Interestingly, E157Q mutation is able to partially restore decrease in integrase enzymatic activity caused by the R263K substitution, thereby acting as a possible secondary, compensatory mutation. Furthermore, the E157Q-R263K double-mutant also displayed enhanced DTG resistance by 10-fold compared with lower-level resistance associated with R263K mutation alone. However, to date, the double-mutant E157Q-R263K has not yet been described in vivo at VF of an INI-based regimen .