The pediatric approach to Hodgkin lymphoma.

Hodgkin lymphoma (HL) occurs throughout the lifespan but is one of the most common cancers in adolescents and young adults (AYA; 15-39 years). HL has become a highly curable disease with survival rates surpassing 90%, including patients with high-risk and advanced stage disease. Unfortunately, intensive treatment carries a risk of short- and long-term toxicity. Given the decades pediatric HL survivors are expected to live after treatment, the pediatric approach to treatment has focused on improving the therapeutic index through response adapted treatment and more recently the incorporation of novel agents. The efforts of pediatric and medical oncologists in research and clinical trial development have long occurred in parallel, but recent efforts have laid the foundation for collaboration with the goal of standardizing AYA care and allowing earlier incorporation of novel therapy for younger patients. This review focuses on the evolution of the management of pediatric HL including epidemiology, biology, and approaches to upfront and salvage treatment regimens.

Primary Mediastinal B-Cell Lymphoma in Children and Young Adults.

Primary mediastinal B-cell lymphoma (PMBCL) is a rare but aggressive mature B-cell lymphoma that arises from thymic B cells and most commonly affects adolescents and young adults. PMBCL is now recognized by the WHO as a distinct entity from diffuse large B-cell lymphoma (DLBCL), not otherwise specified, with a unique clinical presentation and distinct morphologic features and molecular alterations. Similar to classic Hodgkin lymphoma, PMBCL tumors are characterized by alterations in the nuclear factor-κB and JAK/STAT pathways. These tumors also exhibit an immune evasion phenotype marked by upregulation of PD-L1 and loss of B2M. Historic data indicates that outcomes for pediatric patients with PMBCL are inferior compared with pediatric patients with DLBCL treated on the same protocols, and there is no current standard approach to initial treatment. Common regimens used for children with PMBCL include multiagent chemotherapy regimens designed for Burkitt lymphoma, such as Lymphomes Malins B (LMB)-based or Berlin-Frankfurt-Münster (BFM)-based chemotherapy ± rituximab. Based on initial data in adults showing excellent outcomes with the use of DA-EPOCH-R regimens, these regimens have also been adopted in pediatrics, although with mixed results. Novel agents are currently being studied in PMBCL with the goal of improving outcomes and reducing reliance on radiation and/or high-dose chemotherapy. Immune checkpoint blockade with PD-1 inhibition is of particular interest given the upregulation of PD-L1 in PMBCL and the known efficacy of these agents in the relapsed setting. Future efforts in PMBCL will also seek to determine the role of FDG-PET in evaluating response to therapy and the role of biomarkers in risk stratification.

Brentuximab vedotin after autologous transplantation in pediatric patients with relapsed/refractory Hodgkin lymphoma.

Outcomes for children and adolescents with relapsed and refractory Hodgkin lymphoma (HL) are poor, with ∼50% of patients experiencing a subsequent relapse. The anti-CD30 antibody-drug conjugate brentuximab vedotin improved progression-free survival (PFS) when used as consolidation after autologous stem cell transplantation (ASCT) in adults with high-risk relapsed/refractory HL. Data on brentuximab vedotin as consolidative therapy after ASCT in pediatric patients with HL are extremely limited, with data of only 11 patients reported in the literature. We performed a retrospective analysis of 67 pediatric patients who received brentuximab vedotin as consolidation therapy after ASCT for the treatment of relapsed/refractory HL to describe the experience of this regimen in the pediatric population. This is the largest cohort reported to date. We found that brentuximab vedotin was well tolerated with a safety profile similar to that of adult patients. With a median follow-up of 37 months, the 3-year PFS was 85%. These data suggest a potential role for the use of brentuximab vedotin as consolidation therapy after ASCT for children with relapsed/refractory HL.

Molecular Evolution of Classic Hodgkin Lymphoma Revealed Through Whole-Genome Sequencing of Hodgkin and Reed Sternberg Cells.

