High Chance of Finding “Suitable” Unrelated Cord Blood Donations (UCBD) in the Australian Network of Cord Blood Banks (AUSCORD).
Authors: Vowels Marcus R. , Montague Anthony , Gordon Sally , Duignan Peter , Hart Cathie , Tait Brian 
Published: October 2019

Aims: To determine the value of a CB inventory in the country of citizenship of the patient, we investigated the potential to find suitable UCBD in the Auscord inventory for Australian patients who could not identify a matched unrelated bone marrow donor (MUBMD) amongst donors registered either in the ABMDR or international registries.

Methods: Between 7/2003 and 6/2005, search was commenced for 776 Australian patients; 32% of searches resulted in a BM or CB transplant, 22% were cancelled, 46% remained open. Fifty-two patients were unable to find an 8/8 MUBMD (intermediate level class 1 (A, B) and allelic level class 2 (DRB1, DQB1)). The Auscord inventory contained 17,761 UCBD with an ethnic mix of 65% Caucasian, and the remainder with ethnic backgrounds reflective of those in the Australian community. Four, 5 and 6 of 6 matched UCBD with intermediate or higher resolution typing were identified and their nucleated cell (NC) content recorded.

Results: Six patients were 16 years or younger and 46 were older, 19 were female and 33 were male and mean weight was 72.2kg (range 16–85.9kg). Ethnic mix was 68% Caucasian, 8% Asian/Indian, 6% multiple ethnicity, 4% Pacific Islander, 4% Middle Eastern and was not recorded for 14%. One patient (1.9%), of New Guinean background, had no 4, 5 or 6/6 matched UCBD. Two patients (3.8%) had a single 6/6 HLA matched UCBD identified; one had >20 5/6 matched and the other had no 5/6 and >20 4/6 matched UCBD. Twenty-nine patients (55.8%) had between 1 and 15 5/6 and between 1 and >20 4/6 matched and 20 patients (38.5%) had between 2 and >20 4/6 matched UCBD. To determine the potential for these patients to proceed to transplant only those UCBD where allelic DRB1 typing (15,279) was available were evaluated. The NC content of the best matched UCB donation was a mean of 159.2x107 (range 59–281) and provided a NC dose of 2.5x107/kg (range 0.8–13.5) and for the second UCBD was 168.8x107 (range 43–274) with a NC dose of 5.2x107/kg (range 1.3–27.0). Five patients (9.6%; 2 adults and 3 children) had a single best matched UCBD which provided a NC dose of ≥3.5x107/kg, and a further 6 patients (11.5%; 2 children and 4 adults) had a single best matched which provided a NC dose of between 3.0 and 3.49x107/kg. For the 46 patients who had a single best matched which provided a NC dose of <3.5x107/kg, an analysis was then performed combining the NC content of the best match single with a second UCBD which had the highest NC content, whether this UCBD was the same degree of matching or 1 HLA mismatch lower. Thirty-nine of 46 patients (84.4%) had 2 UCBD which provided a combined NC dose of ≥3.5x107/kg, 4 (8.7%) had 2 UCBD which provided a combined NC dose of between 3.0 and 3.49x107/kg, and 3 (6.5%) did not have 2 UCBD which provided a combined NC dose of ≥3.0x107/kg.

Conclusions: These data indicate that for Australian patients who could not identify a MUBMD 92.3% found suitable UCBD in an Australian inventory of 17,716 UCBD that provided an acceptable NC dose. This reality highlights that the ethnic mix of a CB inventory in the country of nationality of the patient is reflected in the community from which the donations are sourced, and that suitable donations could be identified for 89% of adult patients. However, 39% of patients had only 4/6 matched UCBD available and thus a larger inventory may result in identifying more closely matched UCBD.