Synergistic effect of photodynamic therapy with hypericin in combination with hyperthermia on loss of clonogenicity of RIF-1 cells

Enhanced effects of aminolaevulinic acid-based photodynamic therapy through local hyperthermia in rat tumours

“…Thus, although direct tumour cell kill appears to play a major role in the ALA-PDT þ HT effect, immunological and/or vascular effects may explain the differences seen between the in vitro and in vivo findings in this study. Other potential factors that might be involved in the pronounced potentiation of the antitumour effects seen are a concerted action of PDT and HT on certain proteins or supramolecular structures (Prinsze et al, 1991) or a conversion of PDT-induced repairable lesions to irreparable lesions upon HT treatment (Chen et al, 2001). Additionally, increased lactic acid formation during HT, as has already been reported for this tumour model (Kelleher et al, 1995), may also result in a lower pH in tumour tissue, and since acidosis has been found to enhance the efficacy of ALA-PDT in vitro (Wyld et al, 1998), such metabolic changes within the tumour tissue may play a role in the effects of ALA-PDT þ HT.…”

Enhancing the antitumoral effect of hypericin‐mediated photodynamic therapy by hyperthermia

“…In the previous in vitro study, we have demonstrated a synergistic effect on tumor cell killing in the RIF-1 cell line when PDT with hypericin was immediately followed by hyperthermia [7]. It was suggested that this synergistic interaction between hypericin-mediated PDT and hyperthermia could be due to the common cell membrane damage imposed by both treatments.…”

Photodynamic Therapy and Its Role in Combined Modality Anticancer Treatment

“…13,50 Some studies have shown that the timing between therapies is of critical importance and that hyperthermia applied after PDT is more effective than the reversed order. 13,48 There also appears to be a considerable dose-response effect dependent both on the light dose and on the length and temperature of hyperthermia, 53,54 suggesting that there is a need for systematically evaluating this dose-response relationship, in vitro and in vivo, to obtain the optimal treatment parameters for different cancer types.…”

“…48 As the use of focused ultrasound in the management of cancer is fairly new, the combination between PDT and ultrasound has only started to be explored in the last few years. The main hypothesis suggesting that this combination may yield a considerable antitumor effect is based on the fact that there are PS agents that can be triggered by both light energy and ultrasound energy, which should potentiate the response.…”