FDA Approval Summary: Pembrolizumab for the Treatment of Microsatellite Instability-High Solid Tumors

Immunotherapy for the treatment of metastatic small cell lung cancer: Focus on pembrolizumab

AREAS COVERED

The current evidence on the role of pembrolizumab for patients with extensive SCLC is reviewed in this article. Particularly, preclinical and clinical data from phase I/II and III clinical trials, which evaluate the efficacy and toxicity of pembrolizumab for these patients, are summarized based on PubMed/MEDLINE search and relevant articles. In addition, future perspectives on the emerging role of immunotherapy for SCLC are highlighted in light of potentially useful biomarkers.

EXPERT COMMENTARY

Pembrolizumab shows an excellent toxicity profile in recent studies, and significantly prolonged progression-free survival (PFS) but not overall survival (OS) in the phase III clinical trial KN604, in contrast to atezolizumab and durvalumab. The latter two agents have already been approved and incorporated in the daily clinical practice. Further research should be conducted so that phase III clinical trials can validate the potential clinical benefit of this checkpoint inhibitor in combination with other active agents and establish its role in the metastatic setting of SCLC.

Proteomic Studies on the Management of High-Grade Serous Ovarian Cancer Patients: A Mini-Review

High-grade serous ovarian cancer (HGSC) remains the most common and deadly subtype of ovarian cancer. It is characterized by its late diagnosis and frequent relapse despite standardized treatment with cytoreductive surgery and platinum-based chemotherapy. The past decade has seen significant advances in the clinical management and molecular understanding of HGSC following the publication of the Cancer Genome Atlas (TCGA) researchers and the introduction of targeted therapies with anti-angiogenic drugs and poly(ADP-ribose) polymerase inhibitors in specific subgroups of patients. We provide a comprehensive review of HGSC, focusing on the most important molecular advances aimed at providing a better understanding of the disease and its response to treatment. We emphasize the role that proteomic technologies are now playing in these two aspects of the disease, through the identification of proteins and their post-translational modifications in ovarian cancer tumors. Finally, we highlight how the integration of proteomics with genomics, exemplified by the work performed by the Clinical Proteomic Tumor Analysis Consortium (CPTAC), can guide the development of new biomarkers and therapeutic targets.

NMD inhibition by 5-azacytidine augments presentation of immunogenic frameshift-derived neoepitopes

Frameshifted protein sequences elicit tumor-specific T cell-mediated immune responses in microsatellite-unstable (MSI) cancers if presented by HLA class I molecules. However, their expression and presentation are limited by nonsense-mediated RNA decay (NMD). We employed an unbiased immunopeptidomics workflow to analyze MSI HCT-116 cells and identified >10,000 HLA class I-presented peptides including five frameshift-derived InDel neoepitopes. Notably, pharmacological NMD inhibition with 5-azacytidine stabilizes frameshift-bearing transcripts and increases the HLA class I-mediated presentation of InDel neoepitopes. The frameshift mutation underlying one of the identified InDel neoepitopes is highly recurrent in MSI colorectal cancer cell lines and primary patient samples, and immunization with the corresponding neoepitope induces strong CD8+ T cell responses in an HLA-A∗02:01 transgenic mouse model. Our data show directly that pharmacological NMD inhibition augments HLA class I-mediated presentation of immunogenic frameshift-derived InDel neoepitopes thus highlighting the clinical potential of NMD inhibition in anti-cancer immunotherapy strategies.

Predictive Value of KDM5C Alterations for Immune Checkpoint Inhibitors Treatment Outcomes in Patients With Cancer

Lysine (K)-specific demethylase 5C (KDM5C) plays a significant role in the tumor cell proliferation, invasion, drug resistance and the regulation of tumor-related gene expression. Here, we aimed to investigate its predictive value in patients with cancers received immune checkpoint inhibitors (ICIs). We explored the predictive value of KDM5C alterations and the association between KDM5C alteration and immune landscape by using published cohort with clinical outcome and sequenced data from online database. The frequency of KDM5C alterations was 2.1% across 48045 tumor samples with different cancers from 185 studies. KDM5C alterations were correlated with markedly inferior overall survival (OS, 53 vs. 102 months, P<0.0001) than those without. However, in ICI-treated group, patients with KDM5C alterations had a substantially prolonged OS than the wild-type group (not reached vs. 18 months, P=0.0041). The predictive value of KDM5C alterations for ICI treatment outcome was not observed in patients with microsatellite-stable tumors (P=0.2875). Intriguingly, patients with non-small-cell lung cancer and KDM5C alterations receiving ICI had the better progression-free survival than wild type group (13.2 vs. 3.2 months, P=0.0762). Mechanistically, KDM5C altered tumors had dramatically higher TMB level and was associated with significantly higher level of CD8+ T cell infiltration and T effector signature. In conclusion, KDM5C alterations was correlated with enhanced tumor immunogenicity and inflamed anti-tumor immunity, thus resulting in better treatment outcome in cancer patients receiving ICIs.

A novel automated immunoassay for serum NY-ESO-1 and XAGE1 antibodies in combinatory prediction of response to anti-programmed cell death-1 therapy in non-small-cell lung cancer

BACKGROUND

Anti-programmed cell death-1 (PD-1) antibodies (Abs) are key drugs in non-small-cell lung cancer (NSCLC) treatment; however, clinical benefits with anti-PD-1 monotherapy are limited. We reported that serum Abs against cancer-testis antigens NY-ESO-1 and XAGE1 predicted clinical benefits. We aimed to develop a fully automated immunoassay system measuring NY-ESO-1/XAGE1 Abs.

METHODS

Sera from 30 NSCLC patients before anti-PD-1 monotherapy were reacted with recombinant NY-ESO-1 protein- or synthetic XAGE1 peptide-coated magnetic beads. ALP-conjugated Ab and chemiluminescent substrate were added and luminescence measured. These procedures were automated using high sensitivity chemiluminescent enzyme immunoassay (HISCL™). NY-ESO-1/XAGE1 Ab stability was tested under various conditions. Response prediction accuracy was evaluated using area under receiver operating curve (AUROC).

RESULTS

HISCL detected specific serum NY-ESO-1/XAGE1 Abs, which levels in ELISA and HISCL were highly correlated. The Ab levels in HISCL were stable at four temperatures, five freeze/thaw cycles, and long-term storage; the levels were not interfered by common blood components. The Ab levels in 15 NSCLC responders to anti-PD-1 monotherapy were significantly higher than those in non-responders and healthy donors. The AUROC was the highest (0.91; 95% CI, 0.78-1.0) in combinatory prediction with NY-ESO-1/XAGE1 Abs.

CONCLUSION

Our immunoassay system is useful to predict clinical benefits with NSCLC immune-checkpoint therapy.

Immune checkpoint inhibitors in endometrial cancer

The incidence of endometrial cancer (EC) is increasing worldwide. The prognosis for patients diagnosed with early-stage remains good, whereas for patients with recurrent or metastatic disease, the prognosis is poor and treatment options, until recently, were limited. In 2017, pembrolizumab was approved by the US Food and Drug Administration (FDA) for those patients with mistmach repair deficiency (MMRd) or high microsatellite instability (MSI-H) tumors. However, only 20-30 % of EC have MSI, and just over half of these patients benefit from treatment. In 2019, the FDA granted breakthrough therapy designation to lenvatinib in combination with pembrolizumab for the potential treatment of patients with advanced microsatellite stable EC that has progressed after treatment with at least one previous systemic therapy. It appears clear that immune check-point inhibitors will have a definite place in the management of EC, both as single agent or in combination with other targeted agents. In this review, we summarize the current evidence of immune check point blockade and the identification of potential biomarkers, beyond MSI-H or MMRd, that could help to predict response to this agents in correlation with the genomic EC subtypes.

