Clinical and molecular characterization of long-term survivors with extensive-stage small cell lung cancer treated with first-line atezolizumab plus carboplatin and etoposide

Advances in predictive biomarkers associated with immunotherapy in extensive-stage small cell lung cancer

Small cell lung cancer (SCLC) is a highly malignant and poor-prognosis cancer, with most cases diagnosed at the extensive stage (ES). Amidst a landscape marked by limited progress in treatment modalities for ES-SCLC over the past few decades, the integration of immune checkpoint inhibitors (ICIs) with platinum-based chemotherapy has provided a milestone approach for improving prognosis, emerging as the new standard for initial therapy in ES-SCLC. However, only a minority of SCLC patients can benefit from ICIs, which frequently come with varying degrees of immune-related adverse events (irAEs). Therefore, it is crucial to investigate predictive biomarkers to screen potential beneficiaries of ICIs, mitigate the risk of side effects, and improve treatment precision. This review summarized potential biomarkers for predicting ICI response in ES-SCLC, with a primary focus on markers sourced from tumor tissue or peripheral blood samples. The former mainly included PD-L1 expression, tumor mutational burden (TMB), along with cellular or molecular components related to the tumor microenvironment (TME) and antigen presentation machinery (APM), molecular subtypes of SCLC, and inflammatory gene expression profiles. Circulating biomarkers predominantly comprised circulating tumor DNA (ctDNA), circulating tumor cells (CTCs), cytokines, plasma autoantibodies, inflammation-related parameters, and blood TMB. We synthesized and analyzed the research progress of these potential markers. Notably, investigations into PD-L1 expression and TMB have been the most extensive, exhibiting preliminary predictive efficacy in salvage immunotherapy; however, consistent conclusions have yet to be reached across studies. Additionally, novel predictive markers developed based on TME composition, APM, transcriptomic and genomic features provide promising tools for precision immunotherapy. Circulating biomarkers offer the advantages of convenience, non-invasiveness, and a comprehensive reflection of tumor molecular characteristics. They may serve as alternative options for predicting immunotherapy efficacy in SCLC. However, there is a scarcity of studies, and the significant heterogeneity in research findings warrants attention.

Granulocyte colony-stimulating factor has the potential to attenuate the therapeutic efficacy of chemo-immunotherapy for extensive-stage small-cell lung cancer

BACKGROUND

Granulocyte colony-stimulating factor (G-CSF) has the potential to attenuate the anti-tumor immune responses of T-cells by increasing immune suppressive neutrophils and myeloid-derived suppressor cells. However, the clinical impact of G-CSF on the efficacy of immunotherapy remains unknown. This multi-center retrospective analysis evaluated the impact of G-CSF in patients with extensive-stage small-cell lung cancer (ES-SCLC) treated with chemo-immunotherapy.

METHODS

We analyzed 65 patients with ES-SCLC who completed four cycles of induction chemo-immunotherapy and evaluated the effects of G-CSF on progression-free survival (PFS), overall survival (OS), and a durable response to immunotherapy (defined as PFS ≥ 12 months).

RESULTS

Fifty patients (76.9%) received ≥ 1 dose of G-CSF. The PFS of the patients with G-CSF was poorer than that of the patients without G-CSF (median PFS 8.3 vs. 4.9 months, p = 0.009). The OS of the patients with G-CSF tended to be shorter, but not statistically significant, than that of the patients without G-CSF (median OS 24.3 vs. 16.4 months, p = 0.137). In the multivariate analysis, G-CSF administration was associated with poorer PFS (hazard ratio 2.78, 95% CI 1.36-5.69, p = 0.005) and was identified as a determinant of a durable response (odds ratio 0.18, 95% CI 0.04-0.80, p = 0.024). These results were consistent with other definitions of G-CSF administration (administration of ≥ 1 dose of pegfilgrastim, or either ≥ 5 doses of filgrastim or ≥ 1 dose of pegfilgrastim).

CONCLUSIONS

G-CSF has the potential to attenuate the efficacy of immunotherapy; therefore, the indication for G-CSF during chemo-immunotherapy should be carefully considered for ES-SCLC.

Extensive-stage small-cell lung cancer in patients receiving atezolizumab plus carboplatin-etoposide: stratification of outcome based on a composite score that combines gene expression profiling and immune characterization of microenvironment

PURPOSE

Small-cell lung cancer (SCLC) is an aggressive disease with a dismal prognosis. The addition of immune checkpoints inhibitors to standard platinum-based chemotherapy in first-line setting achieves a durable benefit only in a patient subgroup. Thus, the identification of predictive biomarkers is an urgent unmet medical need.

