Immune Checkpoint Inhibitors in Small Cell Lung Cancer: A Partially Realized Potential

Optimizing inpatient care for lung cancer patients with immune checkpoint inhibitor-related pneumonitis using a clinical care pathway algorithm

PURPOSE

Immune checkpoint inhibitor-related pneumonitis (ICI-P) is a condition associated with high mortality, necessitating prompt recognition and treatment initiation. This study aimed to assess the impact of implementing a clinical care pathway algorithm on reducing the time to treatment for ICI-P.

METHODS

Patients with lung cancer and suspected ICI-P were enrolled, and a multimodal intervention promoting algorithm use was implemented in two phases. Pre- and post-intervention analyses were conducted to evaluate the primary outcome of time from ICI-P diagnosis to treatment initiation.

RESULTS

Of the 82 patients admitted with suspected ICI-P, 73.17% were confirmed to have ICI-P, predominantly associated with non-small cell lung cancer (91.67%) and stage IV disease (95%). Pembrolizumab was the most commonly used immune checkpoint inhibitor (55%). The mean times to treatment were 2.37 days in the pre-intervention phase, 3.07 days (p = 0.46), and 1.27 days (p = 0.40) in the post-intervention phases 1 and 2, respectively. Utilization of the immunotoxicity order set significantly increased from 0 to 27.27% (p = 0.04) after phase 2. While there were no significant changes in ICU admissions or inpatient mortality, outpatient pulmonology follow-ups increased statistically significantly, demonstrating enhanced continuity of care. The overall mortality for patients with ICI-P was 22%, underscoring the urgency of optimizing management strategies. Notably, all patients discharged on high-dose corticosteroids received appropriate gastrointestinal prophylaxis and prophylaxis against Pneumocystis jirovecii pneumonia infections at the end of phase 2.

CONCLUSION

Implementing a clinical care pathway algorithm for managing severe ICI-P in hospitalized lung cancer patients standardizes practices, reducing variability in management.

Optimizing Inpatient Care for Lung Cancer Patients with Immune Checkpoint Inhibitor- Related Pneumonitis Using a Clinical Care Pathway Algorithm

Purpose

Immune checkpoint inhibitor-related pneumonitis (ICI-P) is a condition associated with high mortality, necessitating prompt recognition and treatment initiation. This study aimed to assess the impact of implementing a clinical care pathway algorithm on reducing the time to treatment for ICI-P.

Methods

Patients with lung cancer and suspected ICI-P were enrolled, and a multi-modal intervention promoting algorithm use was implemented in two phases. Pre- and post-intervention analyses were conducted to evaluate the primary outcome of time from ICI-P diagnosis to treatment initiation.

Results

Of the 82 patients admitted with suspected ICI-P, 73.17% were confirmed to have ICI-P, predominantly associated with non-small cell lung cancer (91.67%) and stage IV disease (95%). Pembrolizumab was the most commonly used immune checkpoint inhibitor (55%). The mean times to treatment were 2.37 days in the pre-intervention phase and, 3.07 days (p=0.46), and 1.27 days (p=0.40) in the post-intervention phases 1 and 2, respectively. Utilization of the immunotoxicity order set significantly increased from 0% to 27.27% (p = 0.04) after phase 2. While there were no significant changes in ICU admissions or inpatient mortality, outpatient pulmonology follow-ups increased statistically significantly, demonstrating enhanced continuity of care. The overall mortality for patients with ICI-P was 22%, underscoring the urgency of optimizing management strategies. Notably, all patients discharged on high-dose corticosteroids received appropriate gastrointestinal prophylaxis and prophylaxis against Pneumocystis jirovecii pneumonia infections at the end of phase 2.

Conclusion

Implementing a clinical care pathway algorithm for ICI-P management standardizes care practices and enhances patient outcomes, underscoring the importance of structured approaches.

