Chronic myeloid leukemia (CML) is a relatively slowly progressing blood disease, and its prognosis has been improved in recent years due to advances in molecular-targeted drugs, especially tyrosine kinase inhibitors (TKIs). On the other hand, some cases require allogeneic transplantation due to blast crisis. The effect or toxicity of molecular target drugs such as TKIs to male fertility are still unclear. We retrospectively investigated the effects of the drugs to male fertility and usage of cryopreserved semen in cases where sperm was frozen for treatment of CML at our hospital.

We have reviewed 20 male patients with CML who have visited our reproduction center for sperm cryopreservation between February 2013 and March 2025. The used drugs for treatments, the change in semen analyses, and the usage of cryopreserved sperm were retrospectively investigated.

The age of the 20 cases was 30.8 years (19-47). TKIs (nilotinib, dazatinib, and/or bonatinib) were used in 17 cases while antimetabolites and cytotoxic anticancer drugs were used in the other cases. In 10 cases where TKIs were used, semen analysis was performed at least once during follow-up after cryopreservation. The average of duration between cryopreservation and the latest follow-up semen analysis was 6.5±4.7 years. Among five patients who have been using TKI, there was no significant decline in semen parameters. The amount of change (Δ) of concentration and motility between first and the latest semen analyses were +6.2±26.2 million/mL and -9.6±21.8%, respectively. On the other hand, azoospermia persisted in all five cases who underwent allogeneic transplantation. Cryopreserved sperm was used in three cases, and pregnancies and live birth were achieved with intracytoplasmic sperm injection and embryo transfer. On the other hand, two cases have achieved pregnancy and live birth spontaneously during CML treatment with TKIs.

The toxicity of TKIs to male fertility was not significant in the follow-up semen analyses. On the other hand, the cases who underwent allogeneic transplantation revealed prolonged azoospermia. Cryopreserved semen was utilized to achieve successful pregnancy and live birth in such cases. Thus, fertility preservation is still important for CML patients.