Palbociclib: A new hope in the treatment of breast cancer.

Breast cancer being one of the common cancers has high morbidity and mortality. Despite the conventional treatment, the burden of the disease increases year after year. There is a need for newer drugs that target the different mechanisms in the pathogenesis. The interaction of cyclins with cyclin dependent kinases (CDKs) plays a major role in the abnormal cell cycle in cancer and it is considered to be an important target. Palbociclib is a CDK inhibitor currently approved for the treatment of breast cancer. The preclinical studies with breast cancer lines were sensitive to palbociclib and the clinical trials phase I, phase II (PALOMA 1), and phase III (PALOMA 2, 3, PENTELOPE, PEARL) showed that the drug was efficacious when combined other conventional drugs for breast cancer. Palbociclib was also been tested in various other germ cell tumors, melanoma, multiple myeloma, glioblastoma multiforme etc., The major adverse effect of the drug includes hematological toxicity mainly neutropenia, gastrointestinal adverse effects.