Tumor genotype and immune microenvironment in POLE-ultramutated and MSI-hypermutated Endometrial Cancers: New candidates for checkpoint blockade immunotherapy?

Role of Cyclin-Dependent Kinase Inhibitors in Endometrial Cancer

Endometrial Cancer (EC) is an important cause of death in women worldwide. Despite early diagnosis and optimal treatment of localized disease, relapsed patients have few therapeutic options because after first line therapy, currently no standard of care exists. On the basis of endocrine positivity of most endometrioid ECs, Endocrine Therapy (ET) is a reasonable and widely accepted option. Better knowledge of molecular mechanisms involved in cancer highlighted the deregulated activity of Cyclin-Dependent Kinases (CDKs) in the cell cycle as a hallmark of carcinogenesis supporting the development of a new class of drugs: CDK inhibitors (CDKis). The aim of this review is to give an overview on CDKis preclinical, early clinical activity and future development in EC. Use of CDKis has a strong preclinical rationale but we have poor clinical data. Similar to breast cancer, most ongoing trials are investigating synergistic associations between CDKis and ET. These trials will probably help in defining the best clinical setting of CDKis in ECs, which are the best partner drugs, and how to manage CDKis toxicities with a focus on potential biomarkers of response.

Immune check-point in endometrial cancer

BACKGROUND

Endometrial cancer (EC) is one of the most frequent tumors in women. Despite recent advances in treatment approaches, the prognosis in advanced, recurrent, or metastatic disease remains poor. The aim was to provide the clinician with an update, the current status, and the new developments in the management of EC. Based on the new EC molecular classification, we focused on the impact of immune check-point inhibitors.

METHODS

Pivotal trials, published literature, and conference proceedings were reviewed. PubMed and Scopus databases were searched to select English-language articles.

RESULTS

Immune check-point inhibitors are the subject of ongoing studies and their benefit seems to be related to microsatellite instability (MSI) status.

CONCLUSIONS

Immune check-point inhibitors should be considered a promising treatment option to better personalize therapeutic strategies in EC.

Identification of genomic features associated with immunotherapy response in gastrointestinal cancers

Gastrointestinal (GI) cancers prevail and account for an extremely high number of cancer deaths worldwide. The traditional treatment strategies, including surgery, chemotherapy, radiotherapy, and targeted therapy, have a limited therapeutic effect for advanced GI cancers. Recently, immunotherapy has shown promise in treating various refractory malignancies, including the GI cancers with mismatch repair deficiency (dMMR) or microsatellite instability (MSI). Thus, immunotherapy could be a promising treatment approach for GI cancers. Unfortunately, only a small proportion of GI cancer patients currently respond to immunotherapy. Therefore, it is important to discover predictive biomarkers for stratifying GI cancer patients response to immunotherapy. Certain genomic features, such as dMMR/MSI, tumor mutation burden (TMB), and tumor aneuploidy have been associated with tumor immunity and im-munotherapy response and may serve as predictive biomarkers for cancer immunotherapy. In this review, we examined the correlations between tumor immunity and three genomic features: dMMR/MSI, TMB, and tumor aneuploidy. We also explored their correlations using The Cancer Genome Atlas data and confirmed that the dMMR/MSI status, high TMB, and low tumor aneuploidy are associated with elevated tumor immunity in GI cancers. To improve the immunotherapeutic potential in GI cancers, more genetic or genomic features associated with tumor immune response need to be identified. Furthermore, it is worth exploring the combination of different immunotherapeutic methods and the combination of immunotherapy with other therapeutic approaches for cancer therapy.

Endocrinology of obese and nonobese endometrial cancer patients: is there role of tumor molecular-biological type?

Aim: To compare endocrine characteristics of  endometrial cancer (EC) patients based on recent molecular EC types classification. Materials & methods: A total of 234 treatment-naive EC patients as well their tumors were studied. Results: Patients with POLE mutations demonstrated tendency to lower body mass index (BMI) and higher serum estradiol. Patients with p53 overexpression were older and had higher diabetes incidence. In the without characteristic molecular profile group there was no difference in fasting serum insulin, estradiol and testosterone levels between women with BMI ≥30.0 and <30.0. The mismatch repair deficient group patients had a tendency toward later menarche compared with the without characteristic molecular profile group one. Conclusion: Studied endocrine characteristics are associated with BMI or tumor molecular-biological type that might be relevant to EC genesis, course and prognosis.

