We have found G-CSF to be safe in this setting. We use it sparingly to keep the neutrophils > 500.

Bone marrow studies were repeated on June 1st and there was no evidence of MDS or fibrosis. The patient has grade 4 thrombocytopenia (needed transfusions at first but now hold at about 25K) and grade 4 neutropenia. She has been on antimicrobial ppx but we have not given any growth factors as of yet. Would you give neupogen, N-plate? We were thinking of once counts regain to start her with intermittent dosing and see if we can work our way up.

Managing cytopenia induced by TKIs is one of the most difficult issues we come across in CP-CML. Fortunately in this case you have evidence of ongoing disease sensitivity to kinase inhibition which I presume is the explanation for the sustained response to a brief exposure to nilotinib. I doubt this is due to persistence of nilotinib in the blood over a 3 month period, although it would be interesting to exclude this. Unfortunately we no longer provide drug level testing because Novartis no longer support it.

I presume you have repeated the bone marrow studies to see if there are other causes such as MDS or marrow fibrosis.

In these situations we usually don’t stop unless the cytopenia is grade 4. Our preferred approach is to find the TKI dose that provides tolerable cytopenia while maintaining MMR. We will add growth factors +/- transfusions as needed. Dasatinib is easier to titrate for this purpose – we have had some patients on dasatinib 20 mg alternate day and eventually achieved good control. You could do something similar with nilotinib. Whether using more standard doses and stopping every time the cytopenias get too severe is a better approach, we still don’t know. Intermittent therapy has been effective for some patients who have achieved good molecular responses, but I doubt it is the best approach here.

63 year old woman with a hx of benign ethnic neutropenia who was diagnosed with CML in 2017 and at an outside institution was treated with imatinib who responded initially but then was deemed refractory and suffered from pancytopenia. She started coming to our clinic in February 2020 and was started on dasatinib but then suffered from severe headaches and was switched to nilotinib. The patient was on nilotinib for ~ 1 month and became severely thrombocytopenic and neutropenic, with some anemia as well. She was taken off nilotinib and 3 months later is still suffering from pancytopenia. Interestingly her BCR-ABL transcript level continued to decrease with just a recent uptick this week.

I know that nilotinib has a half-life of ~15 hours but it appears that she responds to this much longer. Is there a way by which to test the pharmacokinetics of nilotinib in this patient? We are trying to figure out how to dose her once her counts hopefully rebound, we are trying to avoid HSCT.