Nivolumab and brentuximab vedotin with or without bendamustine for R/R Hodgkin lymphoma in children, adolescents, and young adults.

Children, adolescents, and young adults (CAYA) with relapsed/refractory (R/R) classic Hodgkin lymphoma (cHL) without complete metabolic response (CMR) before autologous hematopoietic cell transplantation (auto-HCT) have poor survival outcomes. CheckMate 744, a phase 2 study for CAYA (aged 5-30 years) with R/R cHL, evaluated a risk-stratified, response-adapted approach with nivolumab plus brentuximab vedotin (BV) followed by BV plus bendamustine for patients with suboptimal response. Risk stratification was primarily based on time to relapse, prior treatment, and presence of B symptoms. We present the primary analysis of the standard-risk cohort. Data from the low-risk cohort are reported separately. Patients received 4 induction cycles with nivolumab plus BV; those without CMR (Deauville score >3, Lugano 2014) received BV plus bendamustine intensification. Patients with CMR after induction or intensification proceeded to consolidation (high-dose chemotherapy/auto-HCT per protocol). Primary end point was CMR any time before consolidation. Forty-four patients were treated. Median age was 16 years. At a minimum follow-up of 15.6 months, 43 patients received 4 induction cycles (1 discontinued), 11 of whom received intensification; 32 proceeded to consolidation. CMR rate was 59% after induction with nivolumab plus BV and 94% any time before consolidation (nivolumab plus BV ± BV plus bendamustine). One-year progression-free survival rate was 91%. During induction, 18% of patients experienced grade 3/4 treatment-related adverse events. This risk-stratified, response-adapted salvage strategy had high CMR rates with limited toxicities in CAYA with R/R cHL. Most patients did not require additional chemotherapy (bendamustine intensification). Additional follow-up is needed to confirm durability of disease control. This trial was registered at www.clinicaltrials.gov as #NCT02927769.

Considerations in Methods and Timing for Delivery of Genetic Counseling Information to Pediatric Oncology Patients and Families.

Many pediatric oncology patients and their families may benefit from genetic counseling and testing; however, identifying the best timing and delivery method for these referrals is sometimes a challenge. The goal of this study was to understand how and when caregivers prefer to receive information about genetic counseling and testing. A total of 56 surveys completed by caregivers at The Johns Hopkins Hospital Pediatric Oncology unit in Baltimore, Maryland were analyzed. A sizeable subset of respondents was interested in receiving information about the availability of genetic counseling from an oncology doctor or nurse, but not a genetic counselor (n=13/55, 24%). Most respondents preferred to be informed about genetic services at diagnosis (n=28/54, 52%) or within 1 to 2 months of diagnosis (n=14/54, 26%). In conclusion, patients and their families may benefit from prompt and early recognition of the risk of cancer predisposition syndromes, preferably within the first 2 months following diagnosis. Oncology professionals are an important source of information, and can introduce the availability of genetic counseling services and motivate families to undergo genetic testing, though alternative communication methods such as brochures may also be useful.

The "Day Zero Talk": the Initial Communication of a Pediatric Oncology Diagnosis by Primary Care Physicians and Other Primary Care Providers.

While much is known about the initial communication of a definitive pediatric cancer diagnosis by the child's pediatric oncologist, little is known about the discussions leading up to this formal conversation, which are often had with nononcologists. We sought to describe these initial conversations regarding the possibility of a child's oncologic diagnosis, from the perspective of both the patient/family as well as the provider. Semistructured interviews were performed with individuals involved with a child with recently diagnosed cancer at a quaternary care institution in an urban, mid-Atlantic city. Interviews were recorded, transcribed, and analyzed using qualitative thematic analysis. In total, 71 people were interviewed, representing the experiences of 29 unique pediatric patients. Patient and caregiver themes included recognition of the urgency of the situation and variety of terms used to indicate the potential of cancer. Physician themes included the impact of health literacy on the discussion and varying opinions on how direct to be regarding the possibility of a cancer diagnosis. The initial discussions of the possibility of a pediatric cancer diagnosis often occur with nononcologists, and this day zero talk is critical in laying the groundwork for future communication with providers.

