Composite biomarkers defined by multiparametric immunofluorescence analysis identify ALK-positive adenocarcinoma as a potential target for immunotherapy

Combining STAT3-Targeting Agents with Immune Checkpoint Inhibitors in NSCLC

Despite recent therapeutic advances, non-small cell lung cancer (NSCLC) remains the leading cause of cancer-related death. Signal transducer and activator of transcription 3 (STAT3) is a transcription factor (TF) with multiple tumor-promoting effects in NSCLC, including proliferation, anti-apoptosis, angiogenesis, invasion, metastasis, immunosuppression, and drug resistance. Recent studies suggest that STAT3 activation contributes to resistance to immune checkpoint inhibitors. Thus, STAT3 represents an attractive target whose pharmacological modulation in NSCLC may assist in enhancing the efficacy of or overcoming resistance to immune checkpoint inhibitors. In this review, we discuss the biological mechanisms through which STAT3 inhibition synergizes with or overcomes resistance to immune checkpoint inhibitors and highlight the therapeutic strategy of using drugs that target STAT3 as potential combination partners for immune checkpoint inhibitors in the management of NSCLC patients.

Functional status and spatial interaction of T cell subsets driven by specific tumor microenvironment correlate with recurrence of non-small cell lung cancer

Background

The anti-tumoral or pro-tumoral roles of CD4+ and CD8+ T cells typify the complexity of T cell subsets function in cancer. In the non-small cell lung cancer (NSCLC), the density and topology of distinct T cell phenotypes at the tumor center (TC) versus the invasive margin (IM) are largely unknown. Here, we investigated T cell subsets density and distribution within TC and IM regions in NSCLC and its impact on the prognosis.

Methods

We performed multiplex immunofluorescence using a tissue microarray of samples from 99 patients with locally advanced NSCLC to elucidate the distributions of tumor cell, T cell subpopulations (CD4/conventional CD4/regulatory CD4/CD8/cytotoxic CD8/pre-dysfunctional CD8/dysfunctional CD8), microvessel density (MVD), cancer-associated fibroblasts (CAFs) and hypoxia-inducible factor-1α (HIF-1α) in TC and IM tissues. Cell-to-cell nearest neighbor distances and interactions were analyzed using the phenoptrreports R package. Cox regression was used to evaluate the associations between T cell subsets density and proximity to tumor cells and recurrence-free survival (RFS). Correlations between different cell subsets were examined by Spearman's or Kruskal-Wallis tests.

Results

In the locally advanced NSCLC, the proportion of tumor cells and CAFs in IM is lower than in the TC, while MVD, CD4+, and CD8+ T lymphocytes were increased, and tumor cells were closer to T lymphocytes and their subsets. The density and proximity of CD4+ and CD8+ T cells in the TC and IM regions were not associated with RFS, but in the IM area, increased density of dysfunctional CD8 and closer regulatory CD4 to tumor cells were independent risk factors for recurrence (HR were 3.536 and 2.884, respectively), and were positively correlated with HIF-1α+CD8 (r = 0.41, P = 0.000) and CAFs (P = 0.017), respectively.s.

Conclusions

In locally advanced NSCLC, the functional status of T cells in the IM region is closely related to recurrence. The density of dysfunctional CD8 and the proximity of regulatory CD4 to tumor cells were independent risk factors for recurrence, and are positively correlated with the hypoxia response of CD8+ T cells and CAFs. Targeting hypoxia or CAFs is expected to further sensitize therapy.