Benefits and risks of PD-1/PD-L1 inhibitors for recurrent small cell lung cancer: A systematic review and meta-analysis

The development of immune checkpoint inhibitors(ICIs) has revolutionized the progress of solid tumors. Ongoing clinical trials are exploring the use of checkpoint inhibitors in recurrent small-cell lung cancer and achieving specific results. Although studies have been conducted to systematically review this issue, we conducted this single-arm meta-analysis in light of the emergence of several new clinical studies. In total, 854 individuals from 11 clinical investigations were enrolled in this single-arm meta-analysis. Median progression-free survival, median overall survival, and objective response rate were 1.65 months, 6.83 months, and 20.5%, respectively, according to pooled analyses. The best treatment regimen in the subgroup analysis was a dual checkpoint inhibitor combined with other treatments, and the drug that worked well for treatment was pembrolizumab. The benefit of programmed death 1/programmed cell death-ligand 1(PD-1/PD-L1) inhibitors alone is limited, and their combination with other therapies is a promising treatment option. Among PD-1/PD-L1 inhibitors, pembrolizumab is the recommended drug.

Tumor immunotherapies by immune checkpoint inhibitors (ICIs); the pros and cons

The main breakthrough in tumor immunotherapy was the discovery of immune checkpoint (IC) proteins, which act as a potent suppressor of the immune system by a myriad of mechanisms. After that, scientists focused on the immune checkpoint molecules mainly. Thereby, much effort was spent to progress novel strategies for suppressing these inhibitory axes, resulting in the evolution of immune checkpoint inhibitors (ICIs). Then, ICIs have become a promising approach and shaped a paradigm shift in tumor immunotherapies. CTLA-4 plays an influential role in attenuation of the induction of naïve and memory T cells by engagement with its responding ligands like B7-1 (CD80) and B7-2 (CD86). Besides, PD-1 is predominantly implicated in adjusting T cell function in peripheral tissues through its interaction with programmed death-ligand 1 (PD-L1) and PD-L2. Given their suppressive effects on anti-tumor immunity, it has firmly been documented that ICIs based therapies can be practical and rational therapeutic approaches to treat cancer patients. Nonetheless, tumor inherent or acquired resistance to ICI and some treatment-related toxicities restrict their application in the clinic. The current review will deliver a comprehensive overview of the ICI application to treat human tumors alone or in combination with other modalities to support more desired outcomes and lower toxicities in cancer patients. Video Abstract.

Development and Validation of a Nomogram for Predicting Overall Survival in Patients with Second Primary Small Cell Lung Cancer After Non-Small Cell Lung Cancer: A SEER-Based Study

Background

Non-small cell lung cancer (NSCLC) survivors are at an increased risk of developing second primary malignancies, such as small cell lung cancer. This paper sought to establish a prognostic nomogram to assess overall survival (OS) in patients with second primary small cell lung cancer (SPSCLC) after NSCLC.

Methods

420 patients who developed SPSCLC after NSCLC were randomly split into the training and validation groups. A nomogram was established by stepwise regression. Area under the curve (AUC) and calibration plots were applied to assess the prognostic performance of the nomogram. Concordance index (C-index), integrated discrimination improvement (IDI), net reclassification index (NRI) and decision curve analysis (DCA) were performed to compare the nomogram with the American Joint Committee on Cancer (AJCC) 8th staging system. Survival risk classification was constructed based on the nomogram.

Results

Five variables were chosen to construct the nomogram. The AUC showed that it had a satisfactory discrimination ability. All calibration plots displayed good concordance between nomogram and observation. The C-index, IDI, NRI and DCA showed the nomogram was superior to the AJCC 8th staging system. The Kaplan-Meier curves suggested huge differences in prognosis among the three risk groups.

Conclusion

This study build a nomogram and risk stratification system for predicting probabilities of OS in patients with SPSCLC after NSCLC, which can help clinicians in individualized survival assessment and treatment decisions.

Synergistic alterations in the multilevel chromatin structure anchor dysregulated genes in small cell lung cancer

Small cell lung cancer (SCLC) is an aggressive form of lung cancer that uniquely changes the chromosomal structure, although the basis of aberrant gene expression in SCLC remains largely unclear. Topologically associated domains (TADs) are structural and functional units of the human genome. Genetic and epigenetic alterations in the cancer genome can lead to the disruption of TAD boundaries and may cause gene dysregulation. To understand the potential regulatory role of this process in SCLC, we developed the TAD boundary alteration-related gene identification in tumors (TARGET) computational framework, which enables the systematic identification of candidate dysregulated genes associated with altered TAD boundaries. Using TARGET to compare gene expression profiles between SCLC and normal human lung fibroblast cell lines, we identified >100 genes in this category, of which 24 were further verified in samples from patients with SCLC using NanoString. The analysis revealed synergistic chromatin structure alteration at the A/B compartment and TAD boundary levels that underlies aberrant gene expression in SCLC. TARGET is a novel and powerful tool that can be used to explore the relationship of chromatin structure alteration to gene dysregulation related to SCLC tumorigenesis, progression, and prognosis.

