SCLC, Paraneoplastic Syndromes, and the Immune System

Single-cell RNA sequencing reveals immune microenvironment of small cell lung cancer-associated malignant pleural effusion

We used 10 × genomics single-cell transcriptome sequencing technology to reveal the tumor immune microenvironment characteristics of small cell lung cancer (SCLC) in a patient with malignant pleural effusion (MPE). A total of 8008 high-quality cells were finally obtained for subsequent bioinformatic analysis, which were divided into 10 cell clusters further identified as B cells, T cells, myeloid cells, NK cells, and cancer cells. Such SCLC related genes as NOTCH1, MYC, TSC22D1, SOX4, BLNK, YBX3, VIM, CD8A, CD8B, and KLF6 were expressed in different degrees during differentiation of T and B cells. Different ligands and receptors between T, B and tumor cells almost interact through MHC II, IL-16, galectin, and APP signaling pathway.

Tackling the current dilemma of immunotherapy in extensive-stage small cell lung cancer: A promising strategy of combining with radiotherapy

Progress in the treatment of small cell lung cancer (SCLC) has been modest over the past decades until the advent of immune checkpoint inhibitors, which have redefined the standard first-line treatment for extensive-stage SCLC (ES-SCLC). However, despite the positive results of several clinical trials, the limited survival benefit achieved suggests that the priming and sustaining of immunotherapeutic efficacy are poor and further investigation is urgently needed. In this review, we aim to summarize the potential mechanisms underlying the limited efficacy of immunotherapy and intrinsic resistance in ES-SCLC, including impaired antigen presentation and limited T cell infiltration. Moreover, to tackle the current dilemma, given the synergistic effects of radiotherapy on immunotherapy, especially the unique advantages of low-dose radiotherapy (LDRT), such as less immunosuppression and lower radiation toxicity, we propose radiotherapy as a booster to enhance the immunotherapeutic efficacy by overcoming the poor priming effect. Recent clinical trials, including ours, have also focused on adding radiotherapy, including LDRT, to first-line treatment of ES-SCLC. Additionally, we also suggest combination strategies to sustain the immunostimulatory effect of radiotherapy, as well as the cancer-immunity cycle, and further improve survival outcomes.

Use of radiation therapy among patients with Extensive-stage Small-cell lung cancer receiving Immunotherapy: Canadian consensus recommendations

OBJECTIVES

Thoracic radiation therapy (TRT) and prophylactic cranial irradiation (PCI) are commonly used in the management of extensive-stage small-cell lung cancer (ES-SCLC); however, Phase III trials of first-line immunotherapy often excluded these options. Guidance is needed regarding appropriate use of TRT, PCI, and magnetic resonance imaging (MRI) surveillance while new data are awaited.

MATERIALS AND METHODS

In two web-based meetings, a pan-Canadian expert working group of five radiation oncologists and four medical oncologists addressed eight clinical questions regarding use of radiation therapy (RT) and MRI surveillance among patients with ES-SCLC receiving immunotherapy. A targeted literature review was conducted using PubMed and conference proceedings to identify recent (January 2019-April 2022) publications in this setting. Fifteen recommendations were developed; online voting was conducted to gauge agreement with each recommendation.

RESULTS

After considering recently available evidence across lung cancer populations and clinical experience, the experts recommended that all patients with a response to chemo-immunotherapy, good performance status (PS), and limited metastases be considered for consolidation TRT (e.g., 30 Gy in 10 fractions). When considered appropriate after multidisciplinary team discussion, TRT can be initiated during maintenance immunotherapy. All patients who respond to concurrent chemo-immunotherapy should undergo restaging with brain MRI to guide decision-making regarding PCI versus MRI surveillance alone. MRI surveillance should be conducted for two years after response to initial therapy. PCI (e.g., 25 Gy in 10 fractions or 20 Gy in 5 fractions) can be considered for patients without central nervous system involvement who have a response to chemo-immunotherapy and good PS. Concurrent treatment with PCI and immunotherapy or with TRT, PCI, and immunotherapy is appropriate after completion of initial therapy. All recommendations were agreed upon unanimously.

CONCLUSIONS

These consensus recommendations provide practical guidance regarding appropriate use of RT and immunotherapy in ES-SCLC while awaiting new clinical trial data.

Posttranslational modifications induce autoantibodies with risk prediction capability in patients with small cell lung cancer

Small cell lung cancer (SCLC) elicits the generation of autoantibodies that result in unique paraneoplastic neurological syndromes. The mechanistic basis for the formation of such autoantibodies is largely unknown but is key to understanding their etiology. We developed a high-dimensional technique that enables detection of autoantibodies in complex with native antigens directly from patient plasma. Here, we used our platform to screen 1009 human plasma samples for 3600 autoantibody-antigen complexes, finding that plasma from patients with SCLC harbors, on average, fourfold higher disease-specific autoantibody signals compared with plasma from patients with other cancers. Across three independent SCLC cohorts, we identified a set of common but previously unknown autoantibodies that are produced in response to both intracellular and extracellular tumor antigens. We further characterized several disease-specific posttranslational modifications within extracellular proteins targeted by these autoantibodies, including citrullination, isoaspartylation, and cancer-specific glycosylation. Because most patients with SCLC have metastatic disease at diagnosis, we queried whether these autoantibodies could be used for SCLC early detection. We created a risk prediction model using five autoantibodies with an average area under the curve of 0.84 for the three cohorts that improved to 0.96 by incorporating cigarette smoke consumption in pack years. Together, our findings provide an innovative approach to identify circulating autoantibodies in SCLC with mechanistic insight into disease-specific immunogenicity and clinical utility.

