Sub theme 3.5
Photodynamic therapy

Goals of research: general outline
Scientific achievements
Future plans: special goals and approach
Running projects
Associated staff

Goals of research: general outline

Main objective of the research programme is to study the interaction between light and living tissue with the purpose of understanding, optimizing and further developing applications of light for diagnosis and treatment of disease. In contrast to other physical modalities used for diagnostic or therapeutic purposes, such as ionizing radiation, light has only shallow penetration in living tissue. This apparent limitation renders it excellently suitable for diagnosis and treatment of superficial disease. Fueled by rapid developments in optoelectronics, lasers and fiber optic technology, these techniques can be applied in vivo, in a non-invasive or minimally invasive manner. Research activities comprise ex vivo and animal experiments, as well as clinical studies. Current research activities are centered around two strongly interrelated research lines: photodynamic therapy (PDT) and optical diagnostics (OD).


Photodynamic therapy is a therapeutic technique that is based on the interaction of a light sensitive drug with light. PDT has been under study for several decades and is now an emerging treatment modality for a range of primarily malignant conditions. It is under clinical investigation for the treatment of cancers of head and neck, bladder, lung, prostate, esophagus, brain, and skin and several non-malignant indications. For age-related macula degeneration (AMD) and non-melanoma skin cancer PDT is now the gold standard therapy.


Early attempts to use optical techniques for detecting cancer date from more than a century ago and were partly inspired by the fluorescent emission from the drugs used in early photodynamic therapy. The dramatic technological developments in optics and optoelectronics that have started a decade ago have enabled the use of a large number of new non invasive non destructive optical sampling techniques to probe inside the body. So far, my research group has a history in fluorescence imaging and spectroscopy as well as diffuse reflection spectroscopy. These techniques have been investigated for the diagnosis of cancer and are currently being used routinely in monitoring photodynamic therapy.

Scientific achievements

In the last 5 years PDT research in my group has focused on the mechanisms of action of different photosensitizers, light dosimetry, light fractionation and the development of clinical applications. Research activities comprised preclinical work on animal models, phantom studies, theory development, clinical experimentation and clinical pilot studies. The most significant achievements of the research group are:

  1. The development of a fractionation scheme for ALA-PDT for basal cell carcinoma. Present clinical results outperform surgery. And the therapy is now being used
  2. The development and clinical evaluation of light dosimetry for PDT of Barrett’s esophagus.
  3. The development and clinical evaluation of a clinical approach to PDT of nasopharyngeal cancer.

Over the last few years a special form of reflection spectroscopy has been developed in my group, and named Differential Path length Spectroscopy. Arjen Amelink received a VIDI grant for this work. This technique measures the scattering of light in a superficial layer of tissue. It is a non invasive technique that van be applied in vivo in animals and humans. It samples the top 100 micrometer of tissue and measures the micro vascular properties and intracellular light scattering. The technique has been studied ex vivo extensively and clinical measurements have been performed in more than 250 patients. It has been used successfully in the bronchoscopic classification of early cancers, and is currently under investigation for diagnosis of cancer in the esophagus, the oral cavity, the brain and breast.

In collaboration with The Physics Department of the University of Utrecht (Prof H.C. Gerritsen) we investigated the possibilities of in vivo optical spectroscopy and spectroscopic imaging based on non-linear optical interactions. This technique commonly used by investigators for ex vivo microscopy was modified for in vivo use in mice. The project (FOM) has lead to 10 publications, a PhD thesis and an intensive collaboration with Philips Research.

Future plans: special goals and approach


We are currently investigating a new approach for treatment planning for PDT of recurrent cancer of the base of the tongue. Our co-worker Robert van Veen received a VENI grant for this work.

To extend dosimetry in clinical PDT beyond the dosimetry of light alone and to investigate various phenomena occurring during PDT we will be performing DPS and fluorescence measurements during clinical PDT (ZonMW PTO 95100107)

Interstitial application of light for PDT in deep seated tumors performed with optical fibers has the limitation that light application is limited to a few hours. For light application over extended periods of time (metronomic PDT) we develop wireless implantable light sources in collaboration with prof. French of the University of Deft (HST klein)

