For 1L osimertinib...Pts with the common del19 mutation were more likely to achieve PFS > 12 months with 1L osimertinib than those with the L747_A750 > P mutation (Odds Ratio 4.14 (1.41-12.15), p 0.0097)....The del19 mutation L747_A750 > P is associated with inferior PFS compared to the common E746_A750del mutation in pts treated with 1L osimertinib.