No hormonal or immune modulation in 26-week juvenile rat and 13-week dog studies
“In 26-week juvenile rat and 13-week dog studies, no evidence of tumorigenicity, hyperplasia, preneoplastic lesions, neoplasia, or hormonal/immune modulation was observed.”
Not studied by the applicant; deoxynucleosides distribute extensively, highest in spleen, liver, kidney and intestine
“No pharmacokinetic studies on organ distribution were performed with exogenous doxecitine and doxribtimine, since sufficient data was available from literature. Exogenous deoxycytidine and deoxythymidine are distributed extensively in the body, with the highest levels in spleen, liver, kidney, and intestine.”
Genotoxic impurity alpha-hydroxythymidine in the doxribtimine drug substance
“A significant safety concern was identified with respect to alpha-hydroxythymidine, a genotoxic impurity present in the doxribtimine drug substance starting material.”