Peri-operative immunotherapy with OK-432.

Area of Science:

• Immunology
• Oncology
• Medical Science

Background:

• Gastric cancer surgery can negatively impact immune function, specifically Natural Killer (NK) cell activity.
• OK-432 is an immunomodulator used in cancer therapy.
• Understanding the immune effects of OK-432 in gastric cancer patients is crucial for optimizing treatment strategies.

Purpose of the Study:

• To investigate the effects of OK-432 on immune responses, including NK cell activity and lymphocyte populations, in gastric cancer patients undergoing surgery.
• To evaluate the safety and efficacy of different administration routes (intradermal vs. intravenous) of OK-432.

Main Methods:

• Patients with gastric cancer received OK-432 via intradermal or intravenous administration pre- and post-operatively.
• Natural Killer (NK) cell activity was measured.
• Flow cytometry was used to analyze proportions of lymphocyte subsets, including Leu 7-positive, Leu 11a-positive, CD4+2HA+ (suppressor-inducer T cells), B cells, OK-M1-positive, and MHC class II antigen-positive cells.

Main Results:

• Intradermal OK-432 enhanced the SU-PS skin reaction but did not prevent the surgical decline in NK activity.
• Changes in NK activity correlated with Leu 11a-positive cells, not Leu 7-positive cells.
• Intradermal OK-432 increased Leu 7-positive and Leu 11a-positive cells in specific patient subgroups.
• Intravenous OK-432 tended to increase suppressor-inducer T cells, B cells, and Leu 7-positive cells.
• Intravenous OK-432 significantly increased OK-M1-positive and MHC class II antigen-positive cells in all patients.
• Intravenous immunotherapy with 0.1 KE of OK-432 was well-tolerated with minimal side effects.

Conclusions:

• While OK-432 can modulate specific immune cell populations and enhance skin reactions in gastric cancer patients, its ability to fully counteract the surgical reduction in NK cell activity is limited.
• Intravenous administration of OK-432 appears to induce broader immune cell changes and is a safe therapeutic option.
• Further research is warranted to explore the clinical significance of these immune changes and optimize OK-432 immunotherapy protocols for gastric cancer treatment.