Charles Rudin, MD, PhD: Small cell lung cancer has historically been a very difficult disease to treat. About two-thirds of the patients have what we call extensive-stage disease, meaning disease that has progressed beyond a field that can be encompassed with radiation treatment. Most of those patients have metastatic disease at the time of diagnosis. For patients who have extensive-stage disease, historically our treatment of choice has been a combination of a platinum-based therapy with etoposide as a second agent. That’s been associated with a median survival of only about 9 or 9½ months and with very low probability of 5-year survival.
Last year we saw, for the first time, a study that really is changing the standard of care. There was a study that combined chemotherapy with immunotherapy, a new approach training the body’s own immune system to react to the cancer and that did show a positive outcome.
Currently our preferred approach to first-line therapy for patients with extensive-stage disease is a combination of carboplatin-etoposide and the PD-L1 [programmed death-ligand 1] inhibitor, atezolizumab. This is based on the outcome from the IMpower133 study, which showed a survival advantage with that regimen. That was associated with a survival advantage of about 2 months on average. But what we’re really interested in is whether those patients might benefit in the long run. We do know that some patients respond to immunotherapy with durable responses, long-lasting responses. So evaluating what the tails of those survival curves look like would be very interesting. We’re hoping the atezolizumab arm in fact includes patients who are long-term benefiters from immunotherapy.
This recent progress is really on the background of many failed phase III clinical trials for extensive-stage small cell lung cancer, looking at drugs like bevacizumab and other antiangiogenic drugs or looking at a variety of agents added to the standard of care, all of which were clearly negative. Those included 3- versus 2-drug trials and maintenance trials, all of which have been really quite negative. We’re very excited and very gratified to see a positive trial in this space, leading to an improved response in overall survival. And I think for the researchers in small cell lung cancer, this is progress we can build on.
Transcript Edited for Clarity