Immune checkpoint inhibitors in small cell lung cancer

Actin dysregulation induces neuroendocrine plasticity and immune evasion: a vulnerability of small cell lung cancer

Small cell lung cancer (SCLC) is aggressive with limited therapeutic options. Despite recent advances in targeted therapies and immunotherapies, therapy resistance is a recurring issue, which might be partly due to tumor cell plasticity, a change in cell fate. Nonetheless, the mechanisms underlying tumor cell plasticity and immune evasion in SCLC remain elusive. CRACD, a capping protein inhibitor that promotes actin polymerization, is frequently inactivated in SCLC. Cracd knockout (KO) transforms preneoplastic cells into SCLC tumor-like cells and promotes in vivo SCLC development driven by Rb1, Trp53, and Rbl2 triple KO. Cracd KO induces neuroendocrine (NE) plasticity and increases tumor cell heterogeneity of SCLC tumor cells via dysregulated NOTCH1 signaling by actin cytoskeleton disruption. CRACD depletion also reduces nuclear actin and induces EZH2-mediated H3K27 methylation. This nuclear event suppresses the MHC-I genes and thereby depletes intratumoral CD8+ T cells for accelerated SCLC tumorigenesis. Pharmacological blockade of EZH2 inhibits CRACD-negative SCLC tumorigenesis by restoring MHC-I expression and immune surveillance. Unsupervised single-cell transcriptomics identifies SCLC patient tumors with concomitant inactivation of CRACD and downregulated MHC-I pathway. This study defines CRACD, an actin regulator, as a tumor suppressor that limits cell plasticity and immune evasion and proposes EZH2 blockade as a viable therapeutic.

Fragmented antibodies in non-small cell lung cancer: A novel nano-engineered delivery system for detection and treatment of cancer

Non-small cell lung cancer (NSCLC) has a long history of defying traditional cytotoxic treatment. Significant advancements in biotechnology, cancer biology, and immunotherapy have provided new insights that have altered the landscape for the management of NSCLC, clearing the way for a new era of pharmaceuticals in the form of monoclonal antibodies and their fragments. Antibody fragments are superior to monoclonal antibodies because of their small size, which allows them to penetrate cells and tissues effectively. When combined with functional nanocarriers, antibody fragments can target cancer cells while offering improved efficacy and fewer off-target effects. We discuss current topics of interest including anti-CTLA-4 mAbs, Talactoferrin alfa (TLF), and the CYFRA 21-1 biomarker, with brief insights into its novel detection system.

Intratumoral Abundance of M2-Macrophages is Associated With Unfavorable Prognosis and Markers of T-Cell Exhaustion in Small Cell Lung Cancer Patients

Small cell lung cancer (SCLC) accounts for about 10% to 15% of lung cancer cases. Unlike non-SCLC, therapy options for SCLC are limited, reflected by a 5-year survival rate of about 7%. At the same time, the rise of immunotherapeutic approaches in cancer therapy has rationalized to account for inflammatory phenotypes in tumors. However, the composition of the inflammatory microenvironment in human SCLC is poorly understood to date. In our study, we used in-depth image analysis of virtual whole-slide-images of 45 SCLC tumors and evaluated different markers of M2-macrophages (CD163 and CD204) together with global immunologic markers (CD4, CD8, CD68, CD38, FOXP3, and CD20) and characterized their abundance intratumorally using quantitative image analysis, combined with a deep-learning model for tumor segmentation. In addition, independent scoring, blinded to the results of the computational analysis, was performed by an expert pathologist (A.Q.) of both CD163/CD204 and PD-L1. To this end, we evaluated the prognostic relevance of the abundance of these cell types to overall survival. Given a 2-tier threshold of the median of the M2 marker CD163 within the study population, there was a 12-month overall survival rate of 22% (95% CI, 10%-47%) for patients with high CD163 abundance and 41% (95% CI, 25%-68%) for patients with low CD163 counts. Patients with increased CD163 had a median overall survival of 3 months compared to 8.34 months for patients with decreased CD163 counts (P = .039), which could be confirmed by an expert pathologist (A.Q., P = .018). By analyzing cases with increased CD163 cell infiltrates, a trend for higher FOXP3 counts and PD-L1 positive cells, together with increased CD8 T-cell infiltrates, was observed, which could be confirmed using an independent cohort at the transcriptional level. Together, we showed that markers of M2 were associated with unfavorable outcome in our study cohort.

Drug resistance mechanism and reversal strategy in lung cancer immunotherapy

Among all malignant tumors, lung cancer has the highest mortality and morbidity rates. The non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) are the most common histological subtypes. Although there are a number of internationally recognized lung cancer therapy regimens, their therapeutic effects remain inadequate. The outlook for individuals with lung carcinoma has ameliorated partly thanks to the intensive study of the tumor microenvironment and immune checkpoint inhibitors. Numerous cancers have been effectively treated with immunotherapy, which has had positive therapeutic results. Global clinical trials have validated that PD-1/PD-L1 inhibitors are effective and safe for treating lung cancer either independently or in combination, and they are gradually being recommended as systemic treatment medications by numerous guidelines. However, the immunotherapy resistance restricts the immunotherapy efficacy due to the formation of tumor immunosuppressive microenvironment and tumor mutations, and immunotherapy is only effective for a small percentage of lung cancer patients. To summarize, while tumor immunotherapy is benefiting an increasing number of lung cancer patients, most of them still develop natural or acquired resistance during immunotherapy. Consequently, a crucial and urgent topic is understanding and tackling drug resistance triggered by immunotherapy in lung cancer treatment. This review will outline the presently recognized mechanisms of immunotherapy resistance and reversal strategies in lung cancer.

Small cell lung cancer patients treated with immune checkpoint inhibitor: a systematic literature review of treatment efficacy, safety and quality of life

BACKGROUND

This systematic literature review examines the current immune checkpoint inhibitors treatment paradigms, treatment gaps and unmet needs for treating SCLC with respect to efficacy, safety, health related quality of life (HRQoL) and cost-effectiveness.

METHODS

A search strategy was developed and executed using the National Library of Medicine bibliographic database (PubMed), Cochrane Library, Embase and Google Scholar. Data regarding efficacy, safety, cost-effectiveness and HRQoL were extracted and entered in a data extraction sheet created a priori.

