Prit,

I don't know about specific PDT / PIT drugs, but as you already know, one difficulty with PDT in general has been that the activating light might not penetrate deeply enough into tissue, so one reason for recurrence could be that the cancer was not completely destroyed.

A couple of years ago I did notice an experimental agent that was trying to overcome that problem called IR700. Hypothetically it can be activated by near infrared light enabling deeper effectiveness (a few centimeters instead of millimeters), although I don't know how real that proved to be in patients. An antibody is attached to it to achieve targeting of cancer cells (e.g., EGFR mAb-IR700). I have not checked research on that for a couple of years, but you can look for updates here:

http://www.ncbi.nlm.nih.gov/pubmed/?term=ir700

Best hopes,

Craig

in PA, USA

The biggest disadvantage of temoporphin in PDT is the associated long photosensitivity of the patient. This can go on to several months with regard to natural sunlight, but at the beginning there have to be somewhat stringent restrictions in the anbient light while during the first days the patient may not even be allowed to watch TV. A secondary disadvantage is that the drug has to be administered via a slow injection otherwise it can be traumatizing to the carrier vein and/or injection site. Temoporphin is a very effective photosensitizer which however may have some contraindications, like in its use in hollow organs or close to main arteries, as it may cause severe stricturing or even arterial bursts. With regard to tissue penetration it is not too bad (excitation at 652 nm) however it would have been better off with a deeper activation wavelength (around 680 nm). Having said that the stricturing considerations would be even more strongly applicable, however you could always acivate it at a more hypsochromic Q-band (e.g. green) to achieve a shallow effect. These are some limitations and disadvantages off the top of my head and in a bit of a rush (sort of a 5 min brainstorm) , but it should be enough to start you digging further....

mTHPC is apolar molecules with high autoaggregation efficiency. I think that including mTHPC into polymer particles may strongly change their structure and properties. Moreover in polymer environment the dye may form aggregates..similar behavior of mTHPC in PEG-liposomes. mTHPC molecules very slow migrate between different binding sites in biological structures (proteins, cellular membranes and so on). Taking this fact into consideration one can expect that including mTHPC into nanoparticles changes significantly it biodistribution...skin photosensitivity post iv administration....dark toxicity