Predictive and prognostic biomarkers with therapeutic targets in colorectal cancer: A 2021 update on current development, evidence, and recommendation

Although therapeutically actionable molecular alterations are widely distributed across many cancer types, only a handful of them show evidence of clinical utility and are recommended for routine clinical practice in the management of cancers of colon and rectum (CRC). This 2021 update aims to provide a succinct summary on the use of prognostic and/or predictive biomarkers (expanded RAS, BRAF, microsatellite-high [MSI-H] or deficient mismatch repair [dMMR], neurotrophic tyrosine receptor kinase [NTRK] fusion genes, and human epidermal growth factor receptor type II [HER2] gene amplification) associated with CRC. Therapeutic implications of each relevant predictive or prognostic biomarker for patients with CRC are described, along with discussion on new developments on (1) biomarker-driven therapies such as testing of BRAF, MLH1 promoter methylation and MMR germline genes in differentiating sporadic CRC or hereditary conditions such as Lynch syndrome; (2) first-line use of immune checkpoint inhibitors in metastatic CRC; (3) risk stratification and therapy selection based on primary tumor location (left-sided vs. right-sided colon cancer); (3) atypical BRAF mutations; (4) use of EGFR directed therapy in the perioperative oligometastatic disease setting; (5) re-challenge of EGFR directed therapy and (6) personalizing therapy of fluoropyrimidine and irinotecan based on new evidence in pharmacogenomic testing. Data are collected and analyzed from available systematic reviews and meta-analyses of treatments with known therapeutic targets in CRC, which may be associated with predictive and/or prognostic biomarkers. Discussions are presented in an application-based format, with goal to empower pharmacists or other clinicians to gain awareness and understanding in biomarker-driven cancer therapy issues.

Resistance to second-generation androgen receptor antagonists in prostate cancer

The introduction of second-generation androgen receptor antagonists (SG-ARAs) has greatly impacted the treatment of metastatic prostate cancer, providing tolerable and efficacious alternatives to chemotherapy. SG-ARAs provide similar therapeutic benefit to abiraterone, a potent CYP17 inhibitor, and do not require the co-administration of prednisone. Despite considerable improvements in clinical outcomes in the settings of both castration sensitivity and castration resistance, the durability of clinical response to the SG-ARAs enzalutamide, apalutamide and darolutamide, similar to abiraterone, is limited by inevitable acquired resistance. Genomic aberrations that confer resistance to SG-ARAs or provide potential alternative treatment modalities have been identified in numerous studies, including alterations of the androgen receptor, DNA repair, cell cycle, PI3K-AKT-mTOR and Wnt-β-catenin pathways. To combat resistance, researchers have explored approaches to optimizing the utility of available treatments, as well as the use of alternative agents with a variety of targets, including AR-V7, AKT, EZH2 and HIF1α. Ongoing research to establish predictive biomarkers for the treatment of tumours with resistance to SG-ARAs led to the approval of the PARP inhibitors olaparib and rucaparib in pre-treated metastatic castration-resistant prostate cancer. The results of ongoing studies will help to shape precision medicine in prostate cancer and further optimize treatment paradigms to maximize clinical outcomes.

Serum Levels of Soluble Urokinase Plasminogen Activator Receptor Predict Tumor Response and Outcome to Immune Checkpoint Inhibitor Therapy

Background

Immune checkpoint inhibitors (ICIs) have led to a paradigm shift in cancer therapy, improving outcomes in the treatment of various malignancies. However, not all patients benefit to the same extend from ICI. Reliable tools to predict treatment response and outcome are missing. Soluble urokinase plasminogen activator receptor (suPAR) is a marker of immune activation, whose levels are prognostic in various cancers. We evaluated circulating suPAR levels as a novel predictive and prognostic biomarker in patients receiving ICI therapy for solid tumors.

Methods

A total of n = 87 patients receiving ICI therapy for different solid malignancies as well as 32 healthy controls were included into this study. Serum levels of suPAR were measured by ELISA prior to and sequentially at two time points during ICI therapy.

Results

Baseline suPAR serum levels were significantly higher in solid tumor patients compared to healthy controls. Importantly, patients with low suPAR levels both before or during ICI treatment were more likely to have a favorable response to treatment at three and six months, respectively. This finding was confirmed by multivariate binary logistic regression analysis including several clinicopathological parameters. Moreover, circulating suPAR levels before and during therapy were an independent prognostic factor for overall survival (OS). As such, patients with initial suPAR levels above our ideal prognostic cut-off value (4.86 ng/ml) had a median OS of only 160 days compared to 705 days for patients with suPAR levels below this cut-off value. Finally, low baseline suPAR levels identified a subgroup of patients who experienced ICI-related side effects which in turn were associated with favorable treatment response and outcome.

Conclusion

Our data suggest that measurements of suPAR serum levels are a previously unknown, easily accessible tool to predict individual treatment response and outcome to ICI therapy. Circulating suPAR might therefore be implemented into stratification algorithms to identify the ideal candidates for ICI treatment.

Clinical Application of the FoundationOne CDx Assay to Therapeutic Decision-Making for Patients with Advanced Solid Tumors

BACKGROUND

Implementation of personalized medicine requires the accessibility of tumor molecular profiling in order to allow prioritization of appropriate targeted therapies for individual patients. Our aim was to study the role of comprehensive genomic profiling assays that may inform treatment recommendations for patients with solid tumors.

MATERIALS AND METHODS

We performed a prospective study to evaluate the feasibility of application of the FoundationOne CDx panel-which detects substitutions, insertions and deletions, and copy number alterations in 324 genes, select gene rearrangements, and genomic signatures including microsatellite instability and tumor mutation burden (TMB)-to patients with advanced or recurrent solid tumors before its approval in Japan.

RESULTS

A total of 181 samples were processed for genomic testing between September 2018 and June 2019, with data being successfully obtained for 175 of these samples, yielding a success rate of 96.7%. The median turnaround time was 41 days (range, 21-126 days). The most common known or likely pathogenic variants were TP53 mutations (n = 113), PIK3CA mutations (n = 33), APC mutations (n = 32), and KRAS mutations (n = 29). Among the 153 patients assessed for TMB, the median TMB was 4 mutations/Mb, and tumors with a high TMB (≥10 mutations/Mb) were more prevalent for lung cancer (11/32) than for other solid tumor types (9/121, Fisher's exact test p < .01). No clear trend toward increased efficacy for immune checkpoint inhibitor (ICI) monotherapy or ICI combination chemotherapy in patients with a high programmed cell death-ligand 1 tumor proportion score or a high TMB was apparent. Among the 174 patients found to harbor known or likely pathogenic actionable alterations, 24 individuals (14%) received matched targeted therapy.

CONCLUSION

The FoundationOne CDx assay was performed with formalin-fixed, paraffin-embedded tumor specimens with a success rate of >95%. Such testing may inform the matching of patients with cancer with investigational or approved targeted drugs.

IMPLICATIONS FOR PRACTICE

This prospective cohort study was initiated to investigate the feasibility and utility of clinical application of FoundationOne CDx. A total of 181 samples were processed for genomic testing between September 2018 and June 2019, with data being successfully obtained for 175 of these samples, yielding a success rate of 96.7%, and 24 individuals (14%) received matched targeted therapy.

Radiomics analysis for predicting pembrolizumab response in patients with advanced rare cancers

BACKGROUND

We present a radiomics-based model for predicting response to pembrolizumab in patients with advanced rare cancers.

METHODS

The study included 57 patients with advanced rare cancers who were enrolled in our phase II clinical trial of pembrolizumab. Tumor response was evaluated using Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 and immune-related RECIST (irRECIST). Patients were categorized as 20 "controlled disease" (stable disease, partial response, or complete response) or 37 progressive disease). We used 3D-slicer to segment target lesions on standard-of-care, pretreatment contrast enhanced CT scans. We extracted 610 features (10 histogram-based features and 600 second-order texture features) from each volume of interest. Least absolute shrinkage and selection operator logistic regression was used to detect the most discriminatory features. Selected features were used to create a classification model, using XGBoost, for the prediction of tumor response to pembrolizumab. Leave-one-out cross-validation was performed to assess model performance.

