Clinical covariates that improve the description of high dose methotrexate pharmacokinetics in a diverse population to inform MTXPK.org

The MTXPK.org webtool was launched in December 2019 and was developed to facilitate model-informed supportive care and optimal use of glucarpidase following the administration of high-dose methotrexate (HDMTX). One limitation identified during the original development of the MTXPK.org tool was the perceived generalizability because the modeled population comprised solely of Nordic pediatric patients receiving 24-h infusions for the treatment of acute lymphoblastic leukemia. The goal of our study is to describe the pharmacokinetics of HDMTX from a diverse patient population (e.g., races, ethnicity, indications for methotrexate, and variable infusion durations) and identify meaningful factors that account for methotrexate variability and improve the model's performance. To do this, retrospectively analyzed pharmacokinetic and toxicity data from pediatric and adolescent young adult patients who were receiving HDMTX (>0.5 g/m2 ) for the treatment of a cancer diagnosis from three pediatric medical centers. We performed population pharmacokinetic modeling referencing the original MTXPK.org NONMEM model (includes body surface area and serum creatinine as covariates) on 1668 patients, 7506 administrations of HDMTX, and 30,250 concentrations. Our results support the parameterizations of short infusion duration (<8 h) and the presence of Down syndrome on methotrexate clearance, the parameterization of severe hypoalbuminemia (<2.5 g/dL) on the intercompartmental clearance (Q2 and Q3), and the parameterization of pleural effusion on the volume of distribution (V1 and V2). These novel parameterizations will increase the generalizability of the MTXPK.org model once they are added to the webtool.

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.

Real-world experience in treating pediatric relapsed/refractory or therapy-related myeloid malignancies with decitabine, vorinostat, and FLAG therapy based on a phase 1 study run by the TACL consortium

Current therapies for relapsed/refractory (R/R) pediatric myeloid neoplasms are inadequately effective. Real-world data (RWD) can improve care by augmenting traditional studies and include individuals not eligible for clinical trials. The Therapeutic Advances in Childhood Leukemia and Lymphoma (TACL) consortium recently completed T2016-003, a phase 1 study of decitabine, vorinostat, fludarabine, cytarabine, and granulocyte colony-stimulating factor (G-CSF) in R/R acute myeloid leukemia (AML), which added epigenetic drugs to a cytotoxic backbone. We report results of RWD from six centers that treated 28 pediatric patients (26 with AML, two with other myeloid neoplasms) identically to the TACL study but who were not enrolled. This allowed unique analyses and the ability to compare data with the 35 TACL study patients. The overall response rate (ORR) (complete response [CR] plus CR with incomplete count recovery) among 26 RWD evaluable patients was 65%. The ORR of 13 patients with relapsed AML with epigenetic alterations was 69% (T2016-003 + RWD: 68%, n = 25), of eight patients with refractory AML was 38% (T2016-003 + RWD: 41%, n = 17) and of five patients with therapy-related AML (t-AML) was 80% (T2016-003 + RWD: 75%, n = 8). The mean number of Grade 3/4 toxicities experienced by the T2016-003-eligible RWD population (n = 22) (one per patient-cycle) was not meaningfully different than those (n = 6) who would have been TACL study-ineligible secondary to comorbidities (two per patient-cycle). Overall, this therapy was well tolerated and effective in pediatric patients with R/R myeloid neoplasms, particularly those with epigenetic alterations, t-AML, and refractory disease.

Influence of albumin and methotrexate clearance on high-dose methotrexate-induced mucositis

