Small cell lung cancer (SCLC) remains one of the most aggressive cancers, and while immunotherapy has shown promise, it's not a silver bullet. The quest to understand who benefits most, and why, continues at full speed. Dr. Christine Hann recently shared insights on the latest data, and it's a mixed bag of breakthroughs and setbacks, highlighting the critical need for better biomarkers to guide treatment decisions.
Dr. Hann, an associate professor of oncology at the Johns Hopkins School of Medicine and a physician at the Johns Hopkins Sidney Kimmel Comprehensive Cancer Center, presented her analysis at the 20th Annual New York Lung Cancers Symposium®. Her presentation focused on how recent SCLC research is shaping treatment strategies for both limited-stage SCLC (LS-SCLC) and extensive-stage SCLC (ES-SCLC). She delved into the consolidation data surrounding durvalumab (Imfinzi), the more complex findings regarding atezolizumab (Tecentriq), and the ongoing search for biomarkers to personalize SCLC treatment.
But here's where it gets controversial... While immunotherapy has become a standard part of SCLC treatment, not everyone responds equally. And this variability underscores the urgency of identifying biomarkers that can predict which patients will truly benefit. Let's break down the key takeaways from Dr. Hann's presentation.
Recent Advances and Setbacks in LS-SCLC: A Closer Look
Dr. Hann started with the ADRIATIC trial (NCT03703297), a phase 3 study examining durvalumab as consolidation therapy for patients with stage III inoperable LS-SCLC. The results, presented at the 2024 ASCO Annual Meeting, were encouraging. Patients receiving durvalumab alone (n = 264) saw a median progression-free survival (PFS) of 16.6 months (95% CI, 10.2-28.2) compared to just 9.2 months (95% CI, 7.4-12.9) with placebo (n = 266), translating to a hazard ratio (HR) of 0.76 (95% CI, 0.61-0.95; P = .0161). Even more impressively, the median overall survival (OS) jumped to 55.9 months (95% CI, 37.3-not evaluable) with durvalumab versus 33.4 months (95% CI, 25.5-39.9) with placebo (HR, 0.73; 95% CI, 0.57-0.93; P = .0104). This clearly demonstrates a significant survival advantage with durvalumab consolidation.
Dr. Hann also emphasized the safety profile of durvalumab in the ADRIATIC trial. Patients in the durvalumab arm received a median of 9 doses (ranging from 1 to 26). While the rate of any-grade all-cause adverse events (AEs) was high at 94.3%, the rate of any-grade immune-mediated AEs was a more manageable 32.1%. A notable adverse effect was radiation pneumonitis, observed in 22.9% of patients.
"Notable findings [from subgroup analyses] were that [patients who received] once-daily and twice-daily [dosing] both seem to benefit [from durvalumab],” Hann said, adding that “These are trends, not absolutes.” This suggests that the benefits of durvalumab are consistent regardless of the radiation dosing schedule, offering flexibility in treatment planning.
Based on these compelling results, the FDA approved durvalumab in December 2024 for adult patients with LS-SCLC whose disease hasn't progressed after platinum-based chemotherapy and radiation therapy. This approval marked a significant step forward in treating this challenging cancer. Dr. Hann also mentioned that the data from the durvalumab/tremelimumab arm of the ADRIATIC trial are still pending and could provide further insights.
However, the path to progress isn't always smooth. Dr. Hann then discussed the NRG-LU005 trial (NCT03811002), a phase 3 study that evaluated concurrent atezolizumab and chemoradiotherapy in LS-SCLC. Disappointingly, the second planned interim analysis revealed no improvements in PFS or OS compared to chemoradiotherapy alone.
And this is the part most people miss... This lack of benefit with concurrent atezolizumab mirrors the findings from the PACIFIC-2 trial (NCT03519971). "It seems like immunotherapy given concurrently with chemoradiation offers no benefit," Dr. Hann explained. The final analysis of PACIFIC-2 confirmed this, showing no significant PFS benefit with concurrent durvalumab and chemoradiotherapy followed by consolidation durvalumab.