A tumor board report of an 83-year-old woman with stage IB grade 3 endometrioid endometrial adenocarcinoma

An 83-year-old woman presented with postmenopausal bleeding ultimately leading to surgery and a final diagnosis of stage IB grade 3 endometrioid endometrial adenocarcinoma. The tumor board reviewed current literature regarding the efficacy of sentinel lymph node dissection in appropriately allocating stage in high-grade endometrial cancer. The optimal role of adjuvant treatment in this setting is unclear. Current literature surrounding adjuvant radiation and chemotherapy, as well as current practices in molecular diagnostics for endometrial cancer were reviewed. The tumor board concluded that literature surrounding sentinel lymph node evaluation in high-grade endometrial cancers is robust enough to incorporate into clinical practice. Based on the best available evidence, a decision was made to treat with external beam radiotherapy and withhold chemotherapy.

Combination Immune Checkpoint Blockade Strategies to Maximize Immune Response in Gynecological Cancers

PURPOSE OF REVIEW

Immune checkpoint blockade targeting PD-1 and PD-L1 improves immune recognition of tumor cells but had only modest success in gynecological cancers as monotherapy. Growing focus has been placed on combination immunotherapy strategies to overcome this resistance, and this review serves to discuss some of the most promising studies in gynecological cancers.

RECENT FINDINGS

PD-1- and PD-L1-targeting antibodies are being combined with many novel agents including anti-CTLA-4 antibodies, PARP inhibitors, targeted agents, and traditional chemotherapy in promising studies with the hopes of increasing the immune response and overcoming resistance by targeting other pathways. Novel immune techniques including vaccines and adoptive cell therapies are also being implemented in gynecological cancers. Immune checkpoint combinations and novel immunotherapy strategies have demonstrated potential to overcome resistance to PD-1/PD-L1 blockade in gynecological cancers. Identification of biomarkers of response and resistance is a priority to tailor specific combination therapies to the appropriate patients.

Successful response to the combination of immunotherapy and chemotherapy in cholangiocarcinoma with high tumour mutational burden and PD-L1 expression: a case report

Background

Cholangiocarcinoma, or bile duct cancer, is a gastrointestinal cancer with limited therapeutic options and a poor outcome. Studies have revealed that some major driver genes are associated with cholangiocarcinoma, but no targeted therapies have been approved. Immune checkpoint inhibitors, which are represented by inhibitors of programmed cell death 1 (PD-1)/programmed death-ligand 1 (PD-L1), have emerged as a potential therapy for multiple types of solid cancers.

Case presentation

A 53-year-old female presented with postoperative recurrence of PD-L1-positive intrahepatic cholangiocarcinoma with a high tumour mutational burden. This patient exhibited a marked response to the combination of anti-PD-1 immunotherapy and chemotherapy.

Conclusions

As far as we know, this is the first case report on the success of the combination of immunotherapy and chemotherapy for advanced cholangiocarcinoma with PD-L1 positivity and a high tumour mutational burden.

CD47 Blockade Inhibits Tumor Progression through Promoting Phagocytosis of Tumor Cells by M2 Polarized Macrophages in Endometrial Cancer

There are rapidly emerging efforts to explore tumor-associated macrophages (TAMs) as a tumor therapy target. Tumor cells express CD47, which can interact with the macrophages' SIRPα transmitting a “don't eat me” signal to macrophages. The expression of CD47 increases in various tumors to evade immune attack. However, the expression of CD47 in endometrial cancer (EC) and the role of CD47-SIRPα in the TAMs which mediate the progression of EC remain unclear. Our study shows that there are increased TAMs in EC which dominantly consist of M2 macrophages and contribute to the progression of EC. We confirm that CD47 is highly expressed in EC tissue using the TCGA database, qPCR, and flow cytometry. Instead of directly promoting the apoptosis of EC cells, anti-CD47 blocking antibody promoted phagocytosis of EC cells by macrophages and the increased phagocytosis ability was mediated by M2 macrophages in a coculture assay. Besides, CD47 blockade inhibited the growth of the EC tumors in vivo and increased the infiltration of macrophages with antitumor ability in the tumor microenvironment (TME). These findings might assist in developing promising strategies that blocked the CD47-SIRPa interaction for EC therapy.

Discordant loss of mismatch repair proteins in advanced endometrial endometrioid carcinoma compared to paired primary uterine tumors

OBJECTIVE

A subset of endometrial cancer is characterized by deficiencies in the mismatch repair (MMR) pathway. MMR testing is a well-established tool to screen for Lynch syndrome, but has also become a companion diagnostic test for immunotherapy. We compared the MMR status of primary and paired metastatic endometrial cancer to determine whether MMR deficiency can occur specifically in advanced endometrial cancer compared to primary tumor.

METHODS

Matched primary uterine and metastatic endometrioid adenocarcinoma from 2009 to 2018 at our institution were identified. PMS2 and MSH6 protein expression in metastatic and matched primary tumor was assessed using clinically validated immunohistochemistry methods for Lynch syndrome screening. MLH1 promoter hypermethylation and microsatellite instability (MSI) were performed in discordant cases.

