Development and conduct of allogeneic stem cell transplant and autologous stem cell gene therapy for inherited immune deficiencies

National Institute Of Allergy And Infectious Diseases

Investigators

Linked publications & trials

Abstract

The first part of this project involves the development of conditioning regimens for allogeneic transplantation of patients with primary immunodeficiencies. In 2007 we initiated a clinical protocol using busulfan, Campath and low dose TBI and treated 44 patients with CGD, 39 of whom received an unrelated donor (MUD) graft. The results were published in the Journal of Clinical Immunology. (Parta et al. JCI). A follow up protocol was initiated in 2016 wherein we transplanted another 40 patients. Amongst these patients we were able to discern that patients with high CRPs (greater than 100mg/dL) prior to transplant, have a significantly higher risk of death despite having similar characteristics like infection or inflammatory disease otherwise. We also saw an improvement in overall engraftment rates but still had a few patients develop mixed chimerism. This data is being prepared for publication. In order to improve outcomes in terms of mixed chimerism as well as to be able to treat patients who would be excluded due to their elevated CRP, we have now opened a new protocol, 000977, which includes the use of pretreatment with tocilizumab and in high-risk patients, emapalumab. This protocol enrolled its first patient in July of 2022 with the first high risk patient doing well two years post transplant. As of 2025 we have now enrolled 15 patients on this protocol including 4 high-risk patients, with no graft loss. We have seen mortality in our high risk patients which included one patient with a high CRP but died from disseminated adenovirus, and a second patient who did not have an elevated CRP but was considered high risk for other reasons, including significant alloimmunization due to multiple granulocyte infusions prior to the transplant. This patient did not engraft and died due to ongoing fungal infection. The standard risk patients have all engrafted without any severe GvHD. Thus we are encouraged that the addition of the biologics tocilizumab and emapalumab will allow us to improve engraftment as well as offer transplant to patients we would otherwise consider high risk. We also initiated a protocol using an anti-cKIT antibody to replace the busulfan conditioning in an effort to reduce overall toxicity in our transplant regimens. We treated a total of 7 patients. All patients had had less toxicity, particularly mucositis during the transplant course and earlier discharge, but have seen a decline in chimerism in all but one with one patient now at 1% chimerism and a few who appear stable in the 10 to 70% range. This protocol was closed due to this poor engraftment and the company supplying the drug was not interested in pursuing an amendment to increase the radiation dose to see if this would improve outcomes. To further expand eligibility, in 2014 we opened a protocol using haploidentical donors. The 1st patient had an ongoing infection refractory to all standard therapy involving the heart and is now 5 years out with complete resolution of his infection. (J Clin Immunol. 2015 Oct;35(7):675-80). We enrolled a total of 7 patients on this protocol but saw severe GvHD in the last 3 patients with 2 of the patients succumbing to its' complications but the 3rd patient recovering and now doing well. This protocol is now closed and a new protocol was opened (19-I-0080). This new protocol used both early and late Campath along with busulfan, TBI, and post-transplant cyclophosphamide. The first patient did very well with full engraftment, and no evidence of GvHD. The second patient developed significant GvHD, thus the protocol was modified to change the timing of the Campath. The third patient then did well with this modification but the fourth patient developed a rare complication known as ADEM and thus this protocol has been closed. Plan are to develop a new haploidentical donor protocol in the future but currently we are focused on our gene therapy studies for patients without a matched donor (see below). As a member of the Primary Immune Deficiency Treatment Consortium (J Allergy Clin Immunol. 2014 Feb;133(2):335-47) we developed a collaborative protocol (6903) to review the results of transplants done for CGD in North America. We published the results on a subgroup of patients with inflammatory bowel disease (Marsh et al, JCI 2019) as well as the overall data (Leiding et al Blood 2023). We have also been involved in a microbiome analysis, (a substudy done in collaboration with Emilia Falcone) of which the first part of this data has been published (Petrovic et al, JACI 2023). A new CGD related PIDTC protocol (6908) will specifically evaluate the autoinflammatory aspects of CGD patients pre and post-transplant and has been approved by the NIH IRB and we have been accruing to the study. In the laboratory, utilizing our established murine models of