Third-party virus-specific T cells for the treatment of double-stranded DNA viral reactivation and posttransplant lymphoproliferative disease after solid organ transplant.

Reactivation or primary infection with double-stranded DNA viruses is common in recipients of solid organ transplants (SOTs) and is associated with significant morbidity and mortality. Treatment with conventional antiviral medications is limited by toxicities, resistance, and a lack of effective options for adenovirus (ADV) and BK polyomavirus (BKPyV). Virus-specific T cells (VSTs) have been shown to be an effective treatment for infections with ADV, BKPyV, cytomegalovirus (CMV), and Epstein-Barr virus (EBV). Most of these studies have been conducted in stem cell recipients, and no large studies have been published in the SOT population to date. In this study, we report on the outcome of quadrivalent third-party VST infusions in 98 recipients of SOTs in the context of an open-label phase 2 trial. The 98 patients received a total of 181 infusions, with a median of 2 infusions per patient. The overall response rate was 45% for BKPyV, 65% for cytomegalovirus, 68% for ADV, and 61% for Epstein-Barr virus. Twenty percent of patients with posttransplant lymphoproliferative disorder had a complete response and 40% of patients had a partial response. All the VST infusions were well tolerated. We conclude that VSTs are safe and effective in the treatment of viral infections in SOT recipients.

Clinical outcomes of hypomethylating agents and venetoclax in newly diagnosed unfit and relapsed/refractory paediatric, adolescent and young adult acute myeloid leukaemia patients.

Venetoclax (VEN) combined with hypomethylating agents (HMA) decitabine or azacitidine is used for adult acute myeloid leukaemia (AML), but its application in paediatric, adolescent and young adult (AYA) AML lacks prospective studies. We performed a retrospective chart review of paediatric and AYA AML patients treated with HMA + VEN at Cincinnati Children's Hospital Medical Centre. Twenty-seven patients received 30 HMA + VEN treatment courses for relapsed/refractory (R/R, n = 21) or newly diagnosed (n = 9) AML due to ineligibility for intensive chemotherapy. The R/R cohort had high-risk cytomolecular genetic alterations and prior extensive treatments, with 50% (n = 9) of relapse patients (n = 18) having undergone haematopoietic stem cell transplantation (HSCT). Venetoclax treatment using the 400 mg adult exposure-equivelant dosing (AED) had a median duration of 21 days (range 7-30 days). Grade 3-4 toxicities included neutropenia (90%), anaemia (64%), thrombocytopenia (64%) and febrile neutropenia (44%). The overall complete remission (CR)/CR with incomplete blood count recovery (CRi) rate was 73% (77% minimal residual disease [MRD] negativity <0.1%), with 60% undergoing HSCT. Among newly diagnosed patients (n = 9), 89% achieved CR/CRi (78% MRD negativity) and 78% proceeded to HSCT. The R/R cohort (n = 21) showed a 67% CR/CRi rate (71% MRD negativity), with 52% undergoing HSCT. These findings support the safety and efficacy of HMA + VEN in paediatric/AYA AML, indicating it as a viable option for patients unfit for intensive chemotherapy. Further studies are necessary to determine optimal venetoclax dosing, chemotherapy combinations and pharmacokinetics in this population.

Multicenter study of pediatric Epstein-Barr virus-negative monomorphic post solid organ transplant lymphoproliferative disorders.