RESULTS

A total of 4961 patients were comprised in all the 12 studies combined. All the studies focus on extensive stage SCLC (ES-SCLC) and not limited stage SCLC (LS-SCLC). All studies used an ICI as the intervention arm and chemotherapy as the control arm. A statistically significant increase in overall survival (OS) and progression free survival (PFS) was observed when ICIs were added to chemotherapy, especially atezolizumab and durvalumab. ICIs in SCLC resulted in immune-related toxicities that have been well-documented in prior immunotherapy trials; their addition to cytotoxic chemotherapy did not worsen chemotherapy-related toxicities. Out of 12 studies, only 3 (25%) included measures to assess the impact of immunotherapy on SCLC patients' HRQoL. Although domain level scores were limited, the addition of ICIs did not seem to worsen symptoms. Two studies conducted a cost-effectiveness analysis of the combination of atezolizumab plus chemotherapy vs. chemotherapy. The addition of atezolizumab to chemotherapy was not found to be cost-effective in either study.

CONCLUSION

Combining ICIs with chemotherapy enhanced OS and PFS as well as not worsening HRQoL. Among all ICIs, PD-L1 inhibitors showed better effectiveness. Future studies should focus on real-world settings and more clinical trials using ICIs for not only ES-SCLC but also LS-SCLC.

Cost-Effectiveness Analysis of Atezolizumab Versus Durvalumab as First-Line Treatment of Extensive-Stage Small-Cell Lung Cancer in the USA

BACKGROUND AND OBJECTIVES

Durvalumab and atezolizumab are approved as first-line therapy in extensive-stage small-cell lung cancer. Although cost-effectiveness analyses compared these immunotherapy drugs with standard chemotherapy-alone regimens, no head-to-head cost-effectiveness comparisons for these treatments exist. The aim of the present analysis is to determine the cost-effectiveness of durvalumab and atezolizumab as first-line therapy for extensive-stage small-cell lung cancer from the US payers' perspective.

METHODS

This study is based on two placebo-controlled, phase 3 clinical trials: CASPIAN and IMpower133. A Markov model was developed to simulate the three health states: progression-free survival, progressed disease, and death in patients with extensive-stage small-cell lung cancer. Transition probabilities were estimated from the clinical trial survival curves and extended with life-time modelling. Health utilities and direct costs of adverse event treatment were included. Main outcome was the incremental cost-effectiveness ratio (ICER) using quality-adjusted life-years saved (QALYS). Sensitivity analysis was performed to assess the impact of variables on the ICER.

RESULTS

Durvalumab group has a cost of $187,503 with an effectiveness of 1.08 while atezolizumab has a cost of $160,219 and an effectiveness of 0.932. Durvalumab is not cost-effective compared to atezolizumab with an ICER of $165,182 QALYS, which is over the willingness-to-pay threshold of $150,000. The model was most sensitive to durvalumab cost and the cost of treating durvalumab adverse effects.

CONCLUSIONS

With the ICER of durvalumab treatment group being very close to $150,000, setting a higher willingness-to-pay threshold or decreasing the drug cost through contract pricing can increase the cost-effectiveness of durvalumab compared to atezolizumab.

Effects of Nivolumab and Ipilimumab on the suppression of cisplatin resistant small cell lung cancer cells

BACKGROUND

Small cell lung cancer (SCLC) accounts for nearly 10-15% of all lung cancer cases. Although many chemotherapy drugs, such as cisplatin and etoposide, were approved as primary therapy for SCLC patients, the prognosis is poor. In this study, we aimed to explore novel therapeutic strategy against SCLC.

METHODS

Two SCLC cell lines, LTEP-P and LTEP-P/DDP1.0, were treated with cisplatin, in the absence or presence of Nivolumab + Ipilimumab combination, and the cell viability was measured. Tumor size and mouse survival rate were examined upon different drug treatments. Protein levels of PD-1 and CTLA4 were detected in normal and SCLC cells by Western blot. Cellular cytotoxicity induced by T lymphocytes was measured by thymidine incorporation assay. Tumor infiltrated T cell populations from LTEP-P and LTEP/DDP1.0 tumor-bearing mice were analyzed by flow cytometry.

RESULTS

LTEP-P cells, but not LTEP/DDP1.0 cells, exhibited decreased cell viability upon cisplatin, Nivolumab and Ipilimumab combinational treatment. T lymphocytes significantly inhibited the growth of LTEP-P cells in the presence of nivolumab and ipilimumab. The combinational therapy improved survival rate and inhibited tumor growth in LTEP-P tumor-bearing mice, but showed no effect on LTEP/DDP1.0 tumor-bearing mice. Nivolumab and Ipilimumab synergized with cisplatin in increasing CD8 + and CD4 + T cell population, while decreasing Treg population in LTEP-P tumor-bearing mice.

CONCLUSIONS

The combinational therapy by cisplatin, Nivolumab and Ipilimumab could be an effective strategy against LTEP-P cells, accompanied with increased cytotoxic T cell populations, but has no significant effect against DDP-resistant lung adenocarcinoma cells.

Effect of operation introducing hyperthermic intraperitoneal chemotherapy on cellular immune function in patients with adenocarcinoma of esophagogastric junction

BACKGROUND

This study aims to take a closer look at the effect of radical operation, introducing hyperthermic intraperitoneal chemotherapy, on cellular immunity for patients suffering from AEG.

METHODS

252 cases of patients with advanced AEG were randomly divided into two distinct groups, namely, a HIPEC group and a surgery only group. T lymphocyte subsets, CD4 + CD25 + T cells, which are known as the regulatory T cells, and the programmed cell death protein 1 (PD-1) contained in T cells were detected by PREO and POD 9.

RESULTS

The two groups differed drastically in terms of the proportion of T lymphocyte subsets and CD4 + CD25 + , CD4 + PD-1 + , CD8 + PD-1 + T cells, based on the observation on POD 9. The percentage of CD3 + , CD3 + CD4 + T cells identified in the HIPEC group outnumbered the percentage in the surgery only group (P < 0.01), whereas the quantity of CD3 + CD8 + , CD4 + CD25 + , CD4 + PD-1 + , CD8 + PD-1 + T cells in the former group was much lower than that of the latter group (P < 0.05).

CONCLUSION

HIPEC, following the operation on patients with advanced AEG, is capable of improving the cellular immune function and facilitating the release of a cellular immunosuppressive state.