Intrathecal chemotherapy-associated cerebral vasospasm in children with hematologic malignancies.

BACKGROUND: Mechanisms of chemotherapy-associated neurotoxicity are poorly understood, and therefore, prevention strategies have not been developed. We hypothesized that a subgroup of children receiving intrathecal cytarabine develops subclinical vasospasm, which may contribute to long-term neurocognitive sequelae of cancer. METHODS: We used transcranial Doppler ultrasound to serially evaluate cerebral blood flow velocities in participants ≤25 years old receiving intrathecal cytarabine for hematologic malignancies. RESULTS: Four of 18 participants (22%) met the criteria for subclinical vasospasm within 4 days of intrathecal cytarabine administration. The distribution of oncologic diagnoses differed between the vasospasm and non-vasospasm groups (p = 0.02). Acute myeloid leukemia was identified as a potential risk factor for vasospasm. Children with vasospasm were more likely to have received intravenous cytarabine (75% versus 0%, p = 0.01) and less likely to have received steroids (25% versus 100%, p = 0.01). CONCLUSIONS: A subpopulation of children with hematologic malignancies develops subclinical vasospasm after intrathecal cytarabine treatment. Future research is needed to determine the long-term clinical consequences of cerebral vasospasm in this population. IMPACT: A subset of children with hematologic malignancies who receive intrathecal cytarabine experience subclinical cerebral vasospasm, as measured by transcranial Doppler ultrasound. Of children receiving intrathecal cytarabine, those who develop cerebral vasospasm are more likely to have diagnosis of acute myeloid leukemia, more likely to receive concurrent intravenous cytarabine, and less likely to receive steroids as part of their chemotherapy regimen, as compared with children without vasospasm. Future research is needed to determine if vasospasm during chemotherapy is associated with higher rates of neurocognitive dysfunction, and if so, to focus on prevention of these long-term sequelae of childhood cancer.

Pediatric Hodgkin Lymphoma, Version 3.2021.

Hodgkin lymphoma (HL) is a highly curable form of cancer, and current treatment regimens are focused on improving treatment efficacy while decreasing the risk of late effects of treatment. The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for pediatric HL provide recommendations on the workup, diagnostic evaluation, and treatment of classic HL, including principles of pathology, imaging, staging, systemic therapy, and radiation therapy. This portion of the NCCN Guidelines focuses on the management of pediatric classic HL in the upfront and relapsed/refractory settings.

Improving Detection of Cancer Predisposition Syndromes in Pediatric Oncology.

Implementation and adherence to consensus statement criteria for referral of pediatric cancer patients for genetic evaluation are critical to identify the 5% to 10% with a genetic cancer predisposition syndrome. The authors implemented a Plan-Do-Study-Act quality improvement initiative aimed at increasing referrals of at-risk patients. Retrospective chart review was followed by educational intervention-with impact assessed over a 9-month prospective chart review. Referral rate improved >2-fold and there was an improvement in documented oncologic history to at least a third-degree relative. The integration of quality improvement can be an effective tool to improve the referral of patients with an elevated risk for a cancer predisposition syndrome.

Pediatric oncology provider perspectives and practices: Supporting patients and families in schooling after cancer diagnosis.

BACKGROUND: Cognitive limitations are common after childhood cancer and require assessment and support in the medical and school setting. Pediatric oncology providers are tasked with educating families about the side effects of disease/treatment, and supporting families as they navigate the associated challenges. Despite this important role, little is known about the training, practice, and knowledge of providers in the domain of cognitive/school impacts. METHODS: An online survey was emailed to Children's Oncology Group (COG) member physicians in the United States. The survey consisted of 42 questions about training and practice, and 4 knowledge questions about neurocognitive impacts and school supports. RESULTS: Surveys were completed by 282 physicians representing 64% of COG institutions and a diverse group of experience and institution size. The pediatric oncologist was reported most frequently (93%) as the person at their institution to provide information to families on this topic, yet 54% reported receiving no specific training in this area and the majority (66%) reported to only "somewhat" understand the issues pediatric oncology patients face when returning to school. A minority reported available institutional guidelines (42%) or screening tools (19%) to assist in making referrals or assessments. Knowledge questions concerning health conditions qualifying children for school supports received the fewest correct answers. The majority (77%) thought more training would be helpful. CONCLUSIONS: Additional training about cognitive impacts and schooling challenges associated with childhood cancer is needed to prepare providers to support parents/children. In addition, establishing policy guidelines and screening procedures may help support providers in providing care.

