Ponatinib Facilitates Treatment-Free Remission By Inducing Deep Molecular Responses

Multiple trials now demonstrate the potential for treatment-free remission (TFR) in patients with sustained deep molecular response to tyrosine kinase inhibitors (TKIs). We describe two patients who remain in treatment-free remission after achieving undetectable BCR-ABL with ponatinib on the phase II PACE trial, despite being multiply resistant/intolerant to other agents or carrying the T315I mutation.

Patient 1 previously had a suboptimal response to imatinib (BCRABL >10% at 15mo) and then was intolerant of nilotinib and dasatinib due to grade 3 liver enzyme abnormalities. He achieved undetectable BCR-ABL (Molecular MD laboratories) by six months on ponatinib. His ponatinib dose was gradually reduced from 45mg/d to 15mg/d due to vascular events (myocardial infarction requiring stenting, carotid stenosis requiring endarterectomy, recurrent ischaemic colitis). At the time of his last episode of colitis, his BCR-ABL had been undetectable for 47 months and hence a decision to attempt TFR was made. He remains in TFR 11 months post-cessation.

Patient 2 progressed on imatinib and was found to carry the T315I mutation. He achieved undetectable BCR-ABL by nine months on ponatinib. His ponatinib dose was also gradually reduced from 45mg/d to 15mg/d due to vascular events (popliteal stenosis requiring stenting, embolic stroke, coronary artery disease requiring stenting). At the time of his last event, his BCR-ABL had been undetectable for 30 months and hence a decision to attempt TFR was made. He remains in TFR 17 months post-cessation.

This series adds to the one prior case report of ponatinib facilitating treatment-free remission (Engel NW et al. J Oncol Pract 2016. 12(6);592-4) and these remissions are notable because they occur in patients not considered for other TFR studies because of refractoriness to other agents or known T315I mutations. This is an alternative avenue to dose reduction to reduce the risk of vascular events in ponatinib-treated patients.