ZEBRA: A Multicenter Phase II Study of Pembrolizumab in Patients with Advanced Small-Bowel Adenocarcinoma

Immunotherapy in small bowel adenocarcinoma: a potential role?

Small bowel adenocarcinoma (SBA) is a rare tumor with an unfavorable prognosis, and due to its rarity, few studies on its treatment are available. Chemotherapy remains the standard of treatment in advanced disease. Recently immunotherapy has demonstrated to be a valid therapeutic option for many solid tumors. We reviewed the data published in literature to understand the impact of immunotherapy in this cancer.

Incidence, clinical management and prognosis of patients with small intestinal adenocarcinomas from 1999 through 2019: A nationwide Dutch cohort study

BACKGROUND

Small intestinal adenocarcinomas (SIAs) are rare. Hence, randomized controlled trials are lacking and understanding of the disease features is limited. This nationwide cohort investigates incidence, treatment and prognosis of SIA patients, to improve disease outcome.

PATIENTS AND METHODS

Data of 2697 SIA patients diagnosed from January 1999 through December 2019 were retrieved from the Netherlands Cancer Registry and Pathology Archive. Incidence was calculated using the revised European Standardized Rate. The influence of patient and tumor characteristics on overall survival (OS) was studied using survival analyses.

RESULTS

The age-standardized incidence rate almost doubled from 0.58 to 1.06 per 100,000 person-years, exclusively caused by an increase in duodenal adenocarcinomas. OS did not improve over time. Independent factors for a better OS were a younger age, jejunal tumors, Lynch syndrome and systemic therapy. Only 13.8% of resected patients was treated with adjuvant chemotherapy, which improved OS compared to surgery alone in stage III disease (HR 0.47 (0.35-0.61)), but not in the limited group of deficient mismatch repair (MMR) patients (n = 53, HR 0.93 (0.25-3.47)). In the first-line setting, CAPOX was associated with improved OS compared to FOLFOX (HR 0.51 (0.36-0.72)). For oligometastatic patients, a metastasectomy significantly improved OS (HR 0.54 (0.36-0.80)).

CONCLUSIONS

The incidence of SIAs almost doubled in the past 20 years, with no improvement in OS. This retrospective non-randomized study suggests the use of adjuvant chemotherapy for stage III disease and first-line CAPOX for metastatic patients. For selected oligometastatic patients, a metastasectomy may be considered. MMR-status testing could aid in clinical decision-making.

Immune signature of small bowel adenocarcinoma and the role of tumor microenvironment

In this editorial we comment on the article published "Clinical significance of programmed cell death-ligand expression in small bowel adenocarcinoma is determined by the tumor microenvironment". Small bowel adenocarcinoma (SBA) is a rare gastrointestinal neoplasm and despite the small intestine's significant surface area, SBA accounts for less than 3% of such tumors. Early detection is challenging and the reason arises from its asymptomatic nature, often leading to late-stage discovery and poor prognosis. Treatment involves platinum-based chemotherapy with a 5-fluorouracil combination, but the lack of effective chemotherapy contributes to a generally poor prognosis. SBAs are linked to genetic disorders and risk factors, including chronic inflammatory conditions. The unique characteristics of the small bowel, such as rapid cell renewal and an active immune system, contributes to the rarity of these tumors as well as the high intratumoral infiltration of immune cells is associated with a favorable prognosis. Programmed cell death-ligand 1 (PD-L1) expression varies across different cancers, with potential discrepancies in its prognostic value. Microsatellite instability (MSI) in SBA is associated with a high tumor mutational burden, affecting the prognosis and response to immunotherapy. The presence of PD-L1 and programmed cell death 1, along with tumor-infiltrating lymphocytes, plays a crucial role in the complex microenvironment of SBA and contributes to a more favorable prognosis, especially in the context of high MSI tumors. Stromal tumor-infiltrating lymphocytes are identified as independent prognostic indicators and the association between MSI status and a favorable prognosis, emphasizes the importance of evaluating the immune status of tumors for treatment decisions.

Successful treatment with trastuzumab plus chemotherapy as the first‑line regimen in advanced small bowel adenocarcinoma harboring HER2 amplification: A report of two cases

Therapeutic options are limited for individuals with unresectable or metastatic small bowel adenocarcinoma (SBA), necessitating palliative chemotherapy. Human epidermal growth factor receptor 2 (HER2) gene amplification or protein overexpression in SBA is exceedingly rare. HER2 amplification mutations/overexpression serves as a potential target for treatment in various malignancies. However, research on targeted therapies for SBA with HER2 mutation is lacking. In this context, the present study reports two cases of advanced SBA with a HER2 amplification mutation. Both patients received the anti-HER2 agent trastuzumab in combination with an oxaliplatin-based chemotherapy regimen as a first-line treatment. Following disease progression, trastuzumab was used in conjunction with other palliative chemotherapy regimens. Notably, anti-HER2 treatment resulted in significantly extended overall survival times without the occurrence of serious treatment-related adverse events. The overall survival times of the two patients were 31 and 15 months. Additionally, a review of the existing literature was conducted with regard to the effectiveness of anti-HER2 agents in the treatment of advanced SBA. It can be concluded that it is imperative to ascertain the HER2 status prior to the initiation of palliative treatment.