The rarity of malignant Hodgkin and Reed Sternberg (HRS) cells in classic Hodgkin lymphoma (cHL) limits the ability to study the genomics of cHL. To circumvent this, our group has previously optimized fluorescence-activated cell sorting to purify HRS cells. Using this approach, we now report the whole-genome sequencing landscape of HRS cells and reconstruct the chronology and likely etiology of pathogenic events leading to cHL. We identified alterations in driver genes not previously described in cHL, APOBEC mutational activity, and the presence of complex structural variants including chromothripsis. We found that high ploidy in cHL is often acquired through multiple, independent chromosomal gains events including whole-genome duplication. Evolutionary timing analyses revealed that structural variants enriched for RAG motifs, driver mutations in B2M, BCL7A, GNA13, and PTPN1, and the onset of AID-driven mutagenesis usually preceded large chromosomal gains. This study provides a temporal reconstruction of cHL pathogenesis. SIGNIFICANCE: Previous studies in cHL were limited to coding sequences and therefore not able to comprehensively decipher the tumor complexity. Here, leveraging cHL whole-genome characterization, we identify driver events and reconstruct the tumor evolution, finding that structural variants, driver mutations, and AID mutagenesis precede chromosomal gains. This article is highlighted in the In This Issue feature, p. 171.

Vital organ sparing with proton therapy for pediatric Hodgkin lymphoma: Toxicity and outcomes in 50 patients.

BACKGROUND AND PURPOSE: With high survival rates for pediatric Hodgkin lymphoma (HL), attention has turned to minimizing treatment-related morbidity and mortality. Chemotherapy and dose of radiation to organs at risk (OARs) contribute to elevated risks of secondary malignancy and cardiopulmonary disease. We sought to characterize the radiation dose to OARs, toxicities, and outcomes for pediatric HL patients treated with proton therapy (PT). MATERIALS AND METHODS: Fifty patients aged 11-21 with HL consecutively treated with PT were evaluated 1-2 months following completion of PT and every 6 months thereafter. Acute and late toxicities were captured retrospectively using CTCAE v5. Patterns of relapse were characterized, and survival was assessed using Kaplan-Meier method. RESULTS: Most (47, 94%) patients received PT to the mediastinum. Median mean heart dose was 4.3 Gy (RBE) and median bilateral lung V20Gy was 5.8%. Median integral dose was 1.7 Gy. For the 27 female patients, a median mean dose of 0.4 and 0.3 Gy (RBE) was delivered to ipsilateral and contralateral breast tissue, respectively. No on-treatment grade 3-5 toxicities were seen. At a median follow-up of 5.3 years, no PT-related grade 3-5 toxicities or secondary malignancies developed. Five patients relapsed at a median time of 9.2 months after PT (range 2.5-24.9 months; 5-year recurrence free survival 90%). Recurrences were both in- and out-of-field in all 5 cases with no marginal failures. All relapsed patients were successfully salvaged (5-year overall survival 100%). CONCLUSION: For pediatric HL patients, proton treatment resulted in marked dose sparing of OARs with low rates of toxicity, no marginal failures, and excellent 5-year survival.

Clofarabine with topotecan, vinorelbine, and thiotepa reinduction regimen for children and young adults with relapsed AML.

Effective reinduction regimens are needed for children with relapsed and refractory acute myeloid leukemia (AML), as outcomes remain poor. Therapeutic options are limited in this heavily pretreated patient population, many of whom have reached lifetime recommended doses of anthracycline chemotherapy. The development of effective non-anthracycline-based salvage regimens is crucial to these patients who are at significant risk of life-threatening cardiotoxicity. We previously reported results of a phase 2 trial of a clofarabine-based regimen with topotecan, vinorelbine, and thiotepa (TVTC) in patients with relapsed acute leukemias. Here we report on an expanded bicenter cohort of 33 patients, <25 years of age, with relapsed/refractory AML treated with up to 2 cycles of the TVTC reinduction regimen from 2007 to 2018. The overall response rate, defined as complete remission or complete remission with partial recovery of platelet count, was 71.4% (95% confidence interval [CI], 41.9-91.6) for those patients in first relapse (n = 14) and 47.4% (95% CI, 24.4-71.1) for patients in second or greater relapse or with refractory disease. Responses were seen across multiple high-risk cytogenetic and molecular subtypes, with 84% of responders successfully bridged to allogeneic stem cell transplantation. The 5-year overall survival for patients in first relapse was 46.2% (95% CI, 19.1-73.3) and 50.0% (95% CI, 26.9-73.1) for patients who responded to TVTC. For pediatric and young adult patients with relapsed/refractory AML, TVTC reinduction compares favorably with currently used salvage regimens and warrants further exploration.

