A narrative review of current and potential prognostic biomarkers for immunotherapy in small-cell lung cancer

Current and future perspectives in extensive-stage small-cell lung cancer

Small-cell lung cancer (SCLC) is a highly aggressive and rapidly proliferative malignancy that has historically had limited therapeutic advancements. Recent advancements in the understanding of SCLC have led to attempts at subtyping the disease based on transcription factor characteristics, offering new insights into its biology and potential therapeutic targets. In addition, significant progress has been made in developing treatment regimens, providing new hope for improved patient outcomes. The introduction of immune checkpoint inhibitors, such as atezolizumab and durvalumab, in combination with traditional chemotherapy, has marked a significant advancement, demonstrating improved overall survival and progression-free survival compared to chemotherapy alone. Despite these advancements, the prognosis for extensive-stage SCLC (ES-SCLC), the more advanced form of SCLC, remains poor, highlighting the critical need for ongoing research and the development of novel therapeutic strategies. New treatment modalities, such as lurbinectedin and anti-Delta-like Canonical Notch Ligand 3 antibodies, are now included in the treatment options for refractory SCLC, and many more treatment strategies involving combination therapies are being studied. Advances in molecular profiling and the identification of biomarkers are aiding in the development of personalized treatment approaches. This review focuses on these recent advancements and emerging strategies in the treatment of ES-SCLC.

Immunotherapy for Limited-Stage Small Cell Lung Cancer: Innovative Treatments and Future Perspectives

BackgroundLimited-stage small cell lung cancer (LS-SCLC) is a highly aggressive tumor characterized by a poor prognosis. While concurrent chemoradiotherapy (CCRT) remains the standard treatment, the high rates of recurrence and poor long-term survival highlight the pressing need for novel therapeutic approaches.PurposeIn recent years, the introduction of immunotherapy, particularly immune checkpoint inhibitors (ICIs), has opened new avenues for the treatment of LS-SCLC. This review highlights the clinical advancements of ICIs in CCRT, consolidation therapy, and neoadjuvant therapy, emphasizing their potential to improve progression-free survival (PFS) and overall survival (OS). This review also discusses management of immunotherapy-related side effects.Research DesignThis is a review article that synthesizes recent research findings on immunotherapy for LS-SCLC.Study SampleNot applicable (review of existing literature).Data Collection and/or AnalysisThis review summarizes key studies exploring the application of immunotherapy in limited-stage small cell lung cancer.Additionally, it examines the role of the tumor microenvironment, tumor mutation burden (TMB), and Programmed cell death 1 ligand 1(PD-L1) as biomarkers for predicting the efficacy of immunotherapy.ResultsThis review emphasizes their potential to improve PFS and OS.ConclusionsDespite the significant advancements in research, the use of ICIs in LS-SCLC continues to face challenges, including the identification of optimal treatment regimens, validation of long-term efficacy, and development of personalized predictive biomarkers. Future research should prioritize large-scale, multicenter clinical trials to refine combination therapy strategies, establish customized treatment approaches, and enhance patient outcomes.

Immune-Cell-Derived Exosomes as a Potential Novel Tool to Investigate Immune Responsiveness in SCLC Patients: A Proof-of-Concept Study

Small cell lung cancer (SCLC) is a highly invasive and rapidly proliferating lung tumor subtype. Most patients respond well to a combination of platinum-based chemotherapy and PD-1/PDL-1 inhibitors. Unfortunately, not all patients benefit from this treatment regimen, and few alternative therapies are available. In this scenario, the identification of new biomarkers and differential therapeutic strategies to improve tumor response becomes urgent. Here, we investigated the role of exosomes (EXs) released from the peripheral blood mononuclear cells (PBMCs) of SCLC patients in mediating the functional crosstalk between the immune system and tumors in response to treatments. In this study, we showed that PBMC-EXs from SCLC patients with different responses to chemoimmunotherapy showed different levels of immune (STING and MAVS) and EMT (Snail and c-Myc) markers. We demonstrated that PBMC-EXs derived from best responder (BR) patients were able to induce a significant increase in apoptosis in SCLC cell lines in vitro compared to PBMC-EXs derived from non-responder (NR) SCLC patients. PBMC-EXs were able to affect cell viability and modulate apoptotic markers, DNA damage and the replication stress pathway, as well as the occurrence of EMT. Our work provides proof of concept that PBMC-EXs can be used as a tool to study the crosstalk between cancer cells and immune cells and that PBMC-EXs exhibit an in vitro ability to promote cancer cell death and reduce tumor aggressiveness.