Multicellular Effects of STAT3 in Non-small Cell Lung Cancer: Mechanistic Insights and Therapeutic Opportunities

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer and accounts for 85% of lung cancer cases. Aberrant activation of the Signal Transducer and Activator of Transcription 3 (STAT3) is frequently observed in NSCLC and is associated with a poor prognosis. Pre-clinical studies have revealed an unequivocal role for tumor cell-intrinsic and extrinsic STAT3 signaling in NSCLC by promoting angiogenesis, cell survival, cancer cell stemness, drug resistance, and evasion of anti-tumor immunity. Several STAT3-targeting strategies have also been investigated in pre-clinical models, and include preventing upstream receptor/ligand interactions, promoting the degradation of STAT3 mRNA, and interfering with STAT3 DNA binding. In this review, we discuss the molecular and immunological mechanisms by which persistent STAT3 activation promotes NSCLC development, and the utility of STAT3 as a prognostic and predictive biomarker in NSCLC. We also provide a comprehensive update of STAT3-targeting therapies that are currently undergoing clinical evaluation, and discuss the challenges associated with these treatment modalities in human patients.

Shifting Gears in Precision Oncology-Challenges and Opportunities of Integrative Data Analysis

For decades, research relating to modification of host immunity towards antitumor response activation has been ongoing, with the breakthrough discovery of immune-checkpoint blockers. Several biomarkers with potential predictive value have been reported in recent studies for these novel therapies. However, with the plethora of therapeutic options existing for a given cancer entity, modern oncology is now being confronted with multifactorial interpretation to devise “the best therapy” for the individual patient. Into the bargain come the multiverse guidelines for established and emerging diagnostic biomarkers, as well as the complex interplay between cancer cells and tumor microenvironment, provoking immense challenges in the therapy decision-making process. Through this review, we present various molecular diagnostic modalities and techniques, such as genomics, immunohistochemistry and quantitative image analysis, which have the potential of becoming powerful tools in the development of an optimal treatment regime when analogized with patient characteristics. We will summarize the underlying complexities of these methods and shed light upon the necessary considerations and requirements for data integration. It is our hope to provide compelling evidence to emphasize on the need for inclusion of integrative data analysis in modern cancer therapy, and thereupon paving a path towards precision medicine and better patient outcomes.

[Overview of Multiplex Immunohistochemistry and Immunofluorescence Techniques in the Lung Cancer Immunotherapy]

肺癌是目前临床上最常见的恶性肿瘤，严重威胁着患者的生命健康及生活质量。程序性细胞死亡受体1（programmed cell death receptor 1, PD-1）及其配体（programmed cell death ligand 1, PD-L1）抑制剂为非小细胞肺癌（non-small cell lung cancer, NSCLC）患者提供了新的治疗策略。现有的生物标志物检测对准确选择免疫治疗受益的患者均有一定的价值，但都存在着局限性。多标记免疫组织化学/免疫荧光（multiplex immunohistochemistry/immunofluorescence, mIHC/IF）技术允许在单一组织切片上同时检测多个抗体，并对细胞组成、细胞功能和细胞-细胞相互作用进行全面研究。国内外已有大量研究使用mIHC/IF技术对肿瘤免疫微环境（tumor immune microenvironment, TIME）下特异性免疫细胞群进行了探索，发现其有助于肺癌患者临床预后判断及疗效预测。肺癌免疫治疗时代，这项技术在转化研究和临床实践中均具有良好的应用前景。本文就mIHC/IF检测方法在肺癌免疫治疗中的研究进展进行了总结和展望。

Is there any place for immune-checkpoint inhibitors in the treatment algorithm of fusion-driven non-small cell lung cancer?-a literature review

The advent of immune-checkpoint inhibitors (ICIs) targeting the programmed death-1 (PD-1)/programmed death ligand-1 (PD-L1) axis, produced a paradigm change of the treatment algorithm for metastatic, non-oncogene addicted, non-small cell lung cancer (NSCLC). However, the majority of patients with oncogene-addicted disease have been excluded from the “immunotherapy revolution”, thus the clinical efficacy of these agents in this subset of patients remains largely unknown. Although pre-clinical evidence provided a good rationale to pursue the investigation of ICI treatment in specific subgroups of oncogene-addicted NSCLC, current available evidence suggested that tumors harboring molecular alterations likely do not represent the best candidate to single agent ICI therapy. Furthermore, the prospect of further improving overall survival (OS) with the combination of tyrosine kinase inhibitors (TKIs) and ICIs led to unexpected poor results and safety issues in recent phase I trials exploring different therapeutic associations. Conversely, the combination of immunotherapy and chemotherapy is emerging as a potential effective strategy in specific subsets of NSCLC patients harboring oncogenic drivers. In this review we particularly focus on the subgroup of patients whose disease harbor oncogenic rearrangements, summarizing current evidence from preclinical and clinical studies and discussing their practical implications, in order to define the potential role of ICIs in the clinical management of fusion-driven NSCLC.