Impact of Bridging Chemotherapy on Clinical Outcomes of CD19-Specific CAR T Cell Therapy in Children/Young Adults with Relapsed/Refractory B Cell Acute Lymphoblastic Leukemia.

Chimeric antigen receptor (CAR) T cells achieve response and durable remission in patients with relapsed/refractory (R/R) B cell malignancies. Following collection of patient T cells, chemotherapy ("bridging chemotherapy") is utilized during the manufacture of CAR T cells. However, the optimal bridging chemotherapy has yet to be defined. Our objective in this study was to report clinical outcomes following bridging chemotherapy in a cohort of pediatric/young adult patients with R/R B cell acute lymphoblastic leukemia (B-ALL) treated with CAR T cell therapy. This retrospective study included patients enrolled on clinical trial NCT01860937 or referred to Memorial Sloan Kettering Cancer Center for commercial CAR T cell therapy (tisagenlecleucel). Bridging chemotherapy (given after T cell collection and before CAR T cell infusion) was defined as high intensity if myelosuppression was expected for >7 days. Outcome comparison analyses were performed in high-intensity versus low-intensity bridging chemotherapy, 1 cycle versus ≥2 cycles of bridging chemotherapy, disease burden at the start of bridging chemotherapy, disease burden at the start of bridging chemotherapy with chemotherapy intensity, tumor debulking by bridging chemotherapy, and disease burden pre-lymphodepleting chemotherapy (LDC) for CAR T cell treatment. The outcomes of this analysis showed that the incidence of grade ≥3 infection was significantly higher (94% versus 56%; P = .019) and overall survival (OS) was significantly lower (hazard ratio, 3.73; 95% confidence interval, 1.39 to 9.97; P = .006) in patients who received ≥2 cycles versus 1 cycle of bridging chemotherapy. No difference in incidence was found for cytokine release syndrome (P > .99) or neurotoxicity/immune effector cell-associated neurotoxicity syndrome (P = .70). Disease burden at the start of bridging chemotherapy, disease burden prior to LDC, and tumor debulking by bridging chemotherapy also did not significantly affect outcomes after CAR T cell therapy in this cohort. In this study, patients receiving ≥2 cycles of bridging chemotherapy had higher rates of infection and lower OS but no difference in CAR-specific toxicity. Clinicians should carefully consider the use of additional cycles of chemotherapy during the bridging period as it delays treatment with CAR T cells and increases the risk of infectious complications. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Combination brentuximab vedotin and bendamustine for pediatric patients with relapsed/refractory Hodgkin lymphoma.

In patients with relapsed/refractory (R/R) Hodgkin lymphoma (HL), achieving a complete metabolic response (CMR) after salvage therapy is associated with superior outcomes, and optimal treatments must be identified. The combination of brentuximab vedotin and bendamustine (BVB), although highly active in adult patients, has not been extensively evaluated in pediatric patients with R/R HL. We performed a multicenter, retrospective review of pediatric patients <21 years of age with R/R HL treated with BVB from January 2016 through July 2019. Response was assessed by local radiologists according to Lugano classification criteria. Twenty-nine patients (17 relapsed, 12 refractory) with a median age of 16 years (range, 10-20) were treated with BVB and received a median of 3 cycles of therapy (range, 2-7). Patients received an infusion of 1.8 mg/kg of BV on day 1 with bendamustine 90 mg/m2 on days 1 and 2 of 3-week cycles. Nineteen patients (66%) achieved a CMR (95% CI, 46-82). An objective response was observed in 23 patients (objective response rate, 79%; 95% CI, 60-92). The most common grade 3 and 4 toxicities were hematologic, and 3 patients (10%) experienced grade 3 infusion reactions. Seventeen of 18 patients underwent successful mobilization and collection of stem cells. Sixteen patients (13 autologous, 3 allogeneic) received a consolidative transplant after BVB. The 3-year post-BVB event-free and overall survival were 65% (95% CI, 46-85) and 89% (95% CI, 74-100), respectively. For pediatric patients with R/R HL, BVB was well tolerated and compared favorably with currently accepted salvage regimens.

Prospective pan-cancer germline testing using MSK-IMPACT informs clinical translation in 751 patients with pediatric solid tumors.

