Favorable Fertility Outcome in a Large Cohort of Sickle Cell Disease Patients Undergoing Allogeneic Hematopoietic Stem Cell Transplantation

Introduction: Fertility preservation is an important consideration for individuals with sickle cell disease (SCD) who may face reproductive challenges. While SCD itself does not directly affect fertility, certain complications and its treatment such as hematopoietic cell transplantation (HCT) can impact the reproductive health in SCD patients. HCT is a potential curative therapy for SCD, however, one of the negative outcomes is the premature gonadal failure and infertility. Both male and female patients have different risk factors that may impact the fertility post-transplant. Therefore, these patients should undergo fertility preservation counselling pre transplant. In this study, we report the fertility outcome of large transplant cohort undergoing Non-myeloablative (NMA) conditioning regimen.

Methods:

We retrospectively collected the data for all SCD patients who were ≥ 14 years old and who underwent allogeneic HCT in our center from 2015 until 2022 with a minimum of 1 year follow up post-transplant.

All patients received hydroxyurea for 2 to 3 months pre- transplant at maximum tolerated dose. The conditioning regimen was alemtuzumab 1 mg /kg divided over 5 days from day - 7 to day -3 and Total Body Irradation 200 cGy on day -2 (with testicular shielding for male patients). Graft versus host disease prophylaxis with sirolimus started from day -1 and continued for at least 1 year post-transplant.

We started the fertility program in October 2019 where all patients get counselled for fertility preservation methods. Male patients undergo sperm cryopreservation after holding hydroxyurea for 3 months and female patients were referred to a specialized oncology fertility clinic for either oocyte cryopreservation or treatment with Gonadotropin-releasing hormone (GnRH) agonists pre transplant.

Primary objective of the study was to assess post-transplant fertility (defined by either ability to conceive for married patients, or development of azoospermia for male patient or secondary amenorrhea for female patients). Secondary objectives were to assess pre transplant fertility, assess the success of different fertility preservations methods and finally to assess for risk factors (pre- transplant and transplant) that affect the fertility potential.

Results:

We identified a total of 200 SCD patients who underwent HCT. Out of these 200 patients, 107 (54%) were included in our fertility program. The median post-transplant follow up was 3.5 years (1 - 7.5). One hundred and twelve patients (56%) were male, and eighty eight (44%) were female patients. All patients were on hydroxyurea pre transplant with average dose 1000 mg and a duration of less than 2 years in 47 (23.5%) patients, 2 to 5 years in 94 (47%) patients and more than 5 years in 59 (39.5%) patients. Other baseline characteristics are shown in table 1.

In the pre-transplant fertility assessment; 58 patients were married and 48 (82%) of them had children pre transplant. 36 male patients attempted sperm cryopreservation and were successful in 33 (91%). 39 female patients received Leuprolide (GNRH agonists) pre-transplant with no complications and 6 female patients attempted oocyte cryopreservation and all were successful. One patient developed cerebral venous thrombosis during the oocyte cryopreservation course.

For the post-transplant fertility assessment; out of 57 married patients 26 (45%) were able to conceive. From these 26 pregnancies; 20 ended with successful live-births, 1 ended with abortion and 5 are still pregnant. 6 patients were able to conceive twice and one patient had one twin babies. For male patients 74 did semen analysis at minimum 1 year post-transplant; 35 (47%) had azoospermia and 39 (53%) had viable sperms. Majority recovered spermatogenesis after 1 year (24 patients), at 2 years (9 patients) and after 3 years (3 patients). Three male patients had Azoospermia at one year but was able to conceive successfully without repeating the test. For female patients 71 (80.7%) were able to regain menses and 17 (19.3%) developed secondary amenorrhea. Table 2 shows the pre and post-transplant fertility measures outcome.

In conclusion

In this study, we have shown the fertility outcomes of male and female patients with SCD undergoing NMA conditioning HCT can be preserved in a significant proportion of patients. All adult patients should be counselled for fertility preservation methods before undergoing curative allogeneic HCT.