Adebrelimab plus chemotherapy and sequential thoracic radiotherapy as first-line therapy for extensive-stage small-cell lung cancer (ES-SCLC): a phase II trial

Background

This phase II prospective trial aimed to investigate the efficacy and safety of adebrelimab (PD-L1 antibody) plus first-line chemotherapy followed by sequential thoracic radiotherapy (TRT) combined with adebrelimab in extensive-stage small-cell lung cancer (ES-SCLC). Biomarkers associated with potential therapeutic effects were also explored.

Methods

Patients with previously untreated ES-SCLC were enrolled at Shandong Cancer Hospital and Institute (Jinan, China). Patients received 4-6 cycles of adebrelimab (20 mg/kg, D1, Q3W) combined with EP/EC (etoposide, 100 mg/m2, D1-3, Q3W and cisplatin, 75 mg/m2, D1, Q3W or carboplatin, AUC = 5, D1, Q3W). Then patients with response sequentially underwent consolidative TRT (≥30 Gy in 10 fractions or ≥50 Gy in 25 fractions, involved-field irradiation), and maintenance adebrelimab until disease progression or intolerable adverse events (AEs). The primary endpoint was overall survival (OS). Genomic and circulating tumour DNA (ctDNA) profiling were also analyzed with tumour tissues and peripheral blood. This trial was registered with ClinicalTrials.gov, NCT04562337.

Findings

From October 2020 to April 2023, 67 patients diagnosed with ES-SCLC were enrolled and received at least one dose of study treatment. All patients were included in the efficacy and safety analyses. 45 patients received sequential TRT as planned. The median OS and progression-free survival (PFS) was 21.4 months (95% CI: 17.2-not reached months) and 10.1 months (95% CI: 6.9-15.5 months), respectively. The confirmed objective response rate was 71.6% (48/67, 95% CI: 59.3-82.0%) and disease control rate was 89.6% (60/67, 95% CI: 79.7-95.7%). There were no treatment-related deaths. The most common grade 3 or higher treatment-related adverse events (TRAEs) were hematological toxicities. The incidence of any grade and G3+ pneumonitis was 25% (17/67) and 6% (4/67), respectively. No unexpected adverse events were observed. Patients without co-mutations of TP53/RB1 in both tissue and peripheral blood displayed longer PFS (tissue, P = 0.071; ctDNA, P = 0.060) and OS (tissue, P = 0.032; ctDNA, P = 0.031).

Interpretation

Adebrelimab plus chemotherapy and sequential TRT as first-line therapy for ES-SCLC showed promising efficacy and acceptable safety.

Funding

This study was funded by the National Natural Science Foundation of China (82172865), Jiangsu Hengrui Pharmaceuticals Co., Ltd. and Amoy Diagnostics Co., Ltd.

Immunotherapy for small cell lung cancer: the current state and future trajectories

Small cell lung cancer (SCLC) constitutes approximately 10% to 15% of all lung cancer diagnoses and represents a pressing global public health challenge due to its high mortality rates. The efficacy of conventional treatments for SCLC is suboptimal, characterized by limited anti-tumoral effects and frequent relapses. In this context, emerging research has pivoted towards immunotherapy combined with chemotherapy, a rapidly advancing field that has shown promise in ameliorating the clinical outcomes of SCLC patients. Through originally developed for non-small cell lung cancer (NSCLC), these therapies have extended new treatment avenues for SCLC. Currently, a nexus of emerging hot-spot treatments has demonstrated significant therapeutic efficacy. Based on the amalgamation of chemotherapy and immunotherapy, and the development of new immunotherapy agents, the treatment of SCLC has seen the hoping future. Progress has been achieved in enhancing the tumor immune microenvironment through the concomitant use of chemotherapy, immunotherapy, and tyrosine kinase inhibitors (TKI), as evinced by emerging clinical trial data. Moreover, a tripartite approach involving immunotherapy, targeted therapy, and chemotherapy appears auspicious for future clinical applications. Overcoming resistance to post-immunotherapy regimens remains an urgent area of exploration. Finally, bispecific antibodies, adoptive cell transfer (ACT), oncolytic virus, monotherapy, including Delta-like ligand 3 (DLL3) and T cell immunoreceptor with Ig and ITIM domains (TIGIT), as well as precision medicine, may present a prospective route towards achieving curative outcomes in SCLC. This review aims to synthesize extant literature and highlight future directions in SCLC treatment, acknowledging the persistent challenges in the field. Furthermore, the continual development of novel therapeutic agents and technologies renders the future of SCLC treatment increasingly optimistic.

