab+urelumab and 37 (62%) received SBRT+nivolumab+cabiralizumab. Seven patients (12%) experienced a DLT (n = 3 grade 3, n = 4 grade 4) in the following anatomic cohorts: abdominal/pelvic (3/17, 18%), liver (1/13, 8%), central lung (2/14, 14%), and peripheral lung (1/12, 8%). Of 41 patients radiographically evaluable for best overall response including 55 radiated and 23 unirradiated RECIST target lesions, 2 had complete responses (5%), 7 had partial responses (17%), 12 had stable disease (29%), and 20 had progression (49%). Median estimated PFS and OS are 3.0 months [95% confidence interval (CI), 2.9-4.8] and 17.0 months (95% CI, 6.8-undetermined), respectively. No patients with elevated pre-SBRT serum IL8 experienced a response. CONCLUSIONS: SBRT to ≤4 sites with nivolumab+urelumab or nivolumab+cabiralizumab for treating advanced solid tumors is feasible with acceptable toxicity and modest antitumor activity.See related commentary by Rodriguez-Ruiz et al., p. 5443.

Improved Survival Associated with Local Tumor Response Following Multisite Radiotherapy and Pembrolizumab: Secondary Analysis of a Phase I Trial.

PURPOSE: Multisite stereotactic body radiotherapy followed by pembrolizumab (SBRT+P) has demonstrated safety in advanced solid tumors (ASTs). However, no studies have examined the relationships between irradiated tumor response, SBRT-induced tumor gene expression, and overall survival (OS). PATIENTS AND METHODS: Patients with AST received SBRT (30-50 Gy in 3-5 fractions) to two to four metastases followed by pembrolizumab (200 mg i.v. every 3 weeks). SBRT was prescribed to a maximum tumor volume of 65 mL. Small metastases received the complete prescribed coverage (complete-Rx), while larger metastases received partial coverage (partial-Rx). Treated metastasis control (TMC) was defined as a lack of progression for an irradiated metastasis. Landmark analysis was used to assess the relationship between TMC and OS. Thirty-five biopsies were obtained from 24 patients: 19 pre-SBRT and 16 post-SBRT (11 matched) prior to pembrolizumab and were analyzed via RNA microarray. RESULTS: Sixty-eight patients (139 metastases) were enrolled with a median follow-up of 10.4 months. One-year TMC was 89.5% with no difference between complete-Rx or partial-Rx. On multivariable analysis, TMC was independently associated with a reduced risk for death (HR, 0.36; 95% confidence interval, 0.17-0.75; P = 0.006). SBRT increased expression of innate and adaptive immune genes and concomitantly decreased expression of cell cycle and DNA repair genes in the irradiated tumors. Elevated post-SBRT expression of DNASE1 correlated with increased expression of cytolytic T-cell genes and irradiated tumor response. CONCLUSIONS: In the context of SBRT+P, TMC independently correlates with OS. SBRT impacts intratumoral immune gene expression associated with TMC. Randomized trials are needed to validate these findings.

Prolonged Pharmacokinetic Interaction Between Capecitabine and a CYP2C9 Substrate, Celecoxib.

This study investigated the time course and magnitude of the pharmacokinetic interaction between capecitabine and the cytochrome P450 (CYP) 2C9 substrate celecoxib, with implications for coadministration of fluoropyrimidines with CYP2C9 substrates such as warfarin. Patients received celecoxib 200 mg orally twice daily continuously, with capecitabine (1000 mg/m2 orally twice daily for 14 days every 21 days) starting 7 days later. Assessment of the drug-drug interaction (DDI) potential was performed using equivalence testing, which assumes that there is no clinically relevant DDI when the calculated 90% confidence intervals (CIs) of the drug exposure ratios fall within the range of 0.80 to 1.25. Comparison of steady-state pharmacokinetic parameters of celecoxib between day 7 (cycle 0, celecoxib only) and day 14 (cycle 1, celecoxib + capecitabine) showed geometric mean ratios of 1.24 (90%CI, 1.04-1.49), 1.30 (1.11-1.53) and 1.28 (1.11-1.47) for maximum plasma concentration, minimum plasma concentration, and area under the concentration-time curve from time zero to 8 hours, respectively. Comparison of day 7 vs day 21 (cycle 1, after 1 week washout of capecitabine) showed a further increase in the geometric mean ratio of maximum plasma concentration (1.39; 90%CI, 1.16-1.66), minimum plasma concentration (1.53; 1.10-2.12) and area under the concentration-time curve from time zero to 8 hours (1.41; 1.19-1.68). Because the 90%CIs fell outside the prespecified equivalence margin, we conclude that coadministration results in a DDI (increased celecoxib exposure) that persists for at least 7 days after capecitabine discontinuation. Close monitoring should be undertaken when administering fluoropyrimidines with CYP2C9 substrates with narrow therapeutic indexes while also weighing the benefits and risks for individual patients.