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.

Systemic Treatments for Advanced Small Bowel Adenocarcinoma: A Systematic Review

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.

Outcomes Following Immune Checkpoint Inhibitor Treatment of Patients With Microsatellite Instability-High Cancers: A Systematic Review and Meta-analysis

Importance

The mismatch repair (MMR) pathway plays a crucial role in repairing DNA replication errors in normal and cancer cells. Defects in DNA MMR proteins that determine the microsatellite instability-high (MSI-H) condition lead to the accumulation of mutations and the generation of neoantigens, which may stimulate the antitumor immune response. Clinical trials have demonstrated that MSI-H status is associated with long-term benefit in patients treated with immune checkpoint inhibitors (ICIs).

Objective

To evaluate the activity of ICIs in terms of overall response rate (ORR), disease control rate (DCR), overall survival (OS), and progression-free survival (PFS) in patients with MSI-H cancers.

Data Sources

Published articles that evaluated ICIs in the treatment of advanced MSI-H tumors from inception to December 2019 were identified by searching the PubMed, EMBASE, and Cochrane Library databases.

Study Selection

Prospective or retrospective studies, published in the English language, providing outcome data with ICIs in patients with MSI-H cancer were selected.

Data Extraction and Synthesis

Author and year of publication, type of studies, diseases included, median follow up, type of ICI, median OS ,and PFS, ORR, DCR and 1-, 2-, and 3-year OS were retrieved. Analysis was performed in December 2019.

Main Outcome and Measures

The primary outcome of interest was ORR. Secondary end points were median PFS, median OS, pooled rate of patients alive at 1, 2 ,and 3 years, and pooled rate of patients that attained disease control rate ([DCR] calculated as the sum of stable disease rate and ORR).

Results

Overall, 939 patients (14 studies) were analyzed mainly in pretreated settings. The pooled ORR was 41.5% (95% CI, 34.9%-48.4%). The pooled DCR was 62.8% (95% CI, 54.5%-70.3%). Pooled median PFS was 4.3 months (95% CI, 3-6.8 months). The pooled median OS was 24 months (95% CI, 20.1-28.5 months). The pooled 1- and 2-year OS were 75.6% (95% CI, 61.8%-85.5%) and 56.5% (95% CI, 46%-66.4%), respectively. Because only 1 study provided 3-year OS data, a formal pooled analysis for 3 years was not possible.

Conclusions and Relevance

In this meta-analysis of patients with pretreated MSI-H cancer, ICIs were associated with high activity independent of tumor type and drug used. Among molecular biomarkers for selection of treatment, MMR proteins may have a predictive value for the activity of immunotherapy.