The advent of immunotherapy has revolutionized cancer treatments. However, the application
of immune checkpoint inhibitors may entail severe side effects, with the risk of therapeutic
resistance. The generation of chimeric antigen receptor (CAR) T-cells or CAR-NK cells
requires specialized molecular laboratories, is costly, and is difficult to adapt
to the rapidly growing number of cancer patients. To provide a simpler but effective
immune therapy, a whole-cell tumor vaccine protocol was established based on ultraviolet
C (UCV)-irradiated 4T1 triple-negative breast cancer cells. The apoptosis of tumor
cells after UVC irradiation was verified using resazurin and Annexin V/propidium iodide
flow cytometric assays. Protective immunity was achieved in immunized BALB/c mice,
showing partial remission. Adoptive transfer of splenocytes or plasma from the mice
in remission showed a protective effect in the naive BALB/c mice that received a living
4T1 tumor cell injection. 4T1-specific IgG antibodies were recorded in the plasma
of the mice following immunization with the whole-cell vaccine. Interleukin-2 (IL-2)
and oligonucleotide 2006 (ODN2006) adjuvants were used for the transfer of splenocytes
from C57BL/6 mice into cyclophosphamide-treated BALB/c mice, resulting in prolonged
survival, reduced tumor growth, and remission in 33% of the cases, without the development
of the graft-versus-host disease. Our approach offers a simple, cost-effective whole-cell
vaccine protocol that can be administered to immunocompetent healthy organisms. The
plasma or the adoptive transfer of HLA-matching immunized donor-derived leukocytes
could be used as an immune cell therapy for cancer patients.
