I would propose two therapeutic options.
1) If the patient has never been treated with imatinib or nilotinib, I would first switch from dasatinib. This is because dasatinib cannot be used beyond the first trimester of pregnancy, and imatinib or nilotinib may be required in case of molecular relapse during the second or third trimester. After switching, she may attempt conception while continuing TKI therapy; however, careful pregnancy testing is needed, and the TKI should be discontinued by around 4 weeks of gestation to minimize fetal exposure.
2) If MMR has been achieved but DMR has not yet been obtained, maintaining TFR during pregnancy would be quite challenging. Therefore, switching from TKI to interferon-α should be considered. A Japanese survey has reported some cases in which patients maintained MMR after switching to interferon-α and successfully achieved pregnancy and delivery, suggesting that this approach may also be worth attempting in this case.

Given her age of 39 years, it would be advisable to minimize delays in achieving pregnancy, for example by considering the concurrent use of assisted reproductive technology (ART) while on interferon-α.

Far be it from me to disagree with the pregnancy experts who have commented here. The two issues are firstly, how deep is MMR? The likelihood of rebound of disease on stopping TKI if the response is in the 0.1% IS range is very high. Secondly, IFN takes a while to capture once started. The biggest risk of TKI related teratogenicity is in the first trimester, safest in the third and variable in the second. Let me toss an idea into the discussion. Why not start IFN immediately while still on TKI, then attempt pregnancy and stop TKI immediately on detecting pregnancy while doing "routine" pregnancy testing. There is some evidence from the German trials that adding IFN to a TKI may be beneficial and having it on board may (wishfully thinking?) reduce the chances of rebound. IFN as well is sage in pregnancy, and as well, there is evidence that it may help with fetal retention (the placenta secretes IFNs) at least in the thrombocytosis literature.

I would like to know if the patient is in deep molecular remission or not, and if yes, for how long? My advice would be to wait for one or preferably two more years before attempting pregnancy. The option of embryo freezing can also be considered. However, if the patient is adamant about conceiving right away, then the strategy suggested by you could be considered, with close monitoring of bcr/abl transcripts, and avoiding TKI exposure during the 1st trimester of pregnancy.

We had one lady who conceived while on Dasatinib with disastrous consequences (macerated baby) etc., and I will definitely recommend not to try to conceive on Dasatinib, and best option is interferon, although we had successful pregnancies with Imatinib.

If the patient, given her advanced age for a first pregnancy, does not wish to continue waiting to achieve a deeper molecular response, which would always represent a safer scenario, the proposed approach can be considered acceptable: to continue dasatinib therapy, perform regular pregnancy testing, and discontinue treatment immediately upon the first positive result.

The answer is yes — we prefer not to risk a relapse while trying to conceive. Since most relapses occur within 3–6 months, and the first 3 months of pregnancy carry the greatest teratogenic risk, we recommend stopping the TKI at the time of the first positive pregnancy test (around 3–5 weeks of gestation). Of course, the patient should be advised to monitor for pregnancy carefully so she can discontinue the TKI promptly.

We also suggest initiating IFN once pregnancy is confirmed, without waiting for an increase in transcript levels, as it is unlikely she will maintain MMR after only 18 months of treatment. Her age is borderline, so I would recommend moving forward without delaying further.