Association of Busulfan Exposure and Outcomes after HCT for Patients with an Inborn Error of Immunity.

Allogeneic HCT is a potentially curative treatment strategy for patients with inborn errors of immunities (IEIs). Objective of this study was to assess the optimal busulfan exposure prior to allogeneic HCT for patients with an IEI who received an intravenous busulfan-based conditioning regimen between 2000 and 2023. Patients from 17 international centers were included. Main outcome of interest was event-free survival (EFS). Patients were categorized into 4 IEI subgroups: combined-immunodeficiency (CID), severe combined immunodeficiency (SCID), neutrophil disorders and hemophagocytic lymphohistiocytosis (HLH)-related disorders. Busulfan exposure was calculated by individual centers (AUCCENTER) and was re-estimated using a validated model (AUCNONMEM). Overall, 562 patients were included: 173 (30.8%) CID, 154 (27.4%) SCID, 101 (18.0%) HLH-related disorders, and 134 (23.8%) neutrophil disorders. Median busulfan AUCNONMEM was 69.0 mg×h/L and correlated poorly with AUCCENTER (r2=0.54). Patients with SCID, HLH-related, and neutrophil disorders were analyzed together (n=389), because CID disease subtype was an effect modifier (p=0.03). Estimated 2-year EFS was 78.5%. In patients with the found optimal busulfan AUCNONMEM of 70-90 mg×h/L, 2-year EFS was superior to <70 mg×h/L (adj-HR 1.97, 95% CI 1.11-3.49, p=0.02), and >90 mg×h/L (adj-HR 5.05, 95% CI 2.43-10.49, p<0.0001). Full donor chimerism increased with higher busulfan AUCNONMEM, plateauing at 90 mg×h/L. For CID patients, optimal AUCNONMEM for donor chimerism was found to be >70 mg×h/L. Improved EFS and higher donor chimerism may be achieved by targeting a cumulative busulfan AUCNONMEM of 80 mg×h/L (range 70-90). Our study stresses the importance to uniformly using a validated population PK-model to estimate the AUCNONMEM.

Antiviral cellular therapy for enhancing T-cell reconstitution before or after hematopoietic stem cell transplantation (ACES): a two-arm, open label phase II interventional trial of pediatric patients with risk factor assessment.

Viral infections remain a major risk in immunocompromised pediatric patients, and virus-specific T cell (VST) therapy has been successful for treatment of refractory viral infections in prior studies. We performed a phase II multicenter study (NCT03475212) for the treatment of pediatric patients with inborn errors of immunity and/or post allogeneic hematopoietic stem cell transplant with refractory viral infections using partially-HLA matched VSTs targeting cytomegalovirus, Epstein-Barr virus, or adenovirus. Primary endpoints were feasibility, safety, and clinical responses (>1 log reduction in viremia at 28 days). Secondary endpoints were reconstitution of antiviral immunity and persistence of the infused VSTs. Suitable VST products were identified for 75 of 77 clinical queries. Clinical responses were achieved in 29 of 47 (62%) of patients post-HSCT including 73% of patients evaluable at 1-month post-infusion, meeting the primary efficacy endpoint (>52%). Secondary graft rejection occurred in one child following VST infusion as described in a companion article. Corticosteroids, graft-versus-host disease, transplant-associated thrombotic microangiopathy, and eculizumab treatment correlated with poor response, while uptrending absolute lymphocyte and CD8 T cell counts correlated with good response. This study highlights key clinical factors that impact response to VSTs and demonstrates the feasibility and efficacy of this therapy in pediatric HSCT.

Secondary bone marrow graft loss after third-party virus-specific T cell infusion: Case report of a rare complication.

Virus-specific T cells (VST) from partially-HLA matched donors have been effective for treatment of refractory viral infections in immunocompromised patients in prior studies with a good safety profile, but rare adverse events have been described. Here we describe a unique and severe adverse event of VST therapy in an infant with severe combined immunodeficiency, who receives, as part of a clinical trial (NCT03475212), third party VSTs for treating cytomegalovirus viremia following bone marrow transplantation. At one-month post-VST infusion, rejection of graft and reversal of chimerism is observed, as is an expansion of T cells exclusively from the VST donor. Single-cell gene expression and T cell receptor profiling demonstrate a narrow repertoire of predominantly activated CD4+ T cells in the recipient at the time of rejection, with the repertoire overlapping more with that of peripheral blood from VST donor than the infused VST product. This case thus demonstrates a rare but serious side effect of VST therapy.

Relevance of lymphocyte proliferation to PHA in severe combined immunodeficiency (SCID) and T cell lymphopenia.