Is there any room for PD-1 inhibitors in combination with platinum-based chemotherapy as frontline treatment of extensive-stage small cell lung cancer? A systematic review and meta-analysis with indirect comparisons among subgroups and landmark survival analyses

Background:

The addition of PD-L1 inhibitors to platinum-based chemotherapy (CT) has newly received United States Food and Drug Administration (FDA) approval in extensive stage-small cell lung cancer (ES-SCLC). PD-1 agents similarly improved survival rates, even if not yet supported by international regulatory agencies. The current work aims to assess different efficacy and safety profiles among chemoimmunotherapy plus immuno-oncology (CT+IO) approaches according to different immune checkpoint inhibitor (ICI) subtypes.

Material & Methods:

We included in our meta-analysis six first-line randomised controlled trials (RCTs) comparing the association of single-agent ICI with CT versus CT alone in ES-SCLC. Pooled hazard ratios (HRs) and risk ratios (RRs) for progression-free survival (PFS), overall survival (OS), objective response rates (ORR), 12-month duration of response rate (DORR), disease control rate (DCR), treatment-related adverse events (TRAEs) and discontinuation rates (DRs) were obtained. Moreover, we performed indirect comparisons according to ICI subtypes, also among subgroups and landmark survival analyses.

Results:

Although no ORR benefit was observed, our results showed how CT+IO significantly improved DORR, resulting in improved PFS and OS with no differences in TRAEs; however, CT+IO led to a significant increase in DR. Interestingly, an Eastern Cooperative Oncology Group performance status (ECOG PS) of 1, the use of cisplatin, and the absence of brain metastases seem to be associated with a survival gain using CT+IO in ES-SCLC. Indirect comparisons suggested a slight advantage in favour of programmed cell death-1 (PD-1) and programmed death ligand 1 (PD-L1) over anti-CTLA-4 agents in terms of efficacy with no additional safety concerns. No further differences were observed between PD-1 and PD-L1 inhibitors among subgroups and landmark survival analyses with benefit trends towards anti-PD-1 in terms of DORR and DR.

Conclusion:

While confirming a survival advantage of CT+IO in selected patients, these results suggested the association of PD-1 inhibitors with CT as a viable option for novel therapeutic approaches in the frontline management of ES-SCLC. Further trials evaluating anti-CTLA-4 agents should be carefully studied in biomarker-selected patients.

Cost-Effectiveness Analysis of Anlotinib as Third- or Further-Line Treatment for Relapsed Small Cell Lung Cancer (SCLC) in China

INTRODUCTION

The survival of patients with relapsed small cell lung cancer (SCLC) has achieved little progress in the last several decades. ALTER1202 confirmed the efficacy and safety of anlotinib as a third- or further-line option for relapsed SCLC. This study aimed to assess the cost-effectiveness of anlotinib compared with placebo as third- or further-line treatment for advanced SCLC in China.

METHODS

A Markov model was developed to simulate the process of advanced SCLC and estimate the incremental cost-effectiveness ratio (ICER) of anlotinib versus placebo. The health outcomes and utilities were derived from the ALTER1202 (NCT03059797) and published sources, respectively. Total costs were calculated from the perspective of Chinese society. One-way and probabilistic sensitivity analyses (PSA) were conducted to explore the model uncertainties.

