Photon activation therapy of RG2 glioma carrying Fischer rats using stable thallium and monochromatic synchrotron radiation

Abstract

75 RG2 glioma-carrying Fischer rats were treated by photon activation therapy (PAT) with monochromatic synchrotron radiation and stable thallium. Three groups were treated with thallium in combination with radiation at different energy; immediately below and above the thallium K-edge, and at 50 keV. Three control groups were given irradiation only, thallium only, or no treatment at all. For animals receiving thallium in combination with radiation to 15 Gy at 50 keV, the median survival time was 30 days, which was 67% longer than for the untreated controls (p = 0.0020) and 36% longer than for the group treated with radiation alone (not significant). Treatment with thallium and radiation at the higher energy levels were not effective at the given absorbed dose and thallium concentration. In the groups treated at 50 keV and above the K-edge, several animals exhibited extensive and sometimes contra-lateral edema, neuronal death and frank tissue necrosis. No such marked changes were seen in the other groups. The results were discussed with reference to Monte Carlo calculated electron energy spectra and dose enhancement factors.

Keeping those telomeres short! an innovative intratumoral long-term drug delivery system

“…The same advantages that iodine-125 seeds contribute to the PAT treatment can be provided through the use of mono-energetic photons from synchrotron radiation beam lines (Yokoya et al 2008;Bobyk et al 2013;Ceberg et al 2012;Adam et al 2005Adam et al , 2006Biston et al 2004;Esteve et al 2002). These beams can be finely tuned to achieve suitable energy photon interactions with the Pd atoms at depth, in tumor, and elicit Auger emission in DNA.…”

Mathematical modelling of the synergistic combination of radiotherapy and indoleamine-2,3-dioxygenase (IDO) inhibitory immunotherapy against glioblastoma

“…The first study was concerned with photon activation therapy using thallium as a dose-enhancing contrast agent. 14 In the second study, the animals were treated with a combination of RT and IDO-inhibitory treatments using intraperitoneal injections of 1-MT. 7 From these works, we extracted the survival times for animals that were untreated, treated with radiation alone to 8, 10 or 15 Gy, treated with 1-MT alone, or treated with the combination of 1-MT and RT to 8 Gy.…”

“…Pooled survival data for glioma carrying Fischer 344 rats, treated with radiation and/or IDO-inhibitory immunotherapy using 1-MT, showing mean (cross), median (line), interquartile range (box), range (whiskers), and outliers (dots). Data from Ceberg et al 14 and Ahlstedt et al 7 1-MT, 1-methyl tryptophan; IDO, indoleamine-2,3-dioxygenase.…”

Nanoparticles as Theranostic Vehicles in Experimental and Clinical Applications—Focus on Prostate and Breast Cancer

“…The photon activation therapy (PAT), sometimes also referred to as photon activated therapy, involving Auger electrons and mentioned for the first time for medical applications over three decades ago, shows a limited amount of publications but is an interesting option for TNPs and therefore discussed here [453,454,455,456,457,458,459,460,461]. The PAT technique is based on the principle of specific tumor localization of a high-Z compound such as platinum (Pt), incorporated in, for example, a CTH drug, after which synchrotron radiation or X-rays directed against the tumor site is used to, via the photoelectric effect, trigger a cascade release of high linear energy transfer (high-LET) Auger electrons.…”