Authors: Ellen Clarke, Future Science Group
The US FDA has recently announced the approval of breakthrough immunotherapy drug pembrolizumab (Keytruda; marketed by Merck & Co, NJ, USA) for the treatment of advanced non-small-cell lung cancer, a condition described in the press release as the ‘deadliest of all cancers’.
Approximately 500 non-small-cell lung cancer patients were treated with the drug pembrolizumab in the largest study yet utilizing immunotherapy to treat lung cancer. A high proportion of patients demonstrated significant long-lasting responses, which prompted the FDA to fast track the drug for approval.
“The approval of this drug and a test to identify patients most likely to benefit has the potential to transform the way that lung cancer is treated,” commented Edward Garon, the principal investigator of the study from the University of California, Los Angeles’ Jonsson Comprehensive Cancer Center (CA, USA). “The quality and duration of disease response that was seen in the trial had previously been extremely rare in lung cancer. For people battling this deadly disease, this approach provides real hope of long-lasting responses while avoiding the toxicities of typical chemotherapy.”
Pembrolizumab produced a superior response rate and duration of response when compared with standard lung cancer treatments. The overall response rate in the 3-year clinical trial was 19%. A major advance in this hard-to-treat cancer was the increase in average duration of response, which was greater than 1 year on average for those who responded.
Acting as a PD-1 inhibitor, pembrolizumab has already proved effective in extending the lives of patients with advanced melanoma. Pembrolizumab enables a patient’s immune system to attack the cancer by blocking the interaction between PD-1 and PD-L1.
In approximately 25% of patients PD-L1 was expressed in at least half of their cells. The overall response rate reported in these patients was close to 50%, making this the first study to validate the association between clinical outcomes and the level of PD-L1 expression for this class of drug.
“We have long believed that harnessing the power of our own immune systems would dramatically alter cancer treatment,” commented Judith Gasson, director of the Jonsson Comprehensive Cancer Center. “Based upon the pioneering work conducted at UCLA, we are beginning to see the clinical benefits of this research in the most challenging cancers.”
There are ongoing studies to measure the effectiveness of pembrolizumab in other types of cancer, and to test it in combination with other drugs.