FINDINGS

The 10 most relevant radiomics features were selected; XGBoost-based classification successfully differentiated between controlled disease (complete response, partial response, stable disease) and progressive disease with high accuracy, sensitivity, and specificity in patients assessed by RECIST (94.7%, 97.3%, and 90%, respectively; p<0.001) and in patients assessed by irRECIST (94.7%, 93.9%, and 95.8%, respectively; p<0.001). Additionally, the common features of the RECIST and irRECIST groups also highly predicted pembrolizumab response with accuracy, sensitivity, specificity, and p value of 94.7%, 97%, 90%, p<0.001% and 96%, 96%, 95%, p<0.001, respectively.

CONCLUSION

Our radiomics-based signature identified imaging differences that predicted pembrolizumab response in patients with advanced rare cancer.

INTERPRETATION

Our radiomics-based signature identified imaging differences that predicted pembrolizumab response in patients with advanced rare cancer.

How to Best Exploit Immunotherapeutics in Advanced Gastric Cancer: Between Biomarkers and Novel Cell-Based Approaches

Despite extensive research efforts, advanced gastric cancer still has a dismal prognosis with conventional treatment options. Immune checkpoint inhibitors have revolutionized the treatment landscape for many solid tumors. Amongst gastric cancer subtypes, tumors with microsatellite instability and Epstein Barr Virus positive tumors provide the strongest rationale for responding to immunotherapy. Various predictive biomarkers such as mismatch repair status, programmed death ligand 1 expression, tumor mutational burden, assessment of tumor infiltrating lymphocytes and circulating biomarkers have been evaluated. However, results have been inconsistent due to different methodologies and thresholds used. Clinical implementation therefore remains a challenge. The role of immune checkpoint inhibitors in gastric cancer is emerging with data from monotherapy in the heavily pre-treated population already available and studies in earlier disease settings with different combinatorial approaches in progress. Immune checkpoint inhibitor combinations with chemotherapy (CT), anti-angiogenics, tyrosine kinase inhibitors, anti-Her2 directed therapy, poly (ADP-ribose) polymerase inhibitors or dual checkpoint inhibitor strategies are being explored. Moreover, novel strategies including vaccines and CAR T cell therapy are also being trialed. Here we provide an update on predictive biomarkers for response to immunotherapy with an overview of their strengths and limitations. We discuss clinical trials that have been reported and trials in progress whilst providing an account of future steps needed to improve outcome in this lethal disease.

Current status of PD-1/PD-L1 blockade immunotherapy in breast cancer

Over the past 10 years, immunotherapy with immune checkpoint inhibitors has revolutionized the management of various cancers. However, immunotherapy in breast cancer has not been successful. Breast cancer has long been recognized as an immunologically 'cold' tumor, although a higher frequency of tumor-infiltrating lymphocytes present in certain subtypes and an association between tumor-infiltrating lymphocytes and favorable prognosis have been reported. In March 2019, the combination of atezolizumab and nanoparticle albumin-bound paclitaxel was granted accelerated approval in the United States for the treatment of programmed death-ligand 1-positive advanced or metastatic triple-negative breast cancer. This finally opened the door for immune checkpoint blockade therapy for breast cancer. Several clinical trials have been conducted using different combinations of immune checkpoint inhibitors and chemotherapy or targeted agents in various treatment settings for metastatic breast cancer and early-stage breast cancer. In this review, we summarize recent advances in immune checkpoint blockade therapy and predictive biomarkers in breast cancer.

Detection of Microsatellite Instability: State of the Art and Future Applications in Circulating Tumour DNA (ctDNA)

Simple Summary

Microsatellite instability (MSI) is a molecular fingerprint for defects in the mismatch repair system (dMMR) and is associated with higher risks of cancers. MSI/dMMR tumours are characterized by the accumulation of mutations throughout the genome, and particularly in microsatellite (MS) DNA repeat sequences. MSI stands as a major biomarker for familial cancer risk assessment, cancer prognosis, and therapeutic choices. Standard-of-care classification of MSI/dMMR tumours is most frequently achieved using immunohistochemistry or PCR-based assay directed against a set of five MS regions. However, novel molecular methods based on tumour tissue or plasma samples have been developed and could enter in the future trends of MSI testing. Here, we provide insights into these emerging approaches and discuss their advantages and limitations.

Abstract

Microsatellite instability (MSI) is a molecular scar resulting from a defective mismatch repair system (dMMR) and associated with various malignancies. MSI tumours are characterized by the accumulation of mutations throughout the genome and particularly clustered in highly repetitive microsatellite (MS) regions. MSI/dMMR status is routinely assessed in solid tumours for the initial screening of Lynch syndrome, the evaluation of cancer prognosis, and treatment decision-making. Currently, pentaplex PCR-based methods and MMR immunohistochemistry on tumour tissue samples are the standard diagnostic methods for MSI/dMMR. Other tissue methods such as next-generation sequencing or real-time PCR-based systems have emerged and represent viable alternatives to standard MSI testing in specific settings. The evolution of the standard molecular techniques has offered the opportunity to extend MSI determination to liquid biopsy based on the analysis of cell-free DNA (cfDNA) in plasma. This review aims at synthetizing the standard and emerging techniques used on tumour tissue samples for MSI/dMMR determination. We also provide insights into the MSI molecular techniques compatible with liquid biopsy and the potential clinical consequences for patients with solid cancers.

Improving Breast Cancer Responses to Immunotherapy-a Search for the Achilles Heel of the Tumor Microenvironment

PURPOSE OF REVIEW

To explore the role of the tumor microenvironment (TME) in breast cancer, identify the changes that occur in the TME during breast cancer progression, and explore the possibility of modifying the TME to improve immune checkpoint inhibitor responses.

RECENT FINDINGS

Emerging evidence shows the TME may be shaped by internal and external factors. Preclinical data suggests it may be possible to shift the TME to allow for better immune infiltration. In this review, we summarize emerging evidence of changes in the TME and how it can affect prognosis and responses to therapy. We also examine pre-clinical and clinical research aiming at modulating TME to increase proportion of patients who benefit from immune checkpoint inhibitors. The composition of the TME in breast cancer is likely dynamic and may be altered. These changes may lead to more or less responses to immunotherapy.

Emerging Trends for Radio-Immunotherapy in Rectal Cancer

Rectal cancer is a heterogeneous disease at the genetic and molecular levels, both aspects having major repercussions on the tumor immune contexture. Whilst microsatellite status and tumor mutational load have been associated with response to immunotherapy, presence of tumor-infiltrating lymphocytes is one of the most powerful prognostic and predictive biomarkers. Yet, the majority of rectal cancers are characterized by microsatellite stability, low tumor mutational burden and poor T cell infiltration. Consequently, these tumors do not respond to immunotherapy and treatment largely relies on radiotherapy alone or in combination with chemotherapy followed by radical surgery. Importantly, pre-clinical and clinical studies suggest that radiotherapy can induce a complete reprograming of the tumor microenvironment, potentially sensitizing it for immune checkpoint inhibition. Nonetheless, growing evidence suggest that this synergistic effect strongly depends on radiotherapy dosing, fractionation and timing. Despite ongoing work, information about the radiotherapy regimen required to yield optimal clinical outcome when combined to checkpoint blockade remains largely unavailable. In this review, we describe the molecular and immune heterogeneity of rectal cancer and outline its prognostic value. In addition, we discuss the effect of radiotherapy on the tumor microenvironment, focusing on the mechanisms and benefits of its combination with immune checkpoint inhibitors.