RESULTS

29 patients were identified with paired primary endometrial endometrioid adenocarcinoma and metastasis or recurrence after the original hysterectomy. Fourteen of 29 cases (48.2%, 14/29) were found to be MMR deficient at the metastatic or recurrent site. Two patients (6.9%, 2/29) showed discordant MMR status with PMS2 protein loss at the metastatic sites and intact expression in the primary uterine tumors. Both discordant cases exhibited abnormal subclonal loss at primary site and MLH1 promoter hypermethylation. High levels of microsatellite instability (MSI-H) was confirmed in one discordant metastatic site.

CONCLUSION

Advanced endometrial cancer can rarely (~7%) show somatic loss of MMR protein expression in recurrent or metastatic sites compared to matched paired primary tumor. MMR testing of recurrent or metastasis should be considered for guiding immunotherapy if primary uterine tumor exhibits abnormal subclonal MMR loss.

Targeted next-generation sequencing identifies clinically relevant somatic mutations in a large cohort of inflammatory breast cancer

Background

Inflammatory breast cancer (IBC) is the most aggressive form of primary breast cancer. Using a custom-made breast cancer gene sequencing panel, we investigated somatic mutations in IBC to better understand the genomic differences compared with non-IBC and to consider new targeted therapy in IBC patients.

Methods

Targeted next-generation sequencing (NGS) of 91 candidate breast cancer-associated genes was performed on 156 fresh-frozen breast tumor tissues from IBC patients. Mutational profiles from 197 primary breast tumors from The Cancer Genome Atlas (TCGA) were used as non-IBC controls for comparison analysis. The mutational landscape of IBC was correlated with clinicopathological data and outcomes.

Results

After genotype calling and algorithmic annotations, we identified 392 deleterious variants in IBC and 320 variants in non-IBC cohorts, respectively. IBC tumors harbored more mutations than non-IBC (2.5 per sample vs. 1.6 per sample, p < 0.0001). Eighteen mutated genes were significantly different between the two cohorts, namely TP53, CDH1, NOTCH2, MYH9, BRCA2, ERBB4, POLE, FGFR3, ROS1, NOTCH4, LAMA2, EGFR, BRCA1, TP53BP1, ESR1, THBS1, CASP8, and NOTCH1. In IBC, the most frequently mutated genes were TP53 (43.0%), PIK3CA (29.5%), MYH9 (8.3%), NOTCH2 (8.3%), BRCA2 (7.7%), ERBB4 (7.1%), FGFR3 (6.4%), POLE (6.4%), LAMA2 (5.8%), ARID1A (5.1%), NOTCH4 (5.1%), and ROS1 (5.1%). After grouping 91 genes on 10 signaling pathways, we found that the DNA repair pathway for the triple-negative breast cancer (TNBC) subgroup, the RTK/RAS/MAPK and cell cycle pathways for the HR^–/HER2⁺ subgroup, the DNA repair, RTK/RAS/MAPK, and NOTCH pathways for the HR⁺/HER2^– subgroup, and the DNA repair, epigenome, and diverse pathways for the HR⁺/HER2⁺ subgroup were all significantly differently altered between IBC and non-IBC. PIK3CA mutation was independently associated with worse metastasis-free survival (MFS) in IBC since the median MFS for the PIK3CA mutant type was 26.0 months and for the PIK3CA wild type was 101.1 months (p = 0.002). This association was observed in TNBC (p = 0.04) and the HR^–/HER2⁺ subgroups (p = 0.0003), but not in the HR⁺/HER2^– subgroup of IBC.

Conclusions

Breast cancer-specific targeted NGS uncovered a high frequency of deleterious somatic mutations in IBC, some of which may be relevant for clinical management.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-1007-x) contains supplementary material, which is available to authorized users.

Peritumoral granulomatous reaction in endometrial carcinoma: association with DNA mismatch repair protein deficiency, particularly loss of PMS2 expression

AIMS

The observation of peritumoral granulomatous reactions (PGRs) in two endometrial carcinomas (ECs) with a PMS2-deficient/MLH1-intact expression pattern led us to investigate whether PGRs in EC were specifically associated with DNA mismatch repair (MMR) protein deficiency, particularly PMS2 loss.