The Mechanisms of PD-L1 Regulation in Non-Small-Cell Lung Cancer (NSCLC): Which Are the Involved Players?

Treatment with inhibition of programmed cell death 1 (PD-1) or its ligand (PD-L1) improves survival in advanced non-small-cell lung cancer (NSCLC). Nevertheless, only a subset of patients benefit from treatment and biomarkers of response to immunotherapy are lacking. Expression of PD-L1 on tumor cells is the primary clinically-available predictive factor of response to immune checkpoint inhibitors, and its relevance in cancer immunotherapy has fostered several studies to better characterize the mechanisms that regulate PD-L1 expression. However, the factors associated with PD-L1 expression are still not well understood. Genomic alterations that activate KRAS, EGFR, and ALK, as well as the loss of PTEN, have been associated with increased PD-L1 expression. In addition, PD-L1 expression is reported to be increased by amplification of CD274, and decreased by STK11 deficiency. Furthermore, PD-L1 expression can be modulated by either tumor extrinsic or intrinsic factors. Among extrinsic factors, the most prominent one is interferon-γ release by immune cells, while there are several tumor intrinsic factors such as activation of the mechanistic target of rapamycin (mTOR), mitogen-activated protein kinase (MAPK) and Myc pathways that can increase PD-L1 expression. A deeper understanding of PD-L1 expression regulation is crucial for improving strategies that exploit inhibition of this immune checkpoint in the clinic, especially in NSCLC where it is central in the therapeutic algorithm. We reviewed current preclinical and clinical data about PD-L1 expression regulation in NSCLC.

Prognostic value and clinicopathological characteristics of PD-L1 overexpression in non-Hodgkin lymphoma: a meta-analysis

BACKGROUND

Programmed cell death ligand 1 (PD-L1) has already been detected in various carcinomas. In non-Hodgkin lymphoma (NHL), however, the prognostic value of PD-L1 overexpression remains unclear.

METHODS

A meta-analysis of 2321 NHL patients from 12 studies was performed. Hazard ratios (HRs) with 95% confidence intervals (CIs) were used to evaluate the correlation between PD-L1 overexpression and prognosis of NHL, and odds ratios (ORs) with 95% CIs were used to assess the association of PD-L1 overexpression with clinicopathological factors.

RESULTS

The results showed that no significant difference between PD-L1 positive and negative groups was detected in NHL (HR: 1.40, 95% CI: 0.90-2.19; P = 0.137). Nevertheless, the results indicated that PD-L1 overexpression was associated with poor prognosis in the subtype of diffuse large B cell lymphoma (DLBCL) (HR: 1.70, 95% CI: 1.05-2.74; P = 0.031). We also performed subgroup analyses and meta-regression. The pooled OR showed that PD-L1 overexpression was associated with B symptoms, higher international prognostic index (IPI) score (3, 4, and 5 points) and Ann Arbor Stages III and IV.

CONCLUSIONS

The meta-analysis demonstrated that PD-L1 expression was not associated with prognosis of NHL but was associated with prognosis of DLBCL.

