BCR-ABL1 transcript at 3months predicts long-term outcomes following second generation tyrosine kinase inhibitor therapy in the patients with chronic myeloid leukaemia in chronic phase who failed Imatinib

The BCR-ABL1 transcript level at 3months can predict long-term outcomes following frontline therapy with Imatinib or Dasatinib in chronic myeloid leukaemia (CML) patients. However, data is lacking for second-generation tyrosine kinase inhibitor (2GTKI) therapy after Imatinib failure. A total of 112 patients with CML in chronic phase receiving 2GTKI after Imatinib failure were reviewed. Treatment outcomes including complete cytogenetic (CCyR), major molecular (MMR) and molecular response 4 center dot 5 (4 center dot 5 log reduction of BCR-ABL1 transcript level, MR4 center dot 5), treatment failure, progression-free and overall survival (OS) were compared according to BCR-ABL1 transcript levels at 3 or 6months, divided into <1%IS, 110%IS and 10%IS. BCR-ABL1 transcript level at 3months showed better correlation with OS (P<0 center dot 001) than that at 6months (P=0 center dot 147). Better OS was also observed in the patients achieving <1%IS (100%) and 110%IS (100%) than those with 10%IS at 3months (70 center dot 6%, P<0 center dot 001). Those with <1%IS showed the best CCyR, MMR and MR4 center dot 5 rates; 110%IS, intermediate; and 10%IS, the lowest CCyR, MMR and MR4 center dot 5 rates. The group with <1%IS at 3months maintained significantly lower BCR-ABL1 transcript level compared to other two groups. In conclusion, the BCR-ABL1 transcript level at 3months is the most relevant surrogate for outcomes following 2GTKI therapy after Imatinib failure.