Faculty Bibliography

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.

UNLABELLED: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.

Epstein-Barr virus (EBV) subverts host epigenetic pathways to switch between viral latency programs, colonize the B cell compartment, and reactivate. Within memory B cells, the reservoir for lifelong infection, EBV genomic DNA and histone methylation marks restrict gene expression. But this epigenetic strategy also enables EBV-infected tumors, including Burkitt lymphomas, to evade immune detection. Little is known about host cell metabolic pathways that support EBV epigenome landscapes. We therefore used amino acid restriction, metabolomic, and CRISPR approaches to identify that an abundant methionine supply and interconnecting methionine and folate cycles maintain Burkitt EBV gene silencing. Methionine restriction, or methionine cycle perturbation, hypomethylated EBV genomes and de-repressed latent membrane protein and lytic gene expression. Methionine metabolism also shaped EBV latency gene regulation required for B cell immortalization. Dietary methionine restriction altered murine Burkitt xenograft metabolomes and de-repressed EBV immunogens in vivo. These results highlight epigenetic/immunometabolism crosstalk supporting the EBV B cell life cycle and suggest therapeutic approaches.

BACKGROUND:Heterozygous germline mutations in cytotoxic T lymphocyte-associated antigen-4 (CTLA4) impair the immunomodulatory function of regulatory T cells. Affected individuals are prone to life-threatening autoimmune and lymphoproliferative complications. A number of therapeutic options are currently being used with variable effectiveness. OBJECTIVE:Our aim was to characterize the responsiveness of patients with CTLA-4 insufficiency to specific therapies and provide recommendations for the diagnostic workup and therapy at an organ-specific level. METHODS:Clinical features, laboratory findings, and response to treatment were reviewed retrospectively in an international cohort of 173 carriers of CTLA4 mutation. Patients were followed between 2014 and 2020 for a total of 2624 months from diagnosis. Clinical manifestations were grouped on the basis of organ-specific involvement. Medication use and response were recorded and evaluated. RESULTS:Among the 173 CTLA4 mutation carriers, 123 (71%) had been treated for immune complications. Abatacept, rituximab, sirolimus, and corticosteroids ameliorated disease severity, especially in cases of cytopenias and lymphocytic organ infiltration of the gut, lungs, and central nervous system. Immunoglobulin replacement was effective in prevention of infection. Only 4 of 16 patients (25%) with cytopenia who underwent splenectomy had a sustained clinical response. Cure was achieved with stem cell transplantation in 13 of 18 patients (72%). As a result of the aforementioned methods, organ-specific treatment pathways were developed. CONCLUSION:Systemic immunosuppressants and abatacept may provide partial control but require ongoing administration. Allogeneic hematopoietic stem cell transplantation offers a possible cure for patients with CTLA-4 insufficiency.

PURPOSE OF REVIEW:Lymphoma is the one of the most common cancer diagnoses among adolescents and young adults (AYAs) aged 15-39. Despite significant advances in outcomes observed in older adults and younger children, improvements in AYAs have lagged behind. The reasons for this are likely multifactorial including disparities in access to health insurance, low rates of enrollment to clinical trials, potential differences in disease biology, and unique psychosocial challenges. Here we will review Hodgkin lymphoma (HL) and primary mediastinal B cell lymphoma (PMBCL), two of the most common aggressive lymphomas that occur in AYAs. We will discuss the current knowledge about disease biology in AYAs, adult and pediatric treatment strategies, novel targeted therapies, and ongoing AYA clinical trials in these lymphoma subtypes. We also will review unique considerations for treatment-related toxicities in AYAs and psychosocial issues relevant to this population. RECENT FINDINGS:Pediatric and adult trials in HL and PMBCL have demonstrated that treatment with dose-intense chemotherapeutic regimens with or without radiation results in high cure rates but can also be associated with long-term toxicity which must be considered in this young population. Novel targeted agents such as the antibody-drug conjugate brentuximab vedotin and/or antibodies targeted against PD-1/PD-L1 have demonstrated activity in the relapsed setting and are currently being evaluated in the upfront setting, which may reduce our reliance on therapies associated with long-term toxicity. AYA-focused clinical trials are currently underway to better elucidate the optimal therapy for lymphomas in this age group. There is an urgent need for clinical trials including AYAs in order to increase the knowledge of age-specific outcomes, toxicities, disease biology, and the need to develop comprehensive AYA care models that meet the unique and complex care needs of this patient population.

