Roxadustat-Induced Central Hypothyroidism in Renal Anemia Patients: Insights From Antineutrophil Cytoplasmic Antibody-Related Vasculitis Cases.

The introduction of hypoxia-inducible factor-prolyl hydroxylase (HIF-PH) inhibitors in Japan in 2019 for treating renal anemia in hemodialysis patients has resulted in an adverse event: central hypothyroidism. Although this adverse event was not widely recognized by the public, it was first documented in Japan in 2021. Despite limited case reports on roxadustat, an oral HIF-PH inhibitor that induces central hypothyroidism, this condition typically improves rapidly upon discontinuation of the drug. In this report, we present rare cases of roxadustat-induced central hypothyroidism in two patients: a woman in her 80s and a man in his 60s, neither of whom had prior thyroid disease. Both patients developed central hypothyroidism shortly after starting roxadustat treatment for renal anemia associated with antineutrophil cytoplasmic antibody-related vasculitis. Notably, neither patient had pituitary tumors or other pituitary hormone disorders. Thyroid function improved with levothyroxine treatment, even when oral roxadustat was continued. Roxadustat may induce central hypothyroidism, highlighting the importance of regularly measuring and evaluating thyroid function when administering this drug to monitor possible changes in thyroid hormone levels.

Short-term and long-term outcomes of patients with anti-melanoma differentiation-associated gene 5 antibody-positive dermatomyositis.

OBJECTIVES: Anti-melanoma differentiation-associated gene 5 (MDA5) antibody-positive dermatomyositis (MDA5-DM) is a subtype of dermatomyositis characterized by frequent interstitial lung disease and reduced muscle involvement. This study aimed to determine the short-term and long-term outcomes of patients with MDA5-DM. METHODS: Information on baseline characteristics, treatments, and short-term and long-term outcomes of patients with MDA5-DM including survival, relapse, and the titer of anti-MDA5 antibody, was retrospectively collected. Descriptive statistics regarding clinical outcomes were calculated, and a comparison of clinical parameters between patients with and without relapse was performed. The short-term survival according to the use of Janus kinase inhibitors (JAKi) was also assessed. RESULTS: A total of 154 patients with MDA5-DM were included in the study. Forty patients (25.9%) died during the remission induction phase, with respiratory failure being the most common cause of mortality. Among the 114 patients who survived the remission induction phase, the 5-year cumulative survival and relapse-free survival rates were 96.8% and 77.4%, respectively, and 7.9% of patients achieved complete drug-free remission. Fifty-four patients achieved normalization of anti-MDA5 antibody titers and only two of them relapsed after normalization. In the severe patients, the 6-month survival rate became significantly higher after the emergence of the JAKi treatment compared with before its existence (p= 0.03). CONCLUSIONS: Although relapse often occurs, the long-term survival of MDA5-DM patients who survived the remission induction phase is generally favorable. The status of the anti-MDA5 antibody is associated with relapse. JAKi may improve the survival of refractory patients with severe MDA5-DM.

New therapies in anti-MDA5 antibody-positive dermatomyositis.

PURPOSE OF REVIEW: This review focuses on treatments for anti-MDA5 antibody-positive dermatomyositis (MDA5-DM), which is a subgroup of dermatomyositis and characterized by frequent rapidly progressive interstitial lung disease and the high mortality rate. Despite conventional immunosuppressive therapies, there are still refractory cases. Newer treatment options are needed. RECENT FINDINGS: The triple combination therapy (high-dose glucocorticoids, calcineurin inhibitor, and intravenous cyclophosphamide) improved patient survival compared to high-dose glucocorticoids and step-wise addition of the immunosuppressants. The triple therapy now has been widely used, but there are still refractory cases. In addition to the conventional-type immunosuppressants, recently the efficacy of Janus kinase inhibitors, biologic agents such as rituximab, plasma exchange, and polymyxin B perfusion for refractory MDA5-DM patients have been reported. However, the majority of those reports regarding new treatments are limited to case series, retrospective studies, and small single-arm studies. Adding antifibrotic drugs to immunosuppressive therapies might have some ancillary benefits. SUMMARY: Several new therapies for MDA5-DM patients have emerged, although the optimal use of those therapies is still unknown. Further research and evidence accumulation will be needed. It is also noted that the intensive immunosuppressive therapies are associated with the higher infection risk.

