The bond between the research laboratory and the clinic is especially strong in the field of photomedicine. Much is learned in preclinical animal models, which is translated to the clinic for investigation, and then refinements in theory and technique are explored back in the laboratory. With many cancers becoming resistant to treatment, photodynamic therapy (PDT) offers a mechanistically distinct alternative. Studies have shown that PDT not only mitigates chemoresistance but also synergizes with chemotherapy and molecularly targeted therapies. From the world of biochemistry comes this unique look at 2 approaches to maximize the photodynamic effect through PDT combinations with targeted therapies: 1) using the molecular response after PDT to guide the selection of targeted agents and 2) preconditioning cancer cells to modulate nuclear molecular targets before PDT.