Cancer busting drug can halt tumours
A new breast cancer drug could also help fight other tumours, according to scientists.
The pill called palbociclib targets the division of cancer cells and has been proved to work against breast cancer, halting and in some cases shrinking tumour growth.
Now a review and additional original research conducted by experts at the Abramson Cancer Centre at the University of Pennsylvania shows it might have the same effect with other cancers.
The drug works by inhibiting the activity of the enzymes CDK4 and CDK6, which drive cell division and increase in number in most cancers.
Amplification of CDK4 is reported in a high percentage of melanomas and esophageal cancers.
The drug is the first of its type to be approved for the treatment of breast cancer.
Lead author Dr Amy Clark, an assistant professor of Haematology/Oncology at Penn's Perelman School of Medicine said: "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.
"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."
The study, published this month in JAMA Oncology, showed that among 17 patients with previously treated mantle-cell lymphoma, palbociclib resulted in one complete response and two partial responses.
Although, median progression-free survival was four months, five patients had progression-free survival greater than one year.
Another phase 2 trial with 29 sarcoma patients treated with palbociclib showed a progression-free survival of 66 percent at 12 weeks.
Also, combining palbociclib with other anti-cancer agents is feasible, and early results in myeloma and some solid tumours have led to more definitive studies.
In both breast and other cancer trials, palbociclib has been shown to be safe with once-daily dosing, and its main adverse effect is reversible neutropenia, an abnormally low count of neutrophils, a type of white blood cell that helps fight infections.
The lower their neutrophil count, the more vulnerable patients are to infectious diseases.
In such cases the drug is temporarily discontinued and reintroduced at a lower dose.
Other side effects included fatigue (33 percent), nausea (30 percent), diarrhea (18 percent), constipation (12 percent), and rash (12 percent).
Senior author, Dr Peter O'Dwyer, a professor of Haematology/Oncology at Penn and director of the Developmental Therapeutics Program added:"This drug has minor effects on normal cells other than neutrophils.
"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.
"In addition to inhibiting the cell cycle, palbociclib has been shown, for example to alter several recently described non-cell cycle functions of CDK4/6, a finding expected to expand its therapeutic role."
The team assessed 130 relevant publications in the literature as well as interpreting their own continuing studies.
They found that in addition to its safety and effectiveness in fighting certain types of breast cancer, early trials of palbociclib have shown promise of effectiveness in cases of lymphoma, sarcoma, and teratoma, tumors that while rare, often afflict younger patients.
In the UK, Palbociclib is presently being used as part of a clinical trial to treat postmenopausal women with breast cancer at The Royal Marsden NHS Foundation Trust. Patients can be referred for the trial until 01 October 2016