A 45-year-old woman with Philadelphia chromosome-positive CML in chronic phase is started on imatinib. After 12 months, BCR-ABL1 transcript level by PCR is 1.2% (IS). According to ELN 2020 response criteria, this response at 12 months is:

• A Warning: consider change of treatment or intensification
• B Failure: immediate switch to second-generation TKI
• C Optimal response ✓
• D Complete molecular remission

Explanation

ELN 2020 response criteria define optimal response at 12 months as BCR-ABL1 ≤1% IS (i.e., MR2 or better), corresponding to ≥MMR (major molecular response). A value of 1.2% just exceeds this threshold and technically constitutes a 'warning' at 12 months per strict ELN criteria; however, at 12 months the optimal threshold is ≤1%. Since 1.2% is above 1% (IS) but below 10%, this is a WARNING response at 12 months. Complete molecular remission requires undetectable BCR-ABL1.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.