Successful haploidentical hematopoietic stem cell transplantation (HSCT) and durable engraftment by repeated donor lymphocyte infusions for a Chinese patient with transfusion-dependent hemoglobin (Hb) Hammersmith and massive splenomegaly.

BACKGROUND: Hemoglobin (Hb) Hammersmith is a rare form of unstable ß-chain hemoglobinopathy causing hemolytic anemia. This rare event led to a more serious transfusion-dependent phenotype in a patient. It was successfully cured by haploidentical hematopoietic stem cell transplantation (HSCT). METHODS AND RESULTS: A 9-year-old mainland Chinese male with a history of neonatal unconjugated hyperbilirubinemia was diagnosed to have hemoglobin (Hb) Hammersmith. He required regular blood transfusion but was unable to be transfused to desired parameters for 8 years prior to transplant due to social and geographical reasons. He subsequently developed marrow hyperplasia and progressive splenomegaly (down to umbilicus level), suggestive of extramedullary hematopoiesis. Eventually, the family came to Hong Kong and complied to a more intensive transfusion regimen and preconditioning chemotherapy 3 months prior to transplant. He underwent haploidentical HSCT using paternal TCRαß/CD45RA-depleted graft but suffered from graft rejection, despite splenic irradiation for massive splenomegaly. It was successfully salvaged with second HSCT with unmanipulated graft from the same donor with additional serotherapy and donor lymphocyte infusions. CONCLUSION: Allogenic haploidentical HSCT for hemoglobin Hammersmith is feasible but adequate immunosuppression during conditioning is crucial. Precise adoptive cell therapy can promote durable engraftment.

Repeated CD45RA-depleted DLI successfully increases donor chimerism in a patient with beta-thalassemia major after haploidentical stem cell transplant.

Allogeneic hematopoietic stem cell transplantation is curative for transfusion-dependent thalassemia, but mixed chimerism (MC) may herald graft rejection. We report a child who failed bone marrow transplant (BMT) from matched unrelated donor (MUD) successfully salvaged with haploidentical peripheral blood stem cell transplant (PBSCT), but had MC in T-lymphocyte compartment despite near-complete donor chimerism in myeloid compartment. MC was successfully improved by repeated CD45RA-depleted donor lymphocyte infusion (DLI). A 2-year-old Chinese girl with beta-thalassemia major underwent 12/12-MUD BMT with HU/AZA/Cy/Flu/Bu/TT conditioning resulted in graft rejection. As donor refused second donation, rescue haploidentical PBSCT was performed with alemtuzumab/fludarabine/treosulfan conditioning. Harvest product was CD3/CD45RA depleted with extra products cryopreserved. Split cell chimerism performed 1-month after haplo-transplant showed 97% mother, 3% MUD, and 0% host for granulocytes but 38% mother, 62% MUD, and 0% host for CD3 + T cells. In view of low haploidentical donor chimerism in T-lymphocyte compartment, CD45RA-depleted DLI using cryopreserved product was performed on day + 38, after thymoglobulin 3 mg/kg given as T-cell depletion 3 days beforehand. T-cell chimerism improved to 51% mother and 49% MUD post-DLI. Second cryopreserved CD45RA-depleted DLI was given 17 days after the first DLI (day + 55), and 100% full chimerism of mother's T cells was gradually established without significant graft-versus-host disease (GVHD) or viral reactivation. To conclude, split lineage chimerism determination is beneficial to guide management strategy. For MC in T-cell compartment, CD45RA-depleted DLI is a potential alternative to unselected T cells as it carries lower risk of GVHD and infection.

Outcomes of allogeneic transplantation for hemoglobin Bart's hydrops fetalis syndrome in Hong Kong.

BACKGROUND: Hemoglobin Bart's hydrops fetalis syndrome (BHFS) was once considered a fatal condition universally. Medical advances over the past three decades have resulted in increasing numbers of BHFS survivors. This retrospective review summarized local territory-wide experience and outcomes of BHFS patients who received allogeneic hematopoietic stem cell transplantation (HSCT) in Hong Kong. METHODS: All BHFS patients who underwent allogeneic HSCT in Hong Kong, either in one of the two former pediatric transplant centers (Queen Mary Hospital and Prince of Wales Hospital) on or before 2019 or in the single territory-wide pediatric transplant center (Hong Kong Children's Hospital) since 2019, from January 1, 1996, till December 31, 2020, were included. Basic demographic data, perinatal history, transplant details, long-term outcomes, and morbidities were reviewed. RESULTS: Total five allogeneic HSCT were performed in two males and three females at a median age of 22 months, which include one 8/8 matched-sibling bone marrow transplant, one 5/6 matched-sibling cord blood transplant with HLA-DR antigenic mismatch, two 12/12 matched-unrelated peripheral blood stem cell transplant (PBSCT), and one haploidentical PBSCT with TCRαß/CD45RA depletion from maternal donor. Neutrophil and platelet engrafted (>20 × 109 /L) at a median of 15 and 22 days, respectively. All achieved near full donor chimerism at 1 month. All patients survived and remained transfusion-independent without significant morbidities with median follow-up duration of 10 years. CONCLUSION: To conclude, local data demonstrated favorable outcome of allogeneic HSCT for BHFS patients, but sample number is small. Non-directive approach in counseling and international collaboration is recommended.

