Session: 901. Health Services Research—Non-Malignant Conditions: Poster III
Hematology Disease Topics & Pathways:
Biological, sickle cell disease, Diseases, Therapies, Hemoglobinopathies, gene therapy, Clinically relevant, transplantation
Methods: We searched the MEDLINE and EMBASE databases for studies reporting HSCT and GT outcomes in SCD. Phase I-III trials, retrospective reviews, and case reports with >1 SCD patient undergoing HSCT or GT were included. All HSC donor types and conditioning regimens were included. References of included studies were screened for additional relevant studies. All titles/abstracts were screened for full text retrieval. Non-English and preclinical studies were excluded. Primary outcomes were overall survival (OS), event-free survival (EFS), graft failure, transplant-related mortality (TRM), graft-versus-host disease (GVHD), and secondary malignancies. Secondary outcomes were end-organ function, acute chest syndrome/vaso-occlusive episodes (ACS/VOE), and health-related quality of life (HRQOL). We used descriptive statistics to analyze data on study characteristics, quality, and effects. Risk of bias was assessed using the Newcastle-Ottawa Scale. Outcome heterogeneity was assessed using sensitivity and subgroup analyses. Publication bias was assessed with funnel plots, where applicable.
Results: We identified 949 titles through database searching and 12 titles from references of included studies (Figure). After removal of duplicate citations (n=147), exclusion of ineligible records (n=716), and merging 42 studies with their primary article, 56 studies were included for data extraction. Of these 56 studies, 53 reported outcomes post-HSCT (n=1149) and 3 reported outcomes post-GT (n=28). Length of follow-up was 3718.6 patient-years and 43.4 patient-years in the HSCT and GT groups, respectively. Median age was 11.5 across HSCT studies; 26/28 GT patients were >18 years. HSCT donor source was matched related donor (n=812), matched unrelated donor (n=73), haploidentical (n=127), or mismatched unrelated donor (n=11) among 1023 HSCT patients.
Two-year OS and EFS for HSCT was 91% and 87%, respectively. OS and EFS were not reported for GT studies. TRM was 74/1042 (7.1%) over a median of 3 years of observation for HSCT, and 0/28 (0%) over a median of 1.6 years of observation for GT. Secondary malignancies were reported in 4 SCD patients from the HSCT group and 1 SCD patient from the GT group.
While the vast majority of HSCT studies reported the absence of ACS/VOE in engrafted patients, the lack of published data on pre- and post-transplant ACS/VOE frequency precluded further analysis. Median annual ACS/VOE episodes decreased from 5.3 to 0 post-transplant in 1 GT study, while a second GT study reported 2 episodes of ACS and 1 VOE post-GT. Fourteen studies (n=375), all from the HSCT group, reported 6 strokes/TIAs out of 2030.5 patient-years of post-transplant follow-up, with 1/6 strokes occurring in engrafted patients. None of the GT studies explicitly commented on stroke as an outcome. Only 1 study quantified changes in tricuspid regurgitant jet velocity post-transplant, and 1 study reported on renal function pre- and post-transplant, both from the HSCT group. There was no change in pulmonary function testing values post-transplant, as reported by 2 HSCT studies. Post-transplant HRQOL was reported for 8 HSCT studies and 0 GT studies, but due to heterogeneity of reporting, meta-analysis could not be performed.
Conclusions: While long-term HSCT and early GT data demonstrate regimen efficacy, reporting of other important post-transplant outcomes such as end-organ function, persistence of SCD-related complications, and patient-important outcomes is lacking for both strategies. Small sample sizes and differential reporting of outcomes preclude comparison between subgroups of HSC sources and conditioning regimens, a limitation of our study. We advocate for standardized reporting to better compare outcomes within and between treatment groups.
Disclosures: Kuo: Celgene: Consultancy; Pfizer: Consultancy, Research Funding; Alexion: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Bioverativ: Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bluebird Bio: Consultancy; Apellis: Consultancy.
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