EXPERIMENTAL DESIGN

Tumor samples from naive extensive-stage (ES) SCLC patients receiving atezolizumab plus carboplatin-etoposide were analyzed by gene expression profiling and two 9-color multiplex immunofluorescence panels, to characterize the immune infiltrate and SCLC subtypes. Associations of tissue biomarkers with time-to-treatment failure (TTF), progression-free survival (PFS) and overall survival (OS), were assessed.

RESULTS

42 patients were included. Higher expression of exhausted CD8-related genes was independently associated with a longer TTF and PFS while increased density of B lymphocytes correlated with longer TTF and OS. Higher percentage of M2-like macrophages close to tumor cells and of CD8+T cells close to CD4+T lymphocytes correlated with increased risk of TF and longer survival, respectively. A lower risk of TF, disease progression and death was associated with a higher density of ASCL1+tumor cells while the expression of POU2F3 correlated with a shorter survival. A composite score combining the expression of exhausted CD8-related genes, B lymphocyte density, ASCL1 tumor expression and quantification of CD163+macrophages close to tumor cells, was able to stratify patients into high-risk and low-risk groups.

CONCLUSIONS

In conclusion, we identified tissue biomarkers and a combined score that can predict a higher benefit from chemoimmunotherapy in ES-SCLC patients.

Big Decisions on Small Cell Lung Cancer: A Focus on Clinical Care Updates and Patient Perspectives

Small cell lung cancer (SCLC) is an uncommon, aggressive high-grade neuroendocrine carcinoma, associated with tobacco use. It is a highly chemosensitive disease that initially responds quickly to systemic therapy, although patients with SCLC tend to develop relapse. Although the landscape of SCLC treatment has remained stagnant for many decades, the field has seen notable advances in the past few years, including the use of immunotherapy, the development of further lines of systemic therapy, the refinement of thoracic and intracranial radiotherapy, and-most recently-the promise of more targeted therapies. Patients with SCLC also must face unique psychosocial burdens in their experience with their cancer, distinct from patients with other lung cancer. In this article, we review the latest literature and future directions in the management and investigation of SCLC, as well as the critical decisions that providers and patients must navigate in the current landscape. We also present the perspectives of several patients with SCLC in conjunction with this summary, to spotlight their individual journeys in the context of this challenging disease.

Sex-specific Difference for Small Cell Lung Cancer from Immunotherapy Advancement

BACKGROUND

The treatment of lung cancer has witnessed significant progress, leading to improved survival rates among patients. It is important to assess the individual contributions of non-small cell lung cancer (NSCLC) and small-cell lung cancer (SCLC) to overall lung-cancer incidence and mortality trends based population, especially sex difference.

METHODS

We analyzed lung cancer mortality based on subtype, gender, and calendar year. The Joinpoint software was used to identify any changes in incidence and trends in mortality.

RESULTS

Incidence and incidence-based mortality declined from 2001 to 2019 both NSCLC and SCLC annually. The most significant decrease occurred between 2016 and 2019 with annual percent change of 5.71%. From 2012 to 2016, the incidence-based mortality of SCLC in women changed by 2.7% in tandem with incidence decreased 2.84%. Remarkably, the incidence-based mortality for women declined notably by 5.23% between 2016 and 2019, even as the incidence showed a less extent of decreasing (-2.59%). The survival rate for women was 15.2% in 2001, 19.3% in 2016, it had increased to 21.3% in 2018 but similar trends not in men. The survival curve showed the change in survival outcomes over time among men and women (median overall survival: 13 vs 23months) receiving immunotherapy for SCLC.

CONCLUSION

Population-level mortality from NSCLC and SCLC in the United States fell sharply from 2016 to 2019 as incidence deceased, and survival improved substantially. Our analysis suggests that approval for and use of immunotherapy may explain the mortality reduction observed during this period, with significant benefits especially for SCLC patient in women.

Construction of a prognostic model for extensive-stage small cell lung cancer patients undergoing immune therapy in northernmost China and prediction of treatment efficacy based on response status at different time points

BACKGROUND AND PURPOSE

Recently, the emergence of immune checkpoint inhibitors has significantly improved the survival of patients with extensive-stage small cell lung cancer. However, not all patients can benefit from immunotherapy; therefore, there is an urgent need for precise predictive markers to screen the population for the benefit of immunotherapy. However, single markers have limited predictive accuracy, so a comprehensive predictive model is needed to better enable precision immunotherapy. The aim of this study was to establish a prognostic model for immunotherapy in ES-SCLC patients using basic clinical characteristics and peripheral hematological indices of the patients, which would provide a strategy for the clinical realization of precision immunotherapy and improve the prognosis of small cell lung cancer patients.