Tumor mutational burden adjusted by neutrophil-to-lymphocyte ratio serves as a potential biomarker for atezolizumab-treated patients with extensive stage small cell lung cancer

BACKGROUND

There is a desperate for the identification of more accurate and efficient biomarkers for ICI responses in patients with SCLC.

METHODS

The data of our study was obtained from IMpower133 study. A total of 202 patients with SCLC received the treatment of placebo plus carboplatin plus etoposide (EC) while a total of 201 patients with SCLC received the treatment of atezolizumab plus EC. Overall survival (OS) was compared using Kaplan Meier analyses. Univariate and multivariate Cox regression analysis were used to determine independent prognostic variables affecting OS in patients with SCLC.

RESULTS

We have demonstrated that a higher TMB adjusted by a lower neutrophil-to-lymphocyte ratio (NLR) is significantly correlated with improved OS, in patients with SCLC subject to either atezolizumab or placebo (P = 0.001 for atezolizumab and P = 0.034 for placebo). Moreover, Cox model showed that TMB < 10 mut/Mb adjusted by NLR ≥ median was an independent factor of OS for atezolizumab-treated SCLC patients (hazard ratio [HR], 2.82; 95% confidence interval; 1.52-5.24; P = 0.001). Both univariate and multivariate cox regression analysis showed that for patients with SCLC harboring low NLR and high TMB, survival is significantly longer in those treated with atezolizumab than those treated with placebo. Survival benefit is significantly higher in atezolizumab-treated patients with SCLC than those treated with placebo (P = 0.018 for TMB cutoff = 10 mut/Mb, P = 0.034 for TMB cutoff = 16 mut/Mb).

CONCLUSION

Our findings provide a promising insight into the utility of NLR-adjusted TMB in the prognosis and immune responses in patients with SCLC.

A Systemic Immune Inflammation Index and PD-L1 (SP142) Expression as a Potential Combined Biomarker of the Clinical Benefit of Chemo-Immunotherapy in Extensive-Stage Small-Cell Lung Cancer

Background: No studies have identified combined biomarkers that may be more reasonable for the assessment of current chemo-immunotherapy in patients with extensive stage small-cell lung cancer (ES-SCLC). Methods: This study was conducted to investigate a combined biomarker with prognostic or predictive value in ES-SCLC. We determined the best independent prognostic biomarker among the four complete blood-count-derived inflammatory biomarkers (CBC-IBs). Subsequently, we analyzed the prognostic or predictive value of combining this independent CBC-IB with PD-L1 (SP142) expression. We prospectively assessed the SP142 analyses in tumor samples at diagnosis. Results: All in all, 55 patients with ES-SCLC were classified into four groups according to the systemic immune inflammation index (SII) (low/high) and SP142 (positive/negative). The best survival was observed in the low-SII/ SP142-positive group, whereas the worst survival was observed in the high-SII/SP142-negative group (p = 0.002). The combined SII-SP142 biomarker was better for predicting both survival and disease progression in patients with ES-SCLC. Conclusions: The combined SII-SP142 biomarker can be readily and universally obtained at a low cost in clinical practice, without requiring advanced genomics technology or specialized expertise. Although further studies are needed to confirm that the combined SII-SP142 biomarker is widely applicable, it should help clinicians to identify the best patients for combined chemotherapy with atezolizumab in ES-SCLC.

Usefulness of baseline immature reticulocyte fraction to mature reticulocyte fraction ratio (IMR) as A prognostic predictor for patients with small cell lung cancer

Background

Small cell lung cancer (SCLC) has a strong invasive ability and a high degree of malignancy, so accurate prognosis prediction is crucial for making the most favorable treatment decision.Unfortunately, there is a scarcity of prognostic indicators specific to SCLC. Reticulocyte levels in blood parameters have been linked to the prognosis of various malignancies. Given SCLC's aggressive characteristics, identifying reliable prognostic markers, such as reticulocyte counts, becomes pivotal in enhancing prognostic accuracy and guiding effective therapeutic strategies.

Objective

This study aimed to evaluate the predictive power of the immature reticulocyte fraction (IRF) to mature reticulocyte fraction (MRF) ratio (IMR) for survival outcomes in patients with SCLC.

Materials and methods

A retrospective analysis was conducted on 192 patients with small cell lung cancer (SCLC). The median values of various prognostic indicators, such as IMR, IRF, MRF, reticulocyte count (RET), SII (systemic immune-inflammatory index), were utilized as cutoff points, categorizing patients into high and low groups. The Kaplan-Meier method, univariate, multivariate analyses Cox regression, and C-index were used to analyze the prognostic factors for overall survival (OS).

