Immunotherapies in the Treatment of Extensive-Stage SCLC

John V. Heymach, MD, PhD: Sandip, we also have the CASPIAN study, which is similar in most ways. Why don’t you take us through that and give any updates there?

Sandip P. Patel, MD: CASPIAN, similar to the IMpower133 study, looked in the frontline extensive-stage small cell lung cancer setting. Here, durvalumab was used with cisplatin or carboplatin for 4 cycles, and then durvalumab could be continued every 3 weeks. Now there’s every-4-week dosing. PCI [prophylactic cranial radiation] was allowed—about 8% of patients had PCI. The control arm got 6 cycles of chemotherapy, as opposed to 4 in IMpower133. And CASPIAN was open label vs IMpower133 was double blinded. The differences were subtle differences. Honestly, it was more similar than different.

With IMpower133 study results, we saw median overall survival on the order of 10 to 12 months and median progression-free survival on the order of 4 to 5 months across both the studies. As Stephen mentioned, concerning the durability of responses, the tail end of the curve in non–small cell lung cancer was 20%, 25%, 30%. OS [overall survival] was 2 years, so we’re looking on the order of about 22%, with control arm of about 17%, in IMpower133 and similar results in CASPIAN. Broadly, it’s the new standard of care. But as Stephen mentioned, there’s the idea that there’s likely a subgroup of patients driving benefit, and we don’t have a great way in a standard-of-care setting to define who those patients may be.

John V. Heymach, MD, PhD: Heather, now I have 2 good choices for approved agents with similar studies. Do you see any criteria from these studies that help you choose 1 vs the other, from your perspective? You mentioned that it’s not busy for small cell lung cancer at your practice, but how would you choose between the 2?

Heather Wakelee, MD: It’s a good question. It’s very hard to tell the difference. If you look at the data, as it stands with OS and long-term benefit, durvalumab vs atezolizumab, it’s very difficult to see a difference. With CASPIAN, we know that adding the tremelimumab didn’t seem to add much other than toxicity. We’re left with single agent. I can’t tell the difference. Maybe we’ll learn more as we start to understand these inflammatory subsets and all that. But for me, it’s very difficult. If there were differences in price, which there aren’t really, that factor would be reasonable to think about. There’s no difference in toxicity, and there’s not really a difference in efficacy. People just get into patterns of what they’re comfortable using.

John V. Heymach, MD, PhD: Yes, that’s right. As we mentioned before with the PD-1 inhibitors in the high PD-L1 group, it’s good to have choices, but what’s important is what combinations get built from here. How do these move forward? It’s reassuring to see 2 similar drugs produce similar results with well-designed studies. It’s good to see that as well.

Transcript Edited for Clarity