Immunotherapy in Adrenocortical Carcinoma: Predictors of Response, Efficacy, Safety, and Mechanisms of Resistance

Adrenocortical carcinoma (ACC) is a rare endocrine malignancy with limited treatment options in the advanced stages. Immunotherapy offers hope for altering the orthodox management of cancer, and its role in advanced ACC has been investigated in different studies. With the aim clarifying the role of immunotherapy in ACC we performed a comprehensive review about this topic focusing on the predictors of response, efficacy, safety, and the mechanisms of resistance. Five clinical trials with four immune checkpoint inhibitors (pembrolizumab, avelumab, nivolumab, and ipilimumab) have investigated the role of immunotherapy in advanced ACC. Despite, the different primary endpoints used in these studies, the reported rates of overall response rate and progression free survival were generally poor. Three main potential markers of response to immunotherapy in ACC have been described: Expression of PD-1 and PD-L1, microsatellite instability and tumor mutational burden. However, none of them has been validated in prospective studies. Several mechanisms of ACC immunoevasion may be responsible of immunotherapy failure, and a greater knowledge of these mechanisms might lead to the development of new strategies to overcome the immunotherapy resistance. In conclusion, although currently the role of immunotherapy is limited, the identification of immunological markers of response and the implementation of strategies to avoid immunotherapy resistance could improve the efficacy of this therapy.

If small molecules immunotherapy comes, can the prime be far behind?

Anti-cancer immunotherapy, which includes cellular immunotherapy, immune checkpoint inhibitors and cancer vaccines, has transformed the treatment strategies of several malignancies in the past decades. Immune checkpoints blockade (ICB) is the most commonly tested therapy and has the potential to induce a durable immune response in different types of cancers. However, all approved immune checkpoint inhibitors (ICIs) are monoclonal antibodies (mAbs), which are fraught with disadvantages including lack of oral bioavailability, prolonged tissue retention and poor membrane permeability. Therefore, the research focus has shifted to developing small molecule inhibitors to obviate the limitations of mAbs. Given the complexity of the tumor micro-environment (TME), the combination of ICIs with various small molecule agonists/inhibitors are currently being tested in clinical trials to improve treatment outcomes and prevent tumor recurrence. In this review, we have summarized the mechanisms and therapeutic potential of several molecular targets, along with the current status of small molecule inhibitors.

Cancer Immunotherapy Update: FDA-Approved Checkpoint Inhibitors and Companion Diagnostics

Immune checkpoint inhibitors (ICIs) are considered a new standard-of-care across many cancer indications. This review provides an update on ICIs approved by the Food and Drug Administration (FDA), with focus on monoclonal antibodies that target the programmed cell death 1 (PD-1) or its ligand, PD-1 ligand 1 (PD-L1), including information on their clinical indications and associated companion diagnostics. The information is further discussed with strategies for identifying predictive biomarkers to guide the clinical use of PD-1/PD-L1-targeted therapies.

CD4 T Cell-Dependent Rejection of Beta-2 Microglobulin Null Mismatch Repair-Deficient Tumors

Inactivation of beta-2 microglobulin (B2M) is considered a determinant of resistance to immune checkpoint inhibitors (ICPi) in melanoma and lung cancers. In contrast, B2M loss does not appear to affect response to ICPis in mismatch repair-deficient (MMRd) colorectal tumors where biallelic inactivation of B2M is frequently observed. We inactivated B2m in multiple murine MMRd cancer models. Although MMRd cells would not readily grow in immunocompetent mice, MMRd B2m null cells were tumorigenic and regressed when treated with anti-PD-1 and anti-CTLA4. The efficacy of ICPis against MMRd B2m null tumors did not require CD8⁺ T cells but relied on the presence of CD4⁺ T cells. Human tumors expressing low levels of B2M display increased intratumoral CD4⁺ T cells. We conclude that B2M inactivation does not blunt the efficacy of ICPi in MMRd tumors, and we identify a unique role for CD4⁺ T cells in tumor rejection. SIGNIFICANCE: B2M alterations, which impair antigen presentation, occur frequently in microsatellite-unstable colorectal cancers. Although in melanoma and lung cancers B2M loss is a mechanism of resistance to immune checkpoint blockade, we show that MMRd tumors respond to ICPis through CD4⁺ T-cell activation.This article is highlighted in the In This Issue feature, p. 1601.

Role of immunotherapy in gastro-enteropancreatic neuroendocrine neoplasms (gep-nens): Current advances and future directions

Neuroendocrine neoplasms (NENs) are heterogeneous tumours originating from neuroendocrine cells (Pearse & Polak, Gut, 1971, 12,783). They were once considered as rare tumours, although their annual incidence has increased significantly and now exceeds seven cases in 100 000 in the USA (Dasari, et al., JAMA oncology, 2017, 3, 1335). They are a group of highly diverse neoplasms and can be classified into the spectrum of well-differentiated neuroendocrine tumours to poorly differentiated neuroendocrine carcinomas. This is entirely based on the tumour differentiation and grade (low, intermediate, high), which is determined by the Ki-67/mitotic index. The lower grades (G1/2) of the well-differentiated group are characterised by a relative indolent clinical course and the ability to secrete a variety of peptide hormones (Kloppel, Visceral medicine, 2017, 33, 324). Higher grades and poorly differentiated tumours tend to be more aggressive and have limited therapeutic options (Sorbye et al., Neuroendocrinology, 2019, 108, 54). In the modern era of immuno-oncology, immune checkpoint inhibitors (ICPIs) that target programmed cell death 1 (pembrolizumab, nivolumab), programmed cell death-ligand1 (avelumab, atezolizumab and durvalumab) or cytotoxic T-lymphocyte-associated protein 4 (ipilimumab) have revolutionised the management of many solid tumours. In patients with gastro-enteropancreatic (GEP)-NENs, there is a limited data regarding the role of ICPIs either as a single agent or in combination regimens. Here, we review the current advances for ICPIs and where they fit in the management of GEP-NENs.

Molecular subtypes of colorectal cancer: An emerging therapeutic opportunity for personalized medicine

Molecular subtypes-based therapies offer new potential framework for desired and precise outcome in clinical settings. Current treatment strategies in colorectal cancer are largely 'one drug fit all' model for patients that display same pathological conditions. However, CRC is a very heterogenous set of malignancy that does not support for above criteria. Each subtype displays different pathological and genetic signatures. Based on these features, therapeutic stratification for individual patients may be designed, which may ultimately lead to improved therapeutic outcomes. In this comprehensive review, we have attempted to briefly outline major CRC pathways. A detailed overview of molecular subtypes and their clinical significance has been discussed. Present and future methods, governing CRC subtyping in the era of personalized therapy with a special emphasis on CMS subtypes of CRC has been reviewed. Together, discovery and validation of new CRC patient stratification methods, screening for novel therapeutic targets, and enhanced diagnosis of CRC may improve the treatment outcome.

ESMO recommendations on the standard methods to detect RET fusions and mutations in daily practice and clinical research

Aberrant activation of RET is a critical driver of growth and proliferation in diverse solid tumours. Multikinase inhibitors (MKIs) showing anti-RET activities have been tested in RET-altered tumours with variable results. The low target specificity with consequent increase in side-effects and off-target toxicities resulting in dose reduction and drug discontinuation are some of the major issues with MKIs. To overcome these issues, new selective RET inhibitors such as pralsetinib (BLU-667) and selpercatinib (LOXO-292) have been developed in clinical trials, with selpercatinib recently approved by the Food and Drug Administration (FDA). The results of these trials showed marked and durable antitumour activity and manageable toxicity profiles in patients with RET-altered tumours. The European Society for Medical Oncology (ESMO) Translational Research and Precision Medicine Working Group (TR and PM WG) launched a collaborative project to review the available methods for the detection of RET gene alterations, their potential applications and strategies for the implementation of a rational approach for the detection of RET fusion genes and mutations in human malignancies. We present here recommendations for the routine clinical detection of targetable RET rearrangements and mutations.