Fulminant myocarditis with adult-onset Still's disease: case-based review.

Myocarditis has been reported as a life-threatening complication of adult-onset Still's disease (AOSD), but fulminant myocarditis with AOSD is very rare. We hereby report a case of a 43-year-old female with fulminant myocarditis with AOSD. She had a refractory AOSD and cardiogenic shock with markedly elevated ferritin level up to 67,370 ng/mL. She was successfully treated with canakinumab and mechanical circulatory support (MCS) such as venoarterial extracorporeal membrane oxygenation and Impella CP. We also reviewed the previous cases of fulminant myocarditis with AOSD published from 1976 to December 2022, and only 8 cases of fulminant myocarditis with AOSD have been reported. The characteristics of these cases showed that the average age at presentation was 37.6 years (range 24-47 years). The time to myocarditis from the onset of AOSD ranged from 2 weeks to 2 years; however, most cases developed myocarditis within 1 year. Initial presenting symptoms included fever, dyspnea, chest pain, myalgia, rash, and sore throat. The median peak ferritin was 13,000 ng/mL. Left ventricular ejection fractions were not greater than 35%. Our case was the first reported case successfully treated with canakinumab and MCS. This review suggests that myocarditis may be an early phase of the complication in patients with AOSD, and the severity of AOSD may correlate with the severity of myocarditis. Canakinumab for AOSD and MCS for fulminant myocarditis may be one of the choices for overcoming the comorbidities.

Allogeneic stem cell transplantation for children and adolescents/young adults with de novo blastic phase chronic myeloid leukemia in the tyrosine kinase inhibitor era.

The analysis of 165 children and adolescents/young adults with de novo blastic phase chronic myeloid leukemia showed disease status at hematopoietic stem cell transplantation was a strong prognostic factor and clearly separated the patient outcomes.

Prognostic Factors for Outcomes of Allogeneic HSCT for Children and Adolescents/Young Adults With CML in the TKI Era.

The breakthrough effects of tyrosine kinase inhibitors (TKIs) have lessened indications for allogeneic hematopoietic stem cell transplantation (HSCT) in chronic myeloid leukemia (CML). However, HSCT is still attractive for children and adolescents/young adults (AYAs) requiring lifelong TKI therapy. Nevertheless, little has been reported on the outcomes of large clinical studies of HSCT targeting these age groups. This study aimed to identify prognostic factors for the outcomes of HSCT, including reduced-intensity conditioning (RIC)-HSCT, for children and AYAs with CML in the TKI era. We performed a registry analysis for 200 patients with CML aged <30 years who underwent pretransplant TKI therapy from the observational nationwide database established by the Japanese Society for Transplantation and Cellular Therapy. The patients received bone marrow (BM), peripheral blood (PB), or cord blood (CB) from either related or unrelated donors. The indication for HSCT for individual patients was determined by the institution according to European LeukemiaNet recommendations and other guidelines. The 5-year overall survival (OS) rates for patients with chronic phase (CP) (n = 124), accelerated phase (AP) (n = 23), and blastic phase (BP) (n = 53) at diagnosis were 82.8%, 71.1%, and 73.3%, respectively, with no significant difference (P =.3293). The strongest predictor of engraftment was transplant source, with CB (hazard ratio [HR], 0.33) and PB (HR, 2.00) (compared with BM) being independent unfavorable and favorable predictors, respectively. Transplant source was also an independent predictor of chronic GVHD, with PB (HR, 1.81) and CB (HR, 0.39) (compared with BM) being unfavorable and favorable predictors, respectively. The strongest predictor of OS rate for patients with CP at diagnosis was disease phase at HSCT, with second or greater CP, AP, or BP (HR, 2.81) (compared with first CP [CP1]) being an unfavorable predictor. In addition, patients with CP at diagnosis who had major and complete molecular responses at HSCT had excellent outcomes, with 5-year OS rates of 100% and 94.4%, respectively. The 5-year OS rate was compared between RIC (n = 31) and myeloablative conditioning (MAC) (n = 58) in patients with CP1, both of which were 89.3%, with no significant difference (P = .9440). On univariate analysis for the RIC cohort with CP at diagnosis, the age at HSCT (HR, 1.27) (increase per year) and the time from diagnosis to HSCT (HR, 1.83) (increase per year) were significant predictors for OS. Our study demonstrates that RIC may be an appropriate alternative to MAC for children and AYAs with CP1. As for the transplant source, we recommend first selecting BM because of a higher engraftment rate compared to CB and a lower incidence of chronic GVHD compared to PB. Although HSCT in the status of a major molecular response is desirable, it is not advisable to continue TKI pointlessly long because age at HSCT and timing of HSCT are prognostic factors that determine survival. The decision to perform RIC-HSCT instead of continuing TKI should be carefully made, considering the possibility of transplant-related complications.

