Case Report: MSS colorectal extrahepatic (non-liver) metastases as the dominant population for immunotherapy combined with multi-target tyrosine kinase inhibitors

Effectiveness and Safety of Immune Checkpoint Inhibitors in Colorectal Cancer: A Systematic Review of Real-World Studies

PURPOSE OF REVIEW

Immune checkpoint inhibitors (ICIs) have demonstrated significant efficacy in the treatment of colorectal cancer (CRC). However, most evidence has come from clinical trials with strict eligibility criteria. Understanding real-world effectiveness and safety of ICIs in CRC is important to guide routine clinical practice across diverse populations.

RECENT FINDINGS

A systematic review following PRISMA guidelines was conducted to identify observational studies evaluating ICI-based regimens compared to conventional or combination therapies in patients with CRC. Three databases (MEDLINE, Embase, and Scopus) were searched from inception through March 15, 2025. Eligible studies reported at least one efficacy outcome (e.g., progression-free survival [PFS], overall survival [OS], etc.) and/or safety outcome (e.g., adverse events) among real-world populations with CRC treated with ICIs. Study quality was assessed using the Newcastle-Ottawa Scale, and a narrative synthesis was performed to summarize the key findings. Eleven real-world studies met the inclusion criteria, encompassing data from 2,049 patients. In MSI-H/dMMR metastatic CRC, real-world findings aligned with the survival benefits observed in clinical trials, demonstrating improved PFS and OS compared to conventional therapies. For MSS/pMMR metastatic CRC, combining ICIs with other agents (e.g., tyrosine kinase inhibitors or chemotherapy) showed improvements but yielded conflicting results. Overall, the safety profiles were comparable to conventional therapies, with treatment-related adverse events occurring at similar rates. Real-world evidence supports the efficacy of ICI monotherapy in MSI-H/dMMR metastatic CRC and suggests potential benefits of ICI-based combination therapies in MSS/pMMR metastatic CRC. However, most of the data are derived from small, single-center cohorts, which limit their generalizability. Further multi-center studies are needed, especially to assess the efficacy of ICI-based combination therapies in the broader CRC population.

Identification of beneficial populations for targeted-immunotherapy combinations: tailoring later-line care for patients with pMMR/MSS metastatic colorectal cancer

Objective

This study explores the benefits of targeted-immunotherapy combination in third-line or beyond treatment for microsatellite stable (MSS) metastatic colorectal cancer (mCRC) in a real-world setting.

Methods

Patients with MSS mCRC who were treated with either a targeted-immunotherapy combination or targeted therapy alone in the third-line or beyond setting at our hospital from August 2018 to August 2022 were included in the study. Inclusion criteria comprised patients treated with targeted therapy alone or in combination with immunotherapy. Effectiveness was compared between treatments, and patients with the potential to benefit from targeted-immunotherapy combination were identified.

Results

Among 71 patients, 31 received targeted therapies alone (TT group) and 40 received a combination of targeted therapy and immunotherapy (TI group). The TI group had higher objective response rates (20% vs 3.2%) and disease control rates (82.5% vs 58.1%). The median progression-free survival was significantly better in the TI group (4.6 vs 4.1 months, P = 0.027). Liver metastasis was associated with poor prognosis, while patients with only lung metastases had the longest median progression-free survival of 12.3 months with combination therapy.

Conclusion

The study indicates that targeted-immunotherapy combination offers more benefits than targeted therapy alone for MSS mCRC in the third-line or beyond setting.

Significant response from fruquintinib plus anti-PD-1 immunotherapy for microsatellite stable metastatic colorectal cancer with liver and lung metastasis in the third line: case report

Background

There are limited treatment options available for patients with metastatic colorectal cancer (mCRC). About 95% of CRC patients have mismatch repair proficient/microsatellite stable (pMMR/MSS) tumors are virtually unresponsive to programmed cell death protein 1 (PD-1) antibody treatment. This report shows that a patient with pMMR/MSS mCRC achieved significant response and the longest progression-free survival (PFS) of 28 months currently reported from tyrosine kinase inhibitors (TKIs) targeting vascular endothelial growth factor receptor (VEGFR) family (VEGFR-1,2,3) (fruquintinib) plus anti-PD-1 immunotherapy in the third line, providing a new and promising treatment option for some MSS mCRC patients.

Case Description

This case details a 65-year-old male with CRC who was diagnosed with pT4aN2bM0, IIIC, and pMMR/MSS after curative surgery in August 2018. Subsequently, he received adjuvant chemotherapy [FOLFOX (folinic acid, fluorouracil, and oxaliplatin) for 5 cycles], first-line treatment (pelvic radiation plus capecitabine), and second-line treatment [TOMIRI (raltitrexed and irinotecan) plus cetuximab for 2 cycles]. Lung, liver, and pelvic cavity metastases worsened in October 2019. He began receiving the fruquintinib plus PD-1 inhibitor (FP) regimen as third-line treatment and after 3 cycles, the size of the lung lesions was significantly reduced and evaluated as partial response (PR), whereas the liver and pelvic cavity lesions remained stable. As of December 2021, he had received a total of 33 courses of FP regimen. In February 2022, liver metastases progressed. In brief, he achieved a long PFS of 28 months and an overall survival (OS) of 40 months from the third-line treatment. Additionally, the patient only experienced mild proteinuria after the combined treatment and tolerated well.

Conclusions

Fruquintinib combined with immunotherapy could exert good therapeutic effects with safety in MSS mCRC patients. And patients with lung metastasis may be the principal beneficiaries.