Further complicating the picture, the phase 2 ACHILES trial (NCT03540420) presented at the 2025 ASCO Annual Meeting, examined consolidation atezolizumab after chemoradiotherapy in LS-SCLC. While the atezolizumab arm showed a numerical improvement in median OS (43.4 months vs. 38.8 months in the observation arm), this difference didn't reach statistical significance. Interestingly, the observation arm performed better than expected compared to other studies, highlighting the variability in SCLC outcomes.
Dr. Hann summarized that current data support the use of durvalumab consolidation for up to two years in patients with at least stable disease after chemoradiation, improving PFS and OS with manageable toxicity. However, atezolizumab given concurrently with chemoradiation or as maintenance/consolidation therapy has not shown a clear benefit in clinical trials so far. Ongoing phase 3 trials with other immunotherapy agents may shed more light on the optimal role of immunotherapy-based combinations in LS-SCLC.
Immunotherapy in ES-SCLC: Benefits and Limitations
Shifting her focus to ES-SCLC, Dr. Hann discussed the landmark Impower133 (NCT02763579) and CASPIAN (NCT03043872) trials, which established the role of first-line immunotherapy in this setting. "The trials were designed slightly differently, but the outcomes were similar," she noted. "There is a small population [of patients who] are doing well [with frontline immunotherapy]. In the rest, we could probably use additional therapy." These trials demonstrated a consistent improvement in median OS with the addition of PD-1 or PD-L1 inhibitors to platinum/etoposide chemotherapy.
However, subsequent studies combining immunotherapy agents in ES-SCLC have largely failed to show additional efficacy benefits compared to single-agent immunotherapy. One exception is the biomarker-based phase 2 SWOG S1929 trial (NCT04334941), which evaluated maintenance atezolizumab alone versus in combination with talazoparib in patients with SLFN11-positive ES-SCLC. This trial showed a potential benefit with the combination, highlighting the importance of biomarker-driven approaches.
This raises a critical question: Should we be focusing more on identifying patients who are most likely to respond to specific immunotherapy combinations based on their unique tumor characteristics?
Dr. Hann also highlighted the IMforte trial (NCT05091567), presented at ASCO 2025, which evaluated first-line maintenance therapy with lurbinectedin (Zepzelca) plus atezolizumab. The combination significantly improved both PFS and OS compared to atezolizumab alone. These data led to the FDA approval of lurbinectedin plus atezolizumab (or atezolizumab and hyaluronidase-tqjs) as maintenance therapy for ES-SCLC patients whose disease has not progressed after frontline induction therapy with atezolizumab, carboplatin, and etoposide.
Dr. Hann emphasized that while etoposide plus a PD-L1 inhibitor is now considered standard frontline therapy, lurbinectedin added to maintenance atezolizumab offers a valuable option for select patients. However, she cautioned that these patients should be relatively fit and without brain metastases at presentation, as the toxicities can be significant.
The Future: Biomarkers and Beyond
Dr. Hann concluded by reiterating the crucial need for predictive biomarkers to better define the role of immunotherapy in SCLC. Key questions remain: Which patients benefit most from immunotherapy as monotherapy versus in combination regimens? What are the optimal treatment strategies for patients with small cell transformation from EGFR-mutant adenocarcinoma, where early data suggest ICIs might not be the most effective? And how can we develop more effective therapies than chemotherapy for patients ineligible for ICIs due to autoimmune conditions, transplants, or paraneoplastic syndrome?
These are all complex questions that require further research. The future of SCLC treatment hinges on our ability to personalize therapy based on individual patient and tumor characteristics.
What are your thoughts? Do you believe biomarker-driven approaches are the key to unlocking the full potential of immunotherapy in SCLC? Are you optimistic about the development of novel therapies for patients who are not candidates for ICIs? Share your opinions and experiences in the comments below! Let's start a conversation about the future of SCLC treatment.