HLA-haploidentical peripheral blood stem cell transplantation following reduced-intensity conditioning with very low-dose antithymocyte globulin for relapsed/refractory acute leukemia in pediatric patients: a single-institution retrospective analysis.

The prognosis of relapsed/refractory (R/R) pediatric acute leukemia is extremely poor. We retrospectively reviewed 20 consecutive pediatric patients with R/R acute leukemia who underwent a first HLA-haploidentical peripheral blood stem cell transplantation following reduced-intensity conditioning (haplo-RIC-PBSCT) with very low-dose antithymocyte globulin (ATG) between 2012 and 2019. Of these 20 patients, 7 patients had acute lymphoblastic leukemia, and 13 had acute myeloid leukemia. At the time of haplo-RIC-PBSCT, 15 patients had active disease. The median follow-up duration for survivors was 56 months (range 22-108 months). Graft-versus-host disease (GVHD) prophylaxis consisted of tacrolimus, short-term methotrexate, methylprednisolone, and ATG 1.25 mg/kg on day-2. The 2-year cumulative incidence of transplant-related mortality and relapse were 5.0% [95% confidence interval (CI) 0.7-30.5%)] and 57.8% (95% CI 37.4-79.6%), respectively. Among the 20 patients, 16 (80.0%) developed grade III-IV acute GVHD, and 2 developed severe chronic GVHD. The 2-year event-free survival and overall survival rates were 40.0% (95% CI 19.3-60.0%) and 50.0% (95% CI 27.1-69.2%), respectively. Although the sample size is small, the survival outcomes of the present study are encouraging.

Pulmonary Actinomycosis and Mucormycosis Coinfection in a Patient With Philadelphia Chromosome-positive Acute Lymphoblastic Leukemia Undergoing Chemotherapy.

Mucormycosis is an opportunistic and progressive infection, while actinomycosis usually grows gradually and rarely develops in immunocompromised patients. Here we report a patient with Philadelphia chromosome-positive acute lymphoblastic leukemia who developed a pulmonary actinomycosis and mucormycosis coinfection. Once the diagnosis of actinomycosis was confirmed by bronchoscopy, lobectomy performed before stem cell transplantation revealed mucormycosis. The patient successfully underwent transplantation using a therapeutic antifungal agent for mucormycosis. When an immunocompromised patient develops an infection of unknown etiology, physicians should consider these pathogens as the possible cause. In addition, surgical intervention should be considered as an important treatment option.

A retrospective analysis of azacitidine treatment for juvenile myelomonocytic leukemia.

