NNRTI-based antiretroviral therapy may increase risk of radiation induced side effects in HIV-1-infected patients.

Abstract

As the incidence of cancer is rising in HIV-1-infected patients, radiotherapy is used more frequently in this patient group. Strong radiation induced side effects have been reported in single patients on antiretroviral therapy. Thus we investigated whether HIV-1 itself or antiretroviral drugs could enhance radiosensitivity in patients. Radiosensitivity after in vitro irradiation of blood lymphocytes was tested in 196 individuals (80 HIV-1-infected patients and 116 healthy controls and cancer patients) using a three color fluorescence in situ hybridization approach to analyze chromosomal aberrations (B/M). Additionally, the NNRTI efavirenz and the NRTIs tenofovir and emtricitabine were tested for radiosensitizing effects in vitro. Lymphocytes from HIV-1-infected patients in the NNRTI + NRTI group were significantly more sensitive to ionizing radiation than in the other groups (patients without treatment or with NRTI + PI or HIV-negative controls). In vitro the triple medication efavirenz, tenofovir and emtricitabine leads to a reduced survival fraction and an increased activation of the DNA repair proteins H2AX, Nbs, Atm and 53BP1 in combination with ionizing radiation. HIV-1 treatment with NNRTI containing therapy regimes possibly sensitizes a subgroup of patients to ionizing radiation. Individual radiosensitivity of HIV-1-infected patients on HAART including NNRTI should be tested before starting radiotherapy.