Results

In our cohort, 138 (71.9 %) were male, 119 (62 %) were smokers, and 82 (57.3 %) were older than 60 years old. The median survival time was 18.15 months.Higher mortality was observed in the high IMR and high IRF groups, while the high MRF group exhibited lower mortality. At the same time, mortality was lower in the high MRF group. Univariate analysis showed that smoking history (P = 0.006), tumor stage (P = 0.002), chemotherapy cycle (P = 0.014), IMR (P = 0.01), and many other factors significantly affected the prognosis of SCLC. Multivariate analysis demonstrated that elevated IMR was an independent adverse predictor of OS (P = 0.039, HR = 0.330). Spearman test confirmed that the prognostic indicators IRF, IMR, and SII were positively correlated with the overall survival rate of patients with SCLC. Kaplan-Meier analysis showed that the OS rate of patients with high IMR was significantly worse (P = 0.0096). In addition, we found that IMR was superior to IRF in distinguishing patients with different outcomes in the low and high groups (P < 0.05). Our novel integration index, combining IMR with the TNM stage system and SII index, exhibited superior prognostic value compared to the original index. Additionally, the combination of prognostic indicators IMR and SII significantly stratified stage I-II SCLC patients (P ＜0.05).

Conclusions

The prognostic index based on peripheral blood IMR stands out as an independent predictor for SCLC patients pre-treatment. Its accessibility through routine blood analysis facilitates immediate clinical application without requiring prolonged scientific research validation. The integration of IMR with the TNM score enhances survival prediction and risk stratification. Notably, when combined with the SII score, the new IMR index demonstrates significant improvements in prognostication for stage I-II small cell lung cancer.

Actionable Driver Events in Small Cell Lung Cancer

Small cell lung cancer (SCLC) stands out as the most aggressive form of lung cancer, characterized by an extremely high proliferation rate and a very poor prognosis, with a 5-year survival rate that falls below 7%. Approximately two-thirds of patients receive their diagnosis when the disease has already reached a metastatic or extensive stage, leaving chemotherapy as the remaining first-line treatment option. Other than the recent advances in immunotherapy, which have shown moderate results, SCLC patients cannot yet benefit from any approved targeted therapy, meaning that this cancer remains treated as a uniform entity, disregarding intra- or inter-tumoral heterogeneity. Continuous efforts and technological improvements have enabled the identification of new potential targets that could be used to implement novel therapeutic strategies. In this review, we provide an overview of the most recent approaches for SCLC treatment, providing an extensive compilation of the targeted therapies that are currently under clinical evaluation and inhibitor molecules with promising results in vitro and in vivo.

Potential predictors of immunotherapy in small cell lung cancer

Lung cancer is one of the leading causes of cancer-related deaths worldwide, with small cell lung cancer (SCLC) having the worst prognosis. SCLC is diagnosed late in the disease's progression, limiting treatment options. The most common treatment for SCLC is chemotherapy. As the disease progresses, immunotherapy, most commonly checkpoint inhibitor medication, becomes more important. Efforts should be made in the development of immunotherapy to map specific biomarkers, which play a role in properly assigning a type of immunotherapy to the right cohort of patients, where the benefits outweigh any risks or adverse effects. The objective of this review was to provide a thorough assessment of current knowledge about the nature of the tumor process and treatment options for small cell lung cancer, with a focus on predictive biomarkers. According to the information obtained, the greatest potential, which has already been directly demonstrated in some studies, has characteristics such as tumor microenvironment composition, tumor mutation burden, and molecular subtyping of SCLC. Several other aspects appear to be promising, but more research, particularly prospective studies on a larger number of probands, is required. However, it is clear that this field of study will continue to expand, as developing a reliable method to predict immunotherapy response is a very appealing goal of current medicine and research in the field of targeted cancer therapy.

Investigation of poor predictive factors in extensive stage small cell lung cancer under etoposide-platinum-atezolizumab treatment

BACKGROUND

The phase III trial IMpower133 showed that platinum and etoposide plus atezolizumab was associated with improved overall survival (OS) and progression free-survival (PFS) when compared to the placebo group in treatment-naïve extensive stage (ES) small cell lung cancer (SCLC). Due to superiority in clinical outcomes, combination immunotherapy plus chemotherapy have become mainstay treatment modalities as first-line treatment in ES-SCLC. Nevertheless, real-world data are still lacking and the search for potential biomarkers is essential. This study aimed to evaluate potential predictive biomarkers applicable in ES-SCLC under combination therapy.

METHODS

Patients with ES-SCLC under etoposide-platinum-atezolizumab enrolled from seven university hospitals affiliated to the Catholic University of Korea were evaluated. Pretreatment clinical parameters were evaluated for association with OS and PFS. Adverse events (AEs) during induction and maintenance phases were also evaluated. p-values below 0.05 were considered statistically significant.

