PD-L1 expression in gastroenteropancreatic neuroendocrine neoplasms grade 3

PD-L1 expression, tumor-infiltrating lymphocytes, and mismatch repair proteins status in digestive neuroendocrine neoplasms: exploring their potential role as theragnostic and prognostic biomarkers

Theragnostic biomarkers are still needed to select patients with digestive neuroendocrine neoplasms (NENs) for an optimal management. The PD-1/PD-L1 pathway plays a pivotal role in T cells activation and host immune response to cancer and PD-L1 expression in tumor and/or immune cells is used to identify patients who would benefit of treatment with immune checkpoint inhibitors. However, its role as a biomarker is still unclear in digestive NENs. We investigated PD-L1 expression in 68 well-characterized digestive NENs (32 NETs, 32 NECs and 4 MiNENs) and TPS and CPS scores were calculated. In addition, tumor infiltrating T-lymphocytes and mismatch repair protein expression (MMR) were evaluated. All results were correlated with clinicopathological features. PD-L1 expression was higher in NECs than in NETs: TPS > 1% and/or CPS > 1 were observed in 16% of NETs, 68.8% of NECs and 50% of MiNENs (p: 0.05). The mean TPS score in positive cases was 6.3% in NETs, 16.2% in NECs and 5% in MiNENs. The CPS score was 4.8 in NETs, 8.1 in NECs and 6 in MiNENs. MMR-deficient neoplasms were more frequently observed in NECs than in NETs (p: < 0.05) as well as intra-tumor immune infiltration (p: 0.00001). No correlation between PD-L1 expression and survival or other clinicopathological parameters was observed. Our results suggest that treatment with immune checkpoint inhibitors may have a potential role only in selected cases, mainly in NECs and MiNENs.

Defining Tumor Microenvironment as a Possible Target for Effective GEP-NENs Immunotherapy-A Systematic Review

Neuroendocrine neoplasms (NENs) are a heterogenous and recurrent group of malignancies originating from neuroendocrine secretory cells diffused on all parts of the human body. Gastro-entero-pancreatic neuroendocrine tumors (GEP-NETs) account for most NENs. Considering the abundance of possible origins, locations, and tumor specifications, there is still no consensus about optimal treatment options for these neoplasms. In light of the escalating immunotherapeutic approaches, it is crucial to define indications for such therapy in GEP-NETs. Bearing in mind the significance of pathophysiological mechanisms and tumor microenvironment (TME) impact on carcinogenesis, defining TME structure and correlation with the immune system in GEP-NETs appears essential. This paper aimed to assess the characterization of the tumor immune microenvironment for a better understanding of the possible therapeutic options in GEP-NETS. The authors performed a systematic review, extracting papers from the PubMed, Web of Science, and Scopus databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Among 3800 articles identified through database searching, 292 were assessed for eligibility. Ultimately, 28 articles were included in the qualitative synthesis. This paper sums up the research on the immune cell infiltrates, immune checkpoint expression, cytokine profile, neoangiogenesis, and microbiome in the TME of GEP-NETs.

Heterogeneous distribution pattern of CD3+ tumor-infiltrated lymphocytes (TILs) and high combined positive score (CPS) favored the prognosis of resected early stage small-cell lung cancer

PURPOSE

This study aimed to illustrate the heterogeneity of immune features in small cell lung cancer (SCLC).

METHODS

Immunohistochemistry (IHC) staining of CD3, CD4, CD8 and PD-L1 were performed with 55 SCLC FFPE samples from radical resections. Quantitative assessment of CD3+ tumor-infiltrated lymphocytes (TILs) to present the heterogeneity in the tumor and the stroma areas. Hotspots of TILs were evaluated to illustrate the potential relationship between TIL-density and its immune competence. Programmed death ligand-1 (PD-L1) expressed on both tumor TILs (t-TILs) and stroma TILs (s-TILs) was evaluated and quantitatively described as values of tumor positive score (TPS) and combined positive score (CPS). The clinical value of TPS and CPS were further identified according to their relationship with disease-free survival (DFS).

RESULTS

More abundant CD3+ TILs were observed in the tumor stroma than that within the parenchyma (15.02±2.25% vs. 1.58±0.35%) . The amount of CD3+ s-TILs were positively correlated with DFS. The CD3+/CD4+ subset of the TILs was found more favorable to DFS compared to the CD3+/CD8+ subset. Hotspots of CD3+ TILs were observed in tumor regions and patients with more Hotspots of CD3+ TILs have better outcomes. CPS were more reliable than TPS to describe PD-L1 expression in SCLC and it was found positively correlated with tumor size and DFS.

