Tumor mutational load predicts survival after immunotherapy across multiple cancer types

Optimal management of gastroesophageal junction cancer

Although recent decades have witnessed incremental improvements in the treatment of gastroesophageal junction (GEJ) carcinoma, outcomes remain modest. For locally advanced esophageal cancer, the addition of chemotherapy and/or radiation to surgery is considered the standard of care. Chemotherapy remains the primary treatment for metastatic disease and improves survival over best supportive care. However, the prognosis for patients with GEJ cancers, which are treated along the same paradigms as esophageal and gastric carcinomas, remain poor because of the emergence of chemoresistance and limited targeted therapeutic approaches, which include agents that target the HER2 and vascular endothelial growth factor pathways. Evaluation of immune checkpoint inhibitors in the chemorefractory setting have confirmed the activity of immunotherapy in esophagogastric cancer. Ongoing immunotherapeutic strategies are being evaluated in both the locally advanced and metastatic settings. This review focuses on the treatment of locally advanced and metastatic GEJ carcinomas, which encompass all tumors that have an epicenter within 5 cm proximal or distal to the anatomical Z-line (Siewert classification). Because the vast majority of GEJ tumors are adenocarcinoma, the management of adenocarcinoma is the focus of this review. Evolving approaches and areas of clinical equipoise are discussed.

Use of targeted next generation sequencing to characterize tumor mutational burden and efficacy of immune checkpoint inhibition in small cell lung cancer

BACKGROUND

Clinically-available biomarkers to identify the fraction of patients with small cell lung cancer (SCLC) who respond to immune-checkpoint inhibitors (ICIs) are lacking. High nonsynonymous tumor mutational burden (TMB), as assessed by whole exome sequencing, correlates with improved clinical outcomes for patients with SCLC treated with ICIs. Whether TMB as assessed by targeted next generation sequencing (NGS) is associated with improved efficacy of ICIs in patients with SCLC is currently unknown. Here we determined whether TMB by targeted NGS is associated with efficacy of ICIs in patients with SCLC.

METHODS

We collected clinicopathologic data from patients with relapsed or refractory SCLC which underwent targeted NGS with TMB assessment by the Dana-Farber Cancer Institute OncoPanel platform. The relationship between TMB and clinical outcomes after treatment with ICIs was investigated.

RESULTS

Among the 52 patients treated with ICIs, we found no significant difference in the objective response rate (ORR) between patients with a TMB above the 50th percentile ("TMB high") and those with a TMB at or below the 50th percentile ("TMB low"). The median progression-free survival (mPFS) and median overall survival (mOS) were significantly longer in patients with a high TMB compared to those with a low TMB (mPFS: 3.3 versus 1.2 months, HR: 0.37 [95% CI: 0.20-0.69], P < 0.01; mOS: 10.4 versus 2.5 months, HR: 0.38 [95% CI: 0.19-0.77], P < 0.01). The one-year PFS and OS rates improved with increasing mutational load when TMB was divided into tertiles.

CONCLUSIONS

These findings show that targeted NGS, a readily available clinical diagnostic test, can be used to identify patients with SCLC who are most likely to benefit from treatment with immune checkpoint inhibitors.

Loss of BAP1 as a candidate predictive biomarker for immunotherapy of mesothelioma

As trials of immune checkpoint inhibitor (ICI) therapies demonstrate responses in only a minority of pleural mesotheliomas (PlMs) and largely exclude patients with the related peritoneal mesothelioma (PeM), clinicians need predictive biomarkers of response and inclusion of PeM patients in future trials. A new study finds that loss of the deubiquitinase BAP1 in PeM correlates with an inflammatory tumor microenvironment, suggesting that BAP1 status might identify PeM, and possibly PlM, patients who would benefit from ICI therapy.

Immune Evasion by Head and Neck Cancer: Foundations for Combination Therapy

Head and neck cancer is disfiguring and deadly, and contemporary treatment has fallen short in terms of morbidity and mortality. The rich immune infiltrate within these tumors designates them as prime candidates for immunotherapy and success with these drugs has been documented for recurrent and metastatic head and neck cancer. Still, single-agent immunotherapy has generated either only transient responses or durable response in only a minority subset of patients. Mapping the immune escape mechanisms enacted by head and neck cancer within the tumor microenvironment allows for rational design of strategies to overcome this tolerance. We outline the immune pathway derangements within the head and neck cancer microenvironment and discuss combination treatment strategies to overcome the limitations of immunologic monotherapy.