Juvenile myelomonocytic leukemia (JMML) is a pediatric hematological malignancy with a poor prognosis. Although several case series have been published describing hematological and molecular responses to azacitidine (AZA) treatment in patients with JMML, the efficacy and safety profile of AZA is not well investigated, especially in Asian children and children undergoing hematopoietic stem cell transplantation (HSCT). We retrospectively analyzed 5 patients who received a total of 12 cycles (median 2 cycles) of AZA treatment in Japan. All five patients were boys and their ages at the time of treatment were 21, 23, 24, 26, and 46 months, respectively. All five patients tolerated AZA treatment, including four patients who received AZA after HSCT. Therapeutic toxicity with AZA was mostly limited to hematological toxicity. The only serious non-hematological adverse event was hyperbilirubinemia (grades III-IV) observed in a patient who received AZA after a second HSCT. Two out of five patients treated with AZA achieved a partial response (PR), while three patients treated for post-transplant relapse did not have an objective response. Future prospective studies should be conducted to develop combination therapies with AZA and other molecular targeted drugs for high-risk patients.

Radiation-sparing reduced-intensity unrelated umbilical cord blood transplantation for rare hematological disorders in children.

Graft failure is a major pitfall of unrelated umbilical cord blood transplantation (CBT) in children with rare hematological disorders other than acute leukemia, such as acquired and inherited bone marrow failure, myelodysplastic syndrome, juvenile myelomonocytic leukemia, and chronic myeloid leukemia. We developed a less-toxic conditioning regimen for CBT that achieves a higher rate of complete donor chimerism, and retrospectively compared it against two other conditioning regimens for CBT performed at our single institution. The engraftment rate with complete donor chimerism was 100% and 5-year event-free survival (5y-EFS) was 90.9% in patients using our latest regimen (n = 11) of reduced-intensity conditioning (RIC) containing fludarabine (Flu) 180 mg/m2, melphalan (MEL) 210 mg/m2, and low-dose rabbit anti-thymocyte globulin (LD-rATG) 2.5 mg/kg without irradiation (regimen C). Outcomes were better than in patients (n = 10) treated with previous regimens involving irradiation (5y-EFS 30.0%, p = 0.004): regimen A, consisting of myeloablative conditioning containing cyclophosphamide (CY) and total body irradiation (TBI) with 8-12 Gy, or regimen B, consisting of RIC with Flu, CY, horse ATG, and thoracoabdominal irradiation (TAI) with 6 Gy. In conclusion, Flu/MEL/LD-rATG (regimen C) without TBI/TAI may be preferable as RIC for unrelated CBT in children with rare hematological disorders.

Hematopoietic Cell Transplantation Rescues Inflammatory Bowel Disease and Dysbiosis of Gut Microbiota in XIAP Deficiency.

BACKGROUND: X-linked inhibitor of apoptosis protein (XIAP) deficiency is an infrequent inborn error of immunity that is often associated with refractory inflammatory bowel disease (IBD). The natural course of XIAP deficiency is typically associated with poor prognosis, and hematopoietic cell transplantation (HCT) is the only curative treatment. OBJECTIVE: To study (1) the effect of HCT on patients with XIAP deficiency undergoing HCT, (2) the status of XIAP deficiency-associated IBD after HCT, and (3) the gut microbiota of XIAP deficiency-associated IBD before and after HCT. METHODS: A nationwide survey of patients with XIAP deficiency was conducted. A spreadsheet questionnaire was collected from the physicians. Feces samples collected from the patients before and after HCT and their healthy family members were analyzed. RESULTS: Twenty-six patients with XIAP deficiency underwent HCT by the end of March 2020, and 22 patients (84.6%) survived. All the survivors underwent a fludarabine-based reduced-intensity condition regimen. Acute graft-versus-host disease was observed in 17 patients (65.4%). Nineteen patients experienced refractory IBD before undergoing HCT. IBD improved remarkably after HCT. After HCT, the colonoscopic and pathological symptoms were restored to normal, and the pediatric ulcerative colitis activity index improved significantly. Gut microbiota indicated dysbiosis before HCT; however, it was improved to resemble that of the healthy family members after HCT. CONCLUSIONS: This study revealed that HCT has a favorable outcome for XIAP deficiency. HCT rescues gut inflammation and dysbiosis in patients with XIAP deficiency.

