Background:Determining the maximum tolerated dose (MTD) and the dose-limiting toxicity (DLT) of sorafenib (S) plus imatinib (IM) in castration-resistant prostate cancer (CRPC) patients.Methods:Refractory CRPC patients were enrolled onto this 3+3 dose escalation designed study. Imatinib pharmacokinetics (PK) were determined on day 15, 4 h post dose with a validated LC–MS assay.Results:Seventeen patients were enrolled; 10 evaluable (6 at 400 mg S qd with 300 mg IM qd (DL0) and 4 at 400 mg S bid with 300 mg IM qd (DL1)); inevaluable patients received <1 cycle. The median age was 73 (57–89); median prostatic serum antigen was 284 ng ml−1 (11.7–9027). Median number of prior non-hormonal therapies was 3 (1–12). Dose-limiting toxicities were diarrhoea and hand-foot syndrome. Maximum tolerated dose was 400 mg S and 300 mg IM both daily. No biochemical responses were observed. Two patients had stable disease by RECIST. Median time to progression was 2 months (1–5). Median OS was 6 months (1–30+) with 3/17 patients (17%) alive at 21 months median follow-up. Ten patients had PK data suggesting that S reduced IM clearance by 55%, resulting in 77% increased exposure (P=0.005; compared with historical data).Conclusion:This is the first report showing that S+IM can be administered in CRPC at a dose of 400 mg S and 300 mg IM, daily.

We conducted a systematic review of grade 3/4 adverse events (AEs) reported in prospective trials enrolling patients with follicular lymphoma (FL) and mantle cell lymphoma (MCL) receiving maintenance rituximab (MR). Random-effects models were used to calculate summary estimates and 95% confidence intervals for the proportion of AEs occurring during MR. Differences by induction program, histology, setting and MR schedule were examined by stratified analyses and univariate random-effects meta-regression. Eleven trials met the search criteria, with nine sufficiently reporting AEs during the MR phase. Of 1009 patients receiving MR, the proportion experiencing cumulative grade 3/4 toxicity was 24% (95% confidence interval [CI]: 14-36%). Patients receiving MR every 6 months as four weekly infusions for 2 years had significantly less toxicity compared with those receiving MR every 2 months (10% vs. 28%; p = 0.035). Patients treated with rituximab alone during induction had fewer toxicities compared to those treated with rituximab plus chemotherapy induction (12% vs. 35%; p = 0.031). Myelosuppression and infections were the most common toxicities. Our literature analysis suggests that MR given every 6 months and rituximab alone as induction may be associated with fewer grade 3/4 AEs for patients with FL and MCL; however, assessing the true independent impact of induction regimens and schedule on toxicity will require prospective trials.

146 Background: IM is an inhibitor of protein-tyrosine kinases including those that are over-expressed in bone metastases and primary prostatic adenocarcinoma. S is a potent inhibitor of wild-type and mutant BRAF, C-RAF, VEGFR2, VEGFR3, FLT3, and PDGFR-beta with modest activity in CRPC. We combined IM+S to determine the maximum tolerated dose (MTD) and the dose-limiting toxicity (DLT) in CRPC pts. Methods: CRPC pts with measurable disease and adequate organ function who failed chemotherapy were eligible. Dose escalation followed a 3+3 study design. Toxicity was scored following CTCAEv3. Responses were defined by RECIST1.0. IM pharmacokinetics (PK) were determined on day 15, 4 h post-dose with a validated LC-MS assay. Results: Seventeen pts were enrolled; 10 were evaluable. At dose level 0 (DL0), 6 pts received S at 400 mg S with 300 mg of IM both given daily. At DL1, 4 pts received 400 mg S twice/day with 300 mg IM daily; inevaluable pts received <1 cycle (5 withdrew consent, 1 rapid early progression, 1 non-compliant). Median age was 73 (57-89) and median PSA was 284 ng/ml (11.7–9027). Median number of prior non-hormonal therapies was 3 (1–12) and 12 pts had Gleason score ≥7 while 15 pts had bone as the major site of metastases. On DL0, 1/6 pts had DLT (gr 3 hand/foot). On DL1, 2/4 pts had DLT (1 gr 3 hand/foot, 1 gr 3 diarrhea). MTD was 300 mg IM and 400 mg S both qd. No biochemical responses were observed. Two pts on DL1 had stable disease radiographically by RECIST (overall clinical benefit for the entire cohort 20%). Median time to progression was 2 months (1-5) while median OS was 6 months (1-30+) with 3/17 patients (17%) remaining alive at a median follow-up of 21 months. Of patients enrolled, 10 had PK data, which suggested that S reduced IM clearance by 40%, resulting in 60% increased exposure (P = 0.009; two-tailed t-test on log-transformed values, compared to historic data). Conclusions: To our knowledge, this is the first report to show that IM+S can be safely combined in CRPC. The phase II recommended dose for future trials is 300 mg IM and 400 mg S, both given daily. The PK interaction might be of questionable clinical relevance because IM concentrations are within the commonly observed range.