GvHD, we have modified the conditioning regimens to induce graft rejection and/or engraftment syndrome with various cytokines to mimic the inflammatory milieu seen in patients as well as manipulating the graft cell composition to assess any donor graft effects. Post-doctoral fellow Andres Zea-Vera has murine data showing a negative impact of high levels of Il-6 and Interferon gamma suggesting that the high CRP and associated pathways seen in patients is directly responsible for the poor outcomes. Some of this data has been presented at various meetings including the CIS and ASH annual meetings. Hula Bayo, a post bac in the lab, is working to perform RNA sec on the marrows of these transplanted mice. We have also initiated a collaboration with the CHI to perform RNA sequence analysis of the clinical bone marrow samples to further analyze the inflammation seen in the hematopoietic niche of CGD patients and its impact on engraftment. The results of the analysis should be completed by the end of this year. The second part of this project involves the use of genetically modified autologous cells for the treatment of patients with XCGD and other immunodeficiencies. We initiated a clinical trial in 2006 to treat XCGD patients and an underlying infection, protocol 07-I-0017. Based on preclinical data in the rhesus as well as clinical data in a patient, we used busulfan at a dose of 10mg/kg prior to infusion of the genetically modified cells. We treated three patients, the results of which were published in Blood. Of the three patients the first had persistent levels of detectable oxidase positive cells more than 7 years post gene therapy; however he developed a progressive pulmonary process which despite an attempt at allogeneic transplant, led to his demise in 2016. The 2nd patient treated on this trial appeared to develop an immune reaction against the transduced cells, with rapid clearance of these cells after initially having 5% marking. The third patient was treated for a fungal lung infection and had an initial marking level of 4% with a subsequent decline to 0.03% where it remained stable until he underwent a MUD transplant due to continued infections. He is now more than 7 years out doing well. In 2015 we developed a collaborative study, Protocol 15-I-0008, using a lentiviral vector for XCGD. The 2nd patient on the trial was treated at NIH in 2016, and continues to have marking in the 20-30% range more than 3 years post treatment. The 2nd NIH patient is now over 4 years post-transplant with resolution of his underlying pulmonary fungal infection with persistent high-level marking of 40%. Our 3rd patient was treated in 2017 and unfortunately developed autoimmune thrombocytopenia, unrelated to the gene therapy, and died of a cerebral hemorrhage. Our most recent patient was treated in 2019 and is doing well with more than 70% oxidase cells at his last evaluation, now 4 years post gene therapy. A total of 9 patients have been treated at the various sites with 3 patients, including the last patient treated in 2020, having loss of their marking. The results, including patients from a London trial that used the same type of conditioning and vector have been published. (Kohn et al. Nature Medicine 2020.) The protocol has been amended and we have entered into a collaboration with SK pharma to produce more vector for 2025 which is being done. We have also obtained the remaining vector from the original trial and will be treating a patient in October.. In 2024 we opened a collaborative study to treat patients with the P47 autosomal recessive form of CGD using a lentiviral vector and treated our first patient in October 2024. This patient obtained high marking, but eventually expired due to an inflammatory process of the lungs. The family was not willing to perform an autopsy and the patient was unable to tolerate a biopsy, so we are unclear on what this process was. In contrast, our collaborators have treated one patient who has done well, so we are planning to treat additional patients assuming that the pulmonary process was specific to this patient. Uimook Choi and Nicole Fama (now at medical school) have also developed vectors for the P67 and P22 forms of CGD which we are hoping to use in the next iterations of our lentiviral based gene therapies. Finally, Karissa Bever (now attending graduate school) worked to optimize a CARD 9 lentivector created by Caroline Kreitzer, a former post doc who has gone on to medical studies. Although Karissa had optimized a vector due to new information regarding the suitability of various promoters, she has modified this vector to a more clinically applicable version with good titre and used the first batch in a xenogenic transplant model. Repeat studies have continued to show high marking. A new post bac has joined the lab in July and will further work with this vector in a murine model in order to show functionality and clinical application of this vector with plans to eventually develop a clinical gene therapy trial in collaboration with the Lionakis lab.