Allopurinol use during pediatric acute lymphoblastic leukemia maintenance therapy safely corrects skewed 6-mercaptopurine metabolism, improving inadequate myelosuppression and reducing gastrointestinal toxicity.

BACKGROUND: Inadequate myelosuppression during maintenance therapy for acute lymphoblastic leukemia (ALL) is associated with an increased risk of relapse. One mechanism is skewed metabolism of 6-mercaptopurine (6MP), a major component of maintenance therapy, which results in preferential formation of the hepatotoxic metabolite (6-methyl mercaptopurine [6MMP]) with low levels of the antileukemic metabolite, 6-thioguanine nucleotides (6TGN). Allopurinol can modify 6MP metabolism to favor 6TGN production and reduce 6MMP. METHODS: Patients in maintenance were considered for allopurinol treatment who had the following features: (a) Grade ≥3 hepatotoxicity; (b) Grade ≥2 nonhepatic gastrointestinal (GI) toxicity; or (c) persistently elevated absolute neutrophil count (ANC) despite >150% protocol dosing of oral chemotherapy. RESULTS: From 2013 to 2017, 13 ALL patients received allopurinol: nine for hepatotoxicity, five for inadequate myelosuppression, and three for nonhepatic GI toxicity (four met multiple criteria). Allopurinol was well tolerated, without significant adverse events. Allopurinol resulted in a significant decrease in the average 6MMP/6TGN ratio (mean reduction 89.1, P = .0001), with a significant increase in 6TGN (mean 550.4, P = .0008) and a significant decrease in 6MMP (mean 13 755, P = .0013). Patients with hepatotoxicity had a significant decrease in transaminase elevation after starting allopurinol (alanine transaminase [ALT] mean decrease 22.1%, P = .02), and all with nonhepatic GI toxicity had improved symptoms. Those with inadequate myelosuppression had a significant increase in the time with ANC in goal (mean increase 26.4%, P = .0004). CONCLUSIONS: Allopurinol during ALL maintenance chemotherapy is a safe, feasible, and effective intervention for those who have altered metabolism of 6MP causing toxicity or inadequate myelosuppression.

Assessment of Online Resources for Returning to School During and After Treatment of Childhood Cancer.

To evaluate current online parent education resources for children returning to school after a cancer diagnosis. Online search was conducted using 3 search engines and terms recommended by affected families. Sites were evaluated by 3 reviewers for understandability and actionability (scored 0-100%) using the Patient Education Materials Assessment Tool (PEMAT). Readability was assessed using Flesch-Kincaid (grade K-12) and content comprehensiveness by a clinical expert review for 5 late effect domains (scored 0-100%). A total of 56 unique online resources were evaluated. Mean understandability and actionability scores were 54% (range 17-83) and 36% (range 0-83) respectively. The mean Flesch-Kincaid grade level was 10th grade (mode 12th). Comprehensiveness of domain coverage was 34% (mode 20%). Some high-quality materials for this topic are available, but generally low scores on the PEMAT scales and high reading level estimates on Flesch-Kincaid indicate parents may have difficulty understanding and using the information. The low scores for comprehensiveness of information indicate parents will likely need to access multiple sources for complete information. A table provides the names, website (URL), and scoring for the 24 top-rated sites and can be used to make recommendations to parents with improved confidence in quality.

Parent perspectives on oncology team communication regarding neurocognitive impacts of cancer therapy and school reentry.