Iron overload and liver cancer

A novel mouse model of liver cancer induced by iron overload through deleting the iron-sensing ubiquitin ligase FBXL5.

In this issue of JEM, Muto et al. (https://doi.org/10.1084/jem.20180900) generate a novel mouse model of liver cancer induced by iron overload by deleting the iron-sensing ubiquitin ligase FBXL5 specifically in hepatocytes and exposure to a chemical carcinogen.

Cancer Biogenesis in Ribosomopathies

Ribosomopathies are congenital diseases with defects in ribosome assembly and are characterized by elevated cancer risks. Additionally, somatic mutations in ribosomal proteins have recently been linked to a variety of cancers. Despite a clear correlation between ribosome defects and cancer, the molecular mechanisms by which these defects promote tumorigenesis are unclear. In this review, we focus on the emerging mechanisms that link ribosomal defects in ribosomopathies to cancer progression. This includes functional "onco-specialization" of mutant ribosomes, extra-ribosomal consequences of mutations in ribosomal proteins and ribosome assembly factors, and effects of ribosomal mutations on cellular stress and metabolism. We integrate some of these recent findings in a single model that can partially explain the paradoxical transition from hypo- to hyperproliferation phenotypes, as observed in ribosomopathies. Finally, we discuss the current and potential strategies, and the associated challenges for therapeutic intervention in ribosome-mutant diseases.

Chimeric Antigen Receptor T Cell Therapy for Solid Tumors: Current Status, Obstacles and Future Strategies

Chimeric antigen receptor T cells (CAR T Cells) have led to dramatic improvements in the survival of cancer patients, most notably those with hematologic malignancies. Early phase clinical trials in patients with solid tumors have demonstrated them to be feasible, but unfortunately has yielded limited efficacy for various cancer types. In this article we will review the background on CAR T cells for the treatment of solid tumors, focusing on the unique obstacles that solid tumors present for the development of adoptive T cell therapy, and the novel approaches currently under development to overcome these hurdles.

The more (mutations), the better

High somatic tumor mutational burden predicts response to immune checkpoint inhibitors across multiple cancers.

Reprogramming the Tumor Microenvironment to Improve Immunotherapy: Emerging Strategies and Combination Therapies

Emerging immunotherapeutic approaches have revolutionized the treatment of multiple malignancies. Immune checkpoint blockers (ICBs) have enabled never-before-seen success rates in durable tumor control and enhanced survival benefit in patients with advanced cancers. However, this effect is not universal, resulting in responder and nonresponder populations not only between, but also within solid tumor types. Although ICBs are thought to be most effective against tumors with more genetic mutations and higher antigen loads, this is not always the case for all cancers or for all patients within a cancer subtype. Furthermore, debilitating and sometimes deadly immune-related adverse events (irAEs) have resulted from aberrant activation of T-cell responses following immunotherapy. Thus, we must identify new ways to overcome resistance to ICB-based immunotherapies and limit irAEs. In fact, preclinical and clinical data have identified abnormalities in the tumor microenvironment (TME) that can thwart the efficacy of immunotherapies such as ICBs. Here, we will discuss how reprogramming various facets of the TME (blood vessels, myeloid cells, and regulatory T cells [Tregs]) may overcome TME-instigated resistance mechanisms to immunotherapy. We will discuss clinical applications of this strategic approach, including the recent successful phase III trial combining bevacizumab with atezolizumab and chemotherapy for metastatic nonsquamous non-small cell lung cancer that led to rapid approval by the U.S. Food and Drug Administration of this regimen for first-line treatment. Given the accelerated testing and approval of ICBs combined with various targeted therapies in larger numbers of patients with cancer, we will discuss how these concepts and approaches can be incorporated into clinical practice to improve immunotherapy outcomes.

Cancer Immune Checkpoint Inhibitor Therapy and the Gut Microbiota

The past decade has seen tremendous advances in both our understanding of cancer immunosuppressive microenvironments and colonic bacteria facilitated by immune checkpoint inhibitor antibodies and next generation sequencing, respectively. Because an important role of the host immune system is to communicate with and regulate the gut microbial community, it should not come as a surprise that the behavior of one is coupled to the other. In this review, we will attempt to dissect some of the studies demonstrating cancer immunotherapy modulation by specific gut microbes and discuss possible molecular mechanisms for this effect.