Selective T cell-depleted haploidentical hematopoietic stem cell transplantation for relapsed/refractory neuroblastoma.

Relapsed/refractory NB carries a bleak outcome, warranting novel treatment options. HaploHSCT induces a graft-versus-NB effect via natural killer cell alloreactivity. Review of patients with relapsed/refractory NB who underwent haploHSCT with ex vivo T-cell depletion in our unit from 2013 through 2018. Ten patients were identified (male=5; median age at haploHSCT=6.45 y, range: 3.49-11.02 y). Indications were relapsed in 7 and refractoriness in 3; disease status at haploHSCT was CR in 2, PR in 6, and PD in 2. All patients received peripheral blood stem cell grafts after ex vivo T-cell depletion (CD3/CD19-depletion=1; TCR-αß/CD19-depletion=4; CD3/CD45RA-depletion=4; and TCR-αß/CD45RA-depletion=1). Conditioning regimens were fludarabine-based. Neutrophils engrafted on median D + 10 (range: D + 9 to +13), and platelets engrafted (≥20 × 109 /L) on median D + 8 (range: D + 5 to D + 14). Early T- and NK-cell recovery were evident. Of the 10 patients, acute rejection developed in 1 (who died of PD despite rescue HSCT), and 1 died of sepsis before engraftment; 8 experienced full donor-chimerism post-HSCT. Among the 8, 6 experienced CR, 1 died of PD, and 1 died of pulmonary hypertensive crisis before evaluation. At publication, 4 were in remission (2.8, 7.4, 28.5, and 58.9 months). No significant GvHD occurred. HaploHSCT with selective ex vivo T-cell depletion may be a safe and useful salvage strategy for relapsed/refractory NB.

Cyclosporin A for persistent or chronic immune thrombocytopenia in children.

Twenty percent of children with immune thrombocytopenia (ITP) develop a chronic course where treatment strategy is less established. Cyclosporin A (CSA) has been shown to be effective in small series of children with chronic ITP and might reduce the need for chronic steroid therapy and/or splenectomy. We reviewed consecutive patients below 18 years old with persistent or chronic ITP treated with CSA in our unit between January 1998 and June 2015. Thirty patients (14 boys and 16 girls) were included. The median age at initial diagnosis of ITP was 5 years (range 0.5-16.2 years). CSA was started at a median of 13.9 months (range 3.4-124 months) after initial diagnosis and given for a median duration of 9.3 months (range 0.2-63.9 months). The median platelet count before commencement was 12 × 10(9)/L (range 4-199 × 10(9)/L). The median dose of CSA was 6 mg/kg/day (range 2.4-7.5 mg/kg/day). Complete response (CR) or response (R) was achieved in 17 patients (57 %), and 7 (23 %) had sustained response. Side effects (most commonly hirsutism) were tolerable and reversible. CSA appeared effective in about half of persistent or chronic ITP patients and safe as a second-line agent in managing these children.

Haploidentical Transplant Achieves Long-Term Remission in Relapsed Refractory Leukemia With Fludarabine-Induced Neurotoxicity Complication.

Hematopoietic stem cell transplant is potentially curative for relapsed/refractory leukemia. However, neurotoxicity is common and has been reported in 11% to 59% of children following hematopoietic stem cell transplant. Most pediatric studies of the neurological effects of hematopoietic stem cell transplant have focused on acute neurotoxicity. Limited information is available for long-term neurotoxicity, particularly those cases that are severe and permanent and caused by conditioning chemotherapy. Here, we report 2 cases of relapsed acute lymphoblastic leukemia that achieved long-term remission by haploidentical hematopoietic stem cell transplant but remained complicated with severe and persistent fludarabine-induced neurotoxicity.

