Dasatinib 302962-49-8

Origin and development

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

Crystal structure ([http://www. pdb. org/pdb/explore. do?structureId=2GQG PDB 2GQG]) of Abl kinase domain (blue) in complex with dasatinib (red). The main targets of dasatinib, are BCR/ABL, Src, c-Kit, ephrin receptors, 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 dasatinib.

Adverse effects

On October 11, 2011 the U. S. Food and Drug Administration (FDA) announced that dasatinib may increase the risk of a rare but serious condition in which there is abnormally high blood pressure in the arteries of the lungs (pulmonary hypertension, PAH). Symptoms of PAH may include shortness of breath, fatigue, and swelling of the body (such as the ankles and legs). In reported cases, patients developed PAH after starting dasatinib, including after more than one year of treatment. And information about this risk has been added to the Warnings and Precautions section of the Sprycel drug label.