NTRK1 and anemia (phenotype): In the expanded safety population, 260 patients treated regardless of their TRK fusion status were analyzed; the most frequent grade 3 and 4 adverse events related to larotrectinib were increased alanine aminotransferase activity (eight (3%) out of 260 patients), anemia (six (2%)) and reduced neutrophil count (five (2%)).