BACKGROUND: Pediatric Epstein-Barr virus-negative monomorphic post solid organ transplant lymphoproliferative disorder [EBV(-)M-PTLD] comprises approximately 10% of M-PTLD. No large multi-institutional pediatric-specific reports on treatment and outcome are available. METHODS: A multi-institutional retrospective review of solid organ recipients diagnosed with EBV(-)M-PTLD aged ≤21 years between 2001 and 2020 in 12 centers in the United States and United Kingdom was performed, including demographics, staging, treatment, and outcomes data. RESULTS: Thirty-six patients were identified with EBV(-)M-PTLD. Twenty-three (63.9%) were male. Median age (range) at transplantation, diagnosis of EBV(-)M-PTLD, and interval from transplant to PTLD were 2.2 years (0.1-17), 14 years (3.0-20), and 8.5 years (0.6-18.3), respectively. Kidney (n = 17 [47.2%]) and heart (n = 13 [36.1%]) were the most commonly transplanted organs. Most were Murphy stage III (n = 25 [69.4%]). Lactate dehydrogenase was elevated in 22/34 (64.7%) and ≥2 times upper limit of normal in 11/34 (32.4%). Pathological diagnoses included diffuse large B-cell lymphoma (n = 31 [86.1%]) and B-non-Hodgkin lymphoma (B-NHL) not otherwise specified (NOS) (n = 5 [13.9%]). Of nine different regimens used, the most common were: pediatric mature B-NHL-specific regimen (n = 13 [36.1%]) and low-dose cyclophosphamide, prednisone, and rituximab (n = 9 [25%]). Median follow-up from diagnosis was 3.0 years (0.3-11.0 years). Three-year event-free survival (EFS) and overall survival (OS) were 64.8% and 79.9%, respectively. Of the seven deaths, six were from progressive disease. CONCLUSIONS: EFS and OS were comparable to pediatric EBV(+) PTLD, but inferior to mature B-NHL in immunocompetent pediatric patients. The wide range of therapeutic regimens used directs our work toward developing an active multi-institutional registry to design prospective studies. PLAIN LANGUAGE SUMMARY: Pediatric Epstein-Barr virus-negative monomorphic post solid organ transplant lymphoproliferative disorders (EBV(-)M-PTLD) have comparable outcomes to EBV(+) PTLD, but are inferior to diffuse large B-cell lymphoma in immunocompetent pediatric patients. The variety of treatment regimens used highlights the need to develop a pediatric PTLD registry to prospectively evaluate outcomes. The impact of treatment regimen on relapse risk could not be assessed because of small numbers. In the intensive pediatric B-non-Hodgkin lymphoma chemoimmunotherapy group, 11 of 13 patients remain alive in complete remission after 0.6 to 11 years.

Burkitt lymphoma after solid-organ transplant: Treatment and outcomes in the paediatric PTLD collaborative.

Burkitt lymphoma arising in paediatric post-solid-organ transplantation-Burkitt lymphoma (PSOT-BL) is a clinically aggressive malignancy and a rare form of post-transplant lymphoproliferative disorder (PTLD). We evaluated 35 patients diagnosed with PSOT-BL at 14 paediatric medical centres in the United States. Median age at organ transplantation was 2.0 years (range: 0.1-14) and age at PSOT-BL diagnosis was 8.0 years (range: 1-17). All but one patient had late onset of PSOT-BL (≥2 years post-transplant), with a median interval from transplant to PSOT-BL diagnosis of 4.0 years (range: 0.4-12). Heart (n = 18 [51.4%]) and liver (n = 13 [37.1%]) were the most frequently transplanted organs. No patients had loss of graft or treatment-related mortality. A variety of treatment regimens were used, led by intensive Burkitt lymphoma-specific French-American-British/Lymphomes Malins B (FAB/LMB), n = 13 (37.1%), and a low-intensity regimen consisting of cyclophosphamide, prednisone and rituximab (CPR) n = 12 (34.3%). Median follow-up was 6.7 years (range: 0.5-17). Three-year event-free and overall survival were 66.2% and 88.0%, respectively. Outcomes of PSOT-BL patients receiving BL-specific intensive regimens are comparable to reported BL outcomes in immunocompetent children. Multi-institutional collaboration is feasible and provides the basis of prospective data collection to determine the optimal treatment regimen for PSOT-BL.

Post-transplant lymphoproliferative disease in children, adolescents, and young adults.

Post-transplant lymphoproliferative disease (PTLD) remains a major complication of transplantation. PTLD is a rare entity and very heterogenous making consensus on diagnosis and treatment very challenging. The majority are Epstein-Barr virus (EBV) driven, CD20+ B-cell proliferations. PTLD does occur following hematopoietic stem cell transplant (HSCT), but due to the relative short risk period and efficacy of pre-emptive therapy, PTLD following HSCT will not be discussed in this review. This review will focus on the epidemiology, role of EBV, clinical presentation, diagnosis and evaluation and the current and emerging treatment strategies for pediatric PTLD following solid organ transplantation.

Use of gemcitabine, oxaliplatin, and anti-CD20 therapy in children and adolescents with non-Hodgkin lymphoma unfit for intensive therapy.