The Impact of NK Cell-Based Therapeutics for the Treatment of Lung Cancer for Biologics: Targets and Therapy

Lung cancer has a dismal prognosis and novel targeted therapies leave still room for major improvements and better outcomes. Immunotherapy targeting immune checkpoint (IC) proteins, either as single agents or in combination with chemotherapy, is active but responders constitute only approximately 10-15% of non-small cell lung cancer (NSCLC) patients. Other effector immune cells such as CAR-T cells or NK cells may help to overcome the limitations of the IC inhibitor therapies for lung cancer. NK cells can kill tumor cells without previous priming and are present in the circulatory system and lymphoid organs. Tissue-residing NK cells differ from peripheral effector cells and, in case of the lung, comprise CD56bright CD16-negative populations showing high cytokine release but low cytotoxicity in contrast to the circulating CD56dim CD16-positive NK cells exhibiting high cytotoxic efficacy. This local attenuation of NK cell killing potency seems due to a specific stage of NK differentiation, immunosuppressive factors as well as presence of myeloid-derived suppressor cells (MDSCs) and regulatory T cells (TREGs). Improved NK cell-based immunotherapies involve IL-2-stimulated effector cells, NK cells expanded with the help of cytokines, permanent NK cell lines, induced pluripotent stem cell-derived NK cells and NK cells armed with chimeric antigen receptors. Compared to CAR T cell therapy, NK cells administration is devoid of graft-versus-host disease (GvHD) and cytokine-release syndrome. Although NK cells are clearly active against lung cancer cells, the low-cytotoxicity differentiation state in lung tumors, the presence of immunosuppressive leucocyte populations, limited infiltration and adverse conditions of the microenvironment need to be overcome. This goal may be achieved in the future using large numbers of activated and armed NK cells as provided by novel methods in NK cell isolation, expansion and stimulation of cytotoxic activity, including combinations with monoclonal antibodies in antibody-dependent cytotoxicity (ADCC). This review discusses the basic characteristics of NK cells and the potential of NK cell preparations in cancer therapy.

Development of a mechanism of action-reflective, dual target cell-based reporter bioassay for a bispecific monoclonal antibody targeting human CTLA-4 and PD-1

T-cell-mediated immunotherapy has generated much excitement after the success of therapeutic biologics targeting immune checkpoint molecules. Bispecific antibodies (BsAbs) that recognize two antigen targets are a fast-growing class of biologics offering promising clinical benefits for cancer immunotherapy. Due to the complexity of the molecule structure and the potential mechanism of action (MOA) that involves more than one signaling pathway, it is critical to develop appropriate bioassays for measuring potency and characterizing the biological properties of BsAbs. Here, we present a dual target, cell-based reporter bioassay for a BsAb that binds human CTLA-4 and PD-1 and targets two subsequent signaling pathways that negatively regulate T-cell activation. This reporter bioassay is capable of measuring the potency of both antigen target arms in one assay, which would not be achievable using two single target bioassays. This dual target reporter bioassay demonstrates good performance characteristics suitable for lot release, stability testing, critical quality attribute assessment, and biological properties characterization of the CTLA-4/PD-1 BsAb. Furthermore, this assay can capture the synergistic effect of anti-CTLA-4 and anti-PD-1 activity of the BsAb. Compared to single target assays, this dual target bioassay could better reflect the potential MOA of BsAbs and could be used for evaluation of other bispecific biologics, as well as antibody combination therapies.

Evasion of Innate Immunity Contributes to Small Cell Lung Cancer Progression and Metastasis

Small cell lung cancer (SCLC) is a pulmonary neuroendocrine cancer with very poor prognosis and limited effective therapeutic options. Most patients are diagnosed at advanced stages, and the exact reason for the aggressive and metastatic phenotype of SCLC is completely unknown. Despite a high tumor mutational burden, responses to immune checkpoint blockade are minimal in patients with SCLC. This may reflect defects in immune surveillance. Here we illustrate that evading natural killer (NK) surveillance contributes to SCLC aggressiveness and metastasis, primarily through loss of NK-cell recognition of these tumors by reduction of NK-activating ligands (NKG2DL). SCLC primary tumors expressed very low level of NKG2DL mRNA and SCLC lines express little to no surface NKG2DL at the protein level. Chromatin immunoprecipitation sequencing showed NKG2DL loci in SCLC are inaccessible compared with NSCLC, with few H3K27Ac signals. Restoring NKG2DL in preclinical models suppressed tumor growth and metastasis in an NK cell-dependent manner. Likewise, histone deacetylase inhibitor treatment induced NKG2DL expression and led to tumor suppression by inducing infiltration and activation of NK and T cells. Among all the common tumor types, SCLC and neuroblastoma were the lowest NKG2DL-expressing tumors, highlighting a lineage dependency of this phenotype. In conclusion, these data show that epigenetic silencing of NKG2DL results in a lack of stimulatory signals to engage and activate NK cells, highlighting the underlying immune avoidance of SCLC and neuroblastoma. SIGNIFICANCE: This study discovers in SCLC and neuroblastoma impairment of an inherent mechanism of recognition of tumor cells by innate immunity and proposes that this mechanism can be reactivated to promote immune surveillance.

Impact of immune checkpoint gene CD155 Ala67Thr and CD226 Gly307Ser polymorphisms on small cell lung cancer clinical outcome

This study was conducted to investigate the impact of genetic variants of immune checkpoint genes on the treatment outcome in small cell lung cancer (SCLC). In the present study, 261 platinum doublet-treated SCLC patients were enrolled. A total of 96 polymorphisms in 33 immune checkpoint-related genes were selected, and their association with chemotherapy response and survival outcomes were analyzed. Among the polymorphisms studied, CD155 rs1058402G > A (Ala67Thr, A67T) and CD226 rs763361C > T (Gly307Ser, G307S) were significantly associated with SCLC treatment outcome. The rs1058402G > A had a worse chemotherapy response and overall survival (under a dominant model, adjusted odds ratio [aOR] = 0.52, 95% confidence interval [CI] = 0.27–0.99, P = 0.05; adjusted hazard ratio [aHR] = 1.55, 95% CI = 1.12–2.14, P = 0.01, respectively). The rs763361C > T had better chemotherapy response and overall survival (under a dominant model, aOR = 2.03, 95% CI = 1.10–3.75, P = 0.02; aHR = 0.69, 95% CI = 0.51–0.94, P = 0.02, respectively). When the rs1058402GA/AA and rs763361CC genotypes were combined, the chemotherapy response and overall survival were significantly decreased as the number of bad genotypes increased (aOR = 0.52, 95% CI = 0.33–0.81, Ptrend = 0.004; aHR = 1.48, 95% CI = 1.19–1.84, Ptrend = 4 × 10⁻⁴, respectively). The 3-D structural model showed that CD155 A67T created a new hydrogen bond and structural change on CD155. These changes resulted in extending the distance and losing the hydrogen bonds between CD155 and CD226, thus weakening CD155/CD226 binding activity. In conclusion, CD155 rs1058402G > A and CD226 rs763361C > T may be useful for predicting the clinical outcomes of SCLC patients after chemotherapy.

