Recent studies have demonstrated that using Palbociclib, a newly developed oral drug that recently received accelerated approval from the US Food and Drug Administration, is effective in combating breast cancer alone and in combination with endocrine therapy. A new study published this month in JAMA Oncology suggests the drug may also be effective against other types of cancer.
After assessing 130 relevant publications, as well as interpreting their own continuing studies, researchers from the Abramson Cancer Center (ACC) found that early trials of palbociclib have shown promise of effectiveness in cases of lymphoma, sarcoma, and teratoma, tumors that while rare, often afflict younger patients.
Pfizer's Palbociclib, brand name Ibrance inhibits the function of the enzymes CDK4 and CDK6 (CDK4/6), which are used to propel cell growth and division in most cancers, NPR reported. This drug is the first CDK4/6 inhibitor to be approved for treatment of breast cancer.
"All living cells undergo cell division and palbociclib's unique capacity to halt the cell division process (also known as the 'cell cycle') therefore has potentially broad applicability," study lead author Dr. Amy S. Clark, a n assistant professor of Hematology/Oncology at Penn's Perelman School of Medicine and Abramson Cancer Center (ACC), said in a statement. "Pairing palbociclib with other anti-cancer therapies such as endocrine therapy, chemotherapy, and targeted therapy can create a powerful combinatorial effect with real promise for addressing a variety of cancers."
Furthermore, a clinical trial showed that, among 17 patients with previously treated mantle-cell lymphoma, palbociclib made one patient’s detectable tumor disappear. In the same trial, it led to at least a 50 percent decrease in total tumor volume in two patients. Another trial with 29 sarcoma patients treated with palbociclib showed a progression-free survival — length of time that a patient is both alive and without worsening of their cancer — of 66 percent at 12 weeks.
“Also, combining palbociclib with other anti-cancer agents is feasible, and early results in myeloma and some solid tumors have led to more definitive studies,” researchers wrote.
In addition to being effective, the drug is safe, too. The breast cancer drug has also proven to be not just effective, but safe too. CDK4/6 enzymes also spur the growth and division of healthy cells. Palbociclib was able to target the enzymes in the cancer cells without doing much damage to healthy tissues, according to NPR.
"This drug has minor effects on normal cells other than neutrophils (white blood cells)," said Dr. Peter J. O'Dwyer, director of the Developmental Therapeutics Program at the ACC. "In tumors, it can cause shrinkage, or more commonly, arrest of growth. As we discover new functions for the CDK4/6 target of this medicine, we are likely to use it in combinations to make other anti-cancer agents work better."
Cancer trials have shown that palbociclibis safe with once-daily dosing. Its main adverse effect is reversible neutropenia, an abnormally low count of neutrophils, a type of white blood cell that helps fight infections. Other side effects include fatigue, nausea, constipation, and rash.
Source: Clark A, Karasic T, DeMichele A, et al. Palbociclib (PD0332991)—a Selective and Potent Cyclin-Dependent Kinase Inhibitor: A Review of Pharmacodynamics and Clinical Development. JAMA Oncology. 2015.