PDT en Hyperthermie: Hyperthermie in combinatie met PDT - Photodynamic Therapy zorgt voor opmerkelijke resultaten - 65% remissie - in proeven bij muizen

1 november 2004: Bron: Pubmed

Duitse onderzoekers hebben al in 2003 in dierproeven aangetoond dat hyperthermie in combinatie of als aanvulling op PDT - Photodynamic therapy voor opmerkelijke resultaten zorgt. Ralph Moss maakt in zijn nieuwsbrief van deze week melding van deze studie. Wat niet gezegd wordt in het studieverslag in Pubmed, althans niet in het abstract is dat volgens Ralph Moss de onderzoekers aantoonden dat bij de muizen door deze combinatie 65% in remissie kwam. Hier de passages uit de neiwusbreif van Ralph Moss en daaronder het abstract van de studie uit Pubmed.

Lately, his research has focused on the effects of combining hyperthermia (therapeutic heat) with photodynamic therapy (PDT). He told the audience that his experiments on mice had shown that tumors can be eradicated using hyperthermia in 15 percent of cases. He obtained similar results in experiments using photodynamic therapy, in which certain frequencies of light are administered after the injection of a sensitizer derived from chlorophyll. However, when he combined the two modalities, experimentally, he achieved 65 percent remissions! There is a powerful synergy between heat and light.

The treatment induces what he calls "vascular collapse" within the tumors, thereby making them unable to survive (Kelleher 2003). True, these results were obtained in laboratory animals, not human beings, but his work could have dramatic benefits for human cancer patients in the future. The great thing about going to excellent regional conferences like this is that one learns about new treatments before they start making headlines.

Abstract uit Pubmed:

Br J Cancer. 2003 Dec 15;89(12):2333-9.

Combined hyperthermia and chlorophyll-based photodynamic therapy: tumour growth and metabolic microenvironment.

Kelleher DK, Thews O, Scherz A, Salomon Y, Vaupel P.

Institute of Physiology and Pathophysiology, Johannes Gutenberg-University Mainz, Duesbergweg 6 D-55099 Mainz, Germany. kelleher@uni-mainz.de

The effects of combined and simultaneously applied localised 43 degrees C hyperthermia (HT) and an antivascular bacteriochlorophyll-serine-based photodynamic therapy (Bchl-ser-PDT) on tumour growth and several microenvironmental parameters were examined. Rats bearing DS-sarcomas were allocated to treatment groups: (i) sham-treatment (control), (ii) Bchl-ser-PDT (20 mg kg(-1) i.v.), (iii) localised HT, (iv) Bchl-ser-PDT+HT. The light source used was an infrared-A irradiator, which, by use of appropriate filters, delivered the different ranges of wavelengths required. Following treatment, tumour volume was monitored. The greatest tumour growth inhibition was seen with Bchl-ser-PDT+HT, and subsequent experiments identified the pathophysiological basis for this effect. Red blood cell flux in tumour microvessels declined rapidly upon Bchl-ser-PDT+HT, reaching approximately 10% of initial values by the end of treatment. Similarly, tumour oxygenation worsened, reaching almost anoxic levels by the end of the treatment period. Assessment of metabolic parameters showed a pronounced increase in lactate levels and a decrease in ATP concentrations after combined treatment. The results presented suggest that vascular collapse and flow stasis resulting in a deterioration of tumour oxygenation and a switch from oxidative to glycolytic glucose turnover are key elements in the tumour eradication seen with this novel approach in which an antivascular PDT and HT are combined and simultaneously applied.

PMID: 14676815 [PubMed - indexed for MEDLINE]