[Immunotherapy for microsatellite-instability-high advanced colorectal cancer]

Area of Science:

• Oncology
• Immunotherapy
• Gastroenterology

Background:

• Microsatellite instability-high (MSI-H) colorectal cancer (CRC) affects 10-15% of patients, with only 5% in metastatic disease.
• Early-stage MSI-H CRC has a good prognosis, but advanced stages show poor response to chemotherapy.
• PD-1 inhibitors have transformed treatment, outperforming traditional therapies in first-line and late-line settings.

Purpose of the Study:

• To review the current treatment landscape for MSI-H metastatic colorectal cancer.
• To discuss strategies for overcoming primary and secondary drug resistance.
• To evaluate the role and safety of neoadjuvant immunotherapy and the Watch-and-Wait strategy.

Main Methods:

• Literature review of studies on MSI-H colorectal cancer treatment.
• Analysis of outcomes with PD-1 inhibitors versus traditional therapies.
• Evaluation of neoadjuvant and adjuvant immunotherapy approaches.

Main Results:

• PD-1 inhibitors significantly improve prognosis in MSI-H CRC, including metastatic disease.
• Neoadjuvant immunotherapy achieves high pathological and clinical complete remission rates.
• The Watch-and-Wait strategy may preserve sphincter function in select rectal cancer patients.

Conclusions:

• Overcoming drug resistance is crucial for improving MSI-H metastatic CRC outcomes.
• Neoadjuvant immunotherapy requires careful patient selection due to potential toxicities.
• Adjuvant immunotherapy research holds promise for future CRC treatment.