Comprehensive genomic profiling of small bowel adenocarcinoma by tissue and plasma biopsy

Small bowel adenocarcinoma (SBA) is a rare and aggressive malignancy with limited treatment options and poor prognosis. The molecular landscape and immunological characteristics of SBA are poorly understood. Here, we performed comprehensive mutation profiling of tissue and plasma biopsies from 143 and 42 patients with SBA. Analysis showed that SBA had a distinct mutation spectrum from left- and right-sided colorectal carcinoma. Plasma biopsy had high concordance with tissue biopsy for single nucleotide variants and structural variants, but low concordance for copy number variations, which showed that plasma biopsy can be an alternative to tissue biopsy. Moreover, we analyzed the association of TMB with clinical and molecular features, and found that TMB was significantly higher in tumors with DNA damage response alterations. Our findings provide valuable insights into the molecular and immunological features of SBA and demonstrate the potential of plasma biopsy as a non-invasive method for SBA diagnosis and treatment.

Genetic profile of Chinese patients with small bowel cancer categorized by anatomic location

BACKGROUND

Small bowel cancer (SBC) is a very rare solid malignancy. Consequently, compared with other malignant gastrointestinal tumors, our knowledge regarding SBC, specifically its molecular attributes, remains limited. Herein, we aim to provide an overview of the gene characteristics of Chinese patients with SBC, We particularly focus on elucidating the genetic intricacies that differentiate SBC patients whose primary tumors originate in distinct anatomical regions within the small bowel.

METHODS

During the period ranging from February 2018 to December 2022, a total of 298 tumor samples were consecutively collected from Chinese patients diagnosed with small bowel cancer.. Next-generation sequencing (NGS) was performed to detect gene mutation, assess microsatellite instability (MSI), and evaluate tumor mutational burden (TMB). Additionally,, IHC was used to analyze the level of PD-L1 expression within the samples.

RESULTS

The outcomes of the next-generation sequencing (NGS) unveiled the predominant gene mutations observed in Chinese patients with small bowel cancer (SBC). The top ten gene mutations identified were as follows: TP53 (53%), KRAS (51%), APC (31%), SMAD4 (19%), VEGFA (15%), CDKN2A (15%), RAC1 (15%), LRP1B (14%), MGMT (14%, CD74 (13%). Subsequent analysis revealed disparities in the gene landscape between the cohort in this study and that of the Memorial Sloan Kettering Cancer Center (MSKCC), Notably, distinguishable mutational frequencies were identified in several genes, including ERBB2, FBXW7, PIK3CA, etc. which exhibited contrasting presence in both this cohort and the MSKCC cohort.. Furthermore, we noticed variations in the frequency of gene mutations among SBC patients depending on the specific anatomical site where the tumors originated within the small bowel. In addition, the distribution of patients with high microsatellite instability (MSI-H) and tumor mutational burden (TMB) levels varied among SBC patients with tumors originating from the duodenum, jejunum, and ileum.

CONCLUSION

Chinese patients with small bowel cancer exhibited a distinct genetic profile in comparison to other populations, highlighting a unique genetic landscape. Furthermore, noticeable disparities in the genetic landscape were observed between patients with cancer situated in the duodenum and those with cancer affecting other regions of the small bowel, this suggests that these patients should be treated differently.

Clinical significance of programmed cell death-ligand expression in small bowel adenocarcinoma is determined by the tumor microenvironment

BACKGROUND

Comprehensive genomic analysis has shown that small bowel adenocarcinoma (SBA) has different genomic profiles from gastric and colorectal cancers. Hence, it is essential to establish chemotherapeutic regimens based on SBA characteristics. The expression of programmed cell death-ligand 1 (PD-L1) and programmed cell death-ligand 2 (PD-L2) in SBA is not fully understood. Anti-PD-L1/PD-1 therapy uses tumor-infiltrating lymphocytes (TILs); therefore, the status of TILs in the tumor microenvironment (TME) may influence their efficacy. The ratio of FoxP3+ to CD8+ T cells has been reported to be useful in predicting the prognosis of digestive system cancers.

AIM

To investigate the clinicopathological significance of PD-L1/2 expression according to the status of TILs in SBA tissues.

