What I was impressed with is they jumped right up to the 600mg and 900mg 191 (BID) doses. To me this means they saw little to no drug interaction that they feel confident enough to jump right to the highest doses used in the 1B.
I just looked up the 191 monotherapy results (#msg-33270341) and in the NR cohort 300mg BID had a 2.5 log drop.