Mismatches in Ethnicity Between Donor and Recipient Affects Overall Survival In Umbilical Cord Blood Transplantation,
Authors: Cheruku Patali Shikhi , Jude Veronica H. , Madden Renee M , LeMaistre Charles F. , Chan Ka Wah , Shaughnessy Paul , Bachier Carlos 
Published: October 2019

Abstract 4159

Limited data is available on the role of ethnicity on outcomes after umbilical cord blood transplants (UCBT). This study retrospectively analyses the role of donor and recipient ethnicity on clinical outcomes after UCBT. All patients (pts) had UCBT at the Texas Transplant Institute in San Antonio where Hispanics make up a large proportion of pts undergoing UCBT. Pts had UCBT between 2001 and 2010. CIBMTR and hospital records supplied the data and included 260 pts who were: White (76), Hispanic (141), Black (19) and Asian (6). Blacks and Asians were excluded from analysis due to small numbers. Characteristics of Whites and Hispanics are described in table. Age, cell dose, myeloablative and non-myeloablative conditioning regimens, and single (s) and double (d) UCBTs were similar between the two ethnicities. More Whites (88%) had UCBT for malignant disease than Hispanics (68%) (p<0.001).

Incidence of graft-versus-host disease (GVHD) was similar between Whites (acute GVHD grades II-IV: 44%, grades III-IV: 15%, limited chronic GVHD: 9% and extensive chronic GVHD: 11%) and Hispanics (acute GVHD grades II-IV: 34%, grades III-IV: 22%, limited chronic GVHD: 28% and extensive chronic GVHD: 15%) and regardless of whether they had malignant or non-malignant disease, standard (CR1, CR2 and CML-CP) or high (all others) risk hematologic malignant disease, s or d UCBT, and age. Disease and non-disease related mortalities (DRM and NDRM) were similar between Whites (DRM: 20% and NDRM: 23%) and Hispanics (DRM: 16% and NDRM: 24%) and regardless of whether they had malignant or non-malignant disease, high or standard-risk malignant disease, s or d UCBT, and age.

Overall survival (OS) was similar between Hispanics (73.7 months) and Whites (70.2 months) and regardless of whether they had malignant or non-malignant disease, high or standard-risk malignant disease, s or d UCBT, and age. Hispanics had a longer OS (88.7 months) than Whites (68.5 months) when each received an ethnically matched s UCB product (p=0.030) and a shorter OS (43.3 months) than Whites (OS=not evaluable (NE), all patients alive) when each received an ethnically mismatched s UCB product (p=0.004). Hispanics with an ethnically mismatched s UCB product and malignant disease had a shorter OS (47.4 months) than Whites (NE, all patients alive) (p=0.016). Whites and Hispanics with ethnically matched and mismatched s UCB products had similar numbers of patients with malignant and high-risk malignant disease. Only 6 of the 163 Whites and Hispanics who had s UCBT were adults (≥18 years).

Improvement in OS in Hispanics with ethnically matched s UCB products was related to an increase in OS from NDRM while worse OS in Hispanics with ethnically mismatched s UCB products was related to decreases in OS from both DRM and NDRM. There was a trend to longer OS among all pts with ethnically matched (82.3 months) versus mismatched (68.5 months) s UCB products (p=0.154). OS was shorter among all Hispanics with mismatched (43.3 months) versus matched (88.7 months) s UCB products (p=0.001). Cell dose, degree of HLA-matching, and percent with malignant and non-malignant disease were similar for all pts and between Whites and Hispanics with ethnically matched and mismatched s UCB products.

In conclusion, ethnic mismatches between donor and recipient appear to affect survival in pediatric s UCBT. The effect of ethnic mismatches was more pronounced in Hispanics than Whites.

Table: CHARACTERISTICS AND OUTCOMES White Hispanic Number of patients 76 141 Median age at transplant, years (range) 9.0 (0.1–79.2) 8.0 (0.1–61.7) Age category, years <18 61 (82%) 116 (82%) ≥18 13 (17%) 21 (15%) Median weight, kg (range) 25 (4–111) 26.3 (4–160) Recipient sex male 43 (57%) 90 (65%) female 31 (41%) 50 (35%) Transplant type single 57 (76%) 107 (76%) double 18 (24%) 34 (24%) Recipient CMV status positive 24 (32%) 61 (43%) negative 27 (36%) 41 (29%) *Malignant disease 66 (88%) 96 (68%) Donor/Recipient ethnicity match, s UCB matched 39 (70%) 57 (53%) mismatched 10 (18%) 28 (26%) HLA-matching, s UCBT 6/6 14 (25%) 9 (8%) 5/6 28 (56%) 50 (47%) 4/6 13 (23%) 44 (41%) Median cell dose x 10'37 TNC/kg (range) 5.7 (1.5–28.5) 5.6 (1.5–45.5) Median days ANC >500/μL 21 (10–50) 20 (10–100) Median days platelets >20K/μL 51 (24–165) 47 (21–167) Median days platelets >50K/μL 60 (29–137) 49 (24–224) Overall survival, months 70.2 73.7 Median follow-up, months (range) 28 (.25–121) 25 (.25–69) * p-value < 0.05

Disclosures:

Shaughnessy: Otsuka: Honoraria, Speakers Bureau; Millenium: Honoraria, Speakers Bureau; Genzyme: Honoraria, Speakers Bureau.