In November 2023, the Ministry of Health (MOH) directed Cordlife Group Limited to conduct further testing of six affected storage tanks and a dry shipper. The results of the further investigations, which have been reviewed by MOH and its panel of experts, revealed that cryopreserved cord blood units (CBUs) stored in one of the storage tanks (Tank B) and the dry shipper are at high risk of adverse impact due to temperature warming events. Hence an estimated 5,300 CBUs from Tank B and the dry shipper are deemed non-viable as they are unlikely to be suitable for stem cell transplant purposes.
2. The remaining five tanks have been assessed to be at low risk of being adversely affected by the temperature warming events. MOH’s experts have recommended that Cordlife test a larger number of CBUs in these five tanks to obtain a more statistically significant result and further ascertain the status of the CBUs stored in these tanks.
Results of Testing of Tank B and Dry Shipper
3. Audits conducted by MOH on Cordlife in August and November 2023 revealed that CBUs in seven of 22 CBU storage tanks had been exposed to suboptimal storage temperatures. On 30 November 2023, MOH’s panel of experts had concluded that the CBUs stored in one of the seven tanks (Tank A) were damaged. MOH subsequently directed Cordlife to conduct a study of the remaining six tanks and a dry shipper. Dry shippers are intended for the transport of CBUs and are not for long-term storage.
4. The definitive way to conclude the viability of the CBUs is to individually test all the CBUs in these affected tanks. However, this is not practical as it would take many years, even decades, to complete all the tests. Instead, Cordlife conducted sample testing through a third-party laboratory. This will provide a preliminary, but meaningful, indication if the warming events had impacted the CBUs stored in these tanks.
5. The study results and root cause analysis indicated that the CBUs stored in Tank B and the dry shipper were at high risk of being adversely affected. Eight out of 12 samples from Tank B, and five out of 12 samples from the dry shipper, had failed the tests.
6. The root cause analysis indicated that there was insufficient liquid nitrogen maintained in Tank B, which had not been rectified due to failure of Cordlife’s staff to act on and escalate the anomalies. The dry shipper had also not been adequately monitored.
7. Given these findings, about 5,300 CBUs in Tank B and the dry shipper are not likely to be suitable for stem-cell transplant purposes and will have to be deemed as non-viable.
Results of Testing of Five other Tanks
8. The remaining five tanks (Tanks C to G), which store approximately 14,000 CBUs, have been assessed through the investigations to be at low risk of being adversely affected by the temperature warming events. All 30 samples from across these tanks have passed the viability and potency tests conducted by an independent third-party laboratory.
9. The root cause analysis indicated that the temperature warming events in four (Tanks D to G) out of five tanks were likely due to misplaced temperature probes during scheduled maintenance, or incorrect mapping of the temperature probe to the tank . For the fifth tank (Tank C), the duration of exposure to the highest temperature of minus 144.7 degrees Celsius might not have caused damage to the CBUs1.
10. MOH’s experts have recommended that Cordlife test a larger number of CBUs in these five tanks to achieve more statistically significant results (at 99% confidence level2). Cordlife has since agreed to test over 200 additional samples across these five tanks and will review the outcome of the test results in consultation with our experts. As the tests, which involve complex processes, have to be carefully carried out, Cordlife expects to take approximately another year to complete the tests.
11. MOH has instructed Cordlife to inform its affected clients if their CBUs fall under the impacted tank (Tank B) and dry shipper, or the other five tanks (Tanks C to G) that have a low risk of being affected, but are awaiting further tests.
12. Affected clients of Cordlife are advised to be patient and await these results before making any decisions, including the transfer of CBUs to another cord blood bank, given that there are significant risks involved in the transfer of CBUs.
13. MOH will continue to closely supervise Cordlife’s rectification of the weaknesses identified in their governance structure, processes, systems and documentation.
MINISTRY OF HEALTH
8 APRIL 2024
1 The acceptable temperature limits for storage of CBU storage tanks is -150 degrees Celsius.
2 This means that 99% of the samples tested must pass both potency and viability tests.