Cell-to-cell distances between tumor-infiltrating inflammatory cells have the potential to distinguish functionally active from suppressed inflammatory cells

Beyond their mere presence, the distribution pattern of inflammatory cells is of special interest. Our hypothesis was that random distribution may be a clear indicator of being non-functional as a consequence of lack of interaction. Here, we have assessed the implication of cell-to-cell distances among inflammatory cells in anal squamous cell carcinoma and a possible association with survival data. Thirty-eight patients suffering from anal carcinoma were studied using tissue microarrays, double staining immunohistochemistry, whole slide scanning and image analysis software. Therapy consisted of concurrent radiochemotherapy. Numbers of stromal and intraepithelial tumor-infiltrating inflammatory cells (TIC) and the distances between cells were quantified. Double-staining of FoxP3(+) cells with either CD8(+), CD1a(+) or CD20(+) cells was performed. Measured cell-to-cell distances were compared to computer simulated cell-to-cell distances leading to the assumption of non-randomly distributed and therefore functional immune cells. Intraepithelial CD1a(+) and CD20(+) cells were randomly distributed and therefore regarded as non-functional. In contrary, stromal CD20(+) cells had a non-random distribution pattern. A non-random distance between CD20(+) and FoxP3(+) cells was associated with a clearly unfavorable outcome. Measured distances between FoxP3(+) cells were distinctly shorter than expected and indicate a functional active state of the regulatory T cells (Treg). Analysis of cell-to-cell distances between TIC has the potential to distinguish between suppressed non-functional and functionally active inflammatory cells. We conclude that in this tumor model most of the CD1a(+) cells are non-functional as are the intraepithelial CD20(+) cells, while stromal CD20(+) cells and FoxP3(+) cells are functional cells.

Radiosensitization by BRAF inhibitor therapy-mechanism and frequency of toxicity in melanoma patients

BACKGROUND

Recent evidence suggests that ionizing radiation may be associated with unexpected side-effects in melanoma patients treated with concomitant BRAF inhibitors. A large multicenter analysis was carried out to generate reliable safety data and elucidate the mechanism.

METHODS

A total of 161 melanoma patients from 11 European skin cancer centers were evaluated for acute and late toxicity, of whom 70 consecutive patients received 86 series of radiotherapy with concomitant BRAF inhibitor therapy. To further characterize and quantify a possible radiosensitization by BRAF inhibitors, blood samples of 35 melanoma patients were used for individual radiosensitivity testing by fluorescence in situ hybridization of chromosomal breaks after ex vivo irradiation.

RESULTS

With radiotherapy and concomitant BRAF inhibitor therapy the rate of acute radiodermatitis ≥2° was 36% and follicular cystic proliferation was seen in 13% of all radiotherapies. Non-skin toxicities included hearing disorders (4%) and dysphagia (2%). Following whole-brain radiotherapy, rates of radiodermatitis ≥2° were 44% and 8% (P < 0.001) for patients with and without BRAF inhibitor therapy, respectively. Concomitant treatment with vemurafenib induced acute radiodermatitis ≥2° more frequently than treatment with dabrafenib (40% versus 26%, P = 0.07). In line with these findings, analysis of chromosomal breaks ex vivo indicated significantly increased radiosensitivity for patients under vemurafenib (P = 0.004) and for patients switched from vemurafenib to dabrafenib (P = 0.002), but not for patients on dabrafenib only. No toxicities were reported after stereotactic treatment.

CONCLUSION

Radiotherapy with concomitant BRAF inhibitor therapy is feasible with an acceptable increase in toxicity. Vemurafenib is a more potent radiosensitizer than dabrafenib.

Analysis of radiation- and 5-FU-induced inhibition of cell proliferation by an automatic colony analyser

Proliferation of Chinese hamster cells B-14 was inhibited by irradiation, by incubation with 5-fluorouracil (5-FU) and by a combination of both treatments. The reduction in proliferation was assayed by the colony formation test, which was evaluated by an automatic colony analyser according to the number and volume of the colonies. It was demonstrated that the number of colonies multiplied by the volume was equivalent to the number of cells in a Petri dish and is called total colony volume. Since this quantity reflects the entire proliferation of cells, it is a more sensitive parameter for measuring cell viability than the clonogenicity of cells. The drug-radiation interaction showed a supra-additive effect, if total colony volume is taken into account, while the traditional scoring of colonies yielded only an additive effect.

The effect of serum albumin on the radiolysis of DNA studied by constant field electrophoresis and compared to alterations caused by low molecular weight OH. scavengers

After radiolysis of calf thymus DNA in 10(-2) mol dm-3 phosphate buffer at pH7 under N2, N2O and air the yields of double-strand breaks (dsb) have been determined by constant field electrophoresis. Double-strand (dsb) breaks were formed according to a linear-quadratic relationship with dose showing a lower G-value under aerobic than under anaerobic conditions (G (air) = 1.4 nmolJ-1; G (N2) = 2.1 nmolJ-1; G (N2O) = 4.9 nmolJ-1). To test the reliability of this system the effect of low molecular weight OH. scavengers which were already used in comparable work with plasmid DNA were studied. The results with plasmid DNA and calf thymus DNA obtained by different techniques of electrophoresis agreed quite well. Under N2 more protection was obtained with ethanol than with DMSO or with t-butanol. Under air, double-strand breakage was further decreased and reached the same level with all of these scavengers. Furthermore the constant field electrophoresis gives similar results as the low-angle light scattering technique for radiation induced double strand breakage of calf thymus DNA. When BSA was used at the same scavenger capacity as the low molecular weight scavengers, the protection against double strand breakage was less if radiolysis was carried out in the presence of proteins. Under anaerobic conditions the protection factor was 13 in the presence of BSA, while with DMSO or t-butanol this factor was about 100 and with ethanol 300. In contrast to the low molecular weight OH. scavengers oxygen enhanced radiation-induced double-strand breakage with BSA. It is assumed that protein peroxyl radicals may cause strand breakage.