RESULTS

Anlotinib was estimated to result in an additional 0.12 quality-adjusted life-years (QALYs) at an incremental cost of $2131.32, resulting in an ICER of $17,741.94/QALY. The ICER did not exceed the willingness-to-pay (WTP) threshold of $30,833 per QALY, which was three times the gross domestic product (GDP) per capita of China in 2019. One-way sensitivity analysis showed that the cost of anlotinib exerted the maximum influence on the result of the model, followed by the utility of progression-free survival (PFS) state in the anlotinib group and median overall survival (mOS) in the anlotinib group. In PSA, the probability of anlotinib being cost-effective was 26.6% and 78.5% when the WTP threshold was one and three times the GDP per capita, respectively.

CONCLUSION

Anlotinib is likely to be a cost-effective option compared with placebo for patients with relapsed SCLC who experience failure of at least two lines of chemotherapy in China.

Atezolizumab: A Review in Extensive-Stage SCLC

Atezolizumab (Tecentriq^®), a fully humanized, monoclonal anti-programmed cell death ligand-1 (PD-L1) antibody, is the first immune checkpoint inhibitor to be approved, in combination with carboplatin and etoposide, for the treatment of adult patients with extensive-stage small cell lung cancer (ES-SCLC). Approval was based on primary data from the multinational phase I/III IMpower133 trial in PD-L1-unselected patients with previously untreated ES-SCLC. In this trial, induction therapy with atezolizumab plus carboplatin and etoposide followed by maintenance therapy with atezolizumab alone significantly prolonged overall survival (OS) and progression-free survival (PFS) compared with carboplatin and etoposide alone. The addition of atezolizumab to chemotherapy was generally well tolerated, with no new safety signals being identified beyond those previously reported for the individual agents. The most common grade 3-4 treatment-related adverse events with this regimen were haematological; the most common immune-related adverse events included rash and hypothyroidism. Importantly, the addition of atezolizumab to chemotherapy improved survival outcomes without adversely impacting patient-reported health-related quality of life (HRQOL). Thus, atezolizumab in combination with carboplatin plus etoposide has emerged as a valuable option for the first-line treatment of ES-SCLC and is being accepted as a standard of care in this setting.

Trilaciclib prior to chemotherapy and atezolizumab in patients with newly diagnosed extensive-stage small cell lung cancer: A multicentre, randomised, double-blind, placebo-controlled Phase II trial

Trilaciclib is an intravenous CDK4/6 inhibitor administered prior to chemotherapy to preserve haematopoietic stem and progenitor cells and immune system function from chemotherapy-induced damage (myelopreservation). The effects of administering trilaciclib prior to carboplatin, etoposide and atezolizumab (E/P/A) were evaluated in a randomised, double-blind, placebo-controlled Phase II study in patients with newly diagnosed extensive-stage small cell lung cancer (ES-SCLC) (NCT03041311). The primary endpoints were duration of severe neutropenia (SN; defined as absolute neutrophil count <0.5 × 109 cells per L) in Cycle 1 and occurrence of SN during the treatment period. Other endpoints were prespecified to assess the effects of trilaciclib on additional measures of myelopreservation, patient-reported outcomes, antitumour efficacy and safety. Fifty-two patients received trilaciclib prior to E/P/A and 53 patients received placebo. Compared to placebo, administration of trilaciclib resulted in statistically significant decreases in the mean duration of SN in Cycle 1 (0 vs 4 days; P < .0001) and occurrence of SN (1.9% vs 49.1%; P < .0001), with additional improvements in red blood cell and platelet measures and health-related quality of life (HRQoL). Trilaciclib was well tolerated, with fewer grade ≥3 adverse events compared with placebo, primarily due to less high-grade haematological toxicity. Antitumour efficacy outcomes were comparable. Administration of trilaciclib vs placebo generated more newly expanded peripheral T-cell clones (P = .019), with significantly greater expansion among patients with an antitumour response to E/P/A (P = .002). Compared with placebo, trilaciclib administered prior to E/P/A improved patients' experience of receiving treatment for ES-SCLC, as shown by reduced myelosuppression, and improved HRQoL and safety profiles.

Immunotherapy in lung cancer

Immunotherapy has emerged as an important treatment modality throughout oncology with a particularly important role in the treatment of lung cancer. Early signals showed responses could be achieved in nonsmall cell lung cancer and small cell lung cancer and these monoclonal antibodies have become standards of care for advanced stage disease. They have also shown promise in earlier-stage disease as complements to radiation or surgery, offering the potential for durable, meaningful survival gains.