Lipid Metabolism and Immune Checkpoints

Immune checkpoints are essential for the regulation of immune cell functions. Although the abrogation of immunosurveillance of tumor cells is known, the regulators of immune checkpoints are not clear. Lipid metabolism is one of the important metabolic activities in organisms. In lipid metabolism, a large number of metabolites produced can regulate the gene expression and activation of immune checkpoints through various pathways. In addition, increasing evidence has shown that lipid metabolism leads to transient generation or accumulation of toxic lipids that result in endoplasmic reticulum (ER) stress and then regulate the transcriptional and posttranscriptional modifications of immune checkpoints, including transcription, protein folding, phosphorylation, palmitoylation, etc. More importantly, the lipid metabolism can also affect exosome transportation of checkpoints and the degradation of checkpoints by affecting ubiquitination and lysosomal trafficking. In this chapter, we mainly empathize on the roles of lipid metabolism in the regulation of immune checkpoints, such as gene expression, activation, and degradation.

Are Markers of Systemic Inflammatory Response Useful in the Management of Patients With Neuroendocrine Neoplasms?

Given the increasing incidence of neuroendocrine neoplasms (NENs) over the past few decades, a more comprehensive knowledge of their pathophysiological bases and the identification of innovative NEN biomarkers represents an urgent unmet need. There is still little advance in the early diagnosis and management of these tumors, due to the lack of sensible and specific markers with prognostic value and ability to early detect the response to treatment. Chronic systemic inflammation is a predisposing factor for multiple cancer hallmarks, as cancer proliferation, progression and immune-evading. Therefore, the relevance of inflammatory biomarkers has been identified as critical in several types of tumours, including NENs. A bidirectional relationship between chronic inflammation and development of NENs has been reported. Neuroendocrine cells can be over-stimulated by chronic inflammation, leading to hyperplasia and neoplastic transformation. As the modulation of inflammatory response represents a therapeutic target, inflammatory markers could represent a promising new key tool to be applied in the diagnosis, the prediction of response to treatment and also as prognostic biomarkers in NENs field. The present review provides an overview of the pre-clinical and clinical data relating the potentially usefulness of circulating inflammatory markers: neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR), cytokines and tissue inflammatory markers (PD-1/PD-L1), in the management of NENs. (1) NLR and PLR have both demonstrated to be promising and simple to acquire biomarkers in patients with advanced cancer, including NEN. To date, in the context of NENs, the prognostic role of NLR and PLR has been confirmed in 15 and 4 studies, respectively. However, the threshold value, both for NLR and PLR, still remains not defined. (2) Cytokines seem to play a central role in NENs tumorigenesis. In particular, IL-8 levels seems to be a good predictive marker of response to anti-angiogenic treatments. (3) PD-1 and PD-L1 expression on tumour cells and on TILs, have demonstrated to be promising predictive and prognostic biomarkers in NENs. Unfortunately, these two markers have not been validated so far and further studies are needed to establish their indications and utility.

Immune Modulation in Lung Cancer: Current Concepts and Future Strategies

Cancer immunotherapy represents the most dynamic field of biomedical research currently, with thoracic immuno-oncology as a forerunner. PD-(L)1 inhibitors are already part of standard first-line treatment for both non-small-cell and small-cell lung cancer, while unprecedented 5-year survival rates of 15-25% have been achieved in pretreated patients with metastatic disease. Evolving strategies are mainly aiming for improvement of T-cell function, increase of immune activation in the tumor microenvironment (TME), and supply of tumor-reactive lymphocytes. Several novel therapeutics have demonstrated preclinical efficacy and are increasingly used in rational combinations within clinical trials. Two overarching trends dominate: extension of immunotherapy to earlier disease stages, mainly as neoadjuvant treatment, and a shift of focus towards multivalent, individualized, mutatome-based antigen-specific modalities, mainly adoptive cell therapies and cancer vaccines. The former ensures ample availability of treated and untreated patient samples, the latter facilitates deeper mechanistic insights, and both in combination build an overwhelming force that is accelerating progress and driving the greatest revolution cancer medicine has seen so far. Today, immune modulation represents the most potent therapeutic modality in oncology, the most important topic in clinical and translational cancer research, and arguably our greatest, meanwhile justified hope for achieving cure of pulmonary neoplasms and other malignancies in the next future.

A randomised phase 2b study comparing the efficacy and safety of belotecan vs. topotecan as monotherapy for sensitive-relapsed small-cell lung cancer

Background

This study compared the efficacy/safety of the camptothecin analogues belotecan and topotecan for sensitive-relapsed small-cell lung cancer (SCLC).

Methods

One-hundred-and-sixty-four patients were randomised (1:1) to receive five consecutive daily intravenous infusions of topotecan (1.5 mg/m²) or belotecan (0.5 mg/m²), every 3 weeks, for six cycles. Main outcomes were objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS), tolerability and toxicity. The study statistical plan was non-inferiority design with ORR as the endpoint.

Results

In the belotecan vs. topotecan groups, ORR (primary endpoint) was 33% vs. 21% (p = 0.09) and DCR was 85% vs. 70% (p = 0.030). PFS was not different between groups. Median OS was significantly longer with belotecan than with topotecan (13.2 vs. 8.2 months, HR = 0.69, 95% CI: 0.48–0.99), particularly in patients aged <65 years, with more advanced disease (i.e., extensive-stage disease, time to relapse: 3–6 months), or Eastern Cooperative Oncology Group performance status 1 or 2. More belotecan recipients completed all treatment cycles (53% vs. 35%; p = 0.022).

Conclusions

The efficacy/safety of belotecan warrants further evaluation in Phase 3 trials. Belotecan potentially offers an alternative to topotecan for sensitive-relapsed SCLC, particularly in patients aged <65 years, with more advanced disease, or poor performance.

Ex Vivo Expansion and Drug Sensitivity Profiling of Circulating Tumor Cells from Patients with Small Cell Lung Cancer

Simple Summary

Small cell lung cancer (SCLC) is an overly aggressive cancer characterized by rapid growth, early metastatic spread, and consequently reducing overall survival. As cancer manifestations can differ uniquely between various types, the rapid proliferation of circulating tumor cells (CTC) originating from SCLC was an adequate sample resource to aid the headway in our drug screening technique. With biomarker detection of liquid biopsy as an emerging tool to assist decision-making in personalized cancer pharmacotherapy. In this study, we developed a rapid and reproducible system for preclinical drug testing via the use of a unique CTCs expansion protocol. The expanded CTCs from SCLC formed multiple types of tumorsphere structures and expressed SCLC-specific tumor markers. The drug sensitivity assessment gathered from in vitro expansion of CTCs was able to generate positive clinical therapeutic outcomes. Thus, SCLC patient-derived CTC spheroids are a useful resource for biomarker development and drug sensitivity assessment providing “real-world” therapeutic response circumstances.