METHODS AND RESULTS

Hysterectomy specimens from 22 MMR protein-intact and 54 MMR protein-deficient ECs were reviewed with specific attention to the presence of a PGR and a tumour-associated lymphoid reaction [including tumour-infiltrating lymphocytes (TILs) and stromal lymphoid infiltrates]. The MMR protein-deficient ECs included 22 cases with combined MLH1/PMS2 loss, 11 with combined MSH2/MSH6 loss, 11 with isolated MSH6 loss, and 10 with PMS2 loss but intact MLH1 staining (including the two 'index' cases). Overall, PGRs were identified in seven of 54 (13%) MMR protein-deficient ECs, five of which showed a PMS2-deficient/MLH1-intact immunophenotype; three of these patients had germline PMS2 mutations and one additional patient had a germline MSH6 mutation. None of the MMR protein-intact tumours showed a PGR. Although five of the seven PGR-positive ECs had a high-grade histological component, six were stage I. Most ECs with PGRs also showed TILs and stromal lymphoid reactions, similarly to MMR protein-deficient ECs in general.

CONCLUSIONS

MMR protein-deficient ECs, particularly those with PMS2 loss, occasionally show PGRs in addition to stromal lymphoid infiltrates and TILs. Therefore, PGRs could be considered to constitute a histological prompt for consideration of Lynch syndrome. The potential prognostic significance of PGRs in EC requires further study.

Estradiol metabolites as biomarkers of endometrial cancer prognosis after surgery

Endometrial cancer (EC) is the most common gynecologic malignancy prevailing after menopause. Defining steroid profiles may help predict the risk of recurrence after hysterectomy, which remains limited due to the lack of reliable markers. Adrenal precursors, androgens, parent estrogens and catechol estrogen metabolites were measured by mass spectrometry (MS) in preoperative serums and those collected one month after hysterectomy from 246 newly diagnosed postmenopausal EC cases. We also examined the associations between steroid hormones and EC status by including 110 healthy postmenopausal women. Steroid concentrations were analyzed in relation to clinicopathological features, recurrence and overall survival (OS). The mean follow-up time was 65.5 months and 26 patients experienced relapse after surgery for a recurrence incidence of 10.6% (6.4% Type I and 29.5% Type II). Recurrence and OS were related to a more aggressive disease but not linked to body mass index. Preoperative levels of estriol (E₃) and estrone-sulfate (E₁-S) were inversely associated with recurrence in a multivariate logistic regression analysis (Hazard ratios (HRs) of 0.31, P=0.039 and 3.01, P=0.024; respectively). All circulating steroids declined considerably after surgery almost reaching those of healthy women, except 4-methoxy-E₂ (4MeO-E₂) for which postoperative levels increased by 35% and were associated to a 68% decreased risk of recurrence (HR=0.32, P=0.015). Women diagnosed with both histological types of EC present significantly higher levels of steroids, in support of their mitogenic effects. The estrogen precursor E₁-S, the anticancer metabolite 4MeO-E₂, and E₃ that exert mixed antagonist and agonist estrogenic activities and immunological effects, are potential independent prognostic factors.

Prognostic implication of programmed cell death 1 protein and its ligand expressions in endometrial cancer

OBJECTIVE

Monoclonal antibodies targeting programmed cell death-1 (PD-1)/programmed death ligand 1 (PD-L1) demonstrated promising clinical response. The predictive/prognostic value of PD-1/PD-L1 immunohistochemistry (IHC) has been evaluated in many cancer types. However, the prognostic value of PD-1/PD-L1 IHC has not been evaluated in endometrial cancer.

METHODS

We conducted a retrospective study to quantify the IHC CD8, PD-1, and PD-L1 expressions in immune cells at center of tumor (CT), invasive margin (IM), and/or tumor cell in 183 primary endometrial cancer samples from a single cohort, followed by their reciprocal combinations, including compartmental differences, and correlated them with overall survival (OS) and progression-free survival (PFS).

RESULTS

In repeated Cox multivariable models adjusted by clinicoimmunopathologic factors, high CT-PD-L1 was an independent adverse prognostic factor for PFS in all patients and in the microsatellite-stable subgroup. Immune marker ratios revealed independently shorter PFS for high CT-PD-L1/CT-CD8 and CT-PD-L1/CT-PD-1 ratios. Classification of endometrial cancer into four groups based on CT-CD8 and CT-PD-L1 revealed significantly different survival among groups.

CONCLUSIONS

The high PD-L1/CD8 ratio and the high expression of PD-L1 on immune cells were independent poor prognostic factors for PFS in endometrial cancer, providing insights into the tumor microenvironment.

Exome analysis of carotid body tumor

Background

Carotid body tumor (CBT) is a form of head and neck paragangliomas (HNPGLs) arising at the bifurcation of carotid arteries. Paragangliomas are commonly associated with germline and somatic mutations involving at least one of more than thirty causative genes. However, the specific functionality of a number of these genes involved in the formation of paragangliomas has not yet been fully investigated.

Methods

Exome library preparation was carried out using Nextera® Rapid Capture Exome Kit (Illumina, USA). Sequencing was performed on NextSeq 500 System (Illumina).