METHODS

This research retrospectively collected data from ES-SCLC patients treated with PD-1/PD-L1 inhibitors between March 1, 2019, and October 31, 2022, at Harbin Medical University Cancer Hospital. The study data was randomly split into training and validation sets in a 7:3 ratio. Variables associated with patients' overall survival were screened and modeled by univariate and multivariate Cox regression analyses. Models were presented visually via Nomogram plots. Model discrimination was evaluated by Harrell's C index, tROC, and tAUC. The calibration of the model was assessed by calibration curves. In addition, the clinical utility of the model was assessed using a DCA curve. After calculating the total risk score of patients in the training set, patients were stratified by risk using percentile partitioning. The Kaplan-Meier method was used to plot OS and PFS survival curves for different risk groups and response statuses at different milestone time points. Differences in survival time groups were compared using the chi-square test. Statistical analysis software included R 4.1.2 and SPSS 26.

RESULTS

This study included a total of 113 ES-SCLC patients who received immunotherapy, including 79 in the training set and 34 in the validation set. Six variables associated with poorer OS in patients were screened by Cox regression analysis: liver metastasis (P = 0.001), bone metastasis (P = 0.013), NLR < 2.14 (P = 0.005), LIPI assessed as poor (P < 0.001), PNI < 51.03 (P = 0.002), and LDH ≥ 146.5 (P = 0.037). A prognostic model for immunotherapy in ES-SCLC patients was constructed based on the above variables. The Harrell's C-index in the training and validation sets of the model was 0.85 (95% CI 0.76-0.93) and 0.88 (95% CI 0.76-0.99), respectively; the AUC values corresponding to 12, 18, and 24 months in the tROC curves of the training set were 0.745, 0.848, and 0.819 in the training set and 0.858, 0.904 and 0.828 in the validation set; the tAUC curves show that the overall tAUC is > 0.7 and does not fluctuate much over time in both the training and validation sets. The calibration plot demonstrated the good calibration of the model, and the DCA curve indicated that the model had practical clinical applications. Patients in the training set were categorized into low, intermediate, and high risk groups based on their predicted risk scores in the Nomogram graphs. In the training set, 52 patients (66%) died with a median OS of 15.0 months and a median PFS of 7.8 months. Compared with the high-risk group (median OS: 12.3 months), the median OS was significantly longer in the intermediate-risk group (median OS: 24.5 months, HR = 0.47, P = 0.038) and the low-risk group (median OS not reached, HR = 0.14, P = 0.007). And, the median PFS was also significantly prolonged in the intermediate-risk group (median PFS: 12.7 months, HR = 0.45, P = 0.026) and low-risk group (median PFS not reached, HR = 0.12, P = 0.004) compared with the high-risk group (median PFS: 6.2 months). Similar results were obtained in the validation set. In addition, we observed that in real-world ES-SCLC patients, at 6 weeks after immunotherapy, the median OS was significantly longer in responders than in non-responders (median OS: 19.5 months vs. 11.9 months, P = 0.033). Similar results were obtained at 12 weeks (median OS: 20.7 months vs 11.9 months, P = 0.044) and 20 weeks (median OS: 20.7 months vs 11.7 months, P = 0.015). Finally, we found that in the real world, ES-SCLC patients without liver metastasis (P = 0.002), bone metastasis (P = 0.001) and a total number of metastatic organs < 2 (P = 0.002) are more likely to become long-term survivors after receiving immunotherapy.

CONCLUSION

This study constructed a new prognostic model based on basic patient clinical characteristics and peripheral blood indices, which can be a good predictor of the prognosis of immunotherapy in ES-SCLC patients; in the real world, the response status at milestone time points (6, 12, and 20 weeks) can be a good indicator of long-term survival in ES-SCLC patients receiving immunotherapy.

Immune heterogeneity in small-cell lung cancer and vulnerability to immune checkpoint blockade

Atezolizumab (anti-PD-L1), combined with carboplatin and etoposide (CE), is now a standard of care for extensive-stage small-cell lung cancer (ES-SCLC). A clearer understanding of therapeutically relevant SCLC subsets could identify rational combination strategies and improve outcomes. We conduct transcriptomic analyses and non-negative matrix factorization on 271 pre-treatment patient tumor samples from IMpower133 and identify four subsets with general concordance to previously reported SCLC subtypes (SCLC-A, -N, -P, and -I). Deeper investigation into the immune heterogeneity uncovers two subsets with differing neuroendocrine (NE) versus non-neuroendocrine (non-NE) phenotypes, demonstrating immune cell infiltration hallmarks. The NE tumors with low tumor-associated macrophage (TAM) but high T-effector signals demonstrate longer overall survival with PD-L1 blockade and CE versus CE alone than non-NE tumors with high TAM and high T-effector signal. Our study offers a clinically relevant approach to discriminate SCLC patients likely benefitting most from immunotherapies and highlights the complex mechanisms underlying immunotherapy responses.