What is photodynamic therapy?

Photodynamic Therapy (PDT) is an innovative treatment that utilizes light of a specific wavelength to activate a complementary photosensitive molecule. These activated molecules then confer therapeutic effects at the target treatment site. PDT is an FDA approved first-line therapy for age-related macular degeneration, and has proven to be safe and effective in thousands of patients. In addition, PDT is used to treat many types of cancer, including esophageal cancer and small-cell lung cancer, and can be used to treat other conditions such as severe acne. As a result, PDT has gained approval from scientists and clinicians in the United States and worldwide. PDT continues to be developed to treat pancreatic, ovarian, and prostate cancers, and much scientific and clinical progress is being made on those fronts. Above is a simple cartoon that provides a basic outline of photodynamic therapy and its components.

PDT Cartoon

A. A photosensitizer (PS) is a photoactivatable multifunctional agent, which upon light activation can serve as both an imaging agent 
and a therapeutic agent.
B. Sequence of administration, localization, and light activation of the PS for PDT or fluorescence imaging.

What are the benefits of combination therapy for treating cancer?

Existing treatments for cancer suffer from major shortfalls including resistance to treatment and post-treatment disease recurrence. This, combined with the need for specific and targeted therapies, highlight the need for new mechanistically rationalized combination therapies that could synergistically enhance treatment response and improve patient outcomes. Several distinctive features of PDT make it an attractive therapy for a range of cancers and other diseases, especially when viewed as a component of a larger treatment regimen

  1. The PS-light combination lends itself to two layers of selectivity
  2. PDT and chemotherapy have proven to be an effective combination treatment
  3. The synthetic nature of photosensitizers allow for rationally-designed molecular targeting
  4. The optical properties of photosensitizers make them a valuable theranostic too

Additional Photobiology Resources