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Laser immunotherapy (LIT) has shown its efficacy against late-stage, metastatic cancers, both in pre-clinical
studies and clinical pilot trials. However, the possible mechanism of LIT is still not fully understood. In
our previous studies, we have shown that LIT induces tumor-specific antibodies that strongly bind to the
target tumors. Tumor resistance in cured animals demonstrated long-term immunological effect of LIT.
Successful transfer of adoptive immunity using spleen cells from LIT-cured animals indicated a long-term
immunological memory of the host system. In clinical trials for the treatment of late-stage melanoma
patients and breast cancer patients, the similar long-term, systemic effects have also been observed. To
further study the immunological mechanism of LIT, immuno-histochemical analysis of patient tumor samples has performed before and after LIT treatment. Our results showed strong evidence that LIT
significantly increases the infiltration of immune cells in the target tumors. Specifically, LIT appeared to
drive the infiltrating immune cell populations in the direction of CD4, CD8 and CD68 T-cells. It is possible
that activation and enhancement of both humeral and cellular arms of the host immune system are achievable
by the treatment of LIT. These special features of LIT have contributed to the success of patient treatment.
The underlying mechanism of LIT appears to be an in-situ autologous whole-cell cancer vaccination, using all
components of tumors as sources of tumor antigens. Our preliminary mechanistic studies and future in-depth
studies will contribute to the understanding and development of LIT as an effective modality for the
treatment of late stage cancer patients who are facing severely limited options.
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