Risk and Factors associated with disease manifestations in systemic lupus erythematosus - lupus nephritis (RIFLE-LN): a ten-year risk prediction strategy derived from a cohort of 1652 patients.

Objectives: Lupus nephritis (LN) remains one of the most severe manifestations in patients with systemic lupus erythematosus (SLE). Onset and overall LN risk among SLE patients remains considerably difficult to predict. Utilizing a territory-wide longitudinal cohort of over 10 years serial follow-up data, we developed and validated a risk stratification strategy to predict LN risk among Chinese SLE patients - Risk and Factors associated with disease manifestations in systemic Lupus Erythematosus - Lupus Nephritis (RIFLE-LN). Methods: Demographic and longitudinal data including autoantibody profiles, clinical manifestations, major organ involvement, LN biopsy results and outcomes were documented. Association analysis was performed to identify factors associated with LN. Regression modelling was used to develop a prediction model for 10-year risk of LN and thereafter validated. Results: A total of 1652 patients were recruited: 1382 patients were assigned for training and validation of the RIFLE-LN model; while 270 were assigned for testing. The median follow-up duration was 21 years. In the training and validation cohort, 845 (61%) of SLE patients developed LN. Cox regression and log rank test showed significant positive association between male sex, age of SLE onset and anti-dsDNA positivity. These factors were thereafter used to develop RIFLE-LN. The algorithm was tested in 270 independent patients and showed good performance (AUC = 0·70). Conclusion: By using male sex, anti-dsDNA positivity, age of SLE onset and SLE duration; RIFLE-LN can predict LN among Chinese SLE patients with good performance. We advocate its potential utility in guiding clinical management and disease monitoring. Further validation studies in independent cohorts are required.

Penicilliosis in children without HIV infection--are they immunodeficient?

BACKGROUND: Penicillium marneffei infection is indigenous to Southeast Asia. Majority of penicilliosis occurs in patients with AIDS, and less commonly with secondary immunodeficiencies. Penicilliosis is rare in otherwise healthy persons, but information on their immunological status is often lacking. METHODS: From 1996 to 2009, we diagnosed penicilliosis in 5 children. Their clinical features, immunological findings, and genetic studies were analyzed. A systematic review of the English and Chinese literature was performed. Case reports/series on patients <18 years with penicilliosis were included, and patients stated to be human immunodeficiency virus (HIV)-positive excluded. RESULTS: All of our 5 patients were HIV negative. Presentations included fungemia (n = 2), multifocal lymphadenopathy (n = 2), and necrotizing pneumonia (n = 1). Four patients had recurrent mucocutaneous candidiasis. Hyperimmunoglobin E syndrome was diagnosed in 1 patient, while another had functional defect in interleukin-12/interferon-γ axis. Three patients were lymphopenic with low natural killer cell counts, but a specific immune defect was not identified. Systematic review of 509 reports on human penicilliosis identified 32 patients aged 3 months to 16 years with no known HIV infection. Twenty-four patients (75%) had disseminated disease, and 55% died of penicilliosis. Eight patients had primary immunodeficiencies or blood disorders, while 4 others had abnormal immune functions. Immune evaluations of the remaining patients were unstated. CONCLUSION: Penicilliosis is a severe disease causing high mortality in children. As an AIDS-defining illness, penicilliosis should be regarded as an indicator for underlying immunodeficiency in HIV-negative individuals. Immunological investigations should be performed, especially in those with recurrent infections. Multicentered collaborative studies are needed to collect information on long-term prognosis and define immune defects underlying penicilliosis.

Safety and immunogenicity of 3 doses of BNT162b2 and CoronaVac in children and adults with inborn errors of immunity.

Our study (NCT04800133) aimed to determine the safety and immunogenicity in patients with IEIs receiving a 3-dose primary series of mRNA vaccine BNT162b2 (age 12+) or inactivated whole-virion vaccine CoronaVac (age 3+) in Hong Kong, including Omicron BA.1 neutralization, in a nonrandomized manner. Intradermal vaccination was also studied. Thirty-nine patients were vaccinated, including 16 with homologous intramuscular 0.3ml BNT162b2 and 17 with homologous intramuscular 0.5ml CoronaVac. Two patients received 3 doses of intradermal 0.5ml CoronaVac, and 4 patients received 2 doses of intramuscular BNT162b2 and the third dose with intradermal BNT162b2. No safety concerns were identified. Inadequate S-RBD IgG and surrogate virus neutralization responses were found after 2 doses in patients with humoral immunodeficiencies and especially so against BA.1. Dose 3 of either vaccine increased S-RBD IgG response. T cell responses against SARS-CoV-2 antigens were detected in vaccinated IEI patients by intracellular cytokine staining on flow cytometry. Intradermal third dose vaccine led to high antibody response in 4 patients. The primary vaccination series of BNT162b2 and CoronaVac in adults and children with IEIs should include 3 doses for optimal immunogenicity.

