Chemoradiation

Results of Phase III Randomized Trial for Use of Docetaxel as a Radiosensitizer in Patients With Head and Neck Cancer, Unsuitable for Cisplatin-Based Chemoradiation.

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PURPOSE: There is a lack of published literature on systemic therapeutic options in cisplatin-ineligible patients with locally advanced head and neck squamous cell carcinoma (LAHNSCC) undergoing chemoradiation. Docetaxel was assessed as a radiosensitizer in this situation.

METHODS: This was a randomized phase II/III study. Adult patients (age = 18 years) with LAHNSCC planned for chemoradiation and an Eastern Cooperative Oncology Group performance status of 0-2 and who were cisplatin-ineligible were randomly assigned in 1:1 to either radiation alone or radiation with concurrent docetaxel 15 mg/m2 once weekly for a maximum of seven cycles. The primary end point was 2-year disease-free survival (DFS).

RESULTS: The study recruited 356 patients between July 2017 and May 2021. The 2-year DFS was 30.3% (95% CI, 23.6 to 37.4) versus 42% (95% CI, 34.6 to 49.2) in the RT and Docetaxel-RT arms, respectively (hazard ratio, 0.673; 95% CI, 0.521 to 0.868; P value = .002). The corresponding median overall survival (OS) was 15.3 months (95% CI, 13.1 to 22.0) and 25.5 months (95% CI, 17.6 to 32.5), respectively (log-rank P value = .035). The 2-year OS was 41.7% (95% CI, 34.1 to 49.1) versus 50.8% (95% CI, 43.1 to 58.1) in the RT and Docetaxel-RT arms, respectively (hazard ratio, 0.747; 95% CI, 0.569 to 0.980; P value = .035). There was a higher incidence of grade 3 or above mucositis (22.2% v 49.7%; P < .001), odynophagia (33.5% v 52.5%; P < .001), and dysphagia (33% v 49.7%; P = .002) with the addition of docetaxel.

CONCLUSION: The addition of docetaxel to radiation improved DFS and OS in cisplatin-ineligible patients with LAHNSCC.

Cell-Specific Radiosensitization by Gold Nanoparticles at Megavoltage Radiation Energies

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Gold nanoparticles (GNPs) have been shown to cause sensitization with kilovoltage (kV) radiation. Differences in the absorption coefficient between gold and soft tissue, as a function of photon energy, predict that maximum enhancement should occur in the kilovoltage (kV) range, with almost no enhancement at megavoltage (MV) energies. Recent studies have shown that GNPs are not biologically inert, causing oxidative stress and even cell death, suggesting a possible biological mechanism for sensitization. The purpose of this study was to assess GNP radiosensitization at clinically relevant MV X-ray energies.

Methods and Materials

Cellular uptake, intracellular localization, and cytotoxicity of GNPs were assessed in normal L132, prostate cancer DU145, and breast cancer MDA-MB-231 cells. Radiosensitization was measured by clonogenic survival at kV and MV photon energies and MV electron energies. Intracellular DNA double-strand break (DSB) induction and DNA repair were determined and GNP chemosensitization was assessed using the radiomimetic agent bleomycin.

Results

GNP uptake occurred in all cell lines and was greatest in MDA-MB-231 cells with nanoparticles accumulating in cytoplasmic lysosomes. In MDA-MB-231 cells, radiation sensitizer enhancement ratios (SERs) of 1.41, 1.29, and 1.16 were achieved using 160 kVp, 6 MV, and 15 MV X-ray energies, respectively. No significant effect was observed in L132 or DU145 cells at kV or MV energies (SER 0.97–1.08). GNP exposure did not increase radiation-induced DSB formation or inhibit DNA repair; however, GNP chemosensitization was observed in MDA-MB-231 cells treated with bleomycin (SER 1.38).

Conclusions

We have demonstrated radiosensitization in MDA-MB-231 cells at MV X-ray energies. The sensitization was cell-specific with comparable effects at kV and MV energies, no increase in DSB formation, and GNP chemopotentiation with bleomycin, suggesting a possible biological mechanism of radiosensitization.

source: IJROBP