Curative efficacy might be an early predictor of prognosis in patients with small cell lung cancer treated with 2 cycles of platinum-based first-line chemotherapy

BACKGROUND

Platinum-based chemotherapy remains the essential therapy for small cell lung cancer (SCLC). Here, we conducted a statistical analysis to explore whether the curative efficacy of 2-cycle platinum-based chemotherapy can predict the survival of patients with SCLC.

METHODS

Fifty-six SCLC patients who had each received 2 cycles of platinum-based chemotherapy were enrolled. The curative efficacy of the chemotherapy was evaluated, mainly by chest computed tomography, and the treatment response was categorized according to the Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. Patients were continuously followed up for progression-free survival (PFS) and overall survival. The 55 patients were separated into 2 groups by the curative efficacy of the 2-cycle first-line platinum-based chemotherapy. All statistical analyses were performed with SPSS software (version 17.0; SPSS, Inc.; Chicago, IL, USA).

RESULTS

Patients who responded to 2-cycle chemotherapy (partial response, PR) had significantly better survival than others who did not (stable disease, SD or progressive disease, PD). The median progression-free survival (mPFS) in the PR group was 6.330 months, which was significantly longer than the 2.870 months seen in SD+PD group (95% CI: 4.631-8.029 vs. 0.000-5.790, P=0.022). The median overall survival (mOS) was 10.870 months in the PR group, which was remarkably longer than the 8.970 months observed in the SD+PD group (95% CI: 9.546-12.194 vs. 6.517-11.423, P=0.028). Curative efficacy had no correlation with clinical features.

CONCLUSIONS

The curative efficacy of 2-cycle first-line platinum-based chemotherapy was significantly correlated with PFS and OS, and showed prognostic value in SCLC patients. Patients who were sensitive to chemotherapy had superior survival to those who were chemotherapy insensitive.

Differential Expression of PD-L1 in Central and Peripheral and TTF1-Positive and -Negative Small-Cell Lung Cancer

Background: Central and peripheral location as well as thyroid transcription factor-I (TTF-1) expression was reported to be associated with different characteristics and prognosis of small-cell lung cancer (SCLC). This study aimed to investigate differential expression of PD-L1 in different SCLC subtypes, and in biopsy and resection specimens.

Methods: We retrospectively analyzed 142 SCLC tumor samples using immunohistochemistry to correlate PD-L1 (22C3) expression with clinicopathologic features and survival data.

Results: PD-L1 expression was found in 19.7% SCLCs (28/142) and was more frequent in females than in males (32%, 16/50 vs. 13%, 12/92, p = 0.009), in central type than in peripheral type SCLCs (26%, 26/100 vs. 4.8%, 2/42, p = 0.003), and in TTF-1 positive than in negative SCLCs (23.8%, 25/105 vs. 8.1%, 3/37, p = 0.039). PD-L1 expression was associated with vascular (p = 0.001) and lymphatic invasion (p = 0.001). There was no significant difference in PD-L1 expression between biopsy and resection specimens. On univariate analysis, patients with PD-L1 expression had significantly shorter progression-free survival (PFS; p = 0.026) and overall survival (OS; p = 0.012). Multivariate analysis revealed that PD-L1 expression was an independent prognostic factor for OS (HR, 2.317; 95% CI 1.199–4.478; p = 0.012) and PFS (HR, 1.636; 95% CI 0.990–2.703; p = 0.051) in SCLC.

Conclusions: PD-L1 expression was more frequent in central type, TTF-1 positive SCLCs, and predicted a poor clinical outcome in these patients. Therefore, tumor location and TTF-1 expression could predict expression status of PD-L1, and could potentially serve as clinical response to immunotherapy.

The benefits of etoposide capsules as maintenance therapy for patients with extensive-stage small cell lung cancer: a prospective two-stage, two-center study

Background

Due to the high incidence and mortality of lung cancer, and etoposide is the standard first-line chemotherapy for small cell lung cancer, to evaluate the efficacy and safety of etoposide capsules at different doses as maintenance therapy for patients with extensive-stage small cell lung cancer (ES-SCLC) who show a response to etoposide plus platinum.