Molecular diagnosis of severe combined immunodeficiency--identification of IL2RG, JAK3, IL7R, DCLRE1C, RAG1, and RAG2 mutations in a cohort of Chinese and Southeast Asian children.

Severe combined immunodeficiencies (SCID) are a group of rare inherited disorders with profound defects in T cell and B cell immunity. From 2005 to 2010, our unit performed testing for IL2RG, JAK3, IL7R, RAG1, RAG2, DCLRE1C, LIG4, AK2, and ZAP70 mutations in 42 Chinese and Southeast Asian infants with SCID adopting a candidate gene approach, based on patient's gender, immune phenotype, and inheritance pattern. Mutations were identified in 26 patients, including IL2RG (n = 19), IL7R (n = 2), JAK3 (n = 2), RAG1 (n = 1), RAG2 (n = 1), and DCLRE1C (n = 1). Among 12 patients who underwent hematopoietic stem cell transplantation, eight patients survived. Complications and morbidities during transplant period were significant, especially disseminated bacillus Calmette-Guérin disease which was often difficult to control. This is the first cohort study on SCID in the Chinese and Southeast Asian population, based on a multi-centered collaborative research network. The foremost issue is service provision for early detection, diagnosis, management, and definitive treatment for patients with SCID. National management guidelines for SCID should be established, and research into an efficient platform for genetic diagnosis is needed.

HLA alleles associated with asparaginase hypersensitivity in Chinese children.

Asparaginase is an important drug to treat childhood haematological malignancies. Data on the association between human leukocyte antigens (HLA) and asparaginase hypersensitivity among Chinese are lacking. We conducted a retrospective study to identify HLA alleles associated with asparaginase hypersensitivity among Chinese children with acute lymphoblastic leukaemia (ALL), mixed phenotype leukaemia and non-Hodgkin lymphoma (NHL), who received asparaginases with HLA typing performed between 2009 and 2019. 107 Chinese patients were analysed. 66.3% (71/107) developed hypersensitivity to at least one of the asparaginases. HLA-B*46:01 (OR 3.8, 95% CI 1.4-10.1, p < 0.01) and DRB1*09:01 (OR 4.3, 95% CI 1.6-11.4, p < 0.01) were significantly associated with L-asparaginase hypersensitivities, which remained significant after adjustment for age, gender and B cell ALL [HLA-B*46:01 (adjusted OR 3.5, 95% 1.3-10.5, p = 0.02) and DRB1*09:01 (OR 4.4, 95% CI 1.6-13.3, p < 0.01)].

Clinical characteristics and genotype-phenotype correlation in 62 patients with X-linked agammaglobulinemia.

INTRODUCTION: X-linked agammagobulinemia (XLA) is a primary immunodeficiency disorder caused by Bruton's tyrosine kinase (Btk) gene mutation. Recent studies suggested genotype-phenotype correlation in XLA, but a definitive association remains controversial. PATIENTS AND METHODS: We examined the relationship between specific Btk gene mutations and severity of clinical presentation in 62 patients with XLA. Disease severity was assessed by the age of disease onset and the presence of severe infections, while mutations were classified into severe and mild based on structural and functional consequence by bioinformatics analysis. RESULTS: Fifty-six Btk mutations were identified in 62 patients from 57 kindreds. Variation in phenotypes was observed, and there was a tendency of association between genotype and age of disease onset as well as occurrence of severe infections. CONCLUSION: A critical analysis of the circumstances upon presentation also revealed that under-recognition of recurrent infections and relevant family history are important hurdles to timely diagnosis of XLA.

Establishing Simultaneous T Cell Receptor Excision Circles (TREC) and K-Deleting Recombination Excision Circles (KREC) Quantification Assays and Laboratory Reference Intervals in Healthy Individuals of Different Age Groups in Hong Kong.