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Background: Methotrexate (MTX) is a cornerstone of therapy for several types of cancer. HDMTX-induced mucositis can impact quality of life and delay subsequent chemotherapy. Objective: The objective of this study was to understand the factors increasing risk for mucositis in patients receiving HDMTX in a multicenter cohort. Methods: A multi-center retrospective study collected data on pediatric and young adult patients ages 0-32 years at diagnosis who received at least one dose of HDMTX (>500 mg/m2) at Children’s Healthcare of Atlanta or Cincinnati Children’s Hospital Medical Center from January 2010 through December 2020. Demographic and clinical variables were manually abstracted, while medications and lab values were electronically pulled from the electronic medical record. Common Terminology Criteria for Adverse Events v5 was used to identify the presence and grade of mucositis after HDMTX administration. Institutional review board approval was obtained at each site. Chi-square and t-tests, as appropriate, were calculated using GraphPad Prism v9. MTX concentrations were fit to a published pharmacokinetic model to estimate clearance using NONMEM. Results: The cohort is described in Table. The rate of mucositis was highest after the first HDMTX administration (54.6%), when the MTX clearance is slowest (30.1%<10 L/hr/1.73m2 and albumin was lowest (14.3%<2.5g/dL). Mucositis was significantly more likely in patients with hypoalbuminemia and in patients with MTX clearance <10 L/hr/1.73m2 (OR 1.75 (CI: 1.503 to 2.028), p<0.0001 and OR 1.43 (CI: 1.236 to 1.653), p<0.0001, respectively). Conclusions: Mucositis after administration of HDMTX is common, with 72% of patients experiencing at least grade 1 mucositis and a third of HDMTX administrations leading to mucositis. Chart abstraction is ongoing at a third hospital to increase the sample size, particularly those of Hispanic/Latino ethnicity, in order to investigate differences by race and ethnicity. In addition, current analyses are evaluating the impact of changes in supportive care on HDMTX-induced mucositis and other adverse events. The results of this study will demonstrate who is at highest risk for adverse events so supportive care can be tailored during this potentially toxic chemotherapy.[Table: see text]

Decitabine and vorinostat with FLAG chemotherapy in pediatric relapsed/refractory AML: Report from the therapeutic advances in childhood leukemia and lymphoma (TACL) consortium

Survival outcomes for relapsed/refractory pediatric acute myeloid leukemia (R/R AML) remain dismal. Epigenetic changes can result in gene expression alterations which are thought to contribute to both leukemogenesis and chemotherapy resistance. We report results from a phase I trial with a dose expansion cohort investigating decitabine and vorinostat in combination with fludarabine, cytarabine, and G-CSF (FLAG) in pediatric patients with R/R AML [NCT02412475]. Thirty-seven patients enrolled with a median age at enrollment of 8.4 (range, 1-20) years. There were no dose limiting toxicities among the enrolled patients, including two patients with Down syndrome. The recommended phase 2 dose of decitabine in combination with vorinostat and FLAG was 10 mg/m2 . The expanded cohort design allowed for an efficacy evaluation and the overall response rate among 35 evaluable patients was 54% (16 complete response (CR) and 3 complete response with incomplete hematologic recovery (CRi)). Ninety percent of responders achieved minimal residual disease (MRD) negativity (<0.1%) by centralized flow cytometry and 84% (n = 16) successfully proceeded to hematopoietic stem cell transplant. Two-year overall survival was 75.6% [95%CI: 47.3%, 90.1%] for MRD-negative patients vs. 17.9% [95%CI: 4.4%, 38.8%] for those with residual disease (p < .001). Twelve subjects (34%) had known epigenetic alterations with 8 (67%) achieving a CR, 7 (88%) of whom were MRD negative. Correlative pharmacodynamics demonstrated the biologic activity of decitabine and vorinostat and identified specific gene enrichment signatures in nonresponding patients. Overall, this therapy was well-tolerated, biologically active, and effective in pediatric patients with R/R AML, particularly those with epigenetic alterations.

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.

Novel germline TRAF3IP3 mutation in a dyad with familial acute B lymphoblastic leukemia

Background

Acute lymphoblastic leukemia (ALL) is the most common hematologic malignancy in children, representing 25% of all new cancer diagnoses. Advances in genomic sequencing have demonstrated that inherited genetic risk factors play a larger role in leukemia development than previously appreciated.

Aim

We identified a father–daughter dyad with childhood B‐cell ALL and aimed to investigate whether the pair shared a gene associated with leukemia predisposition.

Methods

We performed whole exome sequencing on their leukemia and germline samples and RNA‐seq on their leukemia samples.

Results

We discovered a novel germline chromosomal structural variant in chromosome 1q32.2 within the TRAF3IP3 gene. TRAF3IP3 regulates B‐cell lymphopoiesis, and this mutation likely resulted in a predisposition to leukemia by causing expansion of immature B‐cell precursors which are highly vulnerable to secondary somatic mutations. Based on the lack of concordance in the somatic mutational profiles between this dyad's leukemia samples, we suspect that the acquired somatic mutations rather than this germline mutation are what dictated their leukemia phenotypes, which we confirmed through RNA‐seq by comparing to sporadic cases of B‐cell ALL.