Methods

The study was divided into two stages: stage I, a single-center, one-arm prospective study, and stage II, a multicenter, controlled non-randomized prospective study (patients were chosen from ClinicalTrials.gov Identifier: NCT02179528). All patients received six cycles of etoposide plus platinum. Patients who were evaluated as complete remission (CR) or partial remission (PR) entered the maintenance treatment (MT) (etoposide capsule, once a day for 20 days, every 28 days as a cycle, until disease progression). In stage I, the dose of etoposide was 25 mg; in stage II, patients were non-randomized into etoposide capsule (25 mg/50 mg) and observation groups. In this study, the primary endpoints were progression-free survival (PFS) and safety; the secondary endpoint was overall survival (OS). Toxicity was graded according to the Common Terminology Criteria for Adverse Events v3.0.

Results

Ninety-two patients were enrolled. In stage I, the median PFS was 6.700 months (95% CI: 6.408–6.992). In stage II, the median PFS of the MT group was better than that in the NMT group (8.930 vs. 5.900 months, P=0.002). In the pooled analysis, the overall median PFS of the MT group was better than that of the NMT group (7.870 vs. 5.900 months, P=0.003). However, there was no significant difference in OS between the groups (15.030 vs. 14.330 months, P=0.813). Multivariate Cox regression analysis showed that maintenance therapy was an independent protective factor for PFS in patients with ES-SCLC.

Conclusions

Etoposide capsules as maintenance therapy significantly prolonged the PFS of patients with ES-SCLC who responded to etoposide plus platinum, with acceptable tolerability.

Prolonging Survival: The Role of Immune Checkpoint Inhibitors in the Treatment of Extensive-Stage Small Cell Lung Cancer

BACKGROUND

Small cell lung cancer (SCLC) represents approximately 15% of lung cancers, and approximately 70% are diagnosed as extensive-stage SCLC (ES-SCLC). Although ES-SCLC is highly responsive to chemotherapy, patients typically progress rapidly, and there is an urgent need for new therapies. Immune checkpoint inhibitors (ICIs) have recently been investigated in SCLC, and this review provides guidance on the use of these agents in ES-SCLC based on phase III evidence.

METHODS

Published and presented literature on phase III data addressing use of ICIs in ES-SCLC was identified using the key search terms "small cell lung cancer" AND "checkpoint inhibitors" (OR respective aliases). Directed searches of eligible studies were periodically performed to ensure capture of the most recent data.

RESULTS

Six phase III trials were identified, with four assessing the benefits of ICIs plus chemotherapy first-line, one evaluating ICIs as first-line therapy maintenance, and one assessing ICI monotherapy after progression on platinum-based chemotherapy. The addition of ipilimumab or tremelimumab to first-line treatment or as first-line maintenance did not improve survival. Two out of three studies combining PD-1/PD-L1 inhibitors with first-line platinum-based chemotherapy demonstrated significant long-lasting survival benefits and improved quality of life with no unexpected safety concerns. PD-1/PD-L1 inhibitors as first-line maintenance or in later lines of therapy did not improve survival. Biomarker research is ongoing as well as research into the role of ICIs in combination with radiation therapy in limited-stage SCLC.

CONCLUSION

The addition of atezolizumab or durvalumab to first-line platinum-based chemotherapy for ES-SCLC prolongs survival and improves quality of life.

IMPLICATIONS FOR PRACTICE

Platinum-based chemotherapy has been standard of care for extensive-stage small cell lung cancer (ES-SCLC) for more than a decade. Six recent phase III trials investigating immune checkpoint inhibitors (ICIs) have clarified the role of these agents in this setting. Although ICIs were assessed first-line, as first-line maintenance, and in later lines of therapy, the additions of atezolizumab or durvalumab to first-line platinum-based chemotherapy were the only interventions that significantly improved overall survival and increased quality of life. These combinations should therefore be considered standard therapy for first-line ES-SCLC. Biomarker research and investigations into the role of ICIs for limited-stage disease are ongoing.