Recent Findings in the Regulation of Programmed Death Ligand 1 Expression

With the recent approvals for the application of monoclonal antibodies that target the well-characterized immune checkpoints, immune therapy shows great potential against both solid and hematologic tumors. The use of these therapeutic monoclonal antibodies elicits inspiring clinical results with durable objective responses and improvements in overall survival. Agents targeting programmed cell death protein 1 (PD-1; also known as PDCD1) and its ligand (PD-L1) achieve a great success in immune checkpoints therapy. However, the majority of patients fail to respond to PD-1/PD-L1 axis inhibitors. Expression of PD-L1 on the membrane of tumor and immune cells has been shown to be associated with enhanced objective response rates to PD-1/PD-L1 inhibition. Thus, an improved understanding of how PD-L1 expression is regulated will enable us to better define its role as a predictive marker. In this review, we summarize recent findings in the regulation of PD-L1 expression.

Dynamic host immune response in virus-associated cancers

Viruses drive carcinogenesis in human cancers through diverse mechanisms that have not been fully elucidated but include promoting immune escape. Here we investigated associations between virus-positivity and immune pathway alteration for 2009 tumors across six virus-related cancer types. Analysis revealed that for 3 of 72 human papillomavirus (HPV)-positive head and neck squamous cell carcinoma (HNSC) the HPV genome integrated in immune checkpoint genes PD-L1 or PD-L2, driving elevated expression in the corresponding gene. In addition to the previously described upregulation of the PD-1 immunosuppressive pathway in Epstein-Barr virus (EBV)-positive stomach tumors, we also observed upregulation of the PD-1 pathway in cytomegalovirus (CMV)-positive tumors. Furthermore, we found signatures of T-cell and B-cell response in HPV-positive HNSC and EBV-positive stomach tumors and HPV-positive HNSC patients were associated with better survival when T-cell signals were detected. Our work reveals that viral infection may recruit immune effector cells, and upregulate PD-1 and CTLA-4 immunosuppressive pathways.

Multiplexed Immunohistochemistry for Molecular and Immune Profiling in Lung Cancer-Just About Ready for Prime-Time?

As targeted molecular therapies and immuno-oncology have become pivotal in the management of patients with lung cancer, the essential requirement for high throughput analyses and clinical validation of biomarkers has become even more intense, with response rates maintained in the 20%–30% range. Moreover, the list of treatment alternatives, including combination therapies, is rapidly evolving. The molecular profiling and specific tumor-associated immune contexture may be predictive of response or resistance to these therapeutic strategies. Multiplexed immunohistochemistry is an effective and proficient approach to simultaneously identify specific proteins or molecular abnormalities, to determine the spatial distribution and activation state of immune cells, as well as the presence of immunoactive molecular expression. This method is highly advantageous for investigating immune evasion mechanisms and discovering potential biomarkers to assess mechanisms of action and to predict response to a given treatment. This review provides views on the current technological status and evidence for clinical applications of multiplexing and how it could be applied to optimize clinical management of patients with lung cancer.

Challenges and unanswered questions for the next decade of immune-oncology research in NSCLC

Over the last 20 years there have been great advances in the treatment of lung cancer. Immune checkpoint blockade together with targeted therapies have provided oncologists with the means to improve survival of non-small cell lung cancer (NSCLC) and patients with a better quality of life and therapies with manageable toxicity. Maybe in a short period of time the possibility of a cure in metastatic NSCLC will be raised. Therefore, continued research into new drugs, biomarkers and especially combination therapies is necessary in order to expand the clinical benefit of the current treatments to a broader population of NSCLC patients. The purpose of our review is to highlight our thoughts about potential mechanisms of resistance to immunotherapy that, if better explored, can provide us with both biomarkers to predict response to these therapies and partners to combine with and prolong the benefit of immune checkpoint blockade. We are presenting our own experience of immunotherapy with a case report from our institution.

Microfluidics-based immunofluorescence for fast staining of ALK in lung adenocarcinoma

Background

Anaplastic lymphoma kinase (ALK) is a key oncogenic driver in lung adenocarcinoma patients and its fusion proteins are routinely assessed. The microfluidic tissue processor (MTP) device is based on a chip-confined low-volume technology allowing for rapid immunohistochemistry/immunofluorescence (IHC/IF) stainings of formalin-fixed paraffin-embedded (FFPE) or frozen tissue samples.