BACKGROUND: Neurocognitive deficits are common after childhood cancer and impact academic performance. Parents need to be knowledgeable of long-term complications impacting school and the resources necessary to support educational achievement. The oncology team plays an important role in preparing parents for the challenges of returning to school after treatment. METHODS: An online survey developed by parents and stakeholders was used to assess parent experiences and preferences associated with oncology team support around neurocognitive deficits and school transition. Recruitment included social media sites, foundation contacts, and clinic/event flyers. Topics included information content, timing, and frequency of information; and utility or perceived value of information. Inclusion criteria included respondent identifying as a parent (caregiver) of child treated for cancer who has returned to school. RESULTS: Surveys from 203 parents were completed representing diverse geographic locations. Nearly half (48%) did not recall receiving information about neurocognitive deficits. The most frequently reported time to receive this information was at diagnosis, but parents reported a need for conversations throughout the cancer trajectory, especially at transition to survivorship and school reentry. In addition, half of the parents (51%) felt inadequately prepared for the return to school. Information about neuropsychological testing, resources for learning difficulties, educational terms, and legal rights related to school services were the topics most inadequately provided. CONCLUSIONS: Parents feel inadequately prepared by their oncology team for their child's return to school. Research is needed to identify effective oncology team approaches to fill the gaps in knowledge around school reentry after cancer treatment.

Universal premedication and therapeutic drug monitoring for asparaginase-based therapy prevents infusion-associated acute adverse events and drug substitutions.

BACKGROUND: Asparaginase is a critical component of lymphoblastic leukemia therapy, with intravenous pegaspargase (PEG) as the current standard product. Acute adverse events (aAEs) during PEG infusion are difficult to interpret, representing a mix of drug-inactivating hypersensitivity and noninactivating reactions. Asparaginase Erwinia chrysanthemi (ERW) is approved for PEG hypersensitivity, but is less convenient, more expensive, and yields lower serum asparaginase activity (SAA). We began a policy of universal premedication and SAA testing for PEG, hypothesizing this would reduce aAEs and unnecessary drug substitutions. PROCEDURE: Retrospective chart review of patients receiving asparaginase before and after universal premedication before PEG was conducted, with SAA performed 1 week later. We excluded patients who had nonallergic asparaginase AEs. Primary end point was substitution to ERW. Secondary end points included aAEs, SAA testing, and cost. RESULTS: We substituted to ERW in 21 of 122 (17.2%) patients pre-policy, and 5 of 68 (7.4%) post-policy (RR, 0.427; 95% CI, 0.27-0.69, P = 0.028). All completed doses of PEG yielded excellent SAA (mean, 0.90 units/mL), compared with ERW (mean, 0.15 units/mL). PEG inactivation post-policy was seen in 2 of 68 (2.9%), one silent and one with breakthrough aAE. The rate of aAEs pre/post-policy was 17.2% versus 5.9% (RR, 0.342; 95% CI, 0.20-0.58, P = 0.017). Grade 4 aAE rate pre/post-policy was 15% versus 0%. Cost analysis predicts $125 779 drug savings alone per substitution prevented ($12 402/premedicated patient). CONCLUSIONS: Universal premedication reduced substitutions to ERW and aAE rate. SAA testing demonstrated low rates of silent inactivation, and higher SAA for PEG. A substantial savings was achieved. We propose universal premedication for PEG be standard of care.

Successful Treatment of Recurrent Autoimmune Cytopenias in the Context of Sinus Histiocytosis With Massive Lymphadenopathy Using Sirolimus.

Sinus histiocytosis with massive lymphadenopathy (SHML), or Rosai-Dorfman disease (RDD), is a non-neoplastic, lymphoproliferative disorder that usually resolves spontaneously or with minimal conventional chemotherapy. Rarely, SHML can be associated with autoimmune findings. Such cases are often treatment resistant and have high rates of morbidity and mortality. We present a case of a patient with long-standing autoimmunity in the context of SHML, dependent on standard-treatment until he was transitioned to novel monotherapy with sirolimus. Sirolimus treatment resulted in a complete remission, now sustained after discontinuation of all treatments for over 23 months, with no observable long-term sequelae.

