Sorafenib monotherapy in patients with treatment-naïve metastatic renal cell cancer: preliminary results of a phase II intra-patient dose-escalation study

Abstract

e14564 Background: In a phase I dose finding study, the maximum tolerated dose of sorafenib was determined to be 400 mg bid. In subsequent practice, these doses of sorafenib have been associated with minimal or reversible toxicity, which presented an opportunity to explore more intensive dosing. A single institution trial of 44 patients demonstrated complete responses in 26% and partial responses in 36%. 93% of patients were able to be dose escalated. The objective of our study was to confirm these findings. The primary endpoints for this study were safety, feasibility, and toxicity. Secondary endpoints included overall response rate (ORR) and progression- free survival (PFS). Methods: Patients with treatment-naïve metastatic renal cell with clear cell histology were enrolled at Stanford University and the University of Nebraska Medical Center. Cycles consisted of 28 days. Dose limiting toxicity (DLT) was defined as grade 3/ 4 toxicity. Patients received sorafenib 400mg bid for 28 days. If no DLT's were reported after the first cycle, patients were dose escalated to sorafenib 600 mg bid for cycle 2. Patients without DLTs at the end of the second cycle were dose escalated to the highest dose, sorafenib 800 mg bid. Patients continued on therapy until progression or unacceptable toxicity. Results: To date, thirteen patients have been treated. Median age was 63 (47–84) years. The majority (84%) were men. Ten patients had nephrectomy prior to trial initiation. Sites of metastases included lung, nodes, liver, adrenal glands, and bone. Dose escalation was possible in 70% of the patients. Median number of cycles was 7 (3–12). Hand-foot syndrome (skin toxicity) limited escalation in the other 30% of patients. One pathologic complete response was obtained after a patient underwent metastectomy of adrenal gland after 4 cycles. One patient achieved a partial response and seven experienced disease stabilization. Conclusions: This dose-escalation trial is ongoing. Dose escalation has been feasible in 70% of patients. The main toxicity limiting escalation was hand-foot syndrome. Thus far, dose escalation did not result in an increased number of responses as compared to the standard 800mg/d dosing. PFS data will be presented as data matures. [Table: see text]

Enhancing the clinical activity of sorafenib through dose escalation: rationale and current experience

“…The response rate was 32% in this cohort and PFS was greater than 3 months in an additional 50% of patients. In a trial aimed at confirming these results, investigators at Stanford and the University of Nebraska presented the preliminary results of 13 patients treated using a similar protocol [Srinivas et al 2009]. Although dose escalation was possible in 70% of the patients, early results do not yet show enhanced efficacy for this strategy.…”