Immune-Related Cerebellar Ataxia: A Rare Adverse Effect of Checkpoint Inhibitor Therapy

Immune checkpoint inhibitors (ICIs) have led to a revolution in cancer management, mainly due to lasting long-term durable responses in a subset of patients with metastatic solid tumours (Gettinger et al. in JCO 36(17):1675-1684, 2018). As immunotherapy is gradually being applied for the treatment of a large range of solid tumours, the incidence of neurological immune-related adverse events (irAEs) has increased (2). Neurologic toxicities that result in high morbidity rates and even mortality have emerged as serious complications of ICIs (Johnson et al. in J Immuno Cancer 7(1):134, 2019; Wang et al. in JAMA Oncol 4(12):1721, 2018). Small-cell lung cancer (SCLC) is common cause of neurologic paraneoplastic syndrome (Sebastian et al. in J Thorac Oncol 14(11):1878-1880, 2019). Nevertheless, the distinction between neurologic iRAEs and paraneoplastic neurological syndromes (PNSs) in patients with SCLC treated by ICIs remains challenging (Williams et al. JAMA Neurol 73(8):928, 2016). As immunotherapy is gradually being applied for the treatment of a large range of solid tumours, the incidence of neurological autoimmune adverse events has increased. Neurologic toxicities that result in high morbidity rates and even mortality have emerged as serious complications of ICIs and have yet to be fully understood. We report a case of an immune induced cerebellar ataxia in a 47 year-old small-cell neuroendocrine carcinoma patient undergoing checkpoint blockade by atezolizumab, a programmed cell death-1 ligand (PDL-1) inhibitor. After 4 cycles of immunotherapy, the patient presented with kinetic and static cerebellar syndrome leading to the diagnosis of TRIM9-Abs ICI-related cerebellar irAE. Therapeutic management was discussed in multidisciplinary meetings in the lack of therapeutic guidelines. There was no clinical improvement. Because of high morbidity and no treatment evidence, neurologic symptoms developing under ICI require early diagnosis and may indicate the need for definitive treatment discontinuation.

What Are the Biomarkers for Immunotherapy in SCLC?

Small-cell lung cancer (SCLC) is an aggressive malignancy that exhibits a rapid doubling time, a high growth fraction, and the early development of widespread metastases. The addition of immune checkpoint inhibitors to first-line chemotherapy represents the first significant improvement of systemic therapy in several decades. However, in contrast to its effects on non-SCLC, the advantageous effects of immunotherapy addition are modest in SCLC. In particular, only a small number of SCLC patients benefit from immune checkpoint inhibitors. Additionally, biomarkers selection is lacking for SCLC, with clinical trials largely focusing on unselected populations. Here, we review the data concerning the major biomarkers for immunotherapy, namely, programmed death ligand 1 expression and tumour mutational burden. Furthermore, we explore other potential biomarkers, including the role of the immune microenvironment in SCLC, the role of genetic alterations, and the potential links between neurological paraneoplastic syndromes, serum anti-neuronal nuclear antibodies, and outcomes in SCLC patients treated with immunotherapy.

Molecular profiles of small cell lung cancer subtypes: therapeutic implications

Small cell lung cancer (SCLC; accounting for approximately 13%-15% of all lung cancers) is an exceptionally lethal malignancy characterized by rapid doubling time and high propensity to metastasize. In contrast to the increasingly personalized therapies in other types of lung cancer, SCLC is still regarded as a homogeneous disease and the prognosis of SCLC patients remains poor. Recently, however, substantial progress has been made in our understanding of SCLC biology. Advances in genomics and development of new preclinical models have facilitated insights into the intratumoral heterogeneity and specific genetic alterations of this disease. This worldwide resurgence of studies on SCLC has ultimately led to the development of novel subtype-specific classifications primarily based on the neuroendocrine features and distinct molecular profiles of SCLC. Importantly, these biologically distinct subtypes might define unique therapeutic vulnerabilities. Herein, we summarize the current knowledge on the molecular profiles of SCLC subtypes with a focus on their potential clinical implications.

Immunotherapy for extensive stage small cell lung cancer

Small cell lung cancer (SCLC) is an aggressive malignancy. Until recently the standard of care for newly diagnosed patients with extensive-stage disease was chemotherapy consisting of etoposide plus a platinum (EP). The median overall survival (OS) was only about 10 months with this systemic therapy. Immune checkpoint inhibitors were first evaluated as second or subsequent line treatments in extensive stage disease and later in combination with EP in the first-line setting. Recently two randomized phase III trials have demonstrated statistically improved OS with addition of a programmed death ligand-1 (PD-L1) inhibitor to EP. As a result, the standard of care for newly diagnosed patients with extensive-stage SCLC has changed for the first time in decades. However, many patients do not derive benefit from the addition of a PD-L1 inhibitor to EP. In this review we discuss first-line trials of chemoimmunotherapy in extensive stage SCLC and summarize data on second and subsequent line treatment with immune checkpoint inhibitors in immunotherapy-naïve patients. Additionally, we discuss potential biomarkers that could be utilized to select for which patients derive benefit from addition of a PD-L1 inhibitor to EP and propose ways to improve on first-line chemoimmunotherapy.