Emerging trends in colorectal cancer: Dysregulated signaling pathways (Review)

Colorectal cancer (CRC) is the third most frequently detected type of cancer, and the second most common cause of cancer‑related mortality globally. The American Cancer Society predicted that approximately 147,950 individuals would be diagnosed with CRC, out of which 53,200 individuals would succumb to the disease in the USA alone in 2020. CRC‑related mortality ranks third among both males and females in the USA. CRC arises from 3 major pathways: i) The adenoma‑carcinoma sequence; ii) serrated pathway; and iii) the inflammatory pathway. The majority of cases of CRC are sporadic and result from risk factors, such as a sedentary lifestyle, obesity, processed diets, alcohol consumption and smoking. CRC is also a common preventable cancer. With widespread CRC screening, the incidence and mortality from CRC have decreased in developed countries. However, over the past few decades, CRC cases and mortality have been on the rise in young adults (age, <50 years). In addition, CRC cases are increasing in developing countries with a low gross domestic product (GDP) due to lifestyle changes. CRC is an etiologically heterogeneous disease classified by tumor location and alterations in global gene expression. Accumulating genetic and epigenetic perturbations and aberrations over time in tumor suppressor genes, oncogenes and DNA mismatch repair genes could be a precursor to the onset of colorectal cancer. CRC can be divided as sporadic, familial, and inherited depending on the origin of the mutation. Germline mutations in APC and MLH1 have been proven to play an etiological role, resulting in the predisposition of individuals to CRC. Genetic alterations cause the dysregulation of signaling pathways leading to drug resistance, the inhibition of apoptosis and the induction of proliferation, invasion and migration, resulting in CRC development and metastasis. Timely detection and effective precision therapies based on the present knowledge of CRC is essential for successful treatment and patient survival. The present review presents the CRC incidence, risk factors, dysregulated signaling pathways and targeted therapies.

Rheumatic Complications of Immune Checkpoint Inhibitors

Immune checkpoint inhibitors activate the immune system to combat cancer. In doing so, however, they can cause immune-related adverse events (irAEs), including rheumatic syndromes, such as inflammatory arthritis, polymyalgia rheumatica, and myositis. This article reviews rheumatic irAEs that may be encountered in the general medicine practice and provides guidance to support prompt recognition, referral, and treatment of these patients.

Comprehensive Genomic Profiling of Rare Tumors in China: Routes to Immunotherapy

Treatment options for rare tumors are limited, and comprehensive genomic profiling may provide useful information for novel treatment strategies and improving outcomes. The aim of this study is to explore the treatment opportunities of patients with rare tumors using immune checkpoint inhibitors (ICIs) that have already been approved for routine treatment of common tumors. We collected immunotherapy-related indicators data from a total of 852 rare tumor patients from across China, including 136 programmed cell death ligand-1 (PD-L1) expression, 821 tumors mutational burden (TMB), 705 microsatellite instability (MSI) and 355 human leukocyte antigen class I (HLA-I) heterozygosity reports. We calculated the positive rates of these indicators and analyzed the consistency relationship between TMB and PD-L1, TMB and MSI, and HLA-I and PD-L1. The prevalence of PD-L1 positive, TMB-H, MSI-, and HLA-I -heterozygous was 47.8%, 15.5%, 7.4%, and 78.9%, respectively. The consistency ratio of TMB and PD-L1, TMB and MSI, and HLA-I and PD-L1 was 54.8% (78/135), 87.3% (598/685), and 47.4% (54/114), respectively. The prevalence of the four indicators varied widely across tumors systems and subtypes. The probability that neuroendocrine tumors (NETs) and biliary tumors may benefit from immunotherapy is high, since the proportion of TMB-H is as high as 50% and 25.4% respectively. The rates of PD-L1 positivity, TMB-H and MSI-H in carcinoma of unknown primary (CUP) were relatively high, while the rates of TMB-H and MSI-H in soft tissue tumors were both relatively low. Our study revealed the distribution of immunotherapeutic indicators in patients with rare tumors in China. Comprehensive genomic profiling may offer novel therapeutic modalities for patients with rare tumors to solve the dilemma of limited treatment options.

Clinicopathological and molecular characteristics of patients with hypermutant lung cancer: A retrospective cohort study

Tumor mutation burden (TMB) is an independent indicator used to select patients sensitive to immunotherapy. The present study aimed to investigate the clinicopathological and molecular characteristics of patients with hypermutant lung cancer to identify an economical, simple and complementary method for predicting TMB and immunotherapy responses. In total, 1,000 patients with lung cancer were randomly selected, and their samples were submitted to next-generation sequencing, with their TMB status reviewed. The threshold of hypermutation was set to 17.24 mutations (muts)/Mb. The proportion of smokers was higher in the hypermutant cohort (n=67) compared with in the non-hypermutant cohort (n=933; 85.1 vs. 46.6%; P<0.0001). Compared with in the non-hypermutant cohort, the proportion of squamous cell carcinoma cases and small cell lung cancer cases was higher in the hypermutant cohort (22.4 vs. 13.1% and 6.0 vs. 2.6%, respectively). In addition, compared with in the non-hypermutant cohort, mutations in the low-density lipoprotein receptor-related protein 1B were more frequently observed in the hypermutant cohort (67.2 vs. 14.3%; P<0.0001). A similar trend was obtained for all genes tested, except for the EGFR gene. Furthermore, in the hypermutant cohort, the prevalence of microsatellite instability was extremely high (9.0%). The mutation frequency in DNA damage response (DDR) genes was notably higher in the hypermutant cohort, where several DDR-associated genes were enriched, compared with in the non-hypermutant cohort. The enrichment analysis revealed a strong association between mutations in Notch signaling and high TMB. To the best of our knowledge, the present study is the first to comprehensively investigate the clinical and genetic characteristics of patients with hypermutant lung cancer in a Chinese population. The results of the current study suggested that hypermutant lung cancer exerted distinctive clinical and genetic features, which may be used as complementary indicators for screening patients sensitive to immunotherapy.

Genetic and molecular subtype heterogeneity in newly diagnosed early- and advanced-stage endometrial cancer

OBJECTIVE

To characterize and compare the molecular subtypes and profiles of prospectively-accrued newly-diagnosed early- and advanced-stage endometrial cancers (ECs).

METHODS

EC patients consented to an IRB-approved protocol of massively parallel sequencing of 410-468 cancer-related genes; 175 ECs of 7 histologic types (n = 135 FIGO stages I/II, n = 40 FIGO stages III/IV) were included. Previously reported sequencing data from 99 additional advanced-stage ECs were retrieved for comparisons.

RESULTS

Irrespective of histologic type, all 175 ECs could be stratified into the molecular subtypes, with 75 (43%) being of p53 wild-type, 49 (28%) MMR-deficient, 39 (22%) p53 abnormal and 12 (7%) of POLE molecular subtypes. Subtype distribution, mutational and copy number profiles varied according to histologic type. In endometrioid ECs, genetic alterations varied according to histologic grade. Potential therapeutic targets, including high tumor mutational burden, ERBB2 amplification and PIK3CA hotspot mutations, were found across histologic types in 63% (n = 110) of all ECs. Compared to their early-stage counterparts, advanced-stage endometrioid ECs had a significantly higher fraction of genome altered (median 0.1% vs 12%, p < 0.001) and ARID1B mutations (0% vs 11%, p = 0.01), and advanced-stage serous ECs harbored more frequent ERBB2 amplification (18% vs 8%, p > 0.05) and PIK3CA mutations (46% vs 27%, p > 0.05). Whole-genome doubling was found in advanced- but not early-stage carcinosarcomas and clear cell carcinomas.

CONCLUSIONS

Our findings demonstrate the molecular heterogeneity within and across histologic types of EC and the increased genomic complexity of advanced-stage ECs. Molecular subtypes are present across EC histologic types and may help stratify EC patients for prognostic and therapeutic purposes.