METHODS

We performed immunohistochemical analysis for PD-L1, PD-L2, CD8, FoxP3, and DNA mismatch repair (MMR) proteins using formalin-fixed, paraffin-embedded tissues from 50 patients diagnosed with primary SBA. The immunoreactivities of PD-L1 and PD-L2 were determined separately in tumor cells and tumor-infiltrating immune cells throughout the tumor center and invasive margins, and finally evaluated using the combined positive score (CPS). We assessed CD8+ and FoxP3+ T cells in the intratumoral and tumor-surrounding stroma. Subsequently, we calculated and summed the ratio of FoxP3 to CD8+ T cell counts. Immune-related cell densities were graded as low or high. Immunohistochemical results were compared with clinicopathological factors and patient prognosis. The distribution of cancer-specific survival (CSS) was estimated using the Kaplan-Meier method, and the log-rank test was used to test for significant differences in CSS. A Cox proportional hazard model was also used to assess the effect of tumor variables on CSS.

RESULTS

PD-L1 expression was positive in 34% in tumor cells (T-PD-L1) and 54% in tumor-infiltrating immune cells (I-PD-L1) of the cases examined. T-PD-L2 was positive in 34% and I-PD-L2 was positive in 42% of the cases. PD-L1 CPS ≥ 10 and PD-L2 CPS ≥ 10 were observed in 50% and 56% of the cases, respectively. Deficient MMR (dMMR) was 14% of the cases. T-PD-L1, I-PD-L1 and PD-L1 CPS ≥ 10 were all significantly associated with dMMR (P = 0.037, P = 0.009, and P = 0.005, respectively). T-PD-L1, I-PD-L1, and PD-L1 CPS ≥ 10 were all associated with deeper depth of invasion (P = 0.001, P = 0.024, and P = 0.002, respectively). I-PD-L2 expression and PD-L2 CPS ≥ 10 were significantly higher in the differentiated histological type (P = 0.015 and P = 0.030, respectively). The I-PD-L1 and I-PD-L2 levels were significantly associated with better CSS (P = 0.037 and P = 0.015, respectively). CD8-high was significantly associated with less lymph node metastasis (P = 0.047), less distant metastasis (P = 0.024), less peritoneal dissemination (P = 0.034), and earlier TNM stage (P = 0.047). The CD8-high group had better prognosis than the CD8-low group (P = 0.018). FoxP3 expression was not associated with any clinicopathological factors or prognosis. We found that patients with PD-L2 CPS ≥ 10 tended to have worse prognosis in the FoxP3/CD8-low group (P = 0.088).

CONCLUSION

The clinicopathological significance of PD-L1/2 expression may differ depending on the TME status. Immune checkpoint inhibitors may improve the prognosis of SBA patients with low FoxP3/CD8 ratio and PD-L2 expression.

Small intestinal adenocarcinoma accompanied by lynch syndrome: A case report

RATIONALE

Lynch syndrome is caused by germline mutations of DNA mismatch repair genes. A significant risk increase for several types of cancer is one of the characteristics of lynch syndrome.

PATIENT CONCERNS

A 45-year-old female presented to the emergency department with abdominal pain that had persisted for a month.

DIAGNOSES

The abdominal and pelvic computed tomography scan showed edematous and thickening of the proximal small bowel wall, as well as dilatation of the proximal bowel and stomach.

INTERVENTIONS

Tumor resection of the small bowel was performed, and adenocarcinoma was confirmed pathologically. Microsatellite instability was also confirmed.

OUTCOMES

Postoperative imaging revealed soft tissue lesions with potential for tumor seeding. Two months after the first surgery, a secondary surgery was performed as a result of cancer recurrence. The patient received chemotherapy with capecitabine. The latest computed tomography scan, performed 19 months after the cessation of chemotherapy, did not show any recurrence.

LESSONS

In the rare incidence of small bowel cancer genetic mutation testing and detailed family history should be actively considered.

Comparison of different predictive biomarker testing assays for PD-1/PD-L1 checkpoint inhibitors response: a systematic review and network meta-analysis

Background

Accurate prediction of efficacy of programmed cell death 1 (PD-1)/programmed cell death ligand 1 (PD-L1) checkpoint inhibitors is of critical importance. To address this issue, a network meta-analysis (NMA) comparing existing common measurements for curative effect of PD-1/PD-L1 monotherapy was conducted.

Methods

We searched PubMed, Embase, the Cochrane Library database, and relevant clinical trials to find out studies published before Feb 22, 2023 that use PD-L1 immunohistochemistry (IHC), tumor mutational burden (TMB), gene expression profiling (GEP), microsatellite instability (MSI), multiplex IHC/immunofluorescence (mIHC/IF), other immunohistochemistry and hematoxylin-eosin staining (other IHC&HE) and combined assays to determine objective response rates to anti-PD-1/PD-L1 monotherapy. Study-level data were extracted from the published studies. The primary goal of this study was to evaluate the predictive efficacy and rank these assays mainly by NMA, and the second objective was to compare them in subgroup analyses. Heterogeneity, quality assessment, and result validation were also conducted by meta-analysis.

