Dasatinib

Dasatinib, previously known as BMS-354825, is a cancer drug produced by Bristol-Myers Squibb and sold under the trade name Sprycel. Dasatinib is an oral multi- BCR/ABL and Src family tyrosine kinase inhibitor approved for use in patients with chronic myelogenous leukemia (CML) after imatinib treatment and Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL). It is being evaluated for use in numerous other cancers, including advanced prostate cancer.

The drug is named after one of the inventor chemists, Jagabandhu Das, who was a member of the large discovery and development team at Bristol Myers Squibb.

Efficacy
In a Phase I dose escalation study published in June 2006, dasatinib was tested in patients who were resistant to or who could not tolerate imatinib. Complete hematological responses were seen in 37 of 40 patients with chronic-phase CML. Major hematologic responses were seen in 31 of 44 patients with accelerated-phase CML, CML in blast crisis, or Ph+ ALL.

Molecular targets
The main targets of dasatinib, are BCR/ABL, Src, c-Kit, multiple Eph kinases, and several other tyrosine kinases, but not erbB kinases such as EGFR or Her2.

Duration of benefit
Responses were maintained in 95% of patients with chronic-phase CML, with a median follow-up time of >12 months. In patients with accelerated-phase CML, 82% remained in remission, although with a median follow-up of only 5 months. Nearly all patients with CML in blast crisis or Ph+ ALL relapsed within 6 months.

Susceptible genotypes
Responses were seen in patients with all BCR/ABL genotypes, with the exception of T315I mutation, which confers resistance to both dasatinib, nilotinib and imatinib in vitro.

Toxicities
Neutropenia and myelosuppression were common toxic effects. Fifteen patients (of 84, ie 18%) in the above-mentioned study developed pleural effusions, which were felt to be a side effect of dasatinib. Some of these patients required thoracentesis or pleurodesis to treat the effusions. Other adverse events included mild to moderate diarrhea, peripheral edema, and headache. A small number of patients developed abnormal liver function tests which returned to normal without dose adjustments. Mild hypocalcemia was also noted, but did not appear to cause any significant problems.Several cases of pulmonary arterial hypertension (PAH) were found in patients treated with Sprycel.