Severe combined immunodeficiency (SCID) is characterized by a severe deficiency in T cell numbers. We analyzed data collected (n = 307) for PHA-based T cell proliferation from the PIDTC SCID protocol 6901, using either a radioactive or flow cytometry method. In comparing the two groups, a smaller number of the patients tested by flow cytometry had <10% of the lower limit of normal proliferation as compared to the radioactive method (p = 0.02). Further, in patients with CD3+ T cell counts between 51 and 300 cells/µL, there was a higher proliferative response with the PHA flow assay compared to the 3H-T assay (p < 0.0001), suggesting that the method of analysis influences the resolution and interpretation of PHA results. Importantly, we observed many SCID patients with profound T cell lymphopenia having normal T cell proliferation when assessed by flow cytometry. We recommend this test be considered only as supportive in the diagnosis of typical SCID.

Allogeneic hematopoietic cell transplantation is effective for p47phox chronic granulomatous disease: A Primary Immune Deficiency Treatment Consortium study.

BACKGROUND: P47phox (neutrophil cytosolic factor-1) deficiency is the most common cause of autosomal recessive chronic granulomatous disease (CGD) and is considered to be associated with a milder clinical phenotype. Allogeneic hematopoietic cell transplantation (HCT) for p47phox CGD is not well-described. OBJECTIVES: We sought to study HCT for p47phox CGD in North America. METHODS: Thirty patients with p47phox CGD who received allogeneic HCT at Primary Immune Deficiency Treatment Consortium centers since 1995 were included. RESULTS: Residual oxidative activity was present in 66.7% of patients. In the year before HCT, there were 0.38 CGD-related infections per person-years. Inflammatory diseases, predominantly of the lungs and bowel, occurred in 36.7% of the patients. The median age at HCT was 9.1 years (range 1.5-23.6 years). Most HCTs (90%) were performed after using reduced intensity/toxicity conditioning. HCT sources were HLA-matched (40%) and -mismatched (10%) related donors or HLA-matched (36.7%) and -mismatched (13.3%) unrelated donors. CGD-related infections after HCT decreased significantly to 0.06 per person-years (P = .038). The frequency of inflammatory bowel disease and the use of steroids also decreased. The cumulative incidence of graft failure and second HCT was 17.9%. The 2-year overall and event-free survival were 92.3% and 82.1%, respectively, while at 5 years they were 85.7% and 77.0%, respectively. In the surviving patients evaluated, ≥95% donor myeloid chimerism at 1 and 2 years after HCT was 93.8% and 87.5%, respectively. CONCLUSIONS: Patients with p47phox CGD suffer from a significant disease burden that can be effectively alleviated by HCT. Similar to other forms of CGD, HCT should be considered for patients with p47phox CGD.

Síndrome de Wiskott-Aldrich. Dificultades diagnósticas y terapéutucas de un paciente con inmunodeficiencia primario / Wiskott - Aldrich syndrome. Therapeutic and Diagnosis Difficulties in a patient with primary immunodeficiency

Introducción. Las inmunodeficiencias primarias son un grupo de enfermedades de origen genético que implican altera - ciones asociadas a la respuesta inmunológica. El infra diagnóstico de estas conlleva al retraso de tratamiento, evitables en gran parte; Entre estas existe el síndrome de Wiskott-Aldrich; es un trastorno raro, ligado al cromosoma X, recesivo, que se caracteriza por trom - bocitopenia, eczema e inmunodeficiencia donde su tratamiento curativo es el trasplante de medula ósea. CASO CLÍNICO : Paciente de 10 años, con antecedentes de múltiples hospitalizaciones por procesos infecciosos importantes: neumonías recurrentes, menin - gitis, diarreas, erupción cutánea generalizada y trombocitopenia de hasta 9,000 mm³. Después de múltiples estudios realizados, se confirma el diagnóstico de síndrome de Wiskott -Aldrich por inmunogenetica (mutación del gen WAS) y mediante colaboración médica internacional, se realiza trasplante de médula ósea con posterior resolución de su enfermedad. DISCUSION: Las inmunodeficiencias primarias son patologías más comunes de lo que se creía (prevalencia de hasta 1/1200), la evidencia de aparición y su importancia clínica deben ser tomadas en consideración. En este caso de Síndrome de Wiskot-Aldrich en donde el diagnóstico definitivo es in - munogenetico, (actualmente el país no cuenta), además de tratamiento inmuno-oncológico adecuado, el paciente pudo sobrevivir y mejorar su calidad de vida gracias a soporte investigativo y terapéutico multinacional. Existen colaboraciones multicentricas como el consorcio de tratamiento inmunodeficiencias primarias, que tienen como objetivo colaborar activamente en el diagnóstico y tratamien - to estos casos, salvaguardando la vida de estos pacientes y ayudando a comprender estas enfermedades raras...(AU)