Complex sentence: This suppression lasted only 7 months due to the tumor's acquirement of a mutation in the "ETV6-NTRK3" that encoded an entrectinib-reisistant "ETV6-NTRK3" protein.
Split into simpler sentences: This suppression lasted only 7 months due to the tumor's acquirement of a mutation in the "ETV6-NTRK3" gene. The newly mutated gene encoded an entrectinib-reisistant "ETV6-NTRK3" protein.