Initial treatment of seizures in children in an emergency department in rural Japan.

OBJECTIVE: Although the initial treatment of childhood seizures is important, treatment within an appropriate time window is often difficult in resource-limited areas. This study examined childhood seizure treatment in a rural area in Japan. METHODS: We retrospectively investigated children presenting to Nakatsugawa Municipal General Hospital emergency department between 2015 and 2018. From the hospital database, we identified children who were diagnosed with seizures, epilepsy, or acute infectious encephalitis/encephalopathy or were given benzodiazepines. We considered etiology, seizure duration, and treatment according to the specialties of the doctors providing initial care. RESULTS: We extracted 236 seizure events: 40 initially treated by pediatricians, 16 by a mobile doctor team, and 180 by other doctors. Twenty patients had continuous seizures for longer than 5 min on admission. Two were treated by pediatricians at presentation; it took 4 and 7 min after arrival to stop the seizures. Four were treated by a mobile team, and 14 by other doctors; the median response times were 11.5 (range 3-47) and 19 (range 5-60) min, respectively. All patients treated by pediatricians or mobile doctor teams received intravenous or intramuscular diazepam, whereas 50% of those treated by other doctors initially received diazepam suppositories. In three of the 20 events, establishing intravenous access was difficult. SIGNIFICANCE: In rural Japan, many children with seizures are initially treated by doctors other than pediatricians or emergency physicians, and they require a longer time to achieve seizure cessation. Non-intravenous benzodiazepine formulas, which have not yet been approved in Japan, would be helpful.

Impact of melphalan dose during reduced-intensity conditioning on engraftment of cord blood transplantation for chronic Epstein-Barr virus-associated T or NK cell lymphoproliferative diseases.

The rejection rate in cord blood transplants for chronic Epstein-Bar virus-associated T or natural killer cell lymphoproliferative diseases using our standard reduced-intensity conditioning "LPAM140 regimen," which includes fludarabine, melphalan (LPAM), etoposide, and antithymocyte globulin, has been high. To ensure better engraftment, we increased the LPAM dose to 210 mg/m2 ("LPAM210 regimen"). Patient data (n = 22; LPAM140, n = 7; LPAM210, n = 15) were analyzed retrospectively. The engraftment rate after the LPAM210 regimen (100.0%) was significantly higher than that after the LPAM140 regimen (57.1%; P = .002). Fludarabine combined with melphalan (210 mg/m2 ) had a favorable impact on engraftment.

High rates of ovarian function preservation after hematopoietic cell transplantation with melphalan-based reduced intensity conditioning for pediatric acute leukemia: an analysis from the Japan Association of Childhood Leukemia Study (JACLS).

Women are at high risk of hypergonadotropic hypogonadism after hematopoietic cell transplantation (HCT). Hypogonadism is universal after irradiation or busulfan. We hypothesized that reduced intensity conditioning (RIC) might protect ovarian function after HCT. We retrospectively reviewed data from patients with acute leukemia treated according to the Japan Association of Childhood Leukemia Study and nationwide multicenter study protocol. We selected 11 female patients with acute leukemia who received first HCT with RIC, had survived for three or more years after HCT, and were aged ≥ 12 years at the last follow-up visit. Median age at diagnosis, HCT, and last visit were 8, 10, and 17 years. Six patients received HLA-matched bone marrow (BM), two HLA-mismatched BM, and three cord blood. Melphalan was used as conditioning regimen in all patients. At the last visit, six of seven post-pubertal patients at transplantation recovered menstruation, and four of four patients who underwent transplantation at the pre-pubertal began menstruation. Height z scores showed no significant reduction between pre-transplant and post-transplant. No patients received growth hormone treatment. Only one recipient displayed subclinical hypothyroidism. Melphalan-based RIC may be an encouraging option for patients with acute leukemia to avoid ovarian and endocrine dysfunction after HCT.

