Combining Intratumoral Flu Vaccine and Systemic Pembrolizumab in Patients With Early pMMR Colorectal Cancer

Immune checkpoint inhibitor (ICI) treatment has produced striking results in patients with colorectal cancer (CRC) of the subtype deficient mismatch repair (dMMR). The majority of patients, however, have proficient MMR (pMMR) tumors, with limited effect of ICIs. The key difference between dMMR and pMMR tumors is the infiltration of cytotoxic T-cells. dMMR tumors have increased infiltration and thus increased efficacy from ICI treatment. The investigators conducted a proof of concept study where the investigators applied an intratumoral (IT) unaltered flu vaccine in ten patients with non-metastatic pMMR CRC. The intervention increased infiltration of cytotoxic T-cells and the immune checkpoint PD-L1, suggesting that IT flu vaccine primes pMMR tumors to ICI treatment. The investigators aim to test the combination of IT flu vaccine and ICI treatment in patients with non-metastatic pMMR CRC in a new trial. The hypothesis is that IT flu vaccine and ICI treatment will synergistically to induce cancer cell death.

NCT Number	NCT05909423
Lead Sponsor	Zealand University Hospital Collaborators: Slagelse Hospital
Conditions	Colorectal Cancer
Enrollment	21 participants
Start Date	2023-09-01
Primary Completion	2025-09-01 (estimated)
Study Completion	2028-09-01 (estimated)
Updated on ClinicalTrials.gov	2023-06-18