• Antibody-drug conjugates
• Targeting platform – 'OptiLink'
• Light activated cancer therapy – 'ProstaLite'
• MRI contrast agents & imaging
• Photosensitiser innovations
• Additional products and applications

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Targeted light activated cancer therapy - 'ProstaLite'

PhotoBiotics is creating a range of targeting therapeutic entities known as Photo-ImmunoConjugates (PICs), using the OptiLink platform technology for conjugating photosensitisers to relevant antibody fragments (scFvs). ProstaLite is PhotoBiotics’ lead PIC for the targeted light-activated treatment (photodynamic therapy, PDT) of prostate cancer.

PDT uses intravenous photosensitising agents excited via irradiation with fibre-optically delivered cold red laser light. This generates reactive oxygen species (ROS, e.g., singlet oxygen) close to the tumour, ensuring its ultimate destruction.

PICs solve the critical weaknesses in conventional PDT by improving tissue selectivity and localization, resulting in far less proximal tissue damage, faster systemic clearance, and much-reduced skin photosensitivity.

Better localisation of the photosensitiser in target tissues greatly expands the range of treatable indications, and enhances ease of use for both physician and patient.

ProstaLite, created using the OptiLink technology platform, demonstrates:

• Higher selectivity of PICs toward cancer cells than free photosensitiser; almost zero phototoxicity against non-target cell lines; and excellent in vitro cell kill results

• Selective targeting of tumours in vivo

• Significant tumour regression and cure in animal models when treated with the ProstaLite PIC. (see below, and Scientific Publications; The International Journal of Cancer, 2008;122:1155-1163)

• Fewer side effects because in vivo clearance is far superior to free photosensitiser, resulting in high therapeutic indices

Because the OptiLink platform successfully ensures photosensitisers are spaced well ‘apart’, photophysical quenching is prevented. This leads to:-

• Improved singlet oxygen generation = a better photodynamic effect

• Improved fluorescence and better imaging = better imaging

• Reduced aggregation = better product

• Makes antibody fragments 'PDT-efficient' = versatile platform