Findings

144 diagnostic index tests in 49 studies covering 5322 patients were eligible for inclusion. mIHC/IF exhibited highest sensitivity (0.76, 95% CI: 0.57-0.89), the second diagnostic odds ratio (DOR) (5.09, 95% CI: 1.35-13.90), and the second superiority index (2.86). MSI had highest specificity (0.90, 95% CI: 0.85-0.94), and DOR (6.79, 95% CI: 3.48-11.91), especially in gastrointestinal tumors. Subgroup analyses by tumor types found that mIHC/IF, and other IHC&HE demonstrated high predictive efficacy for non-small cell lung cancer (NSCLC), while PD-L1 IHC and MSI were highly efficacious in predicting the effectiveness in gastrointestinal tumors. When PD-L1 IHC was combined with TMB, the sensitivity (0.89, 95% CI: 0.82-0.94) was noticeably improved revealed by meta-analysis in all studies.

Interpretation

Considering statistical results of NMA and clinical applicability, mIHC/IF appeared to have superior performance in predicting response to anti PD-1/PD-L1 therapy. Combined assays could further improve the predictive efficacy. Prospective clinical trials involving a wider range of tumor types are needed to establish a definitive gold standard in future.

Mismatch repair deficiency as prognostic factor for stage III small bowel adenocarcinoma: A multicentric international study

BACKGROUND

Small bowel adenocarcinoma (SBA) is a rare cancer with an aggressive behavior. No study has specifically addressed the putative prognostic role of mismatch repair status in stage III SBAs.

AIMS

We aimed to investigate whether mismatch repair deficiency is associated with cancer-specific survival in a Western cohort of patients with stage III SBAs.

METHODS

In this retrospective multicentric international cohort study, we enrolled 70 patients who underwent surgically resection for stage III SBAs and we analyzed the frequency of mismatch repair deficiency, tested by immunohistochemistry for mismatch repair proteins and by polymerase chain reaction for microsatellite instability, and its association with cancer-specific survival and other clinic-pathologic factors.

RESULTS

We found sixteen (23%) patients with mismatch repair deficient adenocarcinoma, without discordance between immunohistochemical and polymerase chain reaction for microsatellite instability analyses. Mismatch repair deficiency proved to be associated with a better outcome both at univariable analysis (hazard ratio: 0.28, 95% confidence interval: 0.08-0.91, p: 0.035) and in bivariable models adjusted for patient age or gender, tumor site, pT4 stage, tumor budding, and perineural invasion.

CONCLUSION

This study highlights the importance of testing mismatch repair status to improve prognostic stratification in stage III SBAs.

Society for Immunotherapy of Cancer (SITC) clinical practice guideline on immunotherapy for the treatment of gastrointestinal cancer

Gastrointestinal (GI) cancers, including esophageal, gastroesophageal junction, gastric, duodenal and distal small bowel, biliary tract, pancreatic, colon, rectal, and anal cancer, comprise a heterogeneous group of malignancies that impose a significant global burden. Immunotherapy has transformed the treatment landscape for several GI cancers, offering some patients durable responses and prolonged survival. Specifically, immune checkpoint inhibitors (ICIs) directed against programmed cell death protein 1 (PD-1), either as monotherapies or in combination regimens, have gained tissue site-specific regulatory approvals for the treatment of metastatic disease and in the resectable setting. Indications for ICIs in GI cancer, however, have differing biomarker and histology requirements depending on the anatomic site of origin. Furthermore, ICIs are associated with unique toxicity profiles compared with other systemic treatments that have long been the mainstay for GI cancer, such as chemotherapy. With the goal of improving patient care by providing guidance to the oncology community, the Society for Immunotherapy of Cancer (SITC) convened a panel of experts to develop this clinical practice guideline on immunotherapy for the treatment of GI cancer. Drawing from published data and clinical experience, the expert panel developed evidence- and consensus-based recommendations for healthcare professionals using ICIs to treat GI cancers, with topics including biomarker testing, therapy selection, and patient education and quality of life considerations, among others.

Progress in the Treatment of Small Intestine Cancer

OPINION STATEMENT

Small intestine cancer is rare, accounting for approximately 3% of all gastrointestinal malignancies. The most common histological subtypes include adenocarcinoma, neuroendocrine tumours (NETs) and gastrointestinal stromal tumours (GISTs). In localised disease, surgery remains the mainstay of treatment and the best approach to improve survival. Current treatment for small intestine adenocarcinoma (SIA) is extrapolated from small studies and data from colorectal cancer (CRC). There is limited evidence to guide therapy in the adjuvant setting. However, there are small phase II studies in the advanced setting providing evidence for the role of chemotherapy and immunotherapy. There is also limited evidence assessing the efficacy of targeted therapies. Small intestine NETs are rare, with evidence for somatostatin analogue therapy, particularly in the low to intermediate-grade well-differentiated tumours. Poorly differentiated NETs are generally managed with chemotherapy but have worse outcomes compared with well-differentiated NETs. The management of small intestine GISTs is largely targeting KIT mutations with imatinib. Recent trials have provided evidence for effective therapies in imatinib-resistant tumours and the potential role of immunotherapy. The aim of this article was to review the evidence for the current management and recent advances in the management of small intestine adenocarcinoma, NETs and GISTs.