CONCLUSIONS

The immune microenvironment of SCLC was heterogeneous. Hotspots, the amount of CD3/CD4+ TILs and the CPS value were found valuable in determine the anti-tumor immunity and predicting the clinical outcome of SCLC patients.

Neuroendocrine Neoplasms of the Gastrointestinal Tract versus Neuroendocrine Neoplasms of the Gynaecological Tract-Comparison of the Risk Factors and Non-Surgical Treatment Efficacy

Neuroendocrine tumours of the gastrointestinal tract are rare. The incidence has increased in recent years due to improvements in diagnostic methods for detecting these lesions. These tumours have a poor prognosis, especially when detected at an advanced stage. The basis of the treatment is resection, and non-surgical treatments are also standard in the treatment process. The situation is similar in even rarer neuroendocrine tumours of the reproductive tract, which are associated with an equally poor prognosis. In this article, we focus on learning about the risk factors (including genetic mutations) that increase the risk of the disease and comparing the effectiveness of non-surgical treatments-chemotherapy, radiotherapy, peptide receptor radionuclide therapy, somatostatin analogues, and immunotherapy. The efficacy of these treatments varies, and immunotherapy appears to be a promising form of treatment; however, this requires further research.

Potential new applications of immunotherapy for neuroendocrine neoplasms: immune landscape, current status and future perspectives

Neuroendocrine neoplasms (NENs) are a highly heterogeneous class of tumors arising from neuroendocrine cells and peptidergic neurons. After failure of first-line treatment, patients have poor prognosis and limited treatment options. Immune checkpoint inhibitors (ICIs) may be a powerful means of increasing therapeutic efficacy for such patients, but ICIs alone have low response rates and short disease control durations in most NENs and may be effective for only a portion of the population. ICIs combined with other immunotherapies, targeted therapies, or cytotoxic drugs have achieved some efficacy in patients with NENs and are worthy of further exploration to assess their benefits to the population. In addition, accumulating experimental and clinical evidence supports that the interaction between neuroendocrine and immune systems is essential to maintain homeostasis, and assessment of this broad neuroendocrine-immune correlation is essential for NEN treatment. In this review, we summarize the immune microenvironment characteristics, advances in immunotherapy, predictive biomarkers of ICI efficacy for NENs, and the effects of common endocrine hormones on the immune system, highlighting possible new application areas for this promising treatment in neglected NENs.

Evaluation of PD-L1 expression in a large set of gastroenteropancreatic neuroendocrine tumours and correlation with clinicopathological data

BACKGROUND

Targeting programmed death protein 1 (PD-1) or its ligand PD-L1 is a promising therapeutic approach for many types of cancer in which PD-L1 is overexpressed. However, data on PD-L1 expression levels in gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) are limited and contradictory.

METHODS

We evaluated PD-L1 expression in 457 archived, formalin-fixed, paraffin-embedded GEP-NEN samples from 175 patients by immunohistochemistry using the highly sensitive monoclonal anti-PD-L1 antibody 73-10. The immunostaining was semiquantitatively evaluated using a 12-point immunoreactivity score (IRS) taking both PD-L1-positive tumour cells and immune cells into account. Tumour samples with an IRS ≥ 3 were considered PD-L1-positive. Results were correlated with clinicopathological data and with the expression of several typical markers and receptors for neuroendocrine tumours.

RESULTS

Of the GEP-NEN samples, 73% were PD-L1-positive. The median IRS value across all samples was 4.0, corresponding to low expression. PD-L1 immunostaining was predominantly localised at the plasma membrane of the tumour cells. Positive correlations were observed between PD-L1 expression and tumour grading or Ki-67 index, between PD-L1 expression and the expression of chromogranin A, and between PD-L1 expression and the expression of each of the five somatostatin receptors. PD-L1 expression was lower in tumours with lymph node metastases at diagnosis than in those without regional metastasis and lower in high-stage than in earlier-stage tumours. No association was noted between PD-L1 expression and patient survival.

CONCLUSIONS

PD-L1 expression is common in GEP-NENs and increases with malignancy. Therefore, especially in high-grade GEP-NENs, targeting the PD-1/PD-L1 axis could be a promising additional therapeutic strategy.