Survivors of Hodgkin lymphoma (HL) have an increased risk of subsequent malignant neoplasms (SMNs). Response-adapted treatment may decrease this risk by reducing exposure to therapy associated with SMN risk. The Children's Oncology Group study AHOD0031 evaluated response-adapted therapy for children and adolescents with intermediate-risk HL. We report the SMNs among 1711 patients enrolled in AHOD0031. Patients were treated with 4 cycles of doxorubicin, bleomycin, vincristine, etoposide, prednisone, and cyclophosphamide with or without involved-field radiation therapy (RT). Patients with a slow early response to initial chemotherapy were randomized to 2 additional cycles of dexamethasone, etoposide, cisplatin and cytarabine or no additional chemotherapy, and all received RT. At a median follow-up of 7.3 years, an analysis of SMNs was performed. The 10-year cumulative incidence of SMN was 1.3% (95% confidence interval [CI], 0.6-2.0). SMNs included 3 patients with acute myeloid leukemia (AML), 11 with solid tumors, and 3 with non-Hodgkin lymphoma. Sixteen of 17 patients with an SMN had received combined modality therapy. The standardized incidence ratio for SMN was 9.5 (95% CI, 4.5-15.2) with an excess absolute risk of 1.2 per 1000 person-years. The cumulative incidence of SMNs was higher among patients who received RT (P = .037). In multivariate analysis, RT, B symptoms, and race were associated with SMN risk. Given the latency from exposure, we have likely captured all cases of secondary leukemia and myelodysplastic syndrome (MDS). Longer follow-up is needed to determine the risk of solid tumors. Avoidance of RT without sacrificing disease control should remain a goal for future therapeutic approaches. This trial was registered at www.clinicaltrials.gov as #NCT00025259.

Bimiralisib is an orally bioavailable pan-phosphatidylinositol 3-kinase and mammalian target of rapamycin inhibitor which has shown activity against lymphoma in preclinical models. This phase I/II study evaluated the response rate to bimiralisib at 2 continuous dose levels (60 mg and 80 mg) in patients with relapsed/refractory lymphoma. Fifty patients were enrolled and started treatment. The most common histologies were diffuse large B-cell lymphoma (n = 17), follicular lymphoma (n = 9), T-cell lymphoma (n = 8), and others (mostly indolent). Patients had been treated with a median of 5 prior lines of treatment and 44% were considered refractory to their last treatment. Mean duration of treatment (and standard deviations) with 60 mg once daily (o.d.) was 1.3 ± 1.2 months, and with 80 mg o.d. 3.7 ± 3.9 months. On an intention to treat analysis, the overall response rate was 14% with 10% achieving a partial response and 4% a complete response. Thirty-six percent of patients were reported as having stable disease. No dose-limiting toxicities were observed during the phase I portion of the study. Overall, 70% of patients had a grade 3 treatment emergent adverse events (TEAE) and 34% had a grade 4 TEAE; 28% of patients discontinued treatment due to toxicity. The most frequent TEAEs grade ≥3 was hyperglycemia (24%), neutropenia (20%), thrombocytopenia (22%), and diarrhea (12%). Per protocol, hyperglycemia required treatment with oral antihyperglycemic agents in 28% and with insulin in 14%. At 60 mg or 80 mg continuous dosing, bimiralisib showed modest efficacy with significant toxicity in heavily pretreated patients with various histological subtypes of lymphoma.