The evolving paradigm of biomarker actionability: Histology-agnosticism as a spectrum, rather than a binary quality

Precision medicine is progressively revolutionizing oncology, through the identification of biomarkers predictive of treatment response in cancer patients. For three of such biomarkers, namely NTRK-fusions, microsatellite instability and high tumor mutational burden, drugs have been approved by regulatory agencies regardless of tumor histology, realizing the paradigm of histology-agnostic actionability. Several additional biomarkers are being studied in a histology-agnostic manner, and may in the future expand this list. However, most available evidence suggest that histology-agnosticism may be the extreme of a continuous spectrum of actionability, rather than a binary quality. The present review recapitulates such evidence, highlighting opportunities and challenges posed by the emergence of the spectrum of biomarker actionability in the context of a prevalently histology-based oncology.

Non-Coding RNAs Set a New Phenotypic Frontier in Prostate Cancer Metastasis and Resistance

Prostate cancer (PCa) mortality remains a significant public health problem, as advanced disease has poor survivability due to the development of resistance in response to both standard and novel therapeutic interventions. Therapeutic resistance is a multifaceted problem involving the interplay of a number of biological mechanisms including genetic, signaling, and phenotypic alterations, compounded by the contributions of a tumor microenvironment that supports tumor growth, invasiveness, and metastasis. The androgen receptor (AR) is a primary regulator of prostate cell growth, response and maintenance, and the target of most standard PCa therapies designed to inhibit AR from interacting with androgens, its native ligands. As such, AR remains the main driver of therapeutic response in patients with metastatic castration-resistant prostate cancer (mCRPC). While androgen deprivation therapy (ADT), in combination with microtubule-targeting taxane chemotherapy, offers survival benefits in patients with mCRPC, therapeutic resistance invariably develops, leading to lethal disease. Understanding the mechanisms underlying resistance is critical to improving therapeutic outcomes and also to the development of biomarker signatures of predictive value. The interconversions between epithelial-to-mesenchymal transition (EMT) and mesenchymal-to-epithelial transition (MET) navigate the prostate tumor therapeutic response, and provide a novel targeting platform in overcoming therapeutic resistance. Both microRNA (miRNA)- and long non-coding RNA (lncRNA)-mediated mechanisms have been associated with epigenetic changes in prostate cancer. This review discusses the current evidence-based knowledge of the role of the phenotypic transitions and novel molecular determinants (non-coding RNAs) as contributors to the emergence of therapeutic resistance and metastasis and their integrated predictive value in prostate cancer progression to advanced disease.

A Uniform Computational Approach Improved on Existing Pipelines to Reveal Microbiome Biomarkers of Nonresponse to Immune Checkpoint Inhibitors

PURPOSE

While immune checkpoint inhibitors (ICI) have revolutionized the treatment of cancer by producing durable antitumor responses, only 10%-30% of treated patients respond and the ability to predict clinical benefit remains elusive. Several studies, small in size and using variable analytic methods, suggest the gut microbiome may be a novel, modifiable biomarker for tumor response rates, but the specific bacteria or bacterial communities putatively impacting ICI responses have been inconsistent across the studied populations.

EXPERIMENTAL DESIGN

We have reanalyzed the available raw 16S rRNA amplicon and metagenomic sequencing data across five recently published ICI studies (n = 303 unique patients) using a uniform computational approach.

RESULTS

Herein, we identify novel bacterial signals associated with clinical responders (R) or nonresponders (NR) and develop an integrated microbiome prediction index. Unexpectedly, the NR-associated integrated index shows the strongest and most consistent signal using a random effects model and in a sensitivity and specificity analysis (P < 0.01). We subsequently tested the integrated index using validation cohorts across three distinct and diverse cancers (n = 105).

CONCLUSIONS

Our analysis highlights the development of biomarkers for nonresponse, rather than response, in predicting ICI outcomes and suggests a new approach to identify patients who would benefit from microbiome-based interventions to improve response rates.

The progress and challenge of anti-PD-1/PD-L1 immunotherapy in treating non-small cell lung cancer

The use of programmed cell-death protein 1 (PD-1)/programmed cell-death ligand 1 (PD-L1) inhibitors is the standard therapy for the first-line or second-line treatment of patients with non-small-cell lung cancer (NSCLC). In contrast to current traditional treatments such as chemotherapy or radiotherapy, anti-PD-1 and anti-PD-L1 treatments can directly attenuate tumour-mediated exhaustion and effectively modulate the host anti-tumour immune response in vivo. In addition, compared with traditional therapy, PD-1/PD-L1 inhibitor monotherapy can significantly prolong survival without obvious side effects in the treatment of advanced NSCLC. Ideally, several biomarkers could be used to monitor the safety and effectiveness of anti-PD-1 and anti-PD-L1 treatments; however, the current lack of optimal prognostic markers remains a widespread limitation and challenge for further clinical applications, as does the possibility of immune-related adverse events and drug resistance. In this review, we aimed to summarise the latest progress in anti-PD-1/anti-PD-L1 treatment of advanced NSCLC, worldwide, including in China. An exploration of underlying biomarker identification and future challenges will be discussed in this article to facilitate translational studies in cancer immunotherapy.

Differential expression of PD-L1 between primary and metastatic epithelial ovarian cancer and its clinico-pathological correlation

Ovarian cancer (OC) is one of the most common gynecologic cancer, which has the worst prognosis and highest mortality rate. The lack of curative treatment and the high relapse rate, especially in advanced OC, continues to present a clinical challenge, highlighting the need for new therapeutic strategies. This study was performed to compare the expression of PD-L1 in primary epithelial ovarian cancer (EOC) and their corresponding peritoneal metastases, as well as to evaluate its correlation with clinico-pathological parameters. In total, 194 treatment naïve paired EOC and peritoneal metastasis were analyzed by immunohistochemistry for PD-L1 expression. Clinico-pathological information was available for all patients. Significant differences in PD-L1 expression were found between primary EOC and peritoneal metastasis (p < 0.0001). We found discordant tumor cell PD-L1 expression between primary tumors and corresponding peritoneal metastasis in 34% (66/194) of cases. Furthermore, PD-L1 expression in peritoneal metastasis samples was significantly associated with adverse prognostic factors, such as high proliferative index (Ki67) (p = 0.0039) and high histologic grade (p = 0.0330). In conclusion, the discordance of PD-L1 expression between primary EOC and corresponding peritoneal metastases suggests that its assessment as a potential biomarker for predicting response to anti-PD-L1 therapy may require analysis of metastatic lesions.

Development and validation of a multigene variant profiling assay to guide targeted and immuno therapy selection in solid tumors

We present data on analytical validation of the multigene variant profiling assay (CellDx) to provide actionable indications for selection of targeted and immune checkpoint inhibitor (ICI) therapy in solid tumors. CellDx includes Next Generation Sequencing (NGS) profiling of gene variants in a targeted 452-gene panel as well as status of total Tumor Mutation Burden (TMB), Microsatellite instability (MSI), Mismatch Repair (MMR) and Programmed Cell Death-Ligand 1 (PD-L1) respectively. Validation parameters included accuracy, sensitivity, specificity and reproducibility for detection of Single Nucleotide Alterations (SNAs), Copy Number Alterations (CNAs), Insertions and Deletions (Indels), Gene fusions, MSI and PDL1. Cumulative analytical sensitivity and specificity of the assay were 99.03 (95% CI: 96.54-99.88) and 99.23% (95% CI: 98.54% - 99.65%) respectively with 99.20% overall Accuracy (95% CI: 98.57% - 99.60%) and 99.7% Precision based on evaluation of 116 reference samples. The clinical performance of CellDx was evaluated in a subsequent analysis of 299 clinical samples where 861 unique mutations were detected of which 791 were oncogenic and 47 were actionable. Indications in MMR, MSI and TMB for selection of ICI therapies were also detected in the clinical samples. The high specificity, sensitivity, accuracy and reproducibility of the CellDx assay is suitable for clinical application for guiding selection of targeted and immunotherapy agents in patients with solid organ tumors.

