RE:No share price change in US past two days The bcg strain that ibrx is using is more potent than mercks own.There are already trials going on in europe. keytruda is already facing challenge due to patent expiry now their bcg is getting challenged.. cell-based experiments, the new compound, nicknamed RuBCG, was able to significantly increase the efficacy of BCG in cancer cell kill versus BCG or RuvidarTM alone, when non-light activated.