Sunitinib in combination with gemcitabine for advanced solid tumours: a phase I dose-finding study

BACKGROUND

This phase I, dose-finding study determined the maximum tolerated dose (MTD), safety, and pharmacokinetics of sunitinib plus gemcitabine in patients with advanced solid tumours.

METHODS

Two schedules with sunitinib (25-50 mg per day) and IV gemcitabine (750-1250 mg m(-2)) in escalating doses were studied. First, patients received sunitinib on a 4-weeks-on-2-weeks-off schedule (Schedule 4/2) plus gemcitabine on days 1, 8, 22, and 29. Second, patients received sunitinib on a 2-weeks-on-1-week-off schedule (Schedule 2/1) plus gemcitabine on days 1 and 8. The primary endpoint was determination of MTD and tolerability.

RESULTS

Forty-four patients received the combination (Schedule 4/2, n=8; Schedule 2/1, n=36). With no dose-limiting toxicities (DLTs) at maximum dose levels on Schedule 2/1, MTD was not reached. Grade 4 treatment-related AEs and laboratory abnormalities included cerebrovascular accident, hypertension, and pulmonary embolism (n=1 each), and neutropenia (n=3), thrombocytopenia and increased uric acid (both n=2), and lymphopenia (n=1). There were no clinically significant drug-drug interactions. Antitumor activity occurred across dose levels and tumour types. In poor-risk and/or high-grade renal cell carcinoma patients (n=12), 5 had partial responses and 7 stable disease ≥ 6 weeks.

CONCLUSION

Sunitinib plus gemcitabine on Schedule 2/1 with growth factor support was well tolerated and safely administered at maximum doses of each drug, without significant drug-drug interactions.

A drug interaction study evaluating the pharmacokinetics and toxicity of sorafenib in combination with capecitabine

PURPOSE

To address tolerability and a possible pharmacologic interaction of capecitabine with sorafenib.

METHODS

Patients with advanced solid tumors (ECOG PS 0-1) were included. Cohort A received capecitabine 750 mg/m(2) BID and Cohort B received capecitabine 1,000 mg/m(2) BID, both for 14 days of a 21-day cycle. Steady-state PK was obtained for capecitabine alone, sorafenib alone, and in combination. Cohort C explored an alternate schedule of 7-day on/7-day off flat dose capecitabine 1,000 mg BID with continuous dosing of sorafenib 400 mg BID.

RESULTS

A total of 32 patients were enrolled between February 08 and April 09. Hand-foot skin reaction (HFSR) was the primary toxicity with 16 (50%) of the 32 patients experiencing grade 3 events (75% occurring during cycles 1-2). Grade 3 HFSR defined the maximum tolerated dose (MTD) of Cohort C at 1,000 mg BID flat dose of capecitabine. Other grade 3/4 toxicities were rare (diarrhea 6%, mucositis 3%, and fatigue 3%). Capecitabine did not change the C (max) or AUC((0-12)) of sorafenib. Co-administration of sorafenib with capecitabine 750 mg/m(2) (n = 6 patients) increased capecitabine AUC((0-12)) 15% and produced no change in the 5FU AUC((0-12)). At the capecitabine 1,000 mg/m(2) dose level (n = 12 pts), there was a 16% increase in capecitabine AUC((0-12)) and an 8% increase in 5FU AUC((0-12)). However, these trends were not statistically significant.

CONCLUSIONS

Co-administration of sorafenib resulted in a mild increase in capecitabine AUC, although not statistically significant. Capecitabine did not affect the exposure of sorafenib. The rate of grade 3 HFSR is concerning and limits the feasibility of prolonged dosing of sorafenib with capecitabine 1,000 mg/m(2) on the 21-day schedule.

Understanding the molecular-based mechanism of action of the tyrosine kinase inhibitor: sunitinib

