Intratumoral Hydrogen Peroxide With Radiation Therapy in Locally Advanced Breast Cancer: Results From a Phase 1 Clinical Trial.
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<h4>Purpose</h4>Hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) plays a vital role in normal cellular processes but at supraphysiological concentrations causes oxidative stress and cytotoxicity, a property that is potentially exploitable for the treatment of cancer in combination with radiation therapy (RT). We report the first phase 1 trial testing the safety and tolerability of intratumoral H<sub>2</sub>O<sub>2</sub> + external beam RT as a novel combination in patients with breast cancer and exploratory plasma marker analyses investigating possible mechanisms of action.<h4>Methods and materials</h4>Twelve patients with breast tumors ≥3 cm (surgically or medically inoperable) received intratumoral H<sub>2</sub>O<sub>2</sub> with either 36 Gy in 6 twice-weekly fractions (n = 6) or 49.5 Gy in 18 daily fractions (n = 6) to the whole breast ± locoregional lymph nodes in a single-center, nonrandomized study. H<sub>2</sub>O<sub>2</sub> was mixed in 1% sodium hyaluronate gel (final H<sub>2</sub>O<sub>2</sub> concentration 0.5%) before administration to slow drug release and minimize local discomfort. The mixture was injected intratumorally under ultrasound guidance twice weekly 1 hour before RT. The primary endpoint was patient-reported maximum intratumoral pain intensity before and 24 hours postinjection. Secondary endpoints included grade ≥3 skin toxicity and tumor response by ultrasound. Blood samples were collected before, during, and at the end of treatment for cell-death and immune marker analysis.<h4>Results</h4>Compliance with H<sub>2</sub>O<sub>2</sub> and RT was 100%. Five of 12 patients reported moderate pain after injection (grade 2 Common Terminology Criteria for Adverse Events v4.02) with median duration 60 minutes (interquartile range, 20-120 minutes). Skin toxicity was comparable to RT alone, with maintained partial/complete tumor response relative to baseline in 11 of 12 patients at last follow-up (median 12 months). Blood marker analysis highlighted significant associations of TRAIL, IL-1β, IL-4, and MIP-1α with tumor response.<h4>Conclusions</h4>Intratumoral H<sub>2</sub>O<sub>2</sub> with RT is well tolerated with no additional toxicity compared with RT alone. If efficacy is confirmed in a randomized phase 2 trial, the approach has potential as a cost-effective radiation response enhancer in multiple cancer types in which locoregional control after RT alone remains poor.
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Breast Cancer Radiotherapy
Translational Breast Radiobiology
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International journal of radiation oncology, biology, physics, 2020, 108 (4), pp. 1019 - 1029