Potential for a Cure
A baby is born with a defective gene, leading to a life-threatening disease. Standard therapies are limited; the child is faced with battling a chronic condition for life.
But perhaps there is an alternative — one that may lead to a permanent cure.
Gene therapy is designed to restore the function of a patient’s defective gene by introducing a healthy copy, with the potential to permanently correct a genetic disease. This compelling concept has intrigued the medical community for more than 20 years. While still primarily performed as part of research studies, gene therapy is becoming more widely adopted for clinical treatment of some conditions.
GENE THERAPY FOR SCID:
Bubble Boy Disease
For children born with SCID, a parent’s touch can be life-threatening. Often called “bubble boy disease,” SCID devastates the immune system and leaves patients vulnerable to lethal infections. Early death is common, even with existing therapies.
X-linked SCID, the most common form of SCID, is caused by defects in a gene encoding a critical protein called the common gamma chain. Without it, immune system cells called T cells, B cells and natural killer cells do not develop normally.
With the aim of pioneering a safe, effective gene therapy approach, St. Jude scientists have spent years developing an innovative vector for X-linked SCID. The vector is manufactured in the on-site Good Manufacturing Practice (GMP) facility using a process developed at St. Jude. The process, which uses stable cultured cell lines to produce the vector, addresses the challenge of manufacturing large quantities of clinical-grade vector in a reproducible manner.
The vector has been designed with features to reduce the risk of activating cancer-causing genes. It has also been subjected to extensive laboratory testing to ensure it does not readily insert into chromosomes near such genes.
We believe that this new form of gene therapy may offer X-linked SCID patients the best available treatment for their disorder.
Brian P. Sorrentino, MD, director, Division of Experimental Hematology
Clinical trials led by St. Jude and the National Institute of Allergy and Infectious Diseases (NIAID) are assessing whether this vector can safely provide long-lasting health benefits to patients with X-linked SCID.
Read about the St. Jude trial: LVXSCID-ND: Gene Transfer for X-Linked Severe Combined Immunodeficiency in Newly Diagnosed Infants
Featured Research: Early Success for SCID Gene Therapy
In 2016, early results have been published from the X-linked SCID gene therapy trial at NIAID using the St. Jude vector. The outcomes are promising: Two years after gene therapy, the first two patients showed a high level of normal immune function. They stopped taking immune replacement therapy for the first time in their lives. Three other patients have also showed promising immune changes six to nine months after treatment.
THE FUTURE OF GENE THERAPY:
Challenges and Opportunities
To date, results from clinical studies of gene therapies pioneered at St. Jude have been promising. It will be important to follow patients for many years to confirm the therapy’s long-lasting safety and health benefits.
St. Jude researchers are now focused on applying investigational gene therapy approaches to treat X-linked SCID, hemophilia B and a related disorder, hemophilia A. The long-term vision is to apply these technologies to other genetic diseases, such as sickle cell disease, and to explore applications in developing effective immune therapies for cancer.
De Ravin SS, Wu X, Moir S, Kardava L, O’Brien SA, Ulrick J, Kwatemaa N, Little P, Theobald N, Choi U, Su L, Marquesen M, Hilligoss D, Lee J, Buckner CM, Zarember KA, O’Connor G, McVicar D, Kuhns D, Throm RE, Zhou S, Notarangelo LD, Hanson IC, Cowan MJ, Kang E, Hadigan C, Meagher M, Gray JT, Sorrentino BP, Malech HL. Lentiviral hematopoietic stem cell gene therapy for X-linked severe combined immunodeficiency. Sci Transl Med 8(335):335ra57, 2016. doi: 10.1126/scitranslmed.aad8856
Zhou S, Fatima S, Ma Z, Wang YD, Lu T, Janke LJ, Du Y, Sorrentino BP. Evaluating the Safety of Retroviral Vectors Based on Insertional Oncogene Activation and Blocked Differentiation in Cultured Thymocytes. Mol Ther March 9, 2016. Epub ahead of print. doi: 10.1038/mt.2016.55. PMID: 26957223.
Nathwani AC, Reiss UM, Tuddenham EG, Rosales C, Chowdary P, McIntosh J, Della Peruta M, Lheriteau E, Patel N, Raj D, Riddell A, Pie J, Rangarajan S, Bevan D, Recht M, Shen YM, Halka KG, Basner-Tschakarjan E, Mingozzi F, High KA, Allay J, Kay MA, Ng CY, Zhou J, Cancio M, Morton CL, Gray JT, Srivastava D, Nienhuis AW, Davidoff AM. Long-term safety and efficacy of factor IX gene therapy in hemophilia B. N Engl J Med 371(21):1994-2004, 2014. doi: 10.1056/NEJMoa1407309. PMID: 25409372. PMCID: PMC4278802.
Nathwani AC, Tuddenham EG, Rangarajan S, Rosales C, McIntosh J, Linch DC, Chowdary P, Riddell A, Pie AJ, Harrington C, O'Beirne J, Smith K, Pasi J, Glader B, Rustagi P, Ng CY, Kay MA, Zhou J, Spence Y, Morton CL, Allay J, Coleman J, Sleep S, Cunningham JM, Srivastava D, Basner-Tschakarjan E, Mingozzi F, High KA, Gray JT, Reiss UM, Nienhuis AW, Davidoff AM. Adenovirus-associated virus vector-mediated gene transfer in hemophilia B. N Engl J Med 365(25):2357-65, 2011. doi: 10.1056/NEJMoa1108046. PMID: 22149959. PMCID: PMC3265081.
Fischer A, Hacein-Bey-Abina S, Cavazzana-Calvo M. 20 years of gene therapy for SCID. Nat Immunol 11(6):457-60, 2010. doi: 10.1038/ni0610-457. PMID: 20485269.
Throm RE, Ouma AA, Zhou S, Chandrasekaran A, Lockey T, Greene M, De Ravin SS, Moayeri M, Malech HL, Sorrentino BP, Gray JT. Efficient construction of producer cell lines for a SIN lentiviral vector for SCID-X1 gene therapy by concatemeric array transfection. Blood 113(21):5104-10, 2009. doi: 10.1182/blood-2008-11-191049. PMID: 19286997. PMCID: PMC2686181.