Abstract

Small cell lung cancer (SCLC) represents one of the most aggressive malignancies among cancer types. Not only tumor sample availability is limited, but also the ability for tumor cells to rapidly acquire drug resistance are the rate-limiting bottlenecks for overall survival in current clinical settings. A liquid biopsy capable of capturing and enriching circulating tumor cells (CTCs), together with the possibility of drug screening, is a promising solution. Here, we illustrate the development of a highly efficient ex vivo CTC expansion system based on binary colloidal crystals substrate. Clinical samples were enrolled from 22 patients with SCLC in the study. The CTCs were enriched and expanded from the collected peripheral blood samples. Expanded cells were analyzed for protein expression and observed for drug sensitivity with the use of immunofluorescence and ATP titer evaluation, respectively. Successful CTC spheroid proliferation was established after 4 weeks within 82% of all the collected peripheral blood samples from enrolled patients. Upon immunofluorescence analysis, the enriched cells showed positive markers for EpCAM, TTF-1, synaptophysin and negative for CD45. Additionally, the expanded CTCs demonstrated marked heterogeneity in the expression of E-cadherin and N-cadherin. In a preliminary case series, the drug sensitivity of patient-derived CTC to cisplatin and etoposide was studied to see the correlation with the corresponding therapeutic outcome. In conclusion, our study demonstrates that it is possible to efficiently expand CTCs from SCLC within a clinically relevant time frame; the biomarker information generated from enriched CTCs can assist the selection of effective drugs and improve disease outcome.

American Radium Society Appropriate Use Criteria: Radiation Therapy for Limited-Stage SCLC 2020

INTRODUCTION

Combined modality therapy with concurrent chemotherapy and radiation has long been the standard of care for limited-stage SCLC (LS-SCLC). However, there is controversy over best combined modality practices for LS-SCLC. To address these controversies, the American Radium Society (ARS) Thoracic Appropriate Use Criteria (AUC) Committee have developed updated consensus guidelines for the treatment of LS-SCLC.

METHODS

The ARS AUC are evidence-based guidelines for specific clinical conditions that are reviewed by a multidisciplinary expert panel. The guidelines include a review and analysis of current evidence with application of consensus methodology (modified Delphi) to rate the appropriateness of treatments recommended by the panel for LS-SCLC. Agreement or consensus was defined as less than or equal to 3 rating points from the panel median. The consensus ratings and recommendations were then vetted by the ARS Executive Committee and subject to public comment before finalization.

RESULTS

The ARS Thoracic AUC committee developed multiple consensus recommendations for LS-SCLC. There was strong consensus that patients with unresectable LS-SCLC should receive concurrent chemotherapy with radiation delivered either once or twice daily. For medically inoperable T1-T2N0 LS-SCLC, either concurrent chemoradiation or stereotactic body radiation followed by adjuvant chemotherapy is a reasonable treatment option. The panel continues to recommend whole-brain prophylactic cranial irradiation after response to chemoradiation for LS-SCLC. There was panel agreement that prophylactic cranial irradiation with hippocampal avoidance and programmed cell death protein-1/programmed death-ligand 1-directed immune therapy should not be routinely administered outside the context of clinical trials at this time.

CONCLUSIONS

The ARS Thoracic AUC Committee provide consensus recommendations for LS-SCLC that aim to provide a groundwork for multidisciplinary care and clinical trials.

PD-L1 Predicts Poor Prognosis in Surgically Resected Limited Stage Small-Cell Lung Cancer

Purpose

Small-cell lung cancer (SCLC) is an aggressive high-grade neuroendocrine tumor with limited treatment strategies. Programmed death 1 (PD-1) and its ligand (PD-L1), delta-like ligand-3 (DLL-3), and poly ADP-ribose polymerase (PARP) inhibitors have shed light on the treatment of extensive stage-SCLC. However, the expression and prognostic role of PD-L1, DLL-3, and PARP are barely explored in surgically resected limited stage-SCLC (LS-SCLC).

Methods

We retrospectively reviewed 404 SCLC patients from 2011 to 2018 in the First Affiliated Hospital of Xi’an Jiaotong University and collected 43 surgically resected LS-SCLC samples with adequate materials and histological specimens containing abundant tumor cells. Immunohistochemistry staining of PD-L1, DLL-3, and PAPR1 was performed by anti-PD-L1 (22C3/Dako), anti-DLL-3, and anti-PAPR1 antibodies, respectively. Positive expression of PD-L1 was characterized as >5% tumor cells and/or tumor-infiltrating immune cells expressing PD-L1. The correlation between PD-L1, DLL-3, PARP1, and clinicopathological characteristics of surgically resected LS-SCLC patients was performed by χ² test. The survival curves were calculated by the Kaplan–Meier method and analyzed by the Log rank test and Cox proportional hazards model.

Results and Conclusion

63.04% patients were positive for PD-L1, 65.12% were positive for DLL-3, and 20.93% were positive for PARP1. DLL-3 was significantly overexpressed in SCLC tissues, compared with matched para-noncancerous tissues. Male, elder than 60 years old, advanced TNM stage, smoking, and positive PD-L1 expression predicted shorter DFS, while patients received adjuvant therapy performed better DFS. Further multivariate analysis revealed that TNM stage (HR=2.51, 95% CI=1.31–4.78, P=0.005) was an individual prognostic factor for DFS in LS-SCLC. Moreover, advanced TNM stage and positive PD-L1 expression also indicated worse OS, but adjuvant therapy improved OS in LS-SCLC. Multivariate analysis demonstrated that PD-L1 and TNM stage were independent and significant negative predictive factors for OS (HR=2.89, 95% CI=1.21–6.93, P=0.017; HR=2.49, 95% CI=1.25–4.94, P=0.009 for PD-L1 and TNM stage, respectively), while adjuvant treatment was an independent positive prognostic factor for OS (HR=0.37, 95% CI=0.17–0.81, P=0.012).

