This drug kills two birds with one stone

TIPS TO REMEMBER Sutent

The Food & Drug Administration recently approved sunitinib (Sutent, Pfizer) for the treatment of gastrointestinal stromal tumor (GIST) after disease progression on or intolerance to imatinib (Gleevec, Novartis). Sunitinib was also granted accelerated approval for the treatment of metastatic renal cell carcinoma (MRCC). This is the first time that the agency has approved an oncology drug for the treatment of two indications simultaneously.

Demetri and Hutson were pleased to report that sunitinib was fairly well tolerated in clinical studies. Hutson said hypertension was among the adverse effects he has seen most often in his clinical practice. Pfizer recommends that patients be monitored for hypertension and treated as necessary. Hutson has also seen gastrointestinal events (nausea and diarrhea) and dermatologic events (a rash on the face or body, skin discoloration, or hand/foot syndrome, which involves callus formation or blistering on the hands and/or feet).

Sunitinib's side effects are easily traceable to its mechanism of action, said Demetri. The neurotrophic-factor receptor RET, for example, is important in thyroid physiology, so hypothyroidism has been observed after several months of sunitinib therapy. Pfizer advises that patients with symptoms suggestive of hypothyroidism have their thyroid function monitored and be treated accordingly.

Anemia and neutropenia may be associated with sunitinib use, Hutson said. Pfizer suggests that those receiving sunitinib be monitored regularly for myelosuppression and recommends that complete blood counts (CBCs) with platelet count and serum chemistries, including phosphate, be done at the beginning of each sunitinib treatment cycle.

The recommended dose of sunitinib for GIST and MRCC is one 50-mg oral dose once daily, on a schedule of four weeks on treatment followed by two weeks off, Hutson said. Pfizer advises a dose reduction to a minimum of 37.5 mg daily if sunitinib is to be given concomitantly with a strong cytochrome P4503A4 (CYP3A4) inhibitor, and a dose increase to a maximum of 87.5 mg daily if sunitinib is to be given concomitantly with a strong CYP3A4 inducer.