Multiagent immunochemotherapy affords excellent outcomes in pediatric non-Hodgkin lymphoma (NHL); however, scarce data exist for patients unfit for intensive treatment. Rituximab, gemcitabine, and oxaliplatin (R-GemOx) is well tolerated and efficacious in elderly adults with NHL; however, its use has not been described in pediatrics. In this retrospective, single-center study, six children with mature B-cell NHL and significant comorbidities received anti-CD20 therapy with GemOx (rituximab or obinutuzumab or ofatumumab with gemcitabine and oxaliplatin [R/O-GemOx]). R/O-GemOx was well tolerated and resulted in complete response in two of three patients with newly diagnosed NHL and one of three patients with primary refractory NHL. R/O-GemOx is a viable treatment option for children with NHL who cannot tolerate intensive therapy.

Durable remissions achieved with reinfusion of CD19-directed CAR-T despite failure to induce or maintain B-cell aplasia and single-center experience with reinfusion of tisagenlecleucel.

CD19-directed chimeric antigen receptor T lymphocytes (CAR-T) have led to durable remissions in children with refractory and/or multiply relapsed B-lymphoblastic leukemia. For those who relapse or lose B-cell aplasia post CAR-T, the role of CAR-T reinfusion is unclear. We report two cases of durable remission with tisagenlecleucel reinfusion despite failure to achieve or maintain B-cell aplasia, and compare these cases to six additional children who received multiple tisagenlecleucel infusions at our institution. Our experience suggests that reinfusion is safe and may be a definitive therapy for a small subset of patients. Reinfusion can also reintroduce remission and/or B-cell aplasia, allowing for subsequent therapies.

Endothelial injury, F-actin and vitamin-D binding protein after hematopoietic stem cell transplant and association with clinical outcomes.

Endothelial injury after hematopoietic stem cell transplant is an important initiating factor for early transplant toxicities of thrombotic microangiopathy and acute graft versus host disease. We hypothesized that release of the angiopathic molecule filamentous actin from hematopoietic cells lysed during conditioning prior to stem cell transplant would be associated with clinical outcomes. We detected filamentous actin in the blood of 52% of stem cell transplant recipients in the first 14 days after transplant, and children with detectable filamentous actin had significantly elevated risk of thrombotic microangiopathy (p= 0.03) and non-relapse mortality (p= 0.04). Filamentous actin is cleared from the circulation by vitamin D binding protein so we expected that higher levels of vitamin D binding protein would improve outcomes. In a cohort of 190 children receiving allogeneic transplant, risk of thrombotic microangiopathy was reduced in those with serum concentrations of vitamin D binding protein above the median at day 30 (10% vs 31%, p=0.01), and graft versus host disease and non-relapse mortality were reduced in those with levels above the median at day 100 (3% vs 18%, p=0.04 and 0% vs 15%, p=0.002). Western blot analyses demonstrated actin-vitamin D binding protein complexes in the blood, which cleared by day 21-28. Our data support modulation of cytokine secretion and macrophage phenotype by vitamin D binding protein later after transplant. Taken together, our data identify an association between filamentous-actin, a mediator of endothelial damage, and vitamin D binding protein, an actin scavenger, as modifiers of risk of clinical consequences of endothelial injury.

Tolerance of dinutuximab therapy for treatment of high-risk neuroblastoma in two patients with end-stage renal disease on dialysis.

Autologous hematopoietic cell transplant (aHCT) has a significant survival advantage in patients with high-risk (HR) neuroblastoma. Transplant-associated thrombotic microangiopathy (TA-TMA) is a serious complication and may result in chronic renal disease leading to delay in subsequent posttransplant therapy and limitations of treatment options. Dinutuximab represents an important therapeutic advance in the treatment of pediatric HR neuroblastoma, but historically has not been administered in patients with GFR < 60 mL/m2 /min. Here, we present the safe outcome of dinutuximab administration while on renal replacement therapy in two cases of HR neuroblastoma with end-stage renal disease secondary to TA-TMA.

Treatment of posttransplant lymphoproliferative disorder with poor prognostic features in children and young adults: Short-course EPOCH regimens are safe and effective.

No guidelines exist for which intensive chemotherapy regimen is best in pediatric or young adult patients with high-risk posttransplant lymphoproliferative disorder (PTLD). We retrospectively reviewed patients with PTLD who received interval-compressed short-course etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin (SC-EPOCH) regimens at our institution. Eight patients were included with median age of 12 years. All patients achieved a complete response with a manageable toxicity profile. Two patients developed second, clonally unrelated, EBV-positive PTLD and one patient had recurrence at 6 months off therapy. No graft rejection occurred during therapy. All eight patients are alive with median follow-up of 29 months.

Chimeric Antigen Receptor T Cell Therapy in Patients with Multiply Relapsed or Refractory Extramedullary Leukemia.