Opportunities and obstacles of targeted therapy and immunotherapy in small cell lung cancer

Small cell lung cancer (SCLC) is an aggressive malignant tumour which accounts for approximately 13-15% of all newly diagnosed lung cancer cases. To date, platinum-based chemotherapy are still the first-line treatments for SCLC. However, chemotherapy resistance and systemic toxicity limit the long-term clinical outcome of first-line treatment in SCLC. Recent years, targeted therapy and immunotherapy have made great breakthrough in cancer therapy, and researchers aim to exploit both as a single agent or in combination with chemotherapy to improve the survival of SCLC patients, but limited effectiveness and the adverse events remain the major obstacles in the treatment of SCLC. To overcome these challenges for SCLC therapies, prevention and early diagnosis for this refractory disease is very important. At the same time, we should reveal more information about the pathogenesis of SCLC and the mechanism of drug resistance. Finally, new treatment strategies should also be taken into considerations, such as repurposing drug, optimising of targets, combination therapy strategies or prognostic biomarkers to enhance therapeutic effects and decrease the adverse events rates in SCLC patients. This article will review the molecular biology characteristics of SCLC and discuss the opportunities and obstacles of the current therapy for SCLC patients.

The Landscape of Tumor-Specific Antigens in Colorectal Cancer

Over the last few decades, major efforts in cancer research and treatment have intensified. Apart from standard chemotherapy approaches, immunotherapy has gained substantial traction. Personalized immunotherapy has become an important tool for cancer therapy with the discovery of immune checkpoint inhibitors. Traditionally, tumor-associated antigens are used in immunotherapy-based treatments. Nevertheless, these antigens lack specificity and may have increased toxicity. With the advent of next-generation technologies, the identification of new tumor-specific antigens is becoming more important. In colorectal cancer, several tumor-specific antigens were identified and functionally validated. Multiple clinical trials from vaccine-based and adoptive cell therapy utilizing tumor-specific antigens have commenced. Herein, we will summarize the current landscape of tumor-specific antigens particularly in colorectal cancer.

Combination of Ipilimumab and Nivolumab in Cancers: From Clinical Practice to Ongoing Clinical Trials

Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein 1 (PD-1) are inhibitory checkpoints that are commonly seen on activated T cells and have been offered as promising targets for the treatment of cancers. Immune checkpoint inhibitors (ICIs)targeting PD-1, including pembrolizumab and nivolumab, and those targeting its ligand PD-L1, including avelumab, atezolizumab, and durvalumab, and two drugs targeting CTLA-4, including ipilimumab and tremelimumab have been approved for the treatment of several cancers and many others are under investigating in advanced trial phases. ICIs increased antitumor T cells’ responses and showed a key role in reducing the acquired immune system tolerance which is overexpressed by cancer and tumor microenvironment. However, 50% of patients could not benefit from ICIs monotherapy. To overcome this, a combination of ipilimumab and nivolumab is frequently investigated as an approach to improve oncological outcomes. Despite promising results for the combination of ipilimumab and nivolumab, safety concerns slowed down the development of such strategies. Herein, we review data concerning the clinical activity and the adverse events of ipilimumab and nivolumab combination therapy, assessing ongoing clinical trials to identify clinical outlines that may support combination therapy as an effective treatment. To the best of our knowledge, this paper is one of the first studies to evaluate the efficacy and safety of ipilimumab and nivolumab combination therapy in several cancers.

New insights into small-cell lung cancer development and therapy

Small‐cell lung cancer (SCLC) accounts for approximately 15% of lung cancer cases; however, it is characterized by easy relapse and low survival rate, leading to one of the most intractable diseases in clinical practice. Despite decades of basic and clinical research, little progress has been made in the management of SCLC. The current standard first‐line regimens of SCLC still remain to be cisplatin or carboplatin combined with etoposide, and the adverse events of chemotherapy are by no means negligible. Besides, the immunotherapy on SCLC is still in an early stage and novel studies are urgently needed. In this review, we describe SCLC development and current therapy, aiming at providing useful advices on basic research and clinical strategy.

Small cell lung cancer: Recent changes in clinical presentation and prognosis

BACKGROUND

Small cell lung cancer (SCLC) is a leading cause of death all over the world. Diagnostic and therapeutic arsenals have improved in recent years, but we are unsure as to whether these advances have been transferred to clinical practice. The aim of this study was to evaluate differences in SCLC diagnostic processes and short-term survival rates between two recent cohorts.

METHODS

A prospective, observational study was conducted with patients diagnosed with SCLC (either at extensive or limited stages) in the 2011-2016 period. Patients were divided into two cohorts (2011-2013 and 2014-2016) and followed up for 1 year after diagnosis.

RESULTS

Around 713 patients with lung cancer were selected, 134 of whom had SCLC (74 patients in the 2011-2013 cohort and 60 in the 2014-2016 cohort). We observed a chronological increase in the use of endobronchial ultrasound transbronchial needle aspiration (EBUS-TBNA) and positron emission tomography-computed tomography (PET-CT) between the cohorts. Overall, short-term survival was similar between the two groups and improved survival was associated with age and limited stage.

CONCLUSIONS

Changes in diagnostic process in SCLC have been observed towards a more precise stadification. Although short-term survival has not changed for SCLC, it is unclear that the real benefit of PET-CT and EBUS-TBNA is far from correct disease staging.

SATB2 in neuroendocrine neoplasms: strong expression is restricted to well-differentiated tumours of lower gastrointestinal tract origin and is most frequent in Merkel cell carcinoma among poorly differentiated carcinomas

AIMS

Special AT-rich sequence-binding protein 2 (SATB2) is a transcriptional regulator with critical roles in brain, craniofacial and skeletal development. It has emerged as a key marker of lower gastrointestinal (GI) tract columnar epithelial and osteoblastic differentiation. Transcription factor immunohistochemistry is useful in assigning site of origin in well-differentiated neuroendocrine tumours (NETs), and has had a limited role in poorly differentiated neuroendocrine carcinomas (NECs). This study sought to evaluate the role of SATB2 in assigning site of origin in neuroendocrine epithelial neoplasms.

METHODS AND RESULTS

Tissue microarrays were constructed from the following: 317 NETs (37 thyroid, 46 lung, 16 stomach, 12 duodenum, 70 pancreas, 106 jejunoileum, 24 appendix, and six rectosigmoid), 44 phaeochromocytomas/paragangliomas, and 79 NECs (29 Merkel cell, 30 lung, and 20 extrapulmonary visceral); nine appendiceal and 19 rectal NETs were examined in whole sections. SATB2 immunohistochemistry was scored for extent (%) and intensity (0-3+), with an H-score being calculated. SATB2 was expressed by 96% of rectosigmoid NETs, 79% of appendiceal NETs, and only 7% of other well-differentiated neoplasms (P < 0.0001). Expression in lower GI tract NETs (median H-score of 255) was stronger than in other positive tumours (median H-score of 7) (P < 0.0001). Any SATB2 expression was 86% sensitive/93% specific for lower GI tract origin. SATB2 was expressed by 79% of Merkel cell carcinomas (median H-score of 300), 33% of lung NECs (median H-score of 23), and 60% of extrapulmonary visceral NECs (median H-score of 110), with stronger expression in Merkel cell carcinoma (P < 0.001). At an H-score cutoff of ≥150, SATB2 was 69% sensitive/90% specific for Merkel cell carcinoma.