The spectrum of germline predisposition in pediatric cancer continues to be realized. Here we report 751 solid tumor patients who underwent prospective matched tumor-normal DNA sequencing and downstream clinical use (clinicaltrials.gov NCT01775072). Germline pathogenic and likely pathogenic (P/LP) variants were reported. One or more P/LP variants were found in 18% (138/751) of individuals when including variants in low, moderate, and high penetrance dominant or recessive genes, or 13% (99/751) in moderate and high penetrance dominant genes. 34% of high or moderate penetrance variants were unexpected based on the patient's diagnosis and previous history. 76% of patients with positive results completed a clinical genetics visit, and 21% had at least one relative undergo cascade testing as a result of this testing. Clinical actionability additionally included screening, risk reduction in relatives, reproductive use, and use of targeted therapies. Germline testing should be considered for all children with cancer.

Toxicity and response after CD19-specific CAR T-cell therapy in pediatric/young adult relapsed/refractory B-ALL.

Chimeric antigen receptor (CAR) T cells have demonstrated clinical benefit in patients with relapsed/refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL). We undertook a multicenter clinical trial to determine toxicity, feasibility, and response for this therapy. A total of 25 pediatric/young adult patients (age, 1-22.5 years) with R/R B-ALL were treated with 19-28z CAR T cells. Conditioning chemotherapy included high-dose (3 g/m2) cyclophosphamide (HD-Cy) for 17 patients and low-dose (≤1.5 g/m2) cyclophosphamide (LD-Cy) for 8 patients. Fifteen patients had pretreatment minimal residual disease (MRD; <5% blasts in bone marrow), and 10 patients had pretreatment morphologic evidence of disease (≥5% blasts in bone marrow). All toxicities were reversible, including severe cytokine release syndrome in 16% (4 of 25) and severe neurotoxicity in 28% (7 of 25) of patients. Treated patients were assessed for response, and, among the evaluable patients (n = 24), response and peak CAR T-cell expansion were superior in the HD-Cy/MRD cohorts, as compared with the LD-Cy/morphologic cohorts without an increase in toxicity. Our data support the safety of CD19-specific CAR T-cell therapy for R/R B-ALL. Our data also suggest that dose intensity of conditioning chemotherapy and minimal pretreatment disease burden have a positive impact on response without a negative effect on toxicity. This trial was registered at www.clinicaltrials.gov as #NCT01860937.

Maintenance chemotherapy to reduce the risk of a metachronous Wilms tumor in children with bilateral nephroblastomatosis.

From 2009 to 2018, 10 consecutive patients with Wilms tumors and bilateral nephroblastomatosis, who had completed standard therapy, were provided a maintenance chemotherapy regimen consisting of vincristine and dactinomycin every 3 months for 12 months in order to prevent an early metachronous Wilms tumor. One patient (10%) with Beckwith-Wiedemann syndrome developed a new tumor, without anaplasia. There were no significant toxicities reported during maintenance. All patients are currently alive with no evidence of disease. Further investigations are recommended to determine the utility of this approach.

A case of KMT2A-SEPT9 fusion-associated acute megakaryoblastic leukemia.

Acute megakaryoblastic leukemia (AMKL) constitutes ∼5%-15% of cases of non-Down syndrome AML in children, and in the majority of cases, chimeric oncogenes resulting from recurrent gene rearrangements are identified. Based on these rearrangements, several molecular subsets have been characterized providing important prognostic information. One such subset includes a group of patients with translocations involving the KMT2A gene, which has been associated with various fusion partners in patients with AMKL. Here we report the molecular findings of a 2-yr-old girl with AMKL and t(11;17)(q23;25) found to have a KMT2A-SEPT9 fusion identified through targeted RNA sequencing. A KMT2A-SEPT9 fusion in this subset of patients has not previously been reported.

KIR3DL1 Allelic Polymorphism and HLA-B Epitopes Modulate Response to Anti-GD2 Monoclonal Antibody in Patients With Neuroblastoma.