Intrathecal Infusion of Haploidentical Nondonor Lymphocytes for Central Nervous System Leukemic Relapse After Haploidentical Hematopoietic Stem Cell Transplantation.

Leukemic relapse in the central nervous system (CNS) after conventional treatment is associated with a poor prognosis. The effectiveness and safety of IV infusion of human leukocyte antigen (HLA)-mismatched lymphocytes for leukemia, and intrathecal (IT) infusion of HLA-mismatched lymphocytes for cerebrospinal fluid (CSF) dissemination of medulloblastoma have been reported. A 13-year-old girl (HLA-A31) was diagnosed as relapsing from Philadelphia chromosome-positive acute leukemia in the CNS after receiving chemotherapy, tyrosine kinase inhibitors, haploidentical hematopoietic stem cell transplantation (HSCT) from her father (HLA-A31), and craniospinal irradiation. We performed an IT infusion of haploidentical lymphocytes from her mother. Peripheral blood mononuclear cells obtained from her mother (HLA-A31) were administered by IT infusion weekly. Examination of CSF 1 week after first IT showed that lymphocyte counts had increased markedly and the breakpoint cluster region/abelson-bearing cells had disappeared. Furthermore, CD3 T cells in the CSF were negative for HLA-A31, and expressed high HLA-DR. These results indicate the infused non-HSCT-donor lymphocytes did not survive, and that the HSCT donor(father)-derived lymphocytes migrated to the CSF and were activated. The patient showed partial remission for 2 months following this therapy. Serious adverse reactions and graft versus host disease were not observed. To control leukemic CNS dissemination, haploidentical nondonor lymphocytes might contribute to a graft versus leukemia effect.

[Transurethral Injection Using Deflux for Vesicoureteral Reflux in Three Adult Women with Frequent Febrile Urinary Tract Infections].

We report three patients with frequent febrile urinary tract infections (fUTI) who underwent transurethral injection therapy with Deflux for vesicoureteral reflux (VUR). The first case was in a 52-yearold woman who was initially diagnosed with right grade II and left grade I VUR at 18 years of age. She frequently experienced fUTI due to VUR. The second case was in a 29-year-old woman. At age 23,she was diagnosed with right grade III VUR when she developed fUTI. After that,she repeatedly developed fUTI. The third case was in a 40-year-old woman who had frequently experienced fUTI since 25 years of age and had gradually become antibiotics-resistant. She was diagnosed with right grade III VUR when she was referred to our hospital. No visible reflux was confirmed by postoperative voiding cystourethrography after the patients underwent transurethral injection using Deflux. One patient developed fUTI once after surgery,but there were no perioperative complications and no recurrences. Transurethral injection using Deflux for VUR might therefore be safe and effective for treating VUR in adult female patients.

Intensified and prolonged therapy comprising cytarabine, vincristine and prednisolone improves outcome in patients with multisystem Langerhans cell histiocytosis: results of the Japan Langerhans Cell Histiocytosis Study Group-02 Protocol Study.

