Who: Keytruda drug
Where: In the USA
What: Approved by the FDA
When: 2 October 2015
Why: To treat non-small-cell lung cancer
The US Food and Drug Administration (FDA) on 2 October 2015 approved Keytruda (pembrolizumab) drug for the treatment of non-small-cell lung cancer (NSCLC).
However, the agency permitted its use to treat patients with advanced (metastatic) form only whose disease has progressed even after other available treatments and with tumors that express a protein called PD-L1.
The FDA approved for its use with a companion diagnostic, the PD-L1 IHC 22C3 pharmDx test, the first test designed to detect PD-L1 expression in non-small cell lung tumors.
How Keytruda works?
Keytruda works by targeting the cellular pathway known as PD-1/PD-L1 (proteins found on the body’s immune cells and some cancer cells). By blocking this pathway, Keytruda may help the body’s immune system fight the cancer cells.
Significance of Keytruda
Keytruda is the first drug approved in lung cancer for patients whose tumors express PD-L1.
In 2014, the FDA approved its use to treat patients with advanced melanoma, a type of skin cancer, following treatment with ipilimumab, a type of immunotherapy.
The recent approval extending its use to treat NSCLC was based on preliminary clinical trials on 550 patients who could not benefit from the existing therapies including platinum-based chemotherapy.
The drug offers hope to lakhs of patients suffering from lung cancer which is the leading cause of cancer death in the United States, with an estimated 221,200 new diagnoses and 158,040 deaths in 2015.
At present, lung cancer accounts for 13 per cent of all new cancer cases and 19 per cent of cancer related deaths worldwide.
In India, lung cancer constitutes 6.9 per cent of all new cancer cases and 9.3 per cent of all cancer related deaths and is the commonest cause of cancer related mortality in men.
What are non-small-cell lung cancer and PD-L1?
Between the two major types of lung cancer-Small cell lung cancer (SCLC) and Non-small cell lung cancer (NSCLC) – the NSCLC is the most prevalent and deadliest.
It is because around 85 to 90 percent of lung cancers are non-small cell lung cancer (NSCLC) and they are relatively insensitive to chemotherapy, compared to SCLC.
NSCLC is so called in order to differentiate it from the SCLC that look small and are mostly filled with the nucleus (the control centre of cells) and usually caused by smoking.
PD-L1 is a protein that in humans is encoded by the CD274 gene. It has been speculated to play a major role in suppressing the immune system during particular events such as pregnancy, tissue allografts, autoimmune disease (e.g. cancer) and other disease states such as hepatitis.
PD-L1 expression correlated inversely with intraepithelial CD8+ T-lymphocyte count, suggesting that PD-L1 on tumor cells may suppress antitumor CD8+ T cells.