Bluebird sings to a select group of investors

Bluebird’s exclusive disclosure yesterday regarding two crucially important cancer cases that this month caused Lentiglobin clinical trials to be halted sent its stock up 8%. This is great news, therefore – unless you happen not to have registered for the investor conference where the bombshell was dropped. The revelations concerned further analysis of Lentiglobin’s phase I/II sickle cell disease trial, where one subject had developed acute myeloid leukaemia and another myelodysplastic syndrome. They were made at yesterday’s SVB Leerink healthcare conference rather than in a regulatory filing, flying in the face of the company’s promise 10 days ago to be transparent. The gist is that both patients had had very severe sickle cell disease, that the AML might have occurred independently of the vector that delivers Lentiglobin, and that the MDS might not have been MDS at all. Bluebird is continuing its investigation, and the complete analysis of the AML case could now come in a couple of weeks. Yesterday the company’s chief executive, Nick Leschly, said: “We are going to be as transparent as we can be with all stakeholders.” All investors really deserve better.

Two suspected unexpected serious adverse reactions in the HGB-206 sickle cell trial
Case What the markets learned on 16 Feb… …and what (some) investors found out on 25 Feb
AML Occurred >5yrs after dosing; vector detected in patient’s tumour cells, but unclear whether it was “passenger” or "driver"; work needed to investigate whether vector was inserted near oncogenic genes, and whether these were upregulated Patient determined to have chromosomal abnormalities including monosomy 7, partial loss of the short arm of chromosome 11, mutations in RUNX1 and PTPN11; these known AML driver mutations suggest independent mechanism for occurrence of AML
MDS Occurred ~6mth after dosing; not ascertained whether tumour cells were carrying vector; patient had genetic abnormality, trisomy 8, seen in 10-15% of MDS cases, suggesting underlying risk factors No occurrence of blasts or dysplasia in the bone marrow, which suggests that patient might not, in fact, have met criteria for diagnosis of MDS; patient had prolonged anaemia with trisomy 8 and tetraploidy
Source: Bluebird Bio.

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