Results

Exome analysis of 52 CBTs revealed potential driver mutations (PDMs) in 21 genes: ARNT, BAP1, BRAF, BRCA1, BRCA2, CDKN2A, CSDE1, FGFR3, IDH1, KIF1B, KMT2D, MEN1, RET, SDHA, SDHB, SDHC, SDHD, SETD2, TP53BP1, TP53BP2, and TP53I13. In many samples, more than one PDM was identified. There are also 41% of samples in which we did not identify any PDM; in these cases, the formation of CBT was probably caused by the cumulative effect of several not highly pathogenic mutations. Estimation of average mutation load demonstrated 6–8 mutations per megabase (Mb). Genes with the highest mutation rate were identified.

Conclusions

Exome analysis of 52 CBTs for the first time revealed the average mutation load for these tumors and also identified potential driver mutations as well as their frequencies and co-occurrence with the other PDMs.

Electronic supplementary material

The online version of this article (10.1186/s12920-018-0327-0) contains supplementary material, which is available to authorized users.

Colorectal Cancers: An Update on Their Molecular Pathology

Colorectal cancers (CRCs) are the third leading cause of cancer-related mortality worldwide. Rather than being a single, uniform disease type, accumulating evidence suggests that CRCs comprise a group of molecularly heterogeneous diseases that are characterized by a range of genomic and epigenomic alterations. This heterogeneity slows the development of molecular-targeted therapy as a form of precision medicine. Recent data regarding comprehensive molecular characterizations and molecular pathological examinations of CRCs have increased our understanding of the genomic and epigenomic landscapes of CRCs, which has enabled CRCs to be reclassified into biologically and clinically meaningful subtypes. The increased knowledge of the molecular pathological epidemiology of CRCs has permitted their evolution from a vaguely understood, heterogeneous group of diseases with variable clinical courses to characteristic molecular subtypes, a development that will allow the implementation of personalized therapies and better management of patients with CRC. This review provides a perspective regarding recent developments in our knowledge of the molecular and epidemiological landscapes of CRCs, including results of comprehensive molecular characterizations obtained from high-throughput analyses and the latest developments regarding their molecular pathologies, immunological biomarkers, and associated gut microbiome. Advances in our understanding of potential personalized therapies for molecularly specific subtypes are also reviewed.

Microsatellite instability is a biomarker for immune checkpoint inhibitors in endometrial cancer

In recent years, it has become evident that tumor cells have immune escape mechanisms, and immune checkpoint inhibitor therapy (anti-PD-1/PD-L1 antibody) has shown benefit in various cancers. In endometrial tumors with microsatellite-instability (MSI), somatic mutations have the potential to encode ''non-self'' immunogenic antigens, and lymphocytes have been shown to infiltrate the tumor. Therefore, immune checkpoint inhibitor therapy might be effective in endometrial cancers with MSI. Expression of mismatch repair (MMR) proteins (MLH1, PMS2, MSH2, and MSH6), the presence of tumor-infiltrating lymphocytes (CD8+), and PD-1/PD-L1 expression were assessed by immunohistochemistry in 149 patients with endometrial cancer. We examined whether tumors with MSI had an enhanced immune microenvironment and whether MSI could be a predictor of the therapeutic effect of PD-1/PD-L1 immunotherapy in endometrial cancer. Loss of MMR protein expression was identified in 42 (28.2%) of 149 patients (MSI group) with endometrial cancer. There was no significant relationship between MSI status and age (p = 0.193), histological grade (p = 0.097), FIGO stage (p = 0.508), pelvic lymph node metastasis (p = 0.139), or depth of myometrial invasion (p = 0.494). However, the presence of tumor-infiltrating lymphocytes (CD8+) and PD-L1/PD-1 expression were significantly higher in the MSI group compared to the microsatellite-stable group (p = 0.002, p = 0.001, and p = 0.008, respectively). These results suggest that immune checkpoint inhibitors (anti-PD-1/PD-L1 antibody) could be effective in endometrial cancers with MSI. The presence of MSI may be a biomarker for good response to PD-1/PD-L1 immunotherapy in endometrial cancer.

Endometrial cancer evolution: new molecular-biologic types and hormonal-metabolic shifts

The question hidden in the title of this manuscript (whether the topic develops or remains constant) is important for all areas of science. It is also a serious problem for endometrial cancer (EC) study. In recent times the incidence of EC gradually increases in parallel with obesity epidemics. The main point of this review was evaluation of changes in EC area in last few decades, which are not only seen in tumor incidence, but also in its biology, hormonal-metabolic characteristics of patients and in the ratio of risk and anti-risk factors. One can hope that data accumulated recently and summarized here under the notion of EC evolution will find its use for advancement of EC prevention and treatment.