The Challenges of Tumor Mutational Burden as an Immunotherapy Biomarker

Tumor mutational burden (TMB) reflects cancer mutation quantity. Mutations are processed to neo-antigens and presented by major histocompatibility complex (MHC) proteins to T cells. To evade immune eradication, cancers exploit checkpoints that dampen T cell reactivity. Immune checkpoint inhibitors (ICIs) have transformed cancer treatment by enabling T cell reactivation; however, response biomarkers are required, as most patients do not benefit. Higher TMB results in more neo-antigens, increasing chances for T cell recognition, and clinically correlates with better ICI outcomes. Nevertheless, TMB is an imperfect response biomarker. A composite predictor that also includes critical variables, such as MHC and T cell receptor repertoire, is needed.

Management of Non-Colorectal Digestive Cancers with Microsatellite Instability

Microsatellite instability (MSI) is a hallmark of genetic predisposition to DNA damage. It arises from either germline or somatic events leading to impaired function of the mismatch repair system. It can be detected via genetic sequencing or immunohistochemistry with relatively high concordance rates. The presence of MSI in a tumor reflects a high neoantigen load and predicts favorable treatment response to immune checkpoint inhibitors (ICIs). In gastrointestinal cancers, MSI is a predictive biomarker for ICIs with potential prognostic impact but its clinical utility varies widely depending on tumor type. This may be explained by the complexity of tumor microenvironment as highlighted by recent translational studies. In this review, we will discuss the predictive and prognostic value of MSI status in non-colorectal cancers of the digestive system, important clinical trials involving ICIs and potential strategies to overcome resistance to immunotherapy.

Tumour-Agnostic Therapy for Pancreatic Cancer and Biliary Tract Cancer

The prognosis of patients with solid tumours has remarkably improved with the development of molecular-targeted drugs and immune checkpoint inhibitors. However, the improvements in the prognosis of pancreatic cancer and biliary tract cancer is delayed compared to other carcinomas, and the 5-year survival rates of distal-stage disease are approximately 10 and 20%, respectively. However, a comprehensive analysis of tumour cells using The Cancer Genome Atlas (TCGA) project has led to the identification of various driver mutations. Evidently, few mutations exist across organs, and basket trials targeting driver mutations regardless of the primary organ are being actively conducted. Such basket trials not only focus on the gate keeper-type oncogene mutations, such as HER2 and BRAF, but also focus on the caretaker-type tumour suppressor genes, such as BRCA1/2, mismatch repair-related genes, which cause hereditary cancer syndrome. As oncogene panel testing is a vital approach in routine practice, clinicians should devise a strategy for improved understanding of the cancer genome. Here, the gene mutation profiles of pancreatic cancer and biliary tract cancer have been outlined and the current status of tumour-agnostic therapy in these cancers has been reported.

Biomarker Discovery and Validation: Statistical Considerations

Biomarkers have various applications including disease detection, diagnosis, prognosis, prediction of response to intervention, and disease monitoring. In this era of precision medicine, having validated biomarkers to inform clinical decision making is more important than ever. In this article, we discuss best the practices and potential issues in biomarker discovery and validation. We encourage team science partnerships to bring cutting-edge discovery from bench to bedside, leading to improved patient care and outcomes.

Cutaneous squamous-cell carcinoma of the head-neck area refractory to chemo-radiotherapy: benefit from anti-PD-1 immunotherapy

Objective:

Radiotherapy provides excellent results in locally advanced cutaneous squamous-cell carcinoma of the head and neck area (cSCC-HN), with a 2-year local progression-free interval obtained for about 80% of patients. Overexpression of immune checkpoint co-inhibitory molecules, like PD-L1 (programmed death ligand 1), by cancer cells may define local immunosuppression, tumour escape from immune surveillance and reduced radiotherapy efficacy.

Methods:

A 65-year-old female, with a large exophytic cSCC-HN invading adjacent soft tissues, was treated with hypofractionated accelerated chemo-radiotherapy. The patient received four bi-weekly cycles of chemotherapy concurrently with eight fractions of 5.5 Gy (two fractions per week). Two months after the end of chemo-radiotherapy, the tumour was stable in dimensions, without any signs of symptomatic relief. The patient was, after that, treated with anti-PD-1 immunotherapy (nivolumab). The tumour gradually regressed, reaching partial response after four cycles and complete response after 16 cycles of nivolumab. No side-effects related to immunotherapy were recorded. The patient is alive and without evidence of disease 28 months after radiotherapy.

Conclusions:

Treatment of patients with chemo- and radio-resistant cSCC-HN with immunotherapy may optimize the efficacy of radiotherapy by stimulating immunological tumour rejection mechanisms. cSCC-HN patients who fail to respond to chemo-radiotherapy completely are expected to benefit the most from immunotherapy because of the radio-vaccination effect expected from the preceded radiotherapy.

RNA-Seq Reveals Differences in Expressed Tumor Mutation Burden in Colorectal and Endometrial Cancers with and without Defective DNA-Mismatch Repair

Tumor mutation burden (TMB) is an emerging biomarker of immunotherapy response. RNA sequencing in FFPE tissue samples was used for determining TMB in microsatellite-stable (MSS) and microsatellite instability-high (MSI-H) tumors in patients with colorectal or endometrial cancer. Tissue from tumors and paired normal tissue from 46 MSI-H and 12 MSS cases were included. Of the MSI-H tumors, 29 had defective DNA mismatch-repair mutations, and 17 had MLH1 promoter hypermethylation. TMB was measured using the expressed somatic nucleotide variants (eTMB). A method of accurate measurement of eTMB was developed that removes FFPE-derived artifacts by leveraging mutation signatures. There was a significant difference in the median eTMB values observed between MSI-H and MSS cases: 27.3 versus 6.7 mutations/megabase (mut/Mb) (P = 3.5 × 10^-9). Among tumors with defective DNA-mismatch repair, those with mismatch-repair mutations had a significantly higher median eTMB than those with hypermethylation: 28.1 versus 17.5 mut/Mb (P = 0.037). Multivariate analysis showed that MSI status, tumor type (endometrial or colorectal), and age were significantly associated with eTMB. Additionally, using whole-exome sequencing in a subset of these patients, it was determined that DNA TMB correlated well with eTMB (Spearman correlation coefficient, 0.83). These results demonstrate that RNA sequencing can be used for measuring eTMB in FFPE tumor specimens.

Druggable targets meet oncogenic drivers: opportunities and limitations of target-based classification of tumors and the role of Molecular Tumor Boards

The therapeutic landscape of cancer is changing rapidly due to the growing number of approved drugs capable of targeting specific genetic alterations. This aspect, together with the development of noninvasive methods for the assessment of somatic mutations in the peripheral blood of patients, generated a growing interest toward a new tumor-agnostic classification system based on ‘predictive’ biomarkers. The current review article discusses this emerging alternative approach to the classification of cancer and its implications for the selection of treatments. It is suggested that different types of cancers sharing the same molecular profiles could benefit from the same targeted drugs. Although recent clinical trials have demonstrated that this approach cannot be generalized, there are also specific examples that demonstrate the clinical utility of this alternative vision. In this rapidly evolving scenario, a multidisciplinary approach managed by institutional Molecular Tumor Boards is fundamental to interpret the biological and clinical relevance of genetic alterations and the complexity of their relationship with treatment response.

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The identification of oncogenic drivers offers the opportunity to develop target-specific drugs.

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The inhibition of crucial pathways realizes the principle of druggable target to exploit cancer vulnerability.

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The approval of new anticancer agents based on target-based concept represents a paradigm shift in cancer therapy.

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However, only few drugs have been approved so far on an agnostic basis and the concept of biomarker cannot be generalized.

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Tumor Molecular Boards will have an increasing role in the identification of new therapeutic options in selected patients.