Evaluation of Systemic Treatments of Small Intestinal Adenocarcinomas: A Systematic Review and Meta-analysis

IMPORTANCE

Although small intestinal adenocarcinomas (SIAs) are rare, they have a poor prognosis, and the optimal treatment strategies are largely unknown. Because of the lack of high-quality evidence, guidelines for colorectal cancer are often followed in the treatment of SIAs.

OBJECTIVE

To review the current evidence regarding survival benefit of systemic therapies, including chemotherapy, targeted agents, and immunotherapy, for patients with SIAs.

DATA SOURCES

Following the Preferred Reporting Items for Systematic Reviews and Meta-analyses, MEDLINE and Embase were searched for articles published from January 1, 2005, until June 1, 2022.

STUDY SELECTION

Retrospective cohort studies and prospective phase 2 or 3 trials describing survival after systemic therapies for patients with SIAs were eligible for inclusion. Assessment of study eligibility was blinded and performed by 3 reviewers.

DATA EXTRACTION AND SYNTHESIS

The reviewers independently extracted data. Random effects, inverse variance, pairwise meta-analyses were performed.

MAIN OUTCOMES AND MEASURES

Primary outcomes were overall survival (OS) and progression-free survival (PFS) of patients with SIAs after systemic therapies. Measures of interest included hazard ratios for survival and median survival times.

RESULTS

Overall, 57 retrospective cohort and phase 2 studies of 35 176 patients were included. Adjuvant chemotherapy, generally fluoropyrimidine-based, was associated with increased OS in stage I to III SIAs (hazard ratio [HR], 0.60; 95% CI, 0.53-0.68), especially in stage III tumors (HR, 0.55; 95% CI, 0.48-0.64), irrespective of tumor localization. Palliative chemotherapy was also associated with an OS benefit (HR, 0.48; 95% CI, 0.40-0.58). Fluoropyrimidine-oxaliplatin combinations were superior to other regimens (OS: HR, 0.54; 95% CI, 0.30-0.99; PFS: HR, 0.46; 95% CI, 0.30-0.71). Furthermore, bevacizumab added to chemotherapy compared with chemotherapy alone was associated with significantly prolonged PFS (HR, 0.62; 95% CI, 0.43-0.89). Immunotherapy showed a 50% overall response rate in previously treated defective mismatch repair tumors.

CONCLUSIONS AND RELEVANCE

In this systematic review and meta-analysis, adjuvant and palliative chemotherapy were both associated with improved survival of patients with SIAs, especially fluoropyrimidine-based regimens and fluoropyrimidine-oxaliplatin combinations. Adding bevacizumab to chemotherapy appears to prolong PFS and deserves further investigation. Immunotherapy seems beneficial and should be considered for patients with defective mismatch repair tumors. International collaborations should be undertaken to confirm and improve efficacy of systemic therapies for patients with SIAs.

Case report: A case of duodenal adenocarcinoma achieving significantly long survival treating with immune checkpoint inhibitors and chemotherapy without positive biomarkers

Small bowel adenocarcinoma (SBA), particularly duodenal adenocarcinoma (DA), is a rare gastrointestinal cancer with a dismal prognosis. Data on SBA treatments are limited, and the therapeutic strategy remains uncertain. Currently, chemotherapy is the most used treatment; however, it has a poor median progression-free survival (mPFS) of no more than five months in the second-line setting. We report a case with DA that responded well to the immune checkpoint inhibitor (ICI) tislelizumab plus irinotecan in the second-line treatment. To our knowledge, this is the first report of administering ICIs plus chemotherapy to SBA. Despite the absence of microsatellite instability-high (MSI-H) and high tumor mutational burden (TMB), the patient with TP53/KRAS mutation achieved a significantly long PFS of 17 months, and the benefit is still ongoing. The mechanism of this remarkable efficacy might be associated with an increase in tumor immunogenicity after chemotherapy. The current study presents a promising effect of ICIs plus chemotherapy on SBA, affirming the need to investigate the clinical value of this combination in SBA and the underlying mechanism behind it.

