Immunogenic chemotherapy in two mouse colon cancer models

Area of Science:

• Immunology
• Oncology
• Pharmacology

Background:

• Chemotherapeutic drugs can influence antitumor immune responses beyond inducing cell death.
• 5-fluorouracil (5-FU) and oxaliplatin (L-OHP) are standard colon cancer treatments.
• Cyclophosphamide (CP) is investigated for its potential immunomodulatory effects in combination therapy.

Purpose of the Study:

• To evaluate the combined anticancer effects of 5-FU, L-OHP, and CP in mouse colon cancer models.
• To investigate the role of host immune responses, particularly T cells, in mediating the anticancer effects.
• To explore the potential of immune checkpoint blockade to enhance combination therapy efficacy.

Main Methods:

• Utilized CT26 and MC38 mouse colon adenocarcinoma models.
• Administered 5-FU/L-OHP in combination with CP.
• Assessed tumor growth, body weight, and survival rates.
• Analyzed immune cell populations in tumors and spleen.
• Investigated the effect of anti-PD-1 antibody treatment.

Main Results:

• The combination of 5-FU/L-OHP and CP significantly suppressed tumor growth in CT26 models, dependent on T cells.
• Treatment modulated tumor-infiltrating immune cells, increasing CD8+ T cells and altering myeloid-derived suppressor cell proportions.
• In MC38 models, triple therapy showed efficacy, which was further enhanced by anti-PD-1 antibody, leading to protective immunity and cytotoxic T cell generation.

Conclusions:

• The antitumor effects of 5-FU/L-OHP and CP combination therapy are largely mediated by host T cell immunity.
• Immune checkpoint blockade, such as with anti-PD-1 antibody, can significantly enhance the therapeutic efficacy of this combination chemotherapy.
• These findings highlight the potential of combining chemotherapy with immunotherapy for improved colon cancer treatment.