Methods

A novel ALK IF protocol was developed for the MTP device using the primary mouse anti-human ALK antibody clone 5A4. FFPE tumor whole sections from 14 resected lung adenocarcinoma patients documented to be ALK positive (ALK+) by automated chromogenic IHC and/or FISH were used. MTP-derived IF immunoreactivity was measured by computerized analysis of digitalized images on individual frames of tumor epithelia and surrounding stroma, using an ImageJ plug-in.

Results

The 5A4 antibody yielded saturated immunoreactivity at an incubation time of 4 min on a titration curve ranging from 2 to 32 min. Total staining time on the MTP device was 18 min including secondary IgG Alexa Fluor 647. MTP-based ALK IF confirmed all 12 cases; with epithelial signal above stromal staining based on computerized pixel-based measurement. MTP-IF (mean intensity levels 458 to 1301) and chromogenic IHC (H-score 120 to 300) showed an equal range of variation of 2.8 and 2.5 folds, respectively, and a trend for direct correlation (p-value 0.051).

Conclusion

The newly developed protocol for immunofluorescent detection of ALK protein with the MTP device confirms chromogenic IHC results on FFPE lung adenocarcinoma specimens. MTP-based IF is fast and reliable. We foresee this study to be a first step opening the road for further realization of microfluidic-based assays for rapid simultaneous detection of targetable oncogenic and immune-system related markers in their topographical context to investigate tumour heterogeneity and micro-environmental interactions.

Electronic supplementary material

The online version of this article (10.1186/s13000-018-0757-1) contains supplementary material, which is available to authorized users.

The role of automated cytometry in the new era of cancer immunotherapy

The introduction in the clinical practice of several new approaches to cancer immunotherapy has greatly increased the interest in analytical methodologies that can define the immunological profile of patients in the clinical setting. This requires huge effort to obtain reliable monitoring tools that could be used to improve the patient's clinical outcome. The clinical applications of flow cytometry (FCM) in oncology started with the measurement of DNA content for the evaluation of both ploidy and cell cycle profile as potential prognostic parameters in the majority of human solid cancer types. The availability of monoclonal antibodies widely broadened the spectrum of clinical applications of this technique, which rapidly became a fundamental tool for the diagnosis and prognosis of malignant hematological diseases. Among the emerging clinical applications of FCM, the study of minimal residual disease in hematological malignancies, the quantification of blood dendritic cells in various types of tumors, the study of metastatic spread in solid tumors throughout both the analysis of circulating endothelial progenitor cells and the identification and characterization of circulating tumor cells, all appear very promising. More recently, an advanced single cell analysis technique has been developed that combines the precision of mass spectrometry with the unique advantages of FCM. This approach, termed mass cytometry, utilizes antibodies conjugated to heavy metal ions for the analysis of cellular proteins by a mass spectrometer. It provides measurement of over 100 simultaneous cellular parameters in a single sample and has evolved from a promising technology to a high recognized platform for multi-dimensional single-cell analysis. Should a careful standardization of the analytical procedures be reached, both FCM and mass cytometry could effectively become ideal tools for the optimization of new immunotherapeutic approaches in cancer patients.

Role of Immunotherapy for Oncogene-Driven Non-Small Cell Lung Cancer

The clinical application of immune checkpoint inhibitors (ICIs) has led to dramatic changes in the treatment strategy for patients with advanced non-small cell lung cancer (NSCLC). Despite the observation of improved overall survival in NSCLC patients treated with ICIs, their efficacy varies greatly among different immune and molecular profiles in tumors. Particularly, the clinical significance of ICIs for oncogene-driven NSCLC has been controversial. In this review, we provide recent clinical and preclinical data focused on the relationship between oncogenic drivers and immunological characteristics and discuss the future direction of immunotherapy in NSCLC patients harboring such genetic alterations.