RESULTS

A total of 41 patients were evaluated. Six-month survival was 68.6%. As best response to treatment, 26 (63.4%) showed partial response, nine (22.0%) showed stable disease, and four (9.8%) showed progressive disease. During the induction phase, grade I-II AEs occurred in 22 (53.7%) patients, and grade III-IV AEs occurred in 26 (63.4%) patients. During the maintenance phase, nine out of 25 (36.0%) patients experienced any grade AEs. In multivariate analysis for OS, lactate dehydrogenase (LDH), c-reactive protein (CRP), and forced vital capacity (%) were significant factors. In multivariate analysis for PFS, sex, and LDH were significant.

CONCLUSION

In ES-SCLC under etoposide-platinum-atezolizumab, pretreatment CRP, LDH and FVC (%) were independent predictive factors.

Molecular subtyping of small-cell lung cancer based on mutational signatures with different genomic features and therapeutic strategies

Small-cell lung cancer (SCLC) is an exceptionally lethal malignancy characterized by extremely high alteration rates and tumor heterogeneity, which limits therapeutic options. In contrast to non-small-cell lung cancer that develops rapidly with precision oncology, SCLC still remains outside the realm of precision medicine. No recurrent and actionable mutations have been detected. Additionally, a paucity of substantive tumor specimens has made it even more difficult to classify SCLC subtypes based on genetic background. We therefore carried out whole-exome sequencing (WES) on the largest available Chinese SCLC cohort. For the first time, we partitioned SCLC patients into three clusters with different genomic alteration profiles and clinical features based on their mutational signatures. We showed that these clusters presented differences in intratumor heterogeneity and genome instability. Moreover, a wide existence of mutually exclusive gene alterations, typically within similar biological functions, was detected and suggested a high SCLC intertumoral heterogeneity. Particularly, Cluster 1 presented the greatest potential to benefit from immunotherapy, and Cluster 3 constituted recalcitrant SCLC, warranting biomarker-directed drug development and targeted therapies in clinical trials. Our study would provide an in-depth insight into the genome characteristics of the Chinese SCLC cohort, defining distinct molecular subtypes as well as subtype-specific therapies and biomarkers. We propose tailoring differentiated therapies for distinct molecular subgroups, centering on a personalized precision chemotherapy strategy combined with immunization or targeted therapy for patients with SCLC.

Clinical Activity and Safety of Anlotinib Combined with PD-1 Blockades for Patients with Previously Treated Small Cell Lung Cancer

Objective

Anlotinib was the standard monotherapy for patients with previously treated small cell lung cancer (SCLC) in recent years. Programmed cell death protein 1 (PD-1) blockade combined with antiangiogenic targeted drugs have proved to play a synergistic action for cancer treatment clinically. Consequently, the present study was to investigate the efficacy and safety of anlotinib combined with PD-1 blockades for patients with previously treated SCLC.

Methods

A total of 36 patients with SCLC who were treated with at least one previous systemic chemotherapy regimen participated in this study retrospectively. All the patients were administered with anlotinib plus PD-1 blockades therapy. Clinical activity was assessed according to the change of target lesion by imaging evidence and all the subjects were followed up regularly. Safety profiles were collected and documented during the treatment. Univariate analysis was carried out using Log rank test and multivariate analysis was adjusted by Cox regression analysis.

Results

All the 36 patients with previously treated SCLC were able to have their efficacy and safety profile evaluated. The best overall response of the combination regimen showed that complete response was observed in one patient, partial response was noted in 9 patients, stable disease was reported in 19 patients, progressive disease was seen in 7 patients. Therefore, the objective response rate (ORR) of the 36 patients was 27.8% (95% CI: 14.2-45.2%), disease control rate (DCR) was 80.6% (95% CI: 64.0-91.8%). Regarding the prognostic data, the median PFS and OS of the 36 patients was 4.6 months (95% CI: 3.13-6.07) and 9.3 months (95% CI: 3.30-15.30), respectively. The most common treatment-related adverse reactions were hypertension (52.8%), fatigue (47.2%), diarrhea (38.9%), hand and foot reaction (38.9%) and dermal toxicity (33.3%). Furthermore, multivariate Cox regression analysis for PFS indicated that ECOG performance status was an independent factor to predict PFS.

Conclusion

Anlotinib combined with PD-1 blockades regimen preliminarily demonstrated encouraging efficacy and tolerable safety for patients with previously treated SCLC. The conclusion should be validated in prospective clinical trials subsequently.