Hemoglobin thresholds for transfusion in pediatric patients at a large academic health center.

BACKGROUND: Although prior studies support the use of a hemoglobin (Hb) transfusion trigger of 7 to 8 g/dL for most hospitalized adults, there are few studies in pediatric populations. We therefore investigated transfusion practices and Hb triggers in hospitalized children. STUDY DESIGN AND METHODS: We performed a historical cohort study comparing transfusion practices in hospitalized children by service within a single academic institution. Blood utilization data from transfused patients (n = 3370) were obtained from electronic records over 4 years. Hb triggers and posttransfusion Hb levels were defined as the lowest and last Hb measured during hospital stay, respectively, in transfused patients. The mean and percentile distribution for Hb triggers were compared to the evidence-based restrictive transfusion threshold of 7 g/dL. RESULTS: Mean Hb triggers were above the restrictive trigger (7 g/dL) for eight of 12 pediatric services. Among all of the services, there were significant differences between the mean Hb triggers (>2.5 g/dL, p<0.0001) and between the posttransfusion Hb levels (>3 g/dL, p < 0.0001). The variation between the 10th and 90th percentiles for triggers (up to 4 g/dL, p < 0.0001) and posttransfusion Hb levels (up to 6 g/dL, p < 0.0001) were significant. Depending on the service, between 25 and 90% of transfused patients had Hb triggers higher than the restrictive range. CONCLUSIONS: Red blood cell (RBC) transfusion therapy varies significantly in hospitalized children with mean Hb triggers above a restrictive threshold for most services. Our findings suggest that transfusions may be overused and that implementing a restrictive transfusion strategy could decrease the use of RBC transfusions, thereby reducing the associated risks and costs.

An examination of nurse practitioner students' perceptions of knowledge, confidence, and experiences related to caring for lesbian, gay, bisexual, transgender, and queer or questioning patients: A national perspective.

BACKGROUND: Lesbian, gay, bisexual, transgender, and queer or questioning (LGBTQ+) individuals are significantly less likely to have a primary health care provider, be uninsured, and postpone medical care. A health care provider's lack of knowledge in LGBTQ+ health needs, low confidence in discussing sexuality, and bias can result in LGBTQ+ patients choosing to delay or avoid seeking care. These are missed opportunities for health care providers to recognize their unique needs, provide education and preventive screenings and care, and manage chronic conditions. PURPOSE: The aim of this study was to examine nurse practitioner students' perceptions of knowledge, confidence, and experiences related to caring for LGBTQ+ patients. METHODOLOGY: Using a descriptive, cross-sectional survey research design, a 29-item online survey was distributed through email to nurse practitioner students (n = 419) across the United States. RESULTS: Overall, nurse practitioners (NP) students demonstrated infrequent questioning related to gender preferences, sexual terms, and clarification of relationships. Results showed that 77.9% of NP students within two terms of graduation had not received any LGBTQ+-specific training. Almost 75% of the NP students reported not routinely asking about sexuality, and 82% reported infrequently or never asking gender identity. Furthermore, 93.1% of respondents reported providers infrequently or never ask about preferred gender or pronouns, and 86% reported providers infrequently inquire about sexual identity in primary care visits. CONCLUSIONS: Study findings demonstrate the uniqueness of managing care for LGBTQ+ patients and importance for more detailed LGBTQ+ health training in curricula in NP programs. IMPLICATIONS: Closing the gap in health care for LGBTQ+ patients is paramount in addressing global health disparities and population care.

Low-risk relapsed acute lymphoblastic leukemia in children and young adults: what have we learnt and what's next?