Autologous CD19-directed chimeric antigen receptor T lymphocyte (CAR-T) therapy is an approved and effective treatment for the management of patients with refractory and multiply relapsed B cell precursor acute lymphoblastic leukemia (B-ALL). Experience using this therapy in pediatric patients with extramedullary (EM) disease is limited, in part because these patients have frequently been excluded from clinical trials owing to concerns for an increased risk of immune effector cell-associated neurotoxicity syndrome (ICANS). We infused 7 patients with refractory or multiply relapsed B-ALL who presented with isolated EM relapse with tisagenlecleucel. Six patients had isolated central nervous system (CNS) leukemia, and 1 patient had an isolated testicular relapse. An initial complete response was seen in all patients, with 5 patients remaining in CAR-T-induced remission at a median of 18 months from first infusion. Reversible ICANS was seen in 1 patient with CNS leukemia. Durable B cell aplasia occurred in 3 patients, with a median time to B cell recovery of 6.5 months in the other patients. These data suggest that CAR-T therapy has promising safety and efficacy in treating EM leukemia, although definitive conclusions are limited by the small size of the cohort and limited follow-up period.

Chimeric antigen receptor T-cell therapy in patients with neurologic comorbidities.

Chimeric antigen receptor T cells (CAR-T) are an effective and potentially durable treatment for refractory and multiply relapsed B-cell acute lymphoblastic leukemia. Neurotoxicity is frequent after CAR-T cell therapy. Mechanisms driving neurotoxicity are incompletely understood, and symptoms can range from transient and mild to severe and life-threatening. Providers have exercised caution in providing CAR-T to patients with neurological comorbidities or extramedullary disease. Here, we report three patients with prior significant neurologic morbidity who safely tolerated CAR-T cell infusion after bridging therapy with conventional chemotherapy.

EBV-directed viral-specific T-lymphocyte therapy for the treatment of EBV-driven lymphoma in two patients with primary immunodeficiency and DNA repair defects.

Children with ataxia telangiectasia (AT), a primary immunodeficiency caused by mutations in ATM, which is critical for repairing DNA defects, are at risk for the development of hematologic malignancy, frequently driven by infection with Epstein-Barr virus (EBV). Conventional chemotherapy is poorly tolerated by patients with AT, with excessive toxicity even when doses are reduced. Here, we report on two patients with AT and EBV-positive neoplasms who were treated with EBV-targeted viral-specific T cells (VST). One patient had a prolonged complete response to VSTs while the other had a partial response. Therapy was well tolerated without infusion toxicity or graft-versus-host disease.

Pediatric and Young Adult Vulvovaginal Graft-versus-Host Disease.

Vulvovaginal graft-versus-host disease (GVHD) is an underdiagnosed and poorly recognized complication of hematopoietic stem cell transplantation (HSCT). Previous studies have reported findings restricted to predominantly adult populations. We report a case series of pediatric and young adult vulvovaginal GVHD, which was identified in 19 patients (median age, 11.8 years; range, 2.4 to 21.9 years) out of a total 302 female patients who underwent transplantation over an 8-year period at a pediatric HSCT center. The majority of patients had concomitant nongenital GVHD; only 1 patient had isolated vulvovaginal GVHD. The median time from bone marrow transplantation to diagnosis of vulvovaginal GVHD was 30 months (range, 2.3 to 97.5 months). A high percentage of the patients in our series were without vulvar or vaginal symptoms (n = 8; 42%), even though 17 patients (89%) presented with grade 3 disease based on current adult grading scales. Vulvar examination findings most frequently included interlabial and clitoral hood adhesions (89%), loss of architecture of the labia minora or clitoral hood (42%), and skin erosions or fissures (37%). Only 5 patients underwent a speculum exam, none of whom had vaginal GVHD. Examination findings of primary ovarian insufficiency (POI) can overlap with those of GVHD, and 6 patients (32%) in our cohort were diagnosed with POI. Only 1 patient was on systemic hormone replacement therapy at the time of vulvovaginal GVHD diagnosis. The majority of patients (n = 16) were treated with topical steroid therapy, with a median time to response of 43 days. Five patients (26%) had a complete response to therapy, and 10 patients (53%) had a partial response. This case series provides valuable insight into pediatric and young adult vulvovaginal GVHD and highlights the need for increased screening for vulvar disease in this population.

Surgical and anesthetic management for hepatectomy in two pediatric patients with trisomy 18, pulmonary hypertension, and hepatoblastoma.