A successful pembrolizumab treatment case of lung adenocarcinoma after becoming resistant to ALK-TKI treatment due to G1202R mutation

BACKGROUND

In current guidelines, the role of immune checkpoint inhibitors is not yet determined in the treatment strategy for NSCLC harboring ALK translocations.

CASE

A 51-year-old woman with lung adenocarcinoma harboring ALK translocation was treated with alectinib until PD. After the second (CDDP/PEM) and third (crizotinib) line treatment, a second biopsy was performed, revealing PD-L1 tumor proportion score of 70-80% and G1202R mutation of ALK. Pembrolizumab was selected for the fourth line, leading to PR for more than 6 months.

CONCLUSIONS

While alectinib might induce resistance to ALK-TKI, it could increase PD-L1 positive cells to become sensitive to PD-1/PD-L1 inhibitors.

The non-small cell lung cancer immune landscape: emerging complexity, prognostic relevance and prospective significance in the context of immunotherapy

Immunotherapy of non-small cell lung cancer (NSCLC), by immune checkpoint inhibitors, has profoundly improved the clinical management of advanced disease. However, only a fraction of patients respond and no effective predictive factors have been defined. Here, we discuss the prospects for identification of such predictors of response to immunotherapy, by fostering an in-depth analysis of the immune landscape of NSCLC. The emerging picture, from several recent studies, is that the immune contexture of NSCLC lesions is a complex and heterogeneous feature, as documented by analysis for frequency, phenotype and spatial distribution of innate and adaptive immune cells, and by characterization of functional status of inhibitory receptor+ T cells. The complexity of the immune landscape of NSCLC stems from the interaction of several factors, including tumor histology, molecular subtype, main oncogenic drivers, nonsynonymous mutational load, tumor aneuploidy, clonal heterogeneity and tumor evolution, as well as the process of epithelial-mesenchymal transition. All these factors contribute to shape NSCLC immune profiles that have clear prognostic significance. An integrated analysis of the immune and molecular profile of the neoplastic lesions may allow to define the potential predictive role of the immune landscape for response to immunotherapy.

Any Place for Immunohistochemistry within the Predictive Biomarkers of Treatment in Lung Cancer Patients?

The identification of certain genomic alterations (EGFR, ALK, ROS1, BRAF) or immunological markers (PD-L1) in tissues or cells has led to targeted treatment for patients presenting with late stage or metastatic lung cancer. These biomarkers can be detected by immunohistochemistry (IHC) and/or by molecular biology (MB) techniques. These approaches are often complementary but depending on, the quantity and quality of the biological material, the urgency to get the results, the access to technological platforms, the financial resources and the expertise of the team, the choice of the approach can be questioned. The possibility of detecting simultaneously several molecular targets, and of analyzing the degree of tumor mutation burden and of the micro-satellite instability, as well as the recent requirement to quantify the expression of PD-L1 in tumor cells, has led to case by case development of algorithms and international recommendations, which depend on the quality and quantity of biological samples. This review will highlight the different predictive biomarkers detected by IHC for treatment of lung cancer as well as the present advantages and limitations of this approach. A number of perspectives will be considered.

Multiplexed Immunofluorescence Analysis and Quantification of Intratumoral PD-1+ Tim-3+ CD8+ T Cells

Immune cells are important components of the tumor microenvironment and influence tumor growth and evolution at all stages of carcinogenesis. Notably, it is now well established that the immune infiltrate in human tumors can correlate with prognosis and response to therapy. The analysis of the immune infiltrate in the tumor microenvironment has become a major challenge for the classification of patients and the response to treatment. The co-expression of inhibitory receptors such as Program Cell Death Protein 1 (PD1; also known as CD279), Cytotoxic T Lymphocyte Associated Protein 4 (CTLA-4), T-Cell Immunoglobulin and Mucin Containing Protein-3 (Tim-3; also known as CD366), and Lymphocyte Activation Gene 3 (Lag-3; also known as CD223), is a hallmark of T cell exhaustion. We developed a multiparametric in situ immunofluorescence staining to identify and quantify at the cellular level the co-expression of these inhibitory receptors. On a retrospective series of frozen tissue of renal cell carcinomas (RCC), using a fluorescence multispectral imaging technology coupled with an image analysis software, it was found that co-expression of PD-1 and Tim-3 on tumor infiltrating CD8⁺ T cells is correlated with a poor prognosis in RCC. To our knowledge, this represents the first study demonstrating that this automated multiplex in situ technology may have some clinical relevance.