Checkpoint inhibitors in endometrial cancer: preclinical rationale and clinical activity

CONTEXT

Treatment of advanced and recurrent endometrial cancer (EC) is still an unmet need for oncologists and gynecologic oncologists. The Cancer Genome Atlas Research Network (TCGA) recently provided a new genomic classification, dividing EC in four subgroups. Two types of EC, the polymerase epsilon (POLE)-ultra-mutated and the microsatellite instability-hyper-mutated (MSI-H), are characterized by a high mutation rate providing the rationale for a potential activity of checkpoint inhibitors.

MATERIALS AND METHODS

We analyzed all available evidence supporting the role of tumor microenvironment (TME) in EC development and the therapeutic implications offered by immune checkpoint inhibitors in this setting. We performed a review on Pubmed with Mesh keywords 'endometrial cancer' and the name of each checkpoint inhibitor discussed in the article. The same search was operated on clinicaltrial.gov to identify ongoing clinical trials exploring PD-1/PD-L1 and CTLA-4 axis in EC, particularly focusing on POLE-ultra-muted and MSI-H cancer types.

RESULTS

POLE-ultra-mutated and MSI-H ECs showed an active TME expressing high number of neo-antigens and an elevated amount of tumor infiltrating lymphocytes (TILs). Preliminary results from a phase-1 clinical trial (KEYNOTE-028) demonstrated antitumor activity of Pembrolizumab in EC. Moreover, both Pembrolizumab and Nivolumab reported durable clinical responses in POLE-ultra-mutated patients.

CONCLUSIONS

Immune checkpoint inhibitors are an attractive option in POLE-ultra-mutated and MSI-H ECs. Future investigations in these subgroups include combinations of checkpoints inhibitors with chemotherapy and small tyrosine kinase inhibitors (TKIs) to enhance a more robust intra-tumoral immune response.

Correlation of tumor mutational burden and treatment outcomes in patients with colorectal cancer

Background

The Cancer Genome Atlas (TCGA) showed that 16% of colorectal cancers (CRCs) display DNA repair mechanisms and high tumor mutational burden (TMB). Although, there is accumulating evidence of greater benefit of immunotherapy in tumors with high-TMB, its impact on response to chemotherapy is unknown.

Methods

In this retrospective cohort study, we investigated the impact of TMB on progression-free survival (PFS) of CRC patients treated at tertiary care oncology clinics who had their tumors profiled by next-generation sequencing (NGS). Low TMB (TMB-L) and intermediate/high TMB (TMB-I/H) were defined as ≤5 mutations per base (MB) or ≥6 MB, respectively.

Results

Seventy-four CRC patients (61 colon and 13 rectal cancers) were identified from the database. In the TMB-L cohort, irinotecan-based chemotherapy treated patients had improved PFS compared to oxaliplatin-based chemotherapy treated patients (11.9 vs. 6.5 months, P<0.001). No difference in PFS was observed between the two treatment cohorts in TMB-I/H group. There was also no difference in time to recurrence in the TMB-L and TMB-I/H arms in patients treated with oxaliplatin-based therapy in perioperative setting.

Conclusions

TMB-L may be a predictive biomarker in a subset of CRC patients treated with chemotherapy but these results need to confirmed in larger studies.

Vaccination with High-Affinity Epitopes Impairs Antitumor Efficacy by Increasing PD-1 Expression on CD8+ T Cells

Antitumor vaccines encoding self-antigens generally have low immunogenicity in clinical trials. Several approaches are aimed at improving vaccine immunogenicity, including efforts to alter encoded epitopes. Immunization with epitopes altered for increased affinity for the major histocompatibility complex (MHC) or T-cell receptor (TCR) elicits greater numbers of CD8 T cells but inferior antitumor responses. Our previous results suggested that programmed death 1 (PD-1) and its ligand (PD-L1) increased on antigen-specific CD8 T cells and tumor cells, respectively, after high-affinity vaccination. In this report, we use two murine models to investigate whether the dose, MHC affinity, or TCR affinity of an epitope affected the antitumor response via the PD-1/PD-L1 axis. T cells activated with high-affinity epitopes resulted in prolonged APC:T-cell contact time that led to elevated, persistent PD-1 expression, and expression of other checkpoint molecules, in vitro and in vivo Immunization with high-affinity epitopes also decreased antitumor efficacy in the absence of PD-1 blockade. Thus, APC:T-cell contact time can be altered by epitope affinity and lead to therapeutically relevant changes in vaccine efficacy mediated by changes in PD-1 expression. These findings have implications for the use of agents targeting PD-1 expression or function whenever high-affinity CD8 T cells are elicited or supplied by means of vaccination or adoptive transfer. Cancer Immunol Res; 5(8); 630-41. ©2017 AACR.