Conclusion

This research may have identified a novel gene involved in leukemogenesis which may also be involved in de novo cases of ALL. Additional studies are needed to further characterize this TRAF3IP3 structural variant, the co‐occurring somatic mutations within these leukemia samples and their combined role in leukemogenesis.

Chimeric antigen receptor T-cell therapy for marrow and extramedullary relapse of infant acute lymphoblastic leukemia

Chimeric antigen receptor (CAR) T-cells, engineered autologous T-cells that target antigens found in leukemia, have shown durable remissions in relapsed acute lymphoblastic leukemia (ALL). Infant ALL with KMT2A rearrangements (KMT2Ar) is a rare, aggressive form of leukemia associated with extramedullary disease both at diagnosis and at relapse, and overall outcomes for these patients are dismal. Here we report the successful use of tisagenlecleucel, a CAR T-cell product approved for relapsed/refractory ALL, in a patient with KMT2Ar infant ALL who was treated for combined marrow and extramedullary (renal) relapse.

Novel Therapies Potentially Available for Pediatric B-Cell Non-Hodgkin Lymphoma

Burkitt lymphoma, diffuse large B-cell lymphoma (DLBCL), and primary mediastinal B-cell lymphoma are the most common aggressive pediatric mature B-cell non-Hodgkin lymphomas (B-NHLs). Despite excellent survival with current chemotherapy regimens, therapy for Burkitt lymphoma and DLBCL has a high incidence of short- and long-term toxicities. Patients who experience relapse generally have a very poor prognosis. Therefore, novel approaches using targeted therapies to reduce toxicities and improve outcomes in the relapse setting are needed. The addition of rituximab, a monoclonal antibody against CD20, to upfront therapy has improved survival outcomes for high-risk patients and may allow decreased total chemotherapy in those with low-risk disease. Antibody-drug conjugates have been combined with chemotherapy in relapsed/refractory (R/R) NHL, and multiple antibody-drug conjugates are in development. Additionally, bispecific T-cell-engaging antibody constructs and autologous CAR T-cells have been successful in the treatment of R/R acute leukemias and are now being applied to R/R B-NHL with some successes. PD-L1 and PD-L2 on tumor cells can be targeted with checkpoint inhibitors, which restore T-cell-mediated immunity and antitumor responses and can be added to conventional chemotherapy and immune-directed therapies to augment responses. Lastly, trials of small molecule inhibitors targeting cell signaling pathways in NHL subtypes are underway. This article reviews many of the targeted therapies under development that could be considered for future trials in R/R pediatric mature B-NHL.

Desensitization to pegaspargase in children with acute lymphoblastic leukemia and lymphoblastic lymphoma

Hypersensitivity to pegaspargase is associated with inferior survival in pediatric patients with acute lymphoblastic leukemia and lymphoblastic lymphoma. In the past year, drug-supply shortages have led to the lack of an available alternative to pegaspargase. Rather than omit asparaginase from the treatment of acute lymphoblastic leukemia or lymphoblastic lymphoma patients with hypersensitivity to pegaspargase, we continued pegaspargase treatments for nine pediatric patients, utilizing a rapid desensitization protocol. There were no adverse events related to the pegaspargase during desensitization, and all patients who were checked had asparaginase serum levels above the threshold of 0.1 IU/mL at 7 to 14 days after pegaspargase therapy.

Upfront Therapies and Downstream Effects: Navigating Late Effects in Childhood Cancer Survivors in the Current Era

PURPOSE OF REVIEW

As survival rates of those diagnosed with childhood cancer improve over time, the number of long-term survivors continues to grow. Advances have not only been made in the upfront treatment of childhood cancer, but also in the identification and treatment of late complications that may arise as a result of the chemotherapy, radiotherapy, or surgical interventions required to provide a cure.

RECENT FINDINGS

As new therapies emerge that are often more targeted to cancerous cells while sparing healthy tissues, the hope is that cure can be achieved without the same long-term side effects for survivors. However, much is unknown regarding how these novel interventions will impact patients in the years to come. It is critical that we continue to follow patients treated with new modalities in order to identify and treat the long-term complications that may arise in future childhood cancer survivors.