While outcomes for newly diagnosed children with acute lymphoblastic leukemia (ALL) have improved over the last few decades, 10-15% will relapse. Outcomes for those children with relapse remains a challenge, with 5-year overall survival of approximately 35-60%. Large cooperative group trials have identified factors associated with favorable (low risk, LR) outcome at relapse, including later relapse, B-cell phenotype, isolated extramedullary relapse and a good response to initial re-induction therapy. Contemporary therapeutic regimens are aimed at improving outcomes, while decreasing toxicity. A main focus of current research involves how immunotherapy can be best incorporated with cytotoxic chemotherapy to improve survival in relapsed ALL. Here we review therapeutic strategies for LR relapse, including review of recently completed and ongoing trials.

Bosutinib in Resistant and Intolerant Pediatric Patients With Chronic Phase Chronic Myeloid Leukemia: Results From the Phase I Part of Study ITCC054/COG AAML1921.

PURPOSE: Bosutinib is approved for adults with chronic myeloid leukemia (CML): 400 mg once daily in newly diagnosed (ND); 500 mg once daily in resistant/intolerant (R/I) patients. Bosutinib has a different tolerability profile than other tyrosine kinase inhibitors (TKIs) and potentially less impact on growth (preclinical data). The primary objective of this first-in-child trial was to determine the recommended phase II dose (RP2D) for pediatric R/I and ND patients. PATIENTS AND METHODS: In the phase I part of this international, open-label trial (ClinicalTrials.gov identifier: NCT04258943), children age 1-18 years with R/I (per European LeukemiaNet 2013) Ph+ CML were enrolled using a 6 + 4 design, testing 300, 350, and 400 mg/m2 once daily with food. The RP2D was the dose resulting in 0/6 or 1/10 dose-limiting toxicities (DLTs) during the first cycle and achieving adult target AUC levels for the respective indication. As ND participants were only enrolled in phase II, the ND RP2D was selected based on data from R/I patients. RESULTS: Thirty patients were enrolled; 27 were evaluable for DLT: six at 300 mg/m2, 11 at 350 mg/m2 (one DLT), and 10 at 400 mg/m2 (one DLT). The mean AUCs at 300 mg/m2, 350 mg/m2, and 400 mg/m2 were 2.20 µg h/mL, 2.52 µg h/mL, and 2.66 µg h/mL, respectively. The most common adverse event was diarrhea (93%; ≥grade 3: 11%). Seven patients stopped because of intolerance and eight because of insufficient response. Complete cytogenetic and major molecular response to bosutinib appeared comparable with other published phase I/II trials with second-generation TKIs in children. CONCLUSION: Bosutinib was safe and effective. The pediatric RP2D was 400 mg/m2 once daily (max 600 mg/d) with food in R/I patients and 300 mg/m2 once daily (max 500 mg/d) with food in ND patients, which achieved targeted exposures as per adult experience.

SOHO State of the Art Updates and Next Questions | Optimal Timing of Blinatumomab for the Treatment of B-Acute Lymphoblastic Leukemia.

Blinatumomab is a CD19 targeting bi-specific T-cell engager antibody construct developed for the treatment of CD19 expressing B-cell malignancies. Numerous adult and pediatric B-ALL clinical trials have demonstrated blinatumomab's efficacy in the relapse setting as well as in patients with residual disease after upfront chemotherapy. The safety profile of blinatumomab is also favorable, making it a feasible option for most patients. Several key questions remain, including the role of blinatumomab as a replacement for toxic elements of standard chemotherapy regimens in the upfront setting, its role as a bridge to hematopoietic stem cell transplantation, or whether previous blinatumomab impacts the efficacy of subsequent CAR-T cell therapy.

Bronchiolitis Simulation Module in the Pediatric Preclerkship Educational Exercises (PRECEDE) Curriculum.