The JLSG-96 study reported very low mortality rates for children newly diagnosed with multifocal Langerhans cell histiocytosis (LCH). The JLSG-02 study was performed to further improve the prognosis from 2002 to 2009. The present study compared the therapeutic results of these two studies in terms of multisystem disease. All patients were treated with 6 weeks of the Induction A regimen, comprising cytarabine, vincristine and prednisolone, followed by maintenance therapy. Poor responders to Induction A were switched to Induction B. JLSG-02 has been revised from JLSG-96 in the following respects: prednisolone dosage during Induction A increased; duration of maintenance therapy extended from 24 to 48 weeks; cyclosporine introduced to Induction B for progressive disease. One hundred forty-seven children with multisystem LCH were evaluated. Of these, 84 were positive for risk of organ involvement (RO) and 63 were RO-negative. At the 6-week point, 76.2 % of RO+ and 93.7 % of RO- patients responded to Induction A. Five-year event-free survival (EFS) was 46.2 % [95 % confidence (CI), 35.5-56.9] for RO+ and 69.7 % (58.4-81.1) for RO-, which was significantly superior to that in JLSG-96 [26.8 % (13.3-40.4) and 38.9 % (16.4-61.4), respectively]. The intensified induction and prolonged maintenance regimens in JLSG-02 improved EFS in patients with multisystem LCH.

Epstein-Barr Virus-Associated Hemophagocytic Lymphohistiocytosis and Guillain-Barre Syndrome in a 16-Month-Old Child.

A 16-month-old girl was diagnosed with Epstein-Barr virus hemophagocytic lymphohistiocytosis and transferred to our hospital on the 58th day of the hemophagocytic lymphohistiocytosis after treatment failure according to the Hemophagocytic Lymphohistiocytosis-2004 protocol. On admission to our hospital, she had a flaccid paralysis of her lower limbs. Nerve conduction studies showed a acute motor axonal neuropathy, and a diagnosis of Guillain-Barre syndrome was established. Intravenous immunoglobulin G was started on the 57th day of the Guillain-Barre syndrome. To date, her neurological recovery is incomplete. For hemophagocytic lymphohistiocytosis, after treatment failure of THP-COP regimen (pirarubicin, cyclophosphamide, vincristine, and prednisone) and 2 courses of ESCAP regimen (etoposide, prednisone, cytarabine, L-asparaginase), we are now in the process of coordinating unrelated umbilical cord blood transplantation. To the best of our knowledge, we report the youngest case of Guillain-Barre syndrome accompanied by Epstein-Barr virus hemophagocytic lymphohistiocytosis. Rapid progression of Guillain-Barre syndrome, the electrophysiological subtype of Guillain-Barre syndrome, and treatment delay possibly led to poor neurological outcome.

Feasibility of Cancer Immunotherapy with WT1 Peptide Vaccination for Solid and Hematological Malignancies in Children.

BACKGROUND: Advances in cancer immunotherapy in the pediatric field are needed in order to improve the prognosis of children with malignancies. We conducted a prospective phase I/II study of WT1 peptide vaccination for children with relapsed or refractory malignancies. METHODS: The main eligibility criteria were affected tissues or leukemic cells expressing the WT1 gene, and patients (and donors for allogeneic hematopoietic stem cell transplantation) having HLA-A*24:02. Vaccination using the WT1 peptide (CYTWNQMNL), which was modified for higher affinity to this HLA-type molecule with the adjuvant Montanide ISA51, was performed weekly 12 times. RESULTS: Twenty-six patients were enrolled and 13 (50.0%) completed the vaccination 12 times. Evidence for the induction of WT1-specific cytotoxic T-lymphocyte (CTL) responses without severe systemic side effects was obtained. Two out of 12 patients with bulky disease exhibited a transient clinical effect (one mixed response and one stable disease), three out of six patients with minimal residual disease achieved transient molecular remission, and five out of eight patients without a detectable level of the molecular marker, but with a high risk of relapse, had the best outcome of long-term continuous complete remission. CONCLUSIONS: WT1 vaccination is a safe immunotherapy and induced WT1-specific CTL responses in children; however, as a single agent, vaccination only provided patients in remission, but with a high risk of relapse, with "long-term benefits" in the context of its use for relapse prevention. WT1 peptide-based treatments in combination with other modalities, such as anti-tumor drugs or immunomodulating agents, need to be planned.