Small Bowel Adenocarcinoma: 10-Year Experience in a Cancer Center-The Ottawa Hospital (TOH)

(1) Background: Small bowel adenocarcinoma (SBA) is one of the predominant primary small bowel cancers that has a dismal outcome. We aim to report 10 years of experience in SBA management at a regional cancer centre in Canada.; (2) Methods: We retrospectively analysed clinical and pathological data of patients diagnosed with an SBA between 2011 and 2021 at the Ottawa Hospital (TOH), Ottawa, Canada. We describe the clinicopathological features and outcomes, including survival. Potential prognostic factors were analysed using the Cox proportional hazard model for multivariate analysis.; (3) Results: We identified 115 patients with SBA. The duodenum was the most common SBA location representing 61% (70) of the total patients, followed by the jejunum (17%) and ileum (10%). Around 24% (27) of cases presented with bowel obstructions. The majority of patients (56%, 64) had stage IV disease on presentation. Seven patients had MSI-high tumours, while 24% (27) were MS-stable. In terms of management, 48 patients underwent curative surgical resection, 17 of whom received adjuvant chemotherapy. On the other hand, 57 patients (49.5%) with the advanced disease received palliative systemic therapy, and 18 patients (16%) had supportive care only. Over a median follow-up of 21.5 months (range 0-122), the median overall survival was 94, 61, and 34 months for stages II, III, and IV, respectively (p < 0.05). The median recurrence-free survival was 93 and 23 months for stages II and III, respectively. However, there was no statistically significant difference between TNM stages in RFS, p = 0.069. Multivariate Cox regression analysis showed only poor performance status at diagnosis as a predictor for shorter overall survival (p < 0.05). The univariate analysis didn't show any significant correlation between RFS and covariants.; (4) Conclusions: SBA remains one of the most aggressive tumours with a dismal prognosis even after surgical resection. The optimal chemotherapy regimen has not been established. Further studies are needed to explore the role of adjuvant chemotherapy for stages I-III SBA.

PD-L1 evaluation in the gastrointestinal tract: from biological rationale to its clinical application

Immune-checkpoint inhibitors targeting the PD-1/PD-L1 axis have brought significant clinical benefit in many solid cancer types, including gastrointestinal malignancies. However, it has been estimated that only 20-40% of patients respond to treatment. The pattern of expression and potential predictive value of PD-L1 as an immunohistochemical biomarker has been extensively studied in gastrointestinal neoplasms. Until now, its predictive value has been demonstrated, and is currently in use only in upper gastrointestinal malignancies (gastroesophageal adenocarcinoma and esophageal squamous cell carcinoma).

In this Review, we describe the technical aspects and challenges related to PD-L1 immunohistochemical assays, the current role of PD-L1 as a biomarker in clinical practice and we outline the main studies and clinical trials analyzing the prognostic and predictive value of PD-L1 in gastrointestinal cancers.

Immune Checkpoint Inhibitors for Gastrointestinal Malignancies: An Update

Simple Summary

Immune checkpoint inhibitors are a class of anti-cancer therapy that work by harnessing the body’s immune system to promote cancer cell death. These drugs have become standard of care for many types of cancer, including melanoma and lung cancer, after clinical trials showed they work better than traditional chemotherapy. The role of immune checkpoint inhibitors is still evolving in the treatment of cancers of the gastrointestinal tract. This article examines the literature to support the use of immune checkpoint inhibitors to treat cancers of each part of the gastrointestinal system.

Abstract

Gastrointestinal (GI) malignancies are a heterogenous group of cancers with varying epidemiology, histology, disease course, prognosis and treatment options. Immune checkpoint inhibitors (ICIs) have changed the landscape of modern cancer treatment, though they have demonstrated survival benefit in other solid tumors more readily than in GI malignancies. This review article presents an overview of the landscape of ICI use in GI malignancies and highlights recent updates in this rapidly evolving field.

The Efficacy of Immune Checkpoint Inhibitors in Rare Tumors: A Systematic Review of Published Clinical Trials

The immune checkpoint inhibitors (ICIs) entered treatment algorithms in most tumors. However, the data on the efficacy is limited in rare tumors with no phase III studies. We systemically reviewed the clinical trials evaluating the ICI efficacy in rare tumors and included a total of 47 clinical trials in this review. The ICIs demonstrated over 30% response rates in Merkel cell carcinoma and squamous cell carcinoma of the skin and became the standard of care. Additionally, the ICI efficacy was promising in thymic epithelial tumors and gestational trophoblastic neoplasia. In contrast, the ICI efficacy is limited in most sarcomas, germ cell tumors and low-grade neuroendocrine tumors. The ICI efficacy seemed to be improved with combinations targeting tumor microenvironment in sarcomas. The available evidence on ICI efficacy in rare tumors denote a need for better patient selection and novel combination strategies to improve outcomes.