PD-L1 immunohistochemistry for non-small cell lung carcinoma: which strategy should be adopted?

INTRODUCTION

PD-L1 detection with immunohistochemistry (IHC) is the only predictive biomarker available to date for PD-L1/PD1 immunotherapy in thoracic oncology. While many studies have been published on this biomarker, they raise a number of questions concerning mainly, (i) the type of antibody for use and its condition of utilization, (ii) the threshold to be used, (iii) the message and information to communicate to the thoracic oncologist and, (iv) the adoption of this methodology as part of the daily practices of a pathology laboratory. Areas covered: This review provides an update on the use of the different PD-L1 antibodies for IHC in the context of metastatic non-small cell lung cancer (NSCLC) and discusses their use as companion or complementary diagnostic tests. The limits of PD-L1 IHC as a predictive test, the precautions to be adopted as well as some perspectives will then be considered. Expert commentary: IHC for PD-L1 can be considered as a theranostic test, which implies providing an extremely reliable result that avoids any false positive and negative results. PD-L1 IHC requires considerable expertise and specific training of pathologists. PD-L1 IHC can be a companion or complementary diagnostic test depending on the clone employed, the molecular therapy prescribed and the indication of use.

ALK in Non-Small Cell Lung Cancer (NSCLC) Pathobiology, Epidemiology, Detection from Tumor Tissue and Algorithm Diagnosis in a Daily Practice

Patients with advanced-stage non-small cell lung carcinoma (NSCLC) harboring an ALK rearrangement, detected from a tissue sample, can benefit from targeted ALK inhibitor treatment. Several increasingly effective ALK inhibitors are now available for treatment of patients. However, despite an initial favorable response to treatment, in most cases relapse or progression occurs due to resistance mechanisms mainly caused by mutations in the tyrosine kinase domain of ALK. The detection of an ALK rearrangement is pivotal and can be done using different methods, which have variable sensitivity and specificity depending, in particular, on the quality and quantity of the patient’s sample. This review will first highlight briefly some information regarding the pathobiology of an ALK rearrangement and the epidemiology of patients harboring this genomic alteration. The different methods used to detect an ALK rearrangement as well as their advantages and disadvantages will then be examined and algorithms proposed for detection in daily routine practice.

Mechanisms of action and rationale for the use of checkpoint inhibitors in cancer

The large family of costimulatory molecules plays a crucial role in regulation of the immune response. These molecules modulate TCR signalling via phosphorylation cascades. Some of the coinhibitory members of this family, such as PD-1 and CTLA-4, already constitute approved targets in cancer therapy and, since 2011, have opened a new area of antitumour immunotherapy. Many antibodies targeting other inhibitory receptors (Tim-3, VISTA, Lag-3 and so on) or activating costimulatory molecules (OX40, GITR and so on) are under evaluation. These antibodies have multiple mechanisms of action. At the cellular level, these antibodies restore the activation signalling pathway and reprogram T cell metabolism. Tumour cells become resistant to apoptosis when an intracellular PD-L1 signalling is blocked. CD8⁺ T cells are considered to be the main effectors of the blockade of inhibitory receptors. Certain CD8⁺ T cell subsets, such as non-hyperexhausted (CD28⁺, T-bet^high, PD-1^int), follicular-like (CXCR-5⁺) or resident memory CD8⁺ T cells, are more prone to be reactivated by anti-PD-1/PD-L1 monoclonal antibody (mAb). In the future, the challenge will be to rationally combine drugs able to make the tumour microenvironment more permissive to immunotherapy in order to potentiate its clinical activity.