Replicative DNA polymerase defects in human cancers: Consequences, mechanisms, and implications for therapy

The fidelity of DNA replication relies on three error avoidance mechanisms acting in series: nucleotide selectivity of replicative DNA polymerases, exonucleolytic proofreading, and post-replicative DNA mismatch repair (MMR). MMR defects are well known to be associated with increased cancer incidence. Due to advances in DNA sequencing technologies, the past several years have witnessed a long-predicted discovery of replicative DNA polymerase defects in sporadic and hereditary human cancers. The polymerase mutations preferentially affect conserved amino acid residues in the exonuclease domain and occur in tumors with an extremely high mutation load. Thus, a concept has formed that defective proofreading of replication errors triggers the development of these tumors. Recent studies of the most common DNA polymerase variants, however, suggested that their pathogenicity may be determined by functional alterations other than loss of proofreading. In this review, we summarize our current understanding of the consequences of DNA polymerase mutations in cancers and the mechanisms of their mutator effects. We also discuss likely explanations for a high recurrence of some but not other polymerase variants and new ideas for therapeutic interventions emerging from the mechanistic studies.

Characterization of immune regulatory molecules B7-H4 and PD-L1 in low and high grade endometrial tumors

BACKGROUND

The objective of this investigation was to characterize the expression landscape of immune regulatory molecules programmed death-ligand-1 (PD-L1, B7-H1) and B7-H4 in a cohort of endometrial tumors across the spectrum of grade and histology.

MATERIALS AND METHODS

With institutional review board approval, 70 endometrial tumors from patients with known clinical outcomes were identified representing a spectrum of grade and histology. Immunohistochemistry (IHC) was performed for PD-L1 and B7-H4 and scored. Microsatellite instability (MSI) status was assessed for endometrioid tumors using the institutional IHC assay for expression of the mismatch repair (MMR) genes, MLH1, MSH2, MSH6 and PMS2. RNA sequencing data from the Cancer Genome Atlas was queried for expression levels of CD274 (PD-L1 protein) and VTCN1 (B7-H4) across molecular subtypes of endometrial carcinoma and were correlated with a T cell infiltration index.

RESULTS

We identified 40 low grade endometrioid tumors and a cohort of 30 high grade tumors. PD-L1 expression was observed in both high and low grade endometrial tumors (56% vs 35%, p=0.07). In the low grade tumors, PD-L1 expression was associated with MSI status (p<0.01). The high grade cohort had similar rates of PD-L1 expression compared to low grade MSI tumor (56% and 62% respectively), and both were distinct from low grade MSS tumors (22%, p<0.05). High (3+) B7-H4 positive cells were observed in both high and low grade carcinomas (33% and 31% respectively). RNA profiling data from confirmed highest CD274 expression in POLE and MSI tumors that was linearly correlated with T cell infiltration, while VTCN1 expression appeared consistent across molecular subtypes.

CONCLUSIONS

While PD-L1 expression correlated with MSI and high grade tumors, B7-H4 expression was independent of grade, histology and immune cell infiltration. The development and testing of multi-agent therapeutics targeting PD-L1 and B7-H4 may be a novel strategy for endometrial tumors.

The changing landscape of gynaecological cancer diagnosis: implications for histopathological practice in the 21st century

The era of molecular medicine has led to dramatically improved understanding of the genetic events that give rise to different types of cancers. In the case of gynaecological malignancies, this has resulted in distinct shifts in how these tumours are diagnosed in routine surgical pathology practice, with an increased emphasis on accurate subtype diagnosis. This has happened across all sites in the gynaecological tract and for most cell types, but in ways that are site-specific and may appear to be subtle, as in most instances the diagnostic terminology has not changed. For example, the diagnosis of clear cell carcinoma of the ovary is still in use, but the diagnostic criteria and clinical implications are different in 2017 from what they were in 2000. As a result, there can be a failure to appreciate how important these changes are and the resulting necessity of incorporating them into our daily practice. In this review we will describe changes in diagnostic surgical pathology occasioned by improved understanding of molecular events during pathogenesis, for cancers of ovary/tube, endometrium, cervix and vulva, and highlight how current practice differs from that of only a few years ago.