Gray E. Tumour PD-L1 Expression in Small-Cell Lung Cancer: A Systematic Review and Meta-Analysis

Antibodies against programmed death-1 (PD-1), and its ligand, (PD-L1) have been approved recently for the treatment of small-cell lung cancer (SCLC). Although there are previous reports that addressed PD-L1 detection on tumour cells in SCLC, there is no comprehensive meta-analysis on the prevalence of PD-L1 expression in SCLC. We performed a systematic search of the PubMed, Cochrane Library and EMBASE databases to assess reports on the prevalence of PD-L1 expression and the association between PD-L1 expression and overall survival (OS). This meta-analysis included 27 studies enrolling a total of 2792 patients. The pooled estimate of PD-L1 expression was 26.0% (95% CI 17.0–37.0), (22.0% after removing outlying studies). The effect size was significantly heterogeneous (I² = 97.4, 95% CI: 95.5–98.5, p < 0.0001).Positive PD-L1 expression was a favourable prognostic factor for SCLC but not statistically significant (HR = 0.86 (95% CI (0.49–1.50), p = 0.5880; I² = 88.7%, p < 0.0001). Begg’s funnel plots and Egger’s tests indicated no publication bias across included studies (p > 0.05). Overall, there is heterogeneity in the prevalence of PD-L1 expression in SCLC tumour cells across studies. This is significantly moderated by factors such as immunohistochemistry (IHC) evaluation cut-off values, and assessment of PD-L1 staining patterns as membranous and/or cytoplasmic. There is the need for large size, prospective and multicentre studies with well-defined protocols and endpoints to advance the clinical value of PD-L1 expression in SCLC.

Drugs in development for small cell lung cancer

Small cell lung cancer (SCLC) is a particularly lethal subtype of lung cancer whose treatment landscape has been relatively devoid of advance. The recent integration of immunotherapy in the first-line treatment of SCLC has improved overall survival (OS), prompting the first major paradigm shift for this disease in decades. Despite this improvement in outcomes, most patients with SCLC will relapse after initial response. Standard salvage systemic therapy for SCLC remains disappointing, with few approved agents and consistently poor outcomes. The need for novel agents to combat this disease remains pressing. Fortunately, there are several agents in various stages of development that hold potential as novel treatments for advanced SCLC. Lurbinectedin, which targets active transcription, has shown activity in platinum-sensitive and platinum-resistant SCLC as monotherapy and in combination with doxorubicin. Aurora A kinase (AAK) inhibitors showed initial activity when given with paclitaxel but in randomized studies, failed to improve outcomes over paclitaxel plus placebo. However, in the subset of patients with MYC expression, targeting AAK was effective. Similarly, agents targeting poly-ADP ribose (PARP) pair well with other DNA damaging drugs but in the subset of patients whose tumors express Schlafen-11 (SLFN-11), efficacy appeared greater. CDK 4/6 inhibition is being explored, primarily as a means to protect myeloid cells during cytotoxic chemotherapy in a strategy expected to be uniquely effective in SCLC. Ongoing trials are also studying are novel formulations of established cytotoxic agents. Delta-like protein 3 (DLL3) is an appealing therapeutic target given its selective expression on SCLC cells, but after initial exciting results, the antibody-drug conjugate (ADC) Rovalpituzumab tesirine (Rova-T) did not have a favorable efficacy to toxicity profile in randomized trials. Other agents targeting DLL3 are under study. Targeting angiogenesis has yielded modest improvements in the past but newer agents such as anlotinib are renewing interest. While the current therapeutic landscape beyond chemo-immunotherapy remains the same as it was decades ago, drug development for SCLC is rapidly moving forward and promises to deliver the needed novel agents in the very near future.

Cells of origin of lung cancers: lessons from mouse studies

As one of the most common forms of cancer, lung cancers present as a collection of different histological subtypes. These subtypes are characterized by distinct sets of driver mutations and phenotypic appearance, and they often show varying degrees of heterogenicity, aggressiveness, and response/resistance to therapy. Intriguingly, lung cancers are also capable of showing features of multiple subtypes or converting from one subtype to another. The intertumoral and intratumoral heterogeneity of lung cancers as well as incidences of subtype transdifferentiation raise the question of to what extent the tumor characteristics are dictated by the cell of origin rather than the acquired driver lesions. We provide here an overview of the studies in experimental mouse models that try to address this question. These studies convincingly show that both the cell of origin and the genetic driver lesions play a critical role in shaping the phenotypes of lung tumors. However, they also illustrate that there is far from a direct one-to-one relationship between the cell of origin and the cancer subtype, as most epithelial cells can be reprogrammed toward diverse lung cancer fates when exposed to the appropriate set of driver mutations.

