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http://www.nature.com/bjc/journal/vaop/ncurrent/abs/6604059a.html

blocking PS in autologous tumor vaccines confers tumor-specific immunity

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British Journal of Cancer advance online publication 30 October 2007; doi:10.1038/sj.bjc.6604059 www.bjcancer.com

Photodynamic therapy-generated vaccines: relevance of tumour cell death expression

M Korbelik1, B Stott1 and J Sun1

1Department of Cancer Imaging, British Columbia Cancer Agency, Vancouver, British Columbia, Canada



Correspondence to: Dr M Korbelik, Department of Cancer Imaging, British Columbia Cancer Research Centre, 675 West 10th Avenue, Vancouver, British Columbia V5Z 1L3,

Received 30 May 2007; revised 27 September 2007; accepted 27 September 2007; published online 30 October 2007



Recent investigations have established that tumour cells treated in vitro by photodynamic therapy (PDT) can be used for generating potent vaccines against cancers of the same origin. In the present study, cancer vaccines were prepared by treating mouse SCCVII squamous cell carcinoma cells with photosensitiser chlorin e6-based PDT and used against poorly immunogenic SCCVII tumours growing in syngeneic immunocompetent mice. The vaccine potency increased when cells were post-incubated in culture after PDT treatment for 16 h before they were injected into tumour-bearing mice. Interfering with surface expression of phosphatidylserine (annexin V treatment) and apoptosis (caspase inhibitor treatment) demonstrated that this post-incubation effect is affiliated with the expression of changes associated with vaccine cell death. The cured mice acquired resistance to re-challenge with the same tumour, while the engagement of cytotoxic T lymphocytes was demonstrated by detection of high numbers of degranulating CD8+ cells in vaccinated tumours. The vaccines prepared from ex vivo PDT-treated SCCVII tumour tissue were also highly effective, implying that surgically removed tumour tissue can be directly used for PDT vaccines. This opens attractive prospects for employing PDT vaccines tailored for individual patients targeting specific antigens of the patient's tumour.


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