A new major research line has emerged in our group is the development of novel targeted photosensitizers that have a higher specificity for certain cellular targets. In collaboration with the Departments of Immunology and Internal Medicine and the University of St Louis in the USA we are developing photosensitiser-peptide conjugates. At present these are based on somatotsatin analogues for the treatment of neuroendocrine tumours and arthritis. We have demonstrated effective in-vitro targeting and now plan to determine the pharmacokinetics of these molecules in-vivo. In addition we are pursuing the use of nanotechnology in photodynamic therapy. In collaboration with M. J. H. Witjes at University Medical Center Groningen we are investigating the use of antibody targeted photosensitiser loaded liposomes to target head and neck tumours. In collaboration with Dr Koyakutty at the Centre for Nanoscience, Amrita Institute of Medical Science, India we are developing nanoparticle-photosensitiser conjugates where the nanoparticles are based on silica and biodegradable chitosan. We are also combining our approaches to the use of nanoparticles and molecular targeting by developing nanoparticle-photosensitiser conjugates with small peptides such as ocreotide to target specific cells in-vivo. In-vivo studies if these formulations are underway. (ZonMW PTO 95100107) and (Marie Curie EC/220507)


New clinical applications of DPS: mediastinal lymph nodes, Intraoperative optical measurements during breast surgery (IOP: HYMPACT) use of DPS for Molecular imaging (CTMM: MUSIS).

The collaboration with Utrecht University on non-linear Spectral Imaging will be continued. We will be investigating the biologic effects of femto-second laser tissue interactions and investigate the biologic background of the spectral images obtained in animal models. We will develop a miniaturized scan head that will fit into a biopsy needle. In the last phase of the project we will perform pilot experiments on Pig liver and dog prostate. (STW RUU 10320)

Most recent publications
  1. Amelink A, Haringsma J, Sterenborg HJCM. Noninvasive measurement of oxygen saturation of the microvascular blood in Barrett's dysplasia by use of optical spectroscopy.Gastrointest Endosc. 2009; 70:1-6. Epub 2009 Feb 27.
  2. van der Snoek E. M, A. Amelink, M.E. van der Ende, J.C. den Hollander, J.G. den Hollander, F.P. Kroon, R. Vriesendorp, H.A.M. Neumann, D.J. Robinson. Photodynamic therapy with topical metatetrahydroxychlorin (Fosgel®) is ineffective for the treatment of anal intraepithelial neoplasia, grade III. 1: J Acquir Immune Defic Syndr. 2009; 52: 141-3.
  3. E.R.M. de Haas, H.C. de Vijlder, H.J.C.M. Sterenborg, H.A.M. Neumann, D.J. Robinson, Fractionated aminolevulinic acid-photodynamic therapy provides additional evidence for the use of PDT for non-melanoma skin cancer J. Eur. Acad. Dermatol. Venereol. 2008; 22: 426-430
  4. J.G. Aerts, A. Amelink J.P. Hegmans, A. Hemmes, B. Den Hamer, H.J.C.M. Sterenborg, H.C. Hoogsteden, B.N. Lambrecht. HIF1a expression in bronchial biopsies correlates with tumor microvascular saturation determined using optical spectroscopy, Lung Cancer, doi:10.1016/j.lungcan.2007.03.023
  5. de Bruijn, H. S., E. R. M. de Haas, K. M. Hebeda, A. van der Ploeg – van den Heuvel, H. J. C. M. Sterenborg, H. A. M Neumann, and D. J. Robinson (2007) Light fractionation does not enhance the therapeutic efficacy of methyl 5-aminolevulinate mediated photodynamic therapy in normal mouse skin. Photochem. Photobiol. Sci 6: 1325-31.
  6. J.A. Palero, H.S. de Bruijn, H.S. van den Heuvel, H.J.C.M. Sterenborg, H.C. Gerritsen. Spectrally resolved multiphoton imaging of in vivo and excised mouse skin tissues. Biophys J. 2007 93: 992-1007.
  7. R.L. van Veen, D.J. Robinson, P.D. Siersema, H.J.C.M. Sterenborg. The importance of in situ dosimetry during photodynamic therapy of Barrett's esophagus. Gastrointest. Endosc. 2006; 64, 786-788.
  8. J.A. Palero, H.S. de Bruijn, A. van der Ploeg-van den Heuvel, H.J.C.M. Sterenborg, H.C. Gerritsen. In vivo nonlinear spectral imaging in mouse skin. Optics Express, 2006; 14: 4395-4402.
  9. de Haas, E. R. M., B. Kruijt, H. J. C. M. Sterenborg, H. A. M. Neumann, D. J. Robinson. (2006) Fractionated illumination significantly improves the response of superficial basal cell carcinoma to aminolevulinic-acid photodynamic therapy, J Invest Dermatol. 126: 2679-2686
  10. M.P.L. Bard, A. Amelink, V. Noordhoek-Hegt, W.J. Graveland, H.J.C.M. Sterenborg, H.C. Hoogsteden, J.G.J.V. Aerts. Measurement of lung tumor hypoxia measured using differential path-length spectroscopy Am J Respir Crit Care Med, 2005; 171: 1178-1184.