Reconsidering the Cutoff Value for Sensitive and Refractory Relapses in Extensive-Stage SCLC in the Era of Immunotherapy

Treatment patterns and survival outcomes in patients with small-cell lung cancer following failure of first-line platinum-based chemotherapy

PURPOSE

Small-cell lung cancer (SCLC) is an aggressive malignancy with limited treatment options, especially after the failure of first-line (1L) platinum-based chemotherapy. This study evaluated the treatment patterns and survival outcomes of Taiwanese patients with SCLC following 1L treatment failure, focusing on the effects of treatment-free interval (TFI).

METHODS

This retrospective study enrolled 287 patients with SCLC from 2012 to 2021. Data on clinical characteristics, systemic treatments after 1L failure, and survival status were collected. Progression-free survival (PFS) and overall survival (OS) were examined in analyses stratified by TFI. TFI < 90 days and ≥ 90 days denoted resistant relapse and sensitive relapse, respectively.

RESULTS

Second-line (2L) and third-line (3L) chemotherapy was administered to 76% and 54.1% of patients, respectively. Topotecan was administered to 25.4% of patients, primarily those with TFI 90-179 days. Platinum rechallenge was administered to 8.4% of patients, primarily those with TFI ≥ 180 days. The median PFS of patients with 2L treatment was 2.3 months (95% CI 2.2-2.6), and the median OS was 5.1 months (95% CI 4.3-6.2). Patients with TFI ≥ 90 days had significantly longer PFS (2.6 vs 2.2 months, P = 0.011) and OS (9.6 vs 4.0 months, P < 0.0001) than did those with TFI < 90 days. Platinum rechallenge showed similar efficacy to topotecan in patients with sensitive relapse (3.0 vs 2.7 months, P = 0.61).

CONCLUSIONS

Survival outcomes in patients with relapsed SCLC remain poor, particularly in those with platinum-resistant relapse. Our findings highlight the importance of optimizing 1L treatment for delaying disease progression. More effective 2L therapies should be developed to improve survival outcomes in patients with relapsed SCLC.

Recent advances in immunotherapy for small cell lung cancer

PURPOSE OF REVIEW

This review aims to provide an overview of recent advances in immunotherapy for small cell lung cancer (SCLC), with a focus on the current status of immune checkpoint inhibitors (ICIs), novel combination strategies, and key biomarkers.

RECENT FINDINGS

The integration of ICIs into standard chemotherapy has established them as the first-line treatment for extensive-stage SCLC (ES-SCLC). The ADRIATIC trial further demonstrated the efficacy of ICI maintenance therapy in limited-stage SCLC. Additionally, combining radiotherapy with ICIs has shown promising synergistic effects, including the abscopal and radscopal effects. Ongoing investigations into the combination of ICIs with targeted therapies, such as antiangiogenic agents and DNA damage response inhibitors, have yielded encouraging preliminary results. Notably, the novel therapeutic agent tarlatamab, the first bispecific DLL3-directed CD3 T-cell engager, has recently received FDA approval for second-line treatment of ES-SCLC. Advances in omics technologies have shed light on the intra-tumor and inter-tumor heterogeneity of SCLC, leading to the identification of new molecular subtypes and biomarkers, thereby paving the way for precision medicine.

SUMMARY

Despite the improved outcomes associated with immunotherapy in SCLC, the overall clinical benefit remains modest. Further preclinical and clinical studies are essential to identify optimal treatment regimens and enhance therapeutic efficacy.

Efficacy of carboplatin-etoposide rechallenge after first-line chemo-immunotherapy in ES-SCLC: an international multicentric analysis

Background and objectives

Second-line treatment for small-cell lung cancer (SCLC) is primarily guided by the time elapsed since the last platinum dose. Rechallenge with carboplatin and etoposide has demonstrated superior outcomes compared to topotecan if the platinum-free interval (PFI) is longer than 90 days and is considered the standard of care. However, these findings predate the chemo-immunotherapy era. This study investigates the effectiveness of the rechallenge strategy after chemo-immunotherapy in a real-world setting.

Design and methods

We retrospectively reviewed patients with the extensive stage (ES)-SCLC who received rechallenge with carboplatin and etoposide after first-line chemoimmunotherapy between September 2020 and August 2023 in nine European centres. Demographic and clinical data were collected and analysed.

Results

A total of 93 patients were included. Sixty-six (71%) patients had a PFI between 3 and 6 months. Consolidation thoracic radiotherapy and prophylactic cranial irradiation had been administered in 31 (33.3%) patients and 20 (21.5%) patients, respectively. Overall response rate was 59.1%. Median progression-free survival (PFS) was 5 months (95% confidence interval (CI) 4.3-5.7) and median overall survival (OS) was 7 months (95% CI 5.7-8.3). Notably, PFS and OS were not different according to PFI (3-6 m vs > 6 m).

Conclusion

Rechallenge with carboplatin and etoposide is a valid second-line option in patients with ES-SCLC whose disease progresses after first-line chemoimmunotherapy. Our analysis shows similar results to previous studies. Furthermore, outcomes were consistent across patients with different PFIs, confirming its efficacy in patients with a PFI longer than 3 months.

The Evolving Scenario of ES-SCLC Management: From Biology to New Cancer Therapeutics

Small cell lung cancer (SCLC) is an aggressive neuroendocrine carcinoma accounting for 15% of lung cancers with dismal survival outcomes. Minimal changes in therapy and prognosis have occurred in SCLC for the past four decades. Recent progress in the treatment of extensive-stage disease (ES-SCLC) has been marked by incorporating immune checkpoint inhibitors (ICIs) into platinum-based chemotherapy, leading to modest improvements. Moreover, few second-line-and-beyond treatment options are currently available. The main limitation for the molecular study of SCLC has been the scarcity of samples, because only very early diseases are treated with surgery and biopsies are not performed when the disease progresses. Despite all these difficulties, in recent years we have come to understand that SCLC is not a homogeneous disease. At the molecular level, in addition to the universal loss of retinoblastoma (RB) and TP53 genes, a recent large molecular study has identified other mutations that could serve as targets for therapy development or patient selection. In recent years, there has also been the identification of new genetic subtypes which have shown us how intertumor heterogeneity exists. Moreover, SCLC can also develop intratumoral heterogeneity linked mainly to the concept of cellular plasticity, mostly due to the development of resistance to therapies. The aim of this review is to quickly present the current standard of care of ES-SCLC, to focus on the molecular landscapes and subtypes of SCLC, subsequently present the most promising therapeutic strategies under investigation, and finally recap the future directions of ongoing clinical trials for this aggressive disease which still remains a challenge.