CD8, FoxP3, and CD45RO+ Lymphocytic Infiltrates in Type I and Type II Endometrial Cancers in African American and European American Females

African American (AA) females with endometrial carcinoma have a significantly worse prognosis with regard to disease-free survival and overall survival than their European American (EA) counterparts and this finding is true across all stages and grades. The presence of tumor-infiltrating lymphocytes (TILs) has been demonstrated to be of prognostic significance in a variety of malignancies, including endometrial cancers. This study aims to determine whether clinically significant differences in levels of CD8+ cytotoxic T lymphocytes, FoxP3+ regulatory T lymphocytes, and CD45RO+ memory T lymphocytes exist between races and to document the clinical impact of TILs. One hundred ten patients with endometrial adenocarcinoma, treated with hysterectomy from 2003 to 2011 were studied. Patients were selected to provide equal representation across type and grade for both EAs and AAs. Immunohistochemical stains were used to highlight CD8-positive, FoxP3-positive, and CD45RO-positive TILs at the endometrial-myometrial interface on slides from paraffin-embedded tissue. Patients with "high" or "low" levels of TILs were compared with respect to the race, tumor type, and survival. High levels of CD45RO+ TILs were associated with improved overall survival in EA women (hazard ratio, 0.32; 95% confidence interval, 0.11-0.92; P=0.034). Comparatively, AA women with high levels of CD45RO+ TILs received no survival benefit (hazard ratio, 0.96; 95% confidence interval, 0.35-2.64; P=0.94). High levels of CD8-positive or FoxP3-positive TILs, alone, had no impact on survival. EA patients with TILs containing high levels of CD45RO cells but low levels of CD8+ cells lost the survival benefit; however, limited numbers preclude significant conclusions from this observation. Neither tumor type nor race were predictive of the levels of TILs of any type. Further study with a larger sample size is required to determine the impact of TIL subtype combinations on survival.

New classification of endometrial cancers: the development and potential applications of genomic-based classification in research and clinical care

Endometrial carcinoma (EC) is the fourth most common cancer in women in the developed world. Classification of ECs by histomorphologic criteria has limited reproducibility and better tools are needed to distinguish these tumors and enable a subtype-specific approach to research and clinical care. Based on the Cancer Genome Atlas, two research teams have developed pragmatic molecular classifiers that identify four prognostically distinct molecular subgroups. These methods can be applied to diagnostic specimens (e.g., endometrial biopsy) with the potential to completely change the current risk stratification systems and enable earlier informed decision making. The evolution of genomic classification in ECs is shared herein, as well as potential applications and discussion of the essential research still needed in order to optimally integrate molecular classification in to current standard of care.

Immunotherapy and patients treated for cancer with microsatellite instability

Microsatellite instability (MSI) is a tumor phenotype linked to somatic or germline (Lynch syndrome) inactivating alterations of DNA mismatch repair genes. A broad spectrum of neoplasms exhibits MSI phenotype, mainly colorectal cancer, endometrial cancer, and gastric cancer. MSI tumors are characterized by dense immune infiltration and high load of tumor neo-antigens. Growing evidence is accumulating on the efficacy of immune checkpoint inhibition for patients treated for MSI solid tumors. We present a comprehensive overview of MSI phenotype, its biological landscape and current diagnostic methods. Then we focus on MSI as a predictive biomarker of response to immune checkpoint inhibition in the context of colorectal cancer and non-colorectal tumors.

Immunological profiling of molecularly classified high-risk endometrial cancers identifies POLE-mutant and microsatellite unstable carcinomas as candidates for checkpoint inhibition

High-risk endometrial cancer (EC) is an aggressive disease for which new therapeutic options are needed. Aims of this study were to validate the enhanced immune response in highly mutated ECs and to explore immune profiles in other EC subgroups. We evaluated immune infiltration in 116 high-risk ECs from the TransPORTEC consortium, previously classified into four molecular subtypes: (i) ultramutated POLE exonuclease domain-mutant ECs (POLE-mutant); (ii) hypermutated microsatellite unstable (MSI); (iii) p53-mutant; and (iv) no specific molecular profile (NSMP). Within The Cancer Genome Atlas (TCGA) EC cohort, significantly higher numbers of predicted neoantigens were demonstrated in POLE-mutant and MSI tumors compared with NSMP and p53-mutants. This was reflected by enhanced immune expression and infiltration in POLE-mutant and MSI tumors in both the TCGA cohort (mRNA expression) and the TransPORTEC cohort (immunohistochemistry) with high infiltration of CD8⁺ (90% and 69%), PD-1⁺ (73% and 69%) and PD-L1⁺ immune cells (100% and 71%). Notably, a subset of p53-mutant and NSMP cancers was characterized by signs of an antitumor immune response (43% and 31% of tumors with high infiltration of CD8⁺ cells, respectively), despite a low number of predicted neoantigens. In conclusion, the presence of enhanced immune infiltration, particularly high numbers of PD-1 and PD-L1 positive cells, in highly mutated, neoantigen-rich POLE-mutant and MSI endometrial tumors suggests sensitivity to immune checkpoint inhibitors.