CONCLUSIONS

SATB2 is frequently and strongly expressed by lower GI tract NETs; we have adopted it as our rectal NET marker. Relatively frequent and strong expression in Merkel cell carcinoma may have value in assigning NEC site of origin.

Effect of Radical Surgery for Advanced Adenocarcinoma of Esophagogastric Junction on Perioperative Cellular Cell Immunity

Background: To investigate the perioperative peripheral blood levels of CD4⁺CD25⁺ regulatory T cells, programed cell death 1 (PD-1), and lymphocyte activation gene 3 (LAG-3) in patients with advanced Siewert type II adenocarcinoma of esophagogastric junction (AEG). Methods: Patients (n = 102) with advanced Siewert type II AEG underwent open total gastrectomy/proximal gastrectomy with a transhiatal resection of the distal esophagus and lymphadenectomy of the lower mediastinum and the abdominal D2 compartment. Flow cytometry was used to detect CD4⁺CD25⁺ T cells, PD-1 and LAG-3 expression on both CD4⁺ and CD8⁺ T cells in the peripheral blood of the Siewert type II AEG patients prior to surgery and on postoperative day (POD) 1, 3, 7, and 9. Results: The proportion of CD4⁺CD25⁺ T cells rapidly decreased on POD 1, then gradually increased and peaked at POD 7. The proportion of CD4⁺PD-1⁺ T cells significantly increased after surgery, reaching a maximum on POD 1, and remained significantly elevated on POD 3 compared to the preoperative day. The proportion of CD8⁺ PD-1⁺ and CD4⁺LAG-3⁺ T cells gradually increased after surgery and reached a peak at POD 7. The change in proportion of CD8⁺LAG-3⁺ T cells in the peripheral venous blood lymphocytes after surgery was not statistically significant. Conclusion: The change in the CD4⁺PD-1⁺ T lymphocyte ratio may likely reflect the cellular immunity status of the perioperative period.

Tumor-Infiltrating Leukocyte Composition and Prognostic Power in Hepatitis B- and Hepatitis C-Related Hepatocellular Carcinomas

Background: Tumor-infiltrating leukocytes (TILs) are immune cells surrounding tumor cells, and several studies have shown that TILs are potential survival predictors in different cancers. However, few studies have dissected the differences between hepatitis B- and hepatitis C-related hepatocellular carcinoma (HBV−HCC and HCV−HCC). Therefore, we aimed to determine whether the abundance and composition of TILs are potential predictors for survival outcomes in HCC and which TILs are the most significant predictors. Methods: Two bioinformatics algorithms, ESTIMATE and CIBERSORT, were utilized to analyze the gene expression profiles from 6 datasets, from which the abundance of corresponding TILs was inferred. The ESTIMATE algorithm examined the overall abundance of TILs, whereas the CIBERSORT algorithm reported the relative abundance of 22 different TILs. Both HBV−HCC and HCV−HCC were analyzed. Results: The results indicated that the total abundance of TILs was higher in non-tumor tissue regardless of the HCC type. Alternatively, the specific TILs associated with overall survival (OS) and recurrence-free survival (RFS) varied between subtypes. For example, in HBV−HCC, plasma cells (hazard ratio [HR] = 1.05; 95% CI 1.00–1.10; p = 0.034) and activated dendritic cells (HR = 1.08; 95% CI 1.01–1.17; p = 0.03) were significantly associated with OS, whereas in HCV−HCC, monocytes (HR = 1.21) were significantly associated with OS. Furthermore, for RFS, CD8+ T cells (HR = 0.98) and M0 macrophages (HR = 1.02) were potential biomarkers in HBV−HCC, whereas neutrophils (HR = 1.01) were an independent predictor in HCV−HCC. Lastly, in both HBV−HCC and HCV−HCC, CD8+ T cells (HR = 0.97) and activated dendritic cells (HR = 1.09) had a significant association with OS, while γ delta T cells (HR = 1.04), monocytes (HR = 1.05), M0 macrophages (HR = 1.04), M1 macrophages (HR = 1.02), and activated dendritic cells (HR = 1.15) were highly associated with RFS. Conclusions: These findings demonstrated that TILs are potential survival predictors in HCC and different kinds of TILs are observed according to the virus type. Therefore, further investigations are warranted to elucidate the role of TILs in HCC, which may improve immunotherapy outcomes.

Immune checkpoint inhibitors in mCRPC - rationales, challenges and perspectives

The advancement of immune-therapeutics in cancer treatment has proven to be promising in various malignant diseases. However, in castration resistant prostate cancer (mCRPC) major Phase III trials have been unexpectedly disappointing. To contribute to a broader understanding of the role and use of immune-therapeutics in mCRPC, we conducted a systematic review. We searched the websites ClinicalTrials.gov, PubMed and ASCO Meeting Library for clinical trials employing immune checkpoint inhibitors in mCRPC. This article not only describes the rationale of individual trials, but it also summarizes the current status of the field and sheds light on strategies for future success.

Molecular and histopathology directed therapy for advanced bladder cancer

Bladder cancer is a heterogeneous group of tumours with at least 40 histological subgroups. Patients with localized disease can be cured with surgical resection or radiotherapy, but such curative options are limited in the setting of recurrent disease or distant spread, in which case systemic therapy is used to control disease and palliate symptoms. Cytotoxic chemotherapy has been the mainstay of treatment for advanced bladder cancer, but high-quality evidence is lacking to inform the management of rare subgroups that are often excluded from studies. Advances in molecular pathology, the development of targeted therapies and the resurgence of immunotherapy have led to the reclassification of bladder cancer subgroups and rigorous efforts to define predictive biomarkers for cancer therapies. In this Review, we present the current evidence for the management of conventional, variant and divergent urothelial cancer subtypes, as well as non-urothelial bladder cancers, and discuss how the integration of genomic, transcriptomic and proteomic characterization of bladder cancer could guide future therapies.