Introduction: Acute bronchiolitis is a viral infection infecting 90% of children under the age of 2 years, with approximately 200,000 deaths per year. The current standard of care remains largely respiratory support and prevention. Therefore, understanding how to assess and escalate respiratory supportive care is paramount for health care providers taking care of children. Methods: We used a high-fidelity simulator to simulate an infant with progressing respiratory distress in the setting of acute bronchiolitis. The participants were pediatric clerkship medical students during their preclerkship educational exercises (PRECEDE). The students were asked to evaluate and treat the simulated patient. After debriefing, the students repeated the simulation. We assessed both performances via a weighted checklist specifically developed for this case to measure team performance. Students also completed an overall course evaluation. Results: Ninety out of 121 pediatric clerkship students were enrolled. Performance improved from 57% to 86% ( p < .05). Donning appropriate personal protection equipment was the most missed item both pre- and postdebriefing. Overall, the course was well liked and received. Participants requested more simulation opportunities within PRECEDE as well as a summary document to reinforce learning. Discussion: Pediatric clerkship students improved their performance managing progressing respiratory distress due to acute bronchiolitis via a performance-based assessment tool with sound validity evidence. Improvements going forward include improving faculty diversity and offering more simulation opportunities.

Tisagenlecleucel utilisation and outcomes across refractory, first relapse and multiply relapsed B-cell acute lymphoblastic leukemia: a retrospective analysis of real-world patterns.

Background: Tisagenlecleucel was approved by the Food and Drug Administration (FDA) in 2017 for refractory B-cell acute lymphoblastic leukemia (B-ALL) and B-ALL in ≥2nd relapse. Outcomes of patients receiving commercial tisagenlecleucel upon 1st relapse have yet to be established. We aimed to report real-world tisagenlecleucel utilisation patterns and outcomes across indications, specifically including patients treated in 1st relapse, an indication omitted from formal FDA approval. Methods: We conducted a retrospective analysis of real-world tisagenlecleucel utilisation patterns across 185 children and young adults treated between August 30, 2017 and March 6, 2020 from centres participating in the Pediatric Real-World CAR Consortium (PRWCC), within the United States. We described definitions of refractory B-ALL used in the real-world setting and categorised patients by reported Chimeric Antigen Receptor (CAR) T-cell indication, including refractory, 1st relapse and ≥2nd relapse B-ALL. We analysed baseline patient characteristics and post-tisagenlecleucel outcomes across defined cohorts. Findings: Thirty-six percent (n = 67) of our cohort received tisagenlecleucel following 1st relapse. Of 66 evaluable patients, 56 (85%, 95% CI 74-92%) achieved morphologic complete response. Overall-survival (OS) and event-free survival (EFS) at 1-year were 69%, (95% CI 58-82%) and 49%, (95% CI 37-64%), respectively, with survival outcomes statistically comparable to remaining patients (OS; p = 0.14, EFS; p = 0.39). Notably, toxicity was increased in this cohort, warranting further study. Interestingly, of 30 patients treated for upfront refractory disease, 23 (77%, 95% CI 58-90%) had flow cytometry and/or next-generation sequencing (NGS) minimum residual disease (MRD)-only disease at the end of induction, not meeting the historic morphologic definition of refractory. Interpretation: Our findings suggested that tisagenlecleucel response and survival rates overlap across patients treated with upfront refractory B-ALL, B-ALL ≥2nd relapse and B-ALL in 1st relapse. We additionally highlighted that definitions of refractory B-ALL are evolving beyond morphologic measures of residual disease. Funding: St. Baldrick's/Stand Up 2 Cancer, Parker Institute for Cancer Immunotherapy, Virginia and D.K. Ludwig Fund for Cancer Research.

Integration of Genomic Sequencing Drives Therapeutic Targeting of PDGFRA in T-Cell Acute Lymphoblastic Leukemia/Lymphoblastic Lymphoma.

PURPOSE: Patients with relapsed or refractory T-cell acute lymphoblastic leukemia (T-ALL) or lymphoblastic lymphoma (T-LBL) have limited therapeutic options. Clinical use of genomic profiling provides an opportunity to identify targetable alterations to inform therapy. EXPERIMENTAL DESIGN: We describe a cohort of 14 pediatric patients with relapsed or refractory T-ALL enrolled on the Leukemia Precision-based Therapy (LEAP) Consortium trial (NCT02670525) and a patient with T-LBL, discovering alterations in platelet-derived growth factor receptor-α (PDGFRA) in 3 of these patients. We identified a novel mