How would you approach a chronic phase CML patient who is responding to second generation TKI but not yet in molecular remission and is now pregnant?  

If the patient is now pregnant, I would stop the TKI immediately, and initiate therapy with interferon.  If that is not tolerable, I'd recommend hydroxyurea, although it will likely not control relapse into overt chronic phase.

I agree with @Gary J. Schiller that the TKI should be stopped. While there are case reports of successful pregnancies while taking TKIs for CML and there are also cautionary case reports of progression to blast phase during pregnancy when TKIs are stopped, the potential teratogenic risk of the ...