Immune-Checkpoint Blockade Enhances 225Ac-PSMA617 Efficacy in a Mouse Model of Prostate Cancer

Prostate-specific membrane antigen (PSMA)-targeted radionuclide therapy (RNT) may increase tumor immunogenicity. We aimed at exploiting this effect by combining RNT with immunotherapy in a mouse model of prostate cancer (PC). Methods: C57BL/6-mice bearing syngeneic RM1-PGLS tumors were treated with ²²⁵Ac-PSMA617, an anti-PD-1 antibody, or both. Therapeutic efficacy was assessed by tumor volume measurements (CT), time to progression (TTP), and survival. Results: PSMA RNT or anti-PD-1 alone tended to prolong TTP (isotype control, 25 d; anti-PD-1, 33.5 d [P = 0.0153]; RNT, 30 d [P = 0.1038]) and survival (control, 28 d; anti-PD-1, 37 d [P = 0.0098]; RNT, 32 d [P = 0.1018]). Combining PSMA RNT and anti-PD-1 significantly improved disease control compared with either monotherapy. TTP was extended to 47.5 d (P ≤ 0.0199 vs. monotherapies), and survival to 51.5 d (P ≤ 0.0251 vs. monotherapies). Conclusion: PSMA RNT and PD-1 blockade synergistically improve therapeutic outcomes in our PC model, supporting the evaluation of RNT and immunotherapy combinations for PC patients.

Germline genetic contribution to the immune landscape of cancer

Understanding the contribution of the host's genetic background to cancer immunity may lead to improved stratification for immunotherapy and to the identification of novel therapeutic targets. We investigated the effect of common and rare germline variants on 139 well-defined immune traits in ∼9000 cancer patients enrolled in TCGA. High heritability was observed for estimates of NK cell and T cell subset infiltration and for interferon signaling. Common variants of IFIH1, TMEM173 (STING1), and TMEM108 were associated with differential interferon signaling and variants mapping to RBL1 correlated with T cell subset abundance. Pathogenic or likely pathogenic variants in BRCA1 and in genes involved in telomere stabilization and Wnt-β-catenin also acted as immune modulators. Our findings provide evidence for the impact of germline genetics on the composition and functional orientation of the tumor immune microenvironment. The curated datasets, variants, and genes identified provide a resource toward further understanding of tumor-immune interactions.

Pembrolizumab in unresectable or metastatic MSI-high colorectal cancer: safety and efficacy

INTRODUCTION

Microsatellite instability-high (MSI-H) colorectal cancer (CRC) represents a unique subset of CRC characterized by elevated neoantigen expression and a high degree of intraepithelial T-cell infiltrate. These characteristics make MSI-H tumors particularly susceptible to immune checkpoint inhibitors (ICIs) such as pembrolizumab which inhibit the negative regulation of cytotoxic T-cells and promote T-cell mediated anti-tumor activity.

AREAS COVERED

We discuss the drug development of pembrolizumab including the seminal studies which enabled the drug to garner FDA approvals in the refractory and first-line settings for patients with MSI-H CRC, the pharmacokinetic & pharmacodynamic profile of the agent, and the adverse event profile of the ICI. We also discuss unmet needs in the arena of ICIs including strategies to overcome tumor resistance and to increase the applicability of the agents to a broader population of CRC patients.

EXPERT OPINION

Despite the anti-tumor activity of pembrolizumab in patients with MSI-H CRC, 30-35% of patients fail to derive any benefit. Ongoing research efforts are seeking to identify ICI combinations, which can overcome CRC resistance to pembrolizumab, move ICIs into the treatment paradigm for patients with localized MSI-H CRC and enable ICIs to become meaningful treatment options for patients with microsatellite stable CRC.

Gutting it Out: Developing Effective Immunotherapies for Patients With Colorectal Cancer

Risk factors for colorectal cancer (CRC) include proinflammatory diets, sedentary habits, and obesity, in addition to genetic syndromes that predispose individuals to this disease. Current treatment relies on surgical excision and cytotoxic chemotherapies. There has been a renewed interest in immunotherapy as a treatment option for CRC given the success in melanoma and microsatellite instable (MSI) CRC. Immunotherapy with checkpoint inhibitors only plays a role in the 4%-6% of patients with MSIhigh tumors and even within this subpopulation, response rates can vary from 30% to 50%. Most patients with CRC do not respond to this modality of treatment, even though colorectal tumors are frequently infiltrated with T cells. Tumor cells limit apoptosis and survive following intensive chemotherapy leading to drug resistance and induction of autophagy. Pharmacological or molecular inhibition of autophagy improves the efficacy of cytotoxic chemotherapy in murine models. The microbiome clearly plays an etiologic role, in some or most colon tumors, realized by elegant findings in murine models and now investigated in human clinical trials. Recent results have suggested that cancer vaccines may be beneficial, perhaps best as preventive strategies. The search for therapies that can be combined with current approaches to increase their efficacy, and new knowledge of the biology of CRC are pivotal to improve the care of patients suffering from this disease. Here, we review the basic immunobiology of CRC, current "state-of-the-art" immunotherapies and define those areas with greatest therapeutic promise for the future.

PD-L1 Expression Is Associated with Deficient Mismatch Repair and Poor Prognosis in Middle Eastern Colorectal Cancers

Several clinical trials are investigating the use of immune-targeted therapy with Programmed death ligand-1 (PD-L1) inhibitors for colorectal cancer (CRC), with promising results for patients with mismatch repair (MMR) deficiency or metastatic CRC. However, the prognostic significance of PD-L1 expression in CRC is controversial and such data are lacking in CRC from Middle Eastern ethnicity. We carried out this large retrospective study to investigate the prognostic and clinico-pathological impact of PD-L1 expression in Middle Eastern CRC using immunohistochemistry. A total of 1148 CRC were analyzed for PD-L1 expression. High PD-L1 expression was noted in 37.3% (428/1148) cases and was correlated with aggressive clinico-pathological features such as high malignancy grade (p < 0.0001), larger tumor size (p = 0.0007) and mucinous histology (p = 0.0005). Interestingly, PD-L1 expression was significantly higher in patients exhibiting MMR deficiency (p = 0.0169) and BRAF mutation (p = 0.0008). Furthermore, the expression of PD-L1 was found to be an independent marker for overall survival (HR = 1.45; 95% CI = 1.06 - 1.99; p = 0.0200). In conclusion, the results of this study indicate that PD-L1 expression could be a valid biomarker for poor prognosis in Middle Eastern CRC patients. This information can help in decision-making for anti-PD-L1 therapy in Middle Eastern CRC, especially for patients with MMR deficient tumors.

Characteristics of Adrenocortical Carcinoma Associated With Lynch Syndrome

CONTEXT

Lynch syndrome (LS) is the most common inherited colorectal and endometrial cancer syndrome, caused by germline mutations in DNA mismatch repair (MMR) genes. It is also characterized by an increased risk of other tumors with lower prevalence, such as adrenal cortical carcinoma (ACC), an endocrine tumor with an incidence of <2 cases/million individuals/year. Most ACC developed during childhood are associated with hereditary syndromes. In adults, this association is not as well established as in children. Previous studies showed a 3.2% prevalence of LS among patients with ACC.

EVIDENCE ACQUISITION

The objective of this study is to determine the prevalence of ACC in a Spanish LS cohort and their molecular and histological characteristics. This retrospective study includes 634 patients from 220 LS families registered between 1999 and 2018.

EVIDENCE SYNTHESIS

During the follow-up period, 3 patients were diagnosed with ACC (0.47%); all were carriers of a MSH2 germline mutation. The 3 ACC patients presented loss of expression of MSH2 and MSH6 proteins. One tumor analysis showed loss of heterozygosity of the MSH2 wildtype allele. Our findings support previous data that considered ACC as a LS spectrum tumor.

CONCLUSION

MMR protein immunohistochemistry screening could be an efficient strategy to detect LS in patients with ACC.