Feasibility study of active immunotherapy in patients with solid tumors

Area of Science:

• Immunology
• Oncology
• Dermatology

Background:

• Solid tumors present a significant challenge in oncology.
• Immunotherapy aims to harness the patient's immune system to fight cancer.
• Bacillus Calmette-Guérin (BCG), purified protein derivative (PPD), and tumor cells have been explored as immunotherapeutic agents.

Purpose of the Study:

• To evaluate the effects of immunization with BCG, PPD, and tumor cells on cellular immunity in patients with solid tumors.
• To assess the practical feasibility and morbidity associated with this immunotherapy approach.
• To investigate potential mechanisms of immune response, including antigen cross-reactivity and immunologic memory.

Main Methods:

• Forty-five immunocompetent patients with solid tumors were immunized with BCG, PPD, and autologous tumor cells.
• Cutaneous reactions to microbial antigens and tumor cells were assessed.
• Delayed hypersensitivity reactions at previous inoculation sites were observed.
• Morphological changes at vaccine sites, including halo-nevi and depigmentation, were documented.
• Presence of foreign body giant cells in tumor metastases was noted.
• Intralesional injections of non-specific agents (BCG, PPD, Varidase, Mumps) were administered.

Main Results:

• Significant morbidity was observed, including ulcerations and, in one case, systemic tuberculosis.
• Three patients showed possible enhancement of tumor growth.
• A majority of patients developed enhanced cutaneous reactions to antigens.
• Nine patients exhibited delayed hypersensitivity reactions, indicating immunologic memory.
• Twenty patients developed halo-nevi at vaccine sites; three had generalized depigmentation.
• Foreign body giant cells in metastases suggested microbial-tumor antigen cross-reactivity.
• Intralesional injections led to mononuclear cell infiltration and regression of injected lesions.

Conclusions:

• Immunization with BCG, PPD, and tumor cells alters cellular immunity but carries significant risks.
• While local tumor regression was observed with intralesional injections, systemic benefits were not demonstrated.
• The findings suggest potential cross-reactivity between microbial and tumor antigens and highlight the complexity of immune responses in cancer patients.