The clinical experience gathered throughout the years has raised awareness of primary immunodeficiency diseases (PIDD). T cell receptor excision circles (TREC) and kappa-deleting recombination excision circles (KREC) assays for thymic and bone marrow outputs measurement have been widely implemented in newborn screening (NBS) programs for Severe Combined Immunodeficiency. The potential applications of combined TREC and KREC assay in PIDD diagnosis and immune reconstitution monitoring in non-neonatal patients have been suggested. Given that ethnicity, gender, and age can contribute to variations in immunity, defining the reference intervals of TREC and KREC levels in the local population is crucial for setting up cut-offs for PIDD diagnosis. In this retrospective study, 479 healthy Chinese sibling donors (240 males and 239 females; age range: 1 month-74 years) from Hong Kong were tested for TREC and KREC levels using a simultaneous quantitative real-time PCR assay. Age-specific 5th-95th percentile reference intervals of TREC and KREC levels (expressed in copies per µL blood and copies per 106 cells) were established in both pediatric and adult age groups. Significant inverse correlations between age and both TREC and KREC levels were observed in the pediatric age group. A significant higher KREC level was observed in females than males after 9-12 years of age but not for TREC. Low TREC or KREC levels were detected in patients diagnosed with mild or severe PIDD. This assay with the established local reference intervals would allow accurate diagnosis of PIDD, and potentially monitoring immune reconstitution following haematopoietic stem cell transplantation or highly active anti-retroviral therapy in the future.

Clinical and molecular characteristics of 35 Chinese children with Wiskott-Aldrich syndrome.

BACKGROUND: Wiskott-Aldrich syndrome (WAS) is a rare primary immunodeficiency disease, with an incidence of 4/1,000,000 live male births. In China, an estimated number of 35 babies with WAS are born each year, but likely many remain undiagnosed. OBJECTIVES: The objectives of study were to review the clinical and molecular characteristics of a cohort of Chinese children with WAS and to describe the long-term outcome of those who underwent hematopoietic stem cell transplant (HSCT). MATERIALS AND METHOD: Records of 35 patients diagnosed with WAS during 1991-2008 were reviewed. Genetic diagnosis was established by direct gene sequencing. RESULTS: All patients had classical WAS phenotype. WASP mutations were identified in 33 patients from 29 families. Nine patients underwent HSCT at a mean age of 22.1 months (match-unrelated donor, n = 5; mismatched related donor, n = 2; matched-sibling donor, n = 2). Post-transplant immune hemolytic anemia and thrombocytopenia occurred in three patients with complete resolution. All patients survived without significant long-term complications and had full platelet, T and B lymphocyte recovery within 2 years post-transplant. CONCLUSION: In the past decade, there has been significant improvement in clinical and genetic diagnosis of WAS in Chinese. We demonstrated excellent long-term survival in patients who underwent HSCT. Early workup for transplant should be advocated for children with classical WAS before they suffer from major disease complications and morbidities.

Susceptibility to mycobacterial infections in children with X-linked chronic granulomatous disease: a review of 17 patients living in a region endemic for tuberculosis.

BACKGROUND: Chronic granulomatous disease (CGD) is a rare disorder of phagocytic oxidative bursts leading to recurrent pyogenic infections. Affected individuals are most prone to infections caused by staphylococci, Salmonella, Candida, and Aspergillus, but previously we observed a high incidence of Mycobacterium tuberculosis infection in Chinese children with CGD. OBJECTIVE: To determine the spectrum of infections in patients with X-linked CGD, with an emphasis on mycobacterial infections, and to review all CYBB gene mutations identified in our center. RESULTS: From 1988 to 2005, 17 Chinese male children were diagnosed to have X-linked CGD. Fifteen mutations were identified, including 3 splice site defects (IVS1-1G>C, 266G>A, IVS3-1G>A), 5 missense mutations (591T>C, 627T>A, 949T>A, 1039T>A, 1512G>C), 3 nonsense mutations (882C>T, 1451C>A, 1569G>T), 1 insertion (756_757insA), and 3 deletions (660_662delTTC, 727delT, 1341delT). Eight of these were novel mutations. Recurrent pneumonia, lymphadenitis, and bacterial skin abscess were the commonest types of infection. Seven patients had tuberculosis (TB). Seven patients had prolonged scarring or abscess formation at the Calmette-Guérin bacillus (BCG) injection site, and 1 had disseminated BCG infection. Three patients had pulmonary aspergillosis. Four patients underwent hemopoietic stem cell transplantation, but 2 died of complications. CONCLUSIONS: Patients with CGD are susceptible to TB and BCG complications. Our observation suggests that oxidative burst is probably important in host defense against mycobacterial infections. Because interferon-gamma is the key cytokine involved in mycobacterial immunity, there may be a stronger indication for its use in CGD patients living in areas endemic for TB.