Combined cytotoxic chemotherapy and immunotherapy of cancer: modern times

Monoclonal antibodies targeting programmed cell death 1/programmed cell death ligand 1 (PD-1/PD-L1) immune checkpoints have improved the treatments of cancers. However, not all patients equally benefit from immunotherapy. The use of cytotoxic drugs is practically inevitable to treat advanced cancers and metastases. The repertoire of cytotoxics includes 80 products that principally target nucleic acids or the microtubule network in rapidly proliferating tumor cells. Paradoxically, many of these compounds tend to become essential to promote the activity of immunotherapy and to offer a sustained therapeutic effect. We have analyzed each cytotoxic drug with respect to effect on expression and function of PD-(L)1. The major cytotoxic drugs—carboplatin, cisplatin, cytarabine, dacarbazine, docetaxel, doxorubicin, ecteinascidin, etoposide, fluorouracil, gemcitabine, irinotecan, oxaliplatin, paclitaxel and pemetrexed—all have the capacity to upregulate PD-L1 expression on cancer cells (via the generation of danger signals) and to promote antitumor immunogenicity, via activation of cytotoxic T lymphocytes, maturation of antigen-presenting cells, depletion of immunosuppressive regulatory T cells and/or expansion of myeloid-derived suppressor cells. The use of ‘immunocompatible’ cytotoxic drugs combined with anti-PD-(L)1 antibodies is a modern approach, not only for increasing the direct killing of cancer cells, but also as a strategy to minimize the activation of immunosuppressive and cancer cell prosurvival program responses.

Dashing Decades of Defeat: Long Anticipated Advances in the First-line Treatment of Extensive-Stage Small Cell Lung Cancer

PURPOSE OF REVIEW

Small cell lung cancer (SCLC) is an exceptionally lethal subtype of lung cancer. For patients with extensive-stage (ES) disease, which is the majority of patients, platinum-doublet chemotherapy has been the standard of care for decades. Dozens of phase III trials have failed to improve survival over standard platinum plus etoposide. Recent results, however, have met with long-overdue success. This manuscript reviews the new standards of care for ES-SCLC.

RECENT FINDINGS

Two recent phase III trials have shown an improvement in overall survival with concurrent immunotherapy and chemotherapy. In IMpower 133, the addition of the anti-PD-L1 antibody atezolizumab to carboplatin plus etoposide significantly improved both progression-free survival (PFS) and overall survival (OS). This was the first trial in over 30 years to improve survival. In CASPIAN, concurrent durvalumab, another anti-PD-L1 antibody, also led to an improvement in survival. While there is clearly a need to further improve outcomes, the improvement in survival with the addition of atezolizumab or durvalumab to platinum-doublet chemotherapy is a major advance. We now have new standards of care and the potential of a more meaningful benefit for patients with advanced SCLC.

Oncolytic Virotherapy with Myxoma Virus

Oncolytic viruses are one of the most promising novel therapeutics for malignant cancers. They selectively infect and kill cancer cells while sparing the normal counterparts, expose cancer- specific antigens and activate the host immune system against both viral and tumor determinants. Oncolytic viruses can be used as monotherapy or combined with existing cancer therapies to become more potent. Among the many types of oncolytic viruses that have been developed thus far, members of poxviruses are the most promising candidates against diverse cancer types. This review summarizes recent advances that are made with oncolytic myxoma virus (MYXV), a member of the Leporipoxvirus genus. Unlike other oncolytic viruses, MYXV infects only rabbits in nature and causes no harm to humans or any other non-leporid animals. However, MYXV can selectively infect and kill cancer cells originating from human, mouse and other host species. This selective cancer tropism and safety profile have led to the testing of MYXV in various types of preclinical cancer models. The next stage will be successful GMP manufacturing and clinical trials that will bring MYXV from bench to bedside for the treatment of currently intractable malignancies.