Development of a lentiviral gene therapy vector for treatment of haemophagocytic lymphohistiocytosis (HLH) due to perforin deficiency

HLH是一种毁灭性的疾病，患者的免疫系统无法控制感染，然后变得高度异常，导致发烧、肝和脾肿大以及血细胞破坏。这种情况是由某些基因缺陷引起的，经常影响儿童的早期生活。唯一的治疗方法是骨髓移植，如果有匹配的供体，骨髓移植可以成功，但如果HLH得不到控制或没有好的供体可供移植，则会引起严重的并发症。为了提供一种更安全、同样有效的替代方法，我们想用基因疗法来纠正这种情况。在早期的研究中，我们已经证明，如果我们将穿孔素基因引入穿孔素缺陷小鼠的骨髓干细胞，并将其移植到穿孔素缺陷受体中，我们可以恢复免疫系统控制感染和预防HLH的能力。这些都是非常有希望的早期数据，但为了将其用于患者的治疗，我们进行了一系列研究，以表明它既有效又安全。因此，我们计划利用携带穿孔素基因的最佳基因治疗载体，在不同的穿孔素缺乏症模型中进行大量研究。我们将像以前一样纠正骨髓干细胞，但我们也将用活感染挑战纠正后的小鼠，看看这是否能防止HLH的发生。我们还将研究另一种方法，只校正血液（而不是骨髓）免疫细胞，因为这可能是一种更安全的控制疾病的方法。在将其用于患者之前，我们还需要证明这种治疗是安全的。我们将通过多种方式来做到这一点。我们将证明，一旦细胞被纠正，没有证据表明它们会因为基因插入细胞的方式而癌变。我们还将确保通过将基因引入干细胞，这不会改变干细胞池的功能。如果我们能在这些研究中显示出有效性和安全性，那么这一策略就可以在HLH患者中进行临床试验。

HLH is a devastating disorder in which the immune system is unable to control infection and then becomes highly abnormal causing fever, enlargement of the liver and spleen and destruction of blood cells. The condition is caused by defects in certain genes and often affects children early in life. The only treatment is a bone marrow transplant which can be successful if a matched donor is available but is associated with significant complications if HLH is not controlled or if no good donor is available for transplant. To offer a safer and equally effective alternative, we want to use gene therapy to correct the condition. In early studies we have shown that if we introduce the perforin gene into bone marrow stem cells of perforin deficient mice and transplant them in perforin deficient recipients, we can restore the ability of the immune system to control infection and prevent HLH. These are very promising early data but to take this through to being a treatment for patients, we have perform a series of studies to show that it is both effective and safe.We therefore plan to conduct a number of studies in different models of perforin deficiency with an optimal gene therapy vector that carries the perforin gene. We will correct bone marrow stem cells as previously but we will also challenge the corrected mice with a live infection to see if this prevents the onset of HLH. We will also also look at another approach and correct just blood (not bone marrow) immune cells as this may be a safer way of controlling disease.Before taking this to patients, we also need to show that this treatment is safe. We will do this in a number of ways. We will show that once cells have been corrected, there is no evidence that they can then become cancerous because of the way the gene has ben inserted into the cells. We will also ensure that by introducing the gene into stem cells, this does not alter the function of the stem cell pool.If we can show both effectiveness and safety in these studies, then this strategy can be taken forward for a clinical trial in HLH patients.