Understanding Suboptimal Response to Immune Checkpoint Inhibitors

Immune checkpoint inhibitors (ICIs), as a novel class of anticancer therapy, can be more efficacious and less toxic than chemotherapy, but their clinical success is confined to certain tumor types. Elucidating their targets, mechanisms and scope of action, and potential synergism with chemotherapy and/or targeted therapies are critical to widen their clinical indications. Treatment response to an ICI targeting programmed death-1 (anti-PD-1) is sought to be understood here by conducting a preplanned correlative analysis of a phase II clinical trial in patients with small bowel adenocarcinoma (SBA). The cytolytic capacity of circulating immune cells in cancer patients using a novel ex vivo cytotoxicity assay is evaluated, and the utility of circulating biomarkers is investigated to predict and monitor the treatment effect of anti-PD-1. Baseline expression of Bim and NKG7 and upregulation of CX3CR1 in circulating T cells are associated with the clinical benefit of anti-PD-1 in patients with SBA. Overall, these findings suggest that the frequency and cytolytic capacity of circulating, effector immune cells may differentiate clinical response to ICIs, providing a strong rationale to support immune monitoring using patient peripheral blood.

Systemic Treatments for Advanced Small Bowel Adenocarcinoma: A Systematic Review

Simple Summary

Small bowel adenocarcinoma is a rare disease that is usually treated following the protocols in use for colorectal cancer. The aim of this systematic review was to identify the optimal treatment for this disease according to the currently available evidence. We concluded that there is some evidence regarding the use of chemotherapy doublets in this setting, but not to support the use of biological agents. There are encouraging results regarding the use of immunotherapy in selected patients.

Abstract

Small bowel adenocarcinoma (SBA) is a rare disease for which scarce evidence is available. We summarized data available on systemic treatment of advanced SBA. Methods: Scientific literature was evaluated to find phase II or phase III clinical trials on systemic treatment for advanced SBA. MeSH terms were selected and combined for the initial search, then inclusion and exclusion criteria were set in a search protocol. Four medical oncologists looked for evidence on Medline, EMBASE and Cochrane databases. Moreover, abstracts from 2016 to June 2021 from the American Society for Clinical Oncology, European Society for Medical Oncology, Gastrointestinal Cancer Symposium and World Congress on Gastrointestinal Cancer were browsed. The selected studies, matching the inclusion and exclusion criteria, were finally tabulated and analyzed. Results: The trials finally selected were 18 phase II/III clinical trials. Four small phase II trials support the activity of oxaliplatin-based doublets in first-line treatment (CAPOX and mFOLFOX). Conclusion: No good level evidence is available on the use of bevacizumab, anti-epidermal growth factor receptor, targeted agents or immunotherapy. First-line treatments are largely derived from colorectal cancer protocols, mainly oxaliplatin-based doublets.

Therapeutic Strategies for Patients with Advanced Small Bowel Adenocarcinoma: Current Knowledge and Perspectives

Small bowel adenocarcinoma (SBA) is diagnosed at an advanced (unresectable or metastatic) tumor stage in approximately one-third of cases. This is partly due to the non-specific symptomatology and limitations in endoscopic and radiologic detection methods. In this context, the prognosis remains poor and systemic chemotherapy appears to benefit patients when compared to best supportive care alone, despite the absence of randomized controlled trials. The results of a recent large prospective cohort (ARCAD-NADEGE) reported that the absence of chemotherapy was a predictive factor for a lower overall survival (OS) even though poor differentiation and SBA associated with Crohn's disease correlate with poor prognosis. In retrospective series, the median OS ranges from approximately 9 to 18 months with current treatment approaches. A combination of a fluoropyrimidine and oxaliplatin (FOLFOX or CAPOX) appears to be the most utilized and effective first-line chemotherapy regimen. Other front-line alternatives are the combination of 5-FU and cisplatin or fluoropyrimidine and irinotecan (FOLFIRI). In second-line, FOLFIRI is an effective option after progression on platinum-based therapy. Taxane-based therapy appears to be an alternative option, but further evaluation in larger series is needed. To a limited extent, the role of surgical resection for metastatic disease appears to be a valid option, though this approach has not been evaluated in prospective clinical studies. Due to the rareness of the disease, inclusion in clinical trials should be prioritized, and there is hope that targeted therapies and immunotherapy may enter the therapeutic arsenal for these patients.

Small Bowel Adenocarcinoma: From Molecular Insights to Clinical Management

Small bowel adenocarcinoma (SBA) is a rare malignancy, with a rising incidence in recent decades, and accounts for roughly 40% of all cancers of the small bowel. The majority of SBAs arise in the duodenum and are associated with a dismal prognosis. Surgery remains the mainstay of treatment for localized disease, while systemic treatments parallel those used in colorectal cancer (CRC), both in the adjuvant and palliative setting. In fact, owing to the lack of prospective data supporting its optimal management, SBA has historically been treated in the same way as CRC. However, recent genetic and molecular data suggest a distinct profile from other gastrointestinal malignancies and support a more nuanced approach to its management. Herein, we briefly review the state-of-the-art in the clinical management of early-stage and advanced disease and recent discoveries of potentially actionable genetic alterations or pathways along with the most promising ongoing clinical trials, which will hopefully revolutionize the treatment landscape of this orphan disease in the foreseeable future.