Sunitinib is an orally available small-molecule multikinase inhibitor. This agent potently inhibits the vascular endothelial growth factor receptor, platelet-derived growth factor receptor, and c-Kit in addition to other kinases in biochemical and cell-based assays. In several relevant preclinical cancer models, sunitinib exerts significant antiangiogenesis and antitumor effects. In phase I studies, using intermittent dosing schedules, oral administration of doses up to 50 mg/day were reasonably well tolerated and resulted in plasma concentrations in the range of targeted levels needed for sustained kinase inhibition. Biomarker and functional imaging studies showed modulation of circulating markers of angiogenesis as well as a reduction in tumor metabolism. Sunitinib showed clinical activity in patients with renal cell cancer and in patients with imatinib-resistant gastrointestinal stromal tumors. Definitive randomized clinical trials showed significant clinical activity in these two indications leading to regulatory approval. In addition, this drug has showed activity in a variety of other tumor types such as breast, colon, and lung cancer and is being explored in combination with standard drugs in these diseases. The observation that biological and functional imaging effects are reduced during drug-free intervals has prompted the evaluation of protracted dosing schedules. A better understanding of mechanisms involved in resistance to sunitinib provides the rationale for combination strategies that hopefully will result in better clinical effect. Ongoing studies will elucidate the overall role of this drug in cancer treatment.

Sunitinib in solid tumors

BACKGROUND

Until recently, few treatments were available for renal cell carcinoma (RCC) and gastrointestinal stromal tumors (GIST). Several targeted agents inhibiting key pathogenetic pathways have since been developed for RCC (sunitinib, sorafenib, bevacizumab, temsirolimus, everolimus) and GIST (imatinib, sunitinib). Sunitinib is a multi-kinase inhibitor of VEGFR-2, PDGFR (alpha,beta), FLT-3, KIT, CSF-1 and RET.

OBJECTIVE

To summarize the literature regarding the structure, pharmacokinetics, pharmacodynamics, toxicity and current clinical use of sunitinib. Other potential roles for this drug in RCC, GIST and other tumor types will be discussed.

METHODS

A literature search identified relevant (pre)clinical studies of sunitinib and other relevant agents.

RESULTS/CONCLUSIONS

Sunitinib revolutionized the management of advanced RCC and GIST. With the realization that cross-resistance between targeted agents is incomplete, evolving strategies include sequential treatment, concurrent treatment, and biomarker development. Sunitinib also shows promise in several other tumor types that lack therapeutic options. What remains less clear is its role in tumors that are not heavily dependent on a central pathogenetic pathway, especially if effective cytotoxic therapies exist. Future clinical trials will clarify whether there is a role for sunitinib in these tumors, possibly in combination with cytotoxic agents.

Dermatological reactions to the multitargeted tyrosine kinase inhibitor sunitinib

BACKGROUND

The multikinase inhibitor sunitinib has enhanced the treatment of renal cell carcinoma and gastrointestinal stromal tumor through an improved clinical response with decreased systemic toxicities. However, sunitinib is frequently associated with dermatological adverse reactions. The physical and psychosocial impact of frequent dermatological toxicities can affect consistent antineoplastic therapy and quality of life.

PATIENTS AND METHODS

Dermatological adverse reaction information was compiled from Pfizer Medical Information and from abstracts from the 2007 American Society of Clinical Oncology annual meeting, Prostate Cancer Symposium, and Gastrointestinal Cancers Symposium. Published clinical trials of sunitinib in MEDLINE, Cochrane Library, Cochrane Controlled Trials Register, and EMBASE Drugs and Pharmacology databases were also included. Information was accessed on or before June 30, 2007.

RESULTS

In the pooled analysis, all-grade hand-foot skin reaction occurred in 19% of patients (5% grades 3-4), skin discoloration in 28% (0% grades 3-4), dry skin in 16% (1% grades 3-4), skin rash in 13% (1% grades 3-4), dermatitis in 8% (2% grades 3-4), hair color changes in 10% (0% grades 3-4), alopecia in 6% (0% grades 3-4), and phototoxicity in <0.1%.

CONCLUSIONS

Dermatological reactions associated with sunitinib occur frequently. Evidence-based treatment recommendations are needed in order to maximize quality of life and optimize clinical outcome.

Sunitinib

Sunitinib is a small-molecule inhibitor of several receptor tyrosine kinases relevant to tumor angiogenesis, including the vascular endothelial growth factor (VEGF) receptor. Potent inhibition of this related family of receptors and consequent antiangiogenic effects have been demonstrated in vitro and in murine models. Human studies have established 50 mg daily dosing given on an intermittent schedule as a tolerable dose. Significant antitumor effects have been observed, most notably in advanced renal cell carcinoma (RCC) and imatinib refractory/intolerant gastrointestinal stromal tumor (GIST). Sunitinib has received regulatory approval in these two indications, and is at present being investigated across a broad array of solid tumors. Despite these initial results, several questions remain to optimize the utility of this agent.