ASH19: Serious vaso-occlusive crises eliminated in some sickle cell disease patients treated with bluebird bio's LentiGlobin

New data from the ongoing Phase I/II HGB-206 study of bluebird bio's LentiGlobin for sickle cell disease (SCD) were presented at the American Society of Hematology (ASH) annual meeting, with results showing that the investigational gene therapy eliminated serious vaso-occlusive crises (VOCs) and the need for regular red blood cell transfusions at up to 21 months post-treatment.

According to bluebird, results detailed at ASH include 17 patients in Group C of the trial who received LentiGlobin produced via "a refined manufacturing process that increases vector copy number and improves engraftment potential of gene-modified stem cells." Findings showed that in 12 patients in Group C with six or more months of follow-up, median levels of gene therapy-derived anti-sickling haemoglobin, HbAT87Q, were at least 40% of total haemoglobin. The drugmaker indicated that at six months post-treatment, patients produced consistent median levels of HbAT87Q ranging from 44% to 59%.

Results also demonstrated that among the nine patients in Group C with at least six months of follow-up who had four or more VOC or acute chest syndrome (ACS) events in the two years prior to treatment, there was a 99% reduction in annualised rate of VOC and ACS. The company added that there were no reports of ACS or serious VOC at up to 21 months post-treatment in these patients.

Commenting on the results, chief medical officer David Davidson said "exploratory assays show that HbAT87Q is present in most red blood cells of treated patients," which "was associated with substantial reductions of sickle haemoglobin." Davidson added "most importantly, patients in Group C have not experienced any episodes of acute chest syndrome or serious [VOCs] following…treatment."

LentiGlobin for SCD is designed to add functional copies of a modified form of the beta-globin gene into a patient's own haematopoietic stem cells. As well as the ongoing HGB-206 study, bluebird is planning to conduct the Phase III HGB-210 trial, which is expected to begin enrolling patients in early 2020.




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