PURPOSE: In patients with neuroblastoma (NB), treatment with anti-GD2 monoclonal antibody (mAb) directs natural killer (NK) cell-mediated antibody-dependent cellular cytotoxicity (ADCC) against tumor cells. However, tumor cytotoxicity is attenuated by ligation of inhibitory killer immunoglobulin-like receptors (KIRs) by HLA class I molecules. KIR3DL1 polymorphism influences its ability to engage HLA-Bw4 ligands. We tested the hypothesis that poorly interacting combinations of KIR3DL1 and HLA ligands are more permissive of mAb-mediated antitumor effect. METHODS: KIR3DL1 and HLA-B subtyping were performed with a multiplex intermediate-resolution polymerase chain reaction assay for a cohort of 245 patients who were treated with antibody 3F8 for high-risk NB. Patient outcomes were analyzed according to expected degree of interaction between KIR3DL1 and HLA-B subtypes and grouped as strong, weak, or noninteractors. A comparison of NK response to 3F8 mAb opsonized NB cells between strong- and noninteracting donors was performed by flow cytometry. RESULTS: KIR3DL1 and HLA-B subtype combinations associated with noninteraction as a result of lack of receptor expression [KIR3DL1(-)], failure of interaction with inhibitory ligands [KIR3DS1(+)], or absence of KIR ligands resulted in significantly improved overall and progression-free survival. Patients with KIR3DL1 and HLA-B subtype combinations that were predictive of weak interaction had superior outcomes compared with those that were predictive of strong interaction; however, both groups were inferior to those with noninteracting subtype combinations. In vitro analysis of 3F8-mediated ADCC showed that KIR3DL1(-) and 3DS1(+) NK cells were insensitive to inhibition by HLA-Bw4-expressing NB targets. CONCLUSION: We conclude that KIR3LD1 and HLA-B allele combinations can have a prognostic impact on patient survival after treatment with anti-GD2 mAb that relies on NK-ADCC. The survival advantage seen in noninteracting combinations supports the therapeutic disinhibition of individuals with strongly interacting KIR and ligand pairs.

Myeloablative chemotherapy with autologous stem cell transplant for desmoplastic small round cell tumor.

Desmoplastic small round cell tumor (DSRCT), a rare, aggressive neoplasm, has a poor prognosis. In this prospective study, we evaluated the role of myeloablative chemotherapy, followed by autologous stem cell transplant in improving survival in DSRCT. After high-dose induction chemotherapy and surgery, 19 patients with chemoresponsive DSRCT underwent autologous stem cell transplant. Myeloablative chemotherapy consisted of carboplatin (400-700 mg/m(2)/day for 3 days) + thiotepa (300 mg/m(2)/day for 3 days) ± topotecan (2 mg/m(2)/day for 5 days). All patients were engrafted and there was no treatment-related mortality. Seventeen patients received radiotherapy to sites of prior or residual disease at a median of 12 weeks after transplant. Five-year event-free and overall survival were 11 ± 7% and 16 ± 8%, respectively. Two patients survive disease-free 16 and 19 years after transplant (both in complete remission before transplant). 14 patients had progression and died of disease at a median of 18 months following autologous transplant. These data do not justify the use of myeloablative chemotherapy with carboplatin plus thiotepa in patients with DSRCT. Alternative therapies should be considered for this aggressive neoplasm.

Pathology turnaround time in pediatric oncology: a tool to prepare patients and families for the diagnostic waiting period.

There is little data on the amount of time patients and families typically wait for pathology results when pediatric malignancy is suspected. The purpose of this study was to determine the average waiting period after diagnostic intervention for pediatric cancer. Pathology reports were reviewed for pediatric patients who had their initial diagnosis and were followed in the Division of Hematology/Oncology from 2007 through 2010. The average turnaround time (TAT) for all pathology (n=266) was 6.9 days. The TAT for pathology results according to diagnosis was 10.1 days for CNS tumors (n=59), 9.7 days for sarcomas (n=40), 5.4 days for lymphomas (n=31), 5.4 days for neuroblastoma (n=13), 7.3 days for kidney tumors (n=11), 7.2 days for thyroid tumors (n=7), 9.4 days for ovarian tumors (n=7), 7.0 days for schwannomas/neurofibromas (n=5), 5.7 days for testicular tumors (n=3), 5.0 days for hepatoblastoma (n=3), and 7.0 days for nasopharyngeal carcinomas (n=2). Overall the TAT for leukemia was 3.1 days (n=76), with diagnosis by flow cytometry taking 1.2 days and results by bone marrow biopsy taking 4.0 days. The TAT for pediatric oncology pathology after diagnostic intervention varies according to diagnosis. The hope is that this information will better prepare patients and families for the agonizing waiting period associated with diagnosis.