Metastasis Pattern and Survival Analysis in Primary Small Bowel Adenocarcinoma: A SEER-Based Study

Background: Small bowel adenocarcinoma (SBA) is a rare gastrointestinal tumor with high malignancy. The aim of this study was to comprehensively evaluate the distant metastasis pattern and establish nomograms predicting survival for SBA. Methods: From 2010 to 2015, patients diagnosed with SBA were identified based on the Surveillance, Epidemiology, and End Results (SEER) database. Kaplan-Meier survival analysis was applied to compare survival differences between metastasis patterns. Then, univariate and multivariate cox analyses were applied to screened out independent prognostic factors of cancer-specific survival (CSS) and overall survival (OS), and identify the risk factors for metastasis of SBA. To assess the discrimination and calibration of nomograms, the concordance index (C-index), calibration curves, receiver-operating characteristic curve (ROC), and decision curve analysis (DCA) were calculated. Results: Kaplan-Meier curves revealed that metastasis patterns were significantly correlated with CSS (p < 0.001) and OS (p < 0.001). Then, the metastasis pattern was showed to be an independent prognostic factor of OS and CSS in patients with SBA, as well as age, grade, T stage, N stage, surgery, retrieval of regional lymph nodes, and chemotherapy. Combining these factors, we constructed prognostic nomograms, which suggested that the metastasis pattern made the greatest contribution to the survival of patients with SBA. Nomograms for OS and CSS had a C-index of 0.787 and 0.793, respectively. Calibration curves showed an excellent agreement between probability and actual observation in the training and validation cohort. Decision curve analysis also exhibited its clinical value with an improved net benefit. In addition, the models we constructed had better prognostic accuracy and clinical utility than traditional TNM staging based on C-index and ROC. Further, Cox regression analysis showed that old age, poor differentiation, N2, and not receiving chemotherapy were the risk factors for prognosis in patients with metastatic SBA. Conclusion: As an independent prognostic factor, the metastasis pattern exhibited the greatest predictive effect on OS and CSS for patients with SBA. Adjuvant chemotherapy had a positive effect on the survival of patients with SBA. Nomograms for predicting 3-and 5-year OS and CSS of patients with SBA were constructed, which could identify patients with higher risk and might be superior in predicting the survival of patients with SBA than TNM staging.

Immunohistochemistry as predictive and prognostic markers for gastrointestinal malignancies

Biomarkers play a key role in the comprehensive pathologic evaluation of gastrointestinal malignancies. These biomarkers can be predictive, indicating whether a tumor is likely to respond to a particular therapy, or prognostic, providing information about the likely course and outcome of a disease. This review article will discuss available immunohistochemical stains for assessing these markers, including staining rationale, scoring criteria, associated systemic therapies, and pictorial examples. PD-L1, HER2, and mismatch repair status can be evaluated via immunohistochemistry for esophageal, gastric, and colorectal carcinomas. Biomarkers currently play a more limited role in evaluation of pancreatic and small bowel malignancies. Immunohistochemistry can also be used to evaluate biomarker status in gastrointestinal stromal tumors, gastrointestinal malignancies with NTRK gene fusions, and undifferentiated carcinomas with switch-sucrose non-fermentable complex abnormalities.

Molecular profiling and identification of prognostic factors in Chinese patients with small bowel adenocarcinoma

Small bowel adenocarcinoma (SBA) is a rare malignancy with a poor prognosis and limited treatment options. Despite prior studies, molecular characterization of this disease is not well defined, and little is known regarding Chinese SBA patients. In this study, we conducted multigene next-generation sequencing and 16S ribosomal RNA gene sequencing on samples from 76 Chinese patients with surgically resected primary SBA. Compared with colorectal cancer and Western SBA cohorts, a distinctive genomic profile was revealed in Chinese SBA cohorts. According to the levels of clinical actionability to targetable alterations stratified by OncoKB system, 75% of patients harbored targetable alterations, of which ERBB2, BRCA1/2, and C-KIT mutations were the most common targets of highest-level actionable alterations. In DNA mismatch repair-proficient (pMMR) patients, significant associations between high tumor mutational burden and specific genetic alterations were identified. Moreover, KRAS mutations/TP53 wild-type/nondisruptive mutations (KRAS^mut /TP53^wt/non-dis ) were independently associated with an inferior recurrence-free survival (hazard ratio [HR] = 4.21, 95% confidence interval [CI] = 1.94-9.14, P < .001). The bacterial profile revealed Proteobacteia, Actinobacteria, Firmicutes, Bacteroidetes, Fusobacteria, and Cyanobacteria were the most common phyla in SBA. Furthermore, patients were clustered into three subgroups based on the relative abundance of bacterial phyla, and the distributions of the subgroups were significantly associated with the risk of recurrence stratified by TP53 and KRAS mutations. In conclusion, these findings provided a comprehensive molecular basis for understanding SBA, which will be of great significance in improving the treatment strategies and clinical management of this population.