Immune checkpoint inhibitors for small cell lung cancer: opportunities and challenges

Lung cancer is the most common cancer and the leading cause of cancer death worldwide, with an estimated 2.1 million new cases and 1.8 million deaths in 2018. Although small cell lung cancer (SCLC) is the most aggressive type of lung cancer, it shows high response rates to chemotherapy in early lines of therapy. Unfortunately, it is associated with rapid recurrence and relatively poor prognosis. Over the last few years, considerable progress has been made in cancer immunotherapy. One of the most promising ways to activate therapeutic antitumor immunity is via blockade of immune checkpoints, such as cytotoxic T lymphocyte-associated protein-4 (CTLA-4) and programmed cell death protein-1/programmed cell death ligand-1 (PD-1/PD-L1). Immune checkpoint inhibitors show promise as SCLC therapeutics. The overall expectation for immuno-oncology is high, and the outcomes of trials will hopefully reveal a variety of treatment options for SCLC patients. In this review, we discuss the discovery of new immune inhibitory and stimulatory pathways and rational combination strategies to explain the role of immunotherapy in SCLC and its future opportunities and challenges.

Immune Cell Infiltration May Be a Key Determinant of Long-Term Survival in Small Cell Lung Cancer

INTRODUCTION

Although most patients with SCLC die within a few months of diagnosis, a subgroup of patients survive for many years. Factors determining long-term survivorship remain largely unknown. We present the first comprehensive comparative genomic and tumor microenvironment analyses of SCLC between patients with long-term survivorship and patients with the expected survivorship.

METHODS

We compared surgically resected tumors of 23 long-term SCLC survivors (survival >4 years) and 18 SCLC survivors with the expected survival time (survival ≤2 years). There were no significant differences in clinical variables, including TNM staging and curative- versus non-curative-intent surgery between the groups. Gene expression profiling was performed by using microarrays, and tumor microenvironment analyses were performed by immunohistochemistry of prominent immune-related markers.

RESULTS

Immune-related genes and pathways represented the majority of the differentially overexpressed genes in long-term survivorship compared with in expected survivorship. The differences in the immunological tumor microenvironment were confirmed by quantitative immunostaining. Increased numbers of tumor-infiltrating and associated lymphocytes were present throughout tumors of long-term survivors of SCLC. Several differentiating patterns of enhanced antitumor immunity were identified. Although some areas of the tumors of long-term survivors of SCLC also harbored higher numbers of suppressive immune cells (monocytes, regulatory lymphocytes, and macrophages), the ratios of these suppressive cells to CD3-positive lymphocytes were generally lower in the tumors of long-term survivors of SCLC, indicating a less tumor-suppressive microenvironment.

CONCLUSIONS

Our data demonstrate that long-term survivorship of patients with SCLC is strongly influenced by the presence of the immune cells in the tumor microenvironment. Characterization of the antitumor immune responses may identify opportunities for individualized immunotherapies for SCLC.

[Clinical Research Progress of Immune Checkpoint Inhibitors in the Treatment of Small Cell Lung Cancer]

With the in-depth study of tumor immunity, immunotherapy represented by immune checkpoint inhibitors has made a great breakthrough in solid tumors. Small cell lung cancer (SCLC) accounts for about 15%-20% of all lung cancers, with high malignancy, early metastasis and lack of effective treatment strategy. The appearance of immune checkpoint inhibitors brings new hope for SCLC. Several clinical trials have demonstrated the persistent efficacy and clinical activity of the programmed death receptor/ligand 1 (PD-1/L1) and cytotoxic T-lymphocyte antigen 4 (CTLA-4) in the treatment of SCLC. However, its efficacy and safety are not very accurate, and the markers that can effectively predict the efficacy of immunotherapy have not been concluded. In this paper, for further changing the treatment strategy of SCLC clinical practice and providing theoretical basis of research, we reviewed the progress of immune checkpoint inhibitors, related markers in the treatment of SCLC by exploring the value, problems and challenges of immunotherapy in SCLC.
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Complement Activation as a Helping Hand for Inflammophilic Pathogens and Cancer

The complement system, an evolutionarily ancient component of innate immunity, is capable of protecting hosts from invading pathogens, either directly, by lysis of target cells, or indirectly, by mobilization of host immune mechanisms. However, this potentially cytotoxic cascade must be tightly regulated, since improperly controlled complement can damage healthy cells and tissues. The practical importance of this axis is highlighted when impairment of complement regulators or bacterial mechanisms of complement evasion result in pathogenic conditions. Recognition of complement as a "double-edged sword" is widely acknowledged, but another, currently underappreciated aspect of complement function has emerged as an important player in homeostatic balance-the dual outcome of complement-mediated inflammation. In most cases, the proinflammatory properties of complement are beneficial to the host. However, certain pathogens have developed the ability to utilize local inflammation as a source of nutrients and as a way to establish a niche for further colonization. Such a strategy can be illustrated in the example of periodontitis. Interestingly, certain tumors also seem to benefit from complement activation products, which promote a proangiogenic and immunosuppressive microenvironment.

Non-small cell to small cell lung cancer on PD-1 inhibitors: two cases on potential histologic transformation

Introduction

Histologic transformation from non-small cell lung cancer (NSCLC) to small cell lung cancer (SCLC) is a well-recognized mechanism of resistance in EGFR-mutant adenocarcinoma upon treatment with TKIs, but rarely reported with programmed death1 (PD-1) inhibitors. We report two cases of potential transformation during treatment with PD-1 inhibitors.

Case presentations

Case 1, a 65-year-old man was diagnosed with stage IVa lung adenocarcinoma on pleural fluid cytology. He received six cycles of carboplatin and pemetrexed, then maintained on pemetrexed. He had disease progression after nine cycles of pemetrexed and was switched to nivolumab. He progressed after five cycles of nivolumab. Core biopsy of the lung mass revealed SCLC. Case 2, a 68-year-old man was diagnosed with two primary NSCLCs and underwent resection. He had recurrence after several months and was treated with four cycles of carboplatin, paclitaxel, and pembrolizumab on clinical trial, with partial response. He was continued on pembrolizumab and had disease progression after 30 cycles. Biopsy of the new lesions showed SCLC.

Discussion

Histologic transformation from NSCLC to SCLC can be explained by the presence of a common cell precursor. Proposed molecular mechanisms include loss of RB1, TP53 mutations, and MYC amplification. The distinction between transformation and mixed histology tumors is challenging, especially when pathologic material used for the initial diagnosis is limited. The possibility of a second metachronous primary lung cancer cannot be excluded in our cases.

Conclusion

Histologic transformation with PD-1 inhibitors could be under-recognized. Disease progression should prompt re-biopsy to uncover new histology and change in treatment. Future studies are needed to elucidate mechanisms and predictors of transformation.