Children with trisomy 18 are surviving longer and undergoing more aggressive life-sustaining therapy. This report describes two patients with trisomy 18 and hepatoblastoma (HB) successfully resected in the setting of significant pulmonary hypertension. Forty-four previously published cases of the association between HB and trisomy 18 are reviewed. With careful multidisciplinary preoperative planning, successful resection of HB in children with trisomy 18 who have significant pulmonary hypertension is feasible. Because HB and trisomy 18 are increasing in prevalence, the need for timely liver tumor resection in the setting of pulmonary hypertension will be more common.

Virus-Specific T Cells for the Treatment of Systemic Infections Following Allogeneic Hematopoietic Cell and Solid Organ Transplantation.

Viral infections are a major source of morbidity and mortality in the context of immune deficiency and immunosuppression following allogeneic hematopoietic cell (allo-HCT) and solid organ transplantation (SOT). The pharmacological treatment of viral infections is challenging and often complicated by limited efficacy, the development of resistance, and intolerable side effects. A promising strategy to rapidly restore antiviral immunity is the adoptive transfer of virus-specific T cells (VST). This therapy involves the isolation and ex vivo expansion or direct selection of antigen-specific T cells from healthy seropositive donors, followed by infusion into the patient. This article provides a practical guide to VST therapy by reviewing manufacturing techniques, donor selection, and treatment indications. The safety and efficacy data of VSTs gathered in clinical trials over nearly 30 years is summarized. Current challenges and limitations are discussed, as well as opportunities for further research and development.

Cyclic AMP signaling inhibits megakaryocytic differentiation by targeting transcription factor 3 (E2A) cyclin-dependent kinase inhibitor 1A (CDKN1A) transcriptional axis.

Signaling via the intracellular second messenger cyclic AMP (cAMP) has long been implicated in the repression of megakaryocytic differentiation. However, the mechanisms by which cAMP signaling impairs megakaryopoiesis have never been elucidated. In a human CD34(+) cell culture model, we show that the adenylyl cyclase agonist forskolin inhibits megakaryocytic differentiation in a protein kinase A-dependent manner. Using this system to screen for downstream effectors, we identified the transcription factor E2A as a key target in a novel repressive signaling pathway. Specifically, forskolin acting through protein kinase A-induced E2A down-regulation and enforced expression of E2A overrode the inhibitory effects of forskolin on megakaryopoiesis. The dependence of megakaryopoiesis on critical thresholds of E2A expression was confirmed in vivo in haploinsufficient mice and ex vivo using shRNA knockdown in human progenitors. Using a variety of approaches, we further identified p21 (encoded by CDKN1A) as a functionally important megakaryopoietic regulator residing downstream of E2A. These results thus implicate the E2A-CDKN1A transcriptional axis in the control of megakaryopoiesis and reveal the lineage-selective inhibition of this axis as a likely mechanistic basis for the inhibitory effects of cAMP signaling.

Inotuzumab ozogamicin in B-cell precursor acute lymphoblastic leukemia: efficacy, toxicity, and practical considerations.

Inotuzumab ozogamicin (InO) is an antibody drug conjugate composed of a humanized monoclonal antibody targeting the cell surface receptor CD22 coupled to a cytotoxic calicheamicin payload via an acid labile linker. InO has shown significant activity in relapsed and refractory B-cell precursor acute lymphoblastic leukemia (BCP-ALL) in both single agent and combination chemotherapy regimens in adult and pediatric trials. Its use in newly diagnosed elderly patients has also been established while clinical trials investigating its use in newly diagnosed pediatric patients and fit adults are ongoing. Notable toxicities include sinusoidal obstruction syndrome (SOS), particularly in patients who undergo hematopoietic stem cell transplantation (HSCT) after InO as well as myelosuppression and B-cell aplasia which confer increased infection risk, particularly in combination with cytotoxic chemotherapy. In the relapsed/refractory (R/R) setting, the planned subsequent curative therapy modality must be considered when using InO to mitigate SOS risk if proceeding to HSCT and account for potential B-cell aplasia if proceeding to chimeric antigen receptor CAR-T therapy. Studies exploring mechanisms of resistance or failure of InO are ongoing but modulation or loss CD22 expression, alternative CD22 splicing, and high Bcl-2 expression have been implicated. In this review, we will summarize the currently available data on InO, with an emphasis on pediatric trials, and explore future directions including combinatorial therapy.