The NET G3 enigma: dealing with a “new” entity

Neuroendocrine neoplasms of the gastroenteropancreatic system (GEP-NENs) have historically been graded into well-differentiated neuroendocrine tumors (NETs) G 1 and 2 and undifferentiated neuroendocrine carcinomas (NEC) G3 according to the proliferative index Ki-67, with the latter being larger than 20% for G3 NENs. However, clinical and pathological findings have suggested G3 NENs to be heterogeneous, and the most recent World Health Organization (WHO) classification has further subdivided G3 NENs into NET G3 with differentiated features and a usually lower Ki-67 (20–55%) as opposed to undifferentiated NECs. Currently, however, no standard approach to patients with NET G3 has been defined. As opposed to NET G1/G2, application of somatostatin analogues is not recommended, and the response to platinum-based chemotherapy is inferior when compared to NEC. The objective of this short review is to summarize pathological characteristics as well as therapeutic data obtained in patients with NET G3.

Differences in clinicopathology and prognosis between gastroesophageal junctional and gastric non-cardiac neuroendocrine carcinomas: a retrospective comparison study of consecutive 56 cases from a single institution in China

Gastric neuroendocrine carcinoma (NEC), including mixed neuroendocrine-non-neuroendocrine neoplasm (MiNEN), is uncommon and differences in clinicopathological features and outcomes of NEC arising in various gastric regions remain elusive. We investigated 56 consecutive NECs identified among 3961 gastrectomies performed at our center between 2005 and 2021. We then compared clinicopathological characteristics and prognosis between gastroesophageal junctional (GEJ) NECs (N=39) and gastric non-cardiac NECs (N=17). No significant difference was found between the two groups in age, gender, tumor size, mixed non-neuroendocrine carcinoma component, MiNEN, NEC type, metastatic NEC component in lymph nodes, tumor infiltrating lymphocyte, lymph node metastasis, lymphovascular or perineural invasion, intestinal metaplasia in adjacent non-neoplastic mucosa, and expression of P53, PD-L1, TTF-1, HER2, and Ki-67. However, compared to gastric non-cardiac NECs, GEJ NECs displayed a significantly higher frequency of prevalence (2.79% versus 0.66%), pT3-T4 (92.3% versus 64.7%), advanced pathological stage (IIb-IV) (76.9% versus 47.1%), and a significantly lower 5-year overall survival rate (46.1% versus 73.1%) (P<0.05). The GEJ location was the only independent risk factor for overall survival. In stage-stratified comparisons, patients with stage II GEJ NEC demonstrated a significantly lower 5-year survival rate than those with gastric non-cardiac NEC at the same stage. Compared to non-NECs matched for age, gender, tumor location, and pathological summary stage, GEJ NEC was associated with significantly worse prognosis. In conclusion, GEJ NEC showed deeper invasion, more advanced pathological stages, and worse prognosis than gastric non-cardiac NEC. The findings provide pathologic evidence for individualized management strategies for patients with GEJ NEC. Future studies with larger samples are needed.

Immunotherapies for well-differentiated grade 3 gastroenteropancreatic neuroendocrine tumors: A new category in the World Health Organization classification

According to the 2019 World Health Organization (WHO) classification, well-differentiated grade 3 (G3) gastroenteropancreatic (GEP) neuroendocrine tumors (NETs) are a new category of cancer of the digestive system. G3 GEP-NET research and treatment are not as robust as those of lower grade (G1/2) NETs and poorly differentiated neuroendocrine carcinomas (NECs). Previously, the management of high-grade NETs was mainly based on NEC therapies, as high-grade NETs were classified as NECs under the previous WHO classification. Despite this, G3 GEP-NETs are significantly less responsive to platinum-based chemotherapy regimens than NECs, due to their distinct molecular pathogenesis and course of pathological grade transition. Patients with advanced G3 GEP-NETs, who have progressed or are intolerant to chemotherapy regimens such as capecitabine plus temozolomide, have limited treatment choices. Immunotherapy has helped patients with a variety of cancers attain long-term survival through the use of immune checkpoint inhibitors. Immunotherapies, either alone or in combination with other therapies, do not have a clear function in the treatment of G3 GEP-NETs. Currently, the majority of immunotherapy studies, both prospective and retrospective, do not reliably differentiate G3 GEP-NETs from NECs. By contrast, a significant number of studies include non-GEP neuroendocrine neoplasms (NENs). Therefore, there is an urgent need to summarize and evaluate these data to provide more effective therapeutic approaches for patients with this rare tumor. The purpose of this mini-review was to screen and summarize information on G3 GEP-NETs from all studies on NENs immunotherapy.

"Present and future of immunotherapy in Neuroendocrine Tumors"

Immunotherapy, so promising in many neoplasms, still does not have a precise role in the treatment of neuroendocrine neoplasms (NENs). In this article, we provide an overview on the current knowledge about immunotherapy with immune checkpoint inhibitors (ICIs) applied to NENs, evaluating future perspectives in this setting of tumors.Evidence so far available for ICIs in gastroenteropancreatic (GEP)-NENs is definitively not as robust as for other tumors such as Small Cell Lung Cancer or Merkel Cell Carcinoma. In fact, with regard to the well-differentiated forms of NENs (NETs), the results obtained nowadays have been disappointing. However, the near future, might reserve interesting results for ICIs in GEP-NEN from a total of nine different ICI drugs, used throughout 19 randomised controlled trials. Such numbers highlight the growing attention gathering around NENs and ICIs, in response to the need of stronger evidences supporting such therapy.For the future, the most important aspect will be to study strategies that can make NETs more susceptible to response to ICI and, thus, enhance the effectiveness of these treatments. Therefore, the combination of conventional therapy, target therapy and immunotherapy deserve attention and warrant to be explored. A sequential chemotherapy, possibly inducing an increase in tumor mutational burden and tested before immunotherapy, could be a hypothesis deserving more consideration. A radiation treatment that increases tumor-infiltrating lymphocytes, could be another approach to explore before ICIs in NENs. Equally essential will be the identification of biomarkers useful for selecting patients potentially responsive to this type of treatment.

Immunotherapeutics at the spearhead: current status in targeting neuroendocrine neoplasms

PURPOSE

Recent advances in the field of immunotherapy have significantly prolonged the survival of patients with aggressive carcinomas, but the role of immunotherapy in neuroendocrine neoplasms (NENs) remains to be elucidated.

METHODS AND RESULTS

We report a patient diagnosed with a well-differentiated grade 3 pancreatic NEN (pNEN) and type 3 liver metastases who received compassionate nivolumab as a fifth line treatment and achieved a durable partial response of more than 34 months. We have performed a systematic review to the literature on tumor microenvironment and potential biomarkers in the field of NEN including the tumor mutational burden, the tumor infiltrating lymphocytes, the programmed cell death ligand 1, and the mismatch repair system. The potential role of the immune system modulation together with a critical assessment of the recent phase II clinical studies in NEN including monotherapy with anti-PD-1/PD-L1 monoclonal antibodies, and combination therapies including anti-PD-1 along with anti-CTLA-4 monoclonal antibodies are also provided.

CONCLUSION

Immunotherapeutics are gaining a post in the field of NENs in cases progressing during the course of the disease, dictating urgently the identification of biomarkers that will enable selection of NEN patients who may benefit from this treatment.

Myeloid and T-Cell Microenvironment Immune Features Identify Two Prognostic Sub-Groups in High-Grade Gastroenteropancreatic Neuroendocrine Neoplasms

High-grade Gastroenteropancreatic Neuroendocrine neoplasms (H-NENs) comprehend well-differentiated tumors (NET G3) and poorly differentiated carcinomas (NEC) with proliferative activity indexes as mitotic count (MC) >20 mitoses/10 HPF and Ki-67 >20%. At present, no specific therapy for H-NENs exists and the several evidences of microenvironment involvement in their pathogenesis pave the way for tailored therapies. Forty-five consecutive cases, with available information about T-cell, immune, and non-immune markers, from surgical pathology and clinical databases of 2 Italian institutions were immunostained for Arginase, CD33, CD163 and CD66 myeloid markers. The association between features was assessed by Spearman’s correlation coefficient. A unsupervised K-means algorithm was used to identify clusters of patients according to inputs of microenvironment features and the relationship between clusters and clinicopathological features, including cancer-specific survival (CSS), was analyzed. The H-NEN population was composed of 6 (13.3%) NET G3 and 39 (86.7%) NEC. Overall, significant positive associations were found between myeloid (CD33, CD163 and Arginase) and T/immune markers (CD3, CD4, CD8, PD-1 and HLA-I). Myeloid and T-cell markers CD3 and CD8 identified two clusters of patients from unsupervised K-means analysis. Cases grouped in cluster 1 with more myeloid infiltrates, T cell, HLA and expression of inhibitory receptors and ligands in the stroma (PD-1, PD-L1) had significantly better CSS than patients in cluster 2. Multivariable analysis showed that Ki-67 (>55 vs. <55, HR 8.60, CI 95% 2.61–28.33, p < 0.0001) and cluster (1 vs. 2, HR 0.43, CI 95% 0.20–0.93, p = 0.03) were significantly associated with survival. High grade gastroenteropancreatic neuroendocrine neoplasms can be further classified into two prognostic sub-populations of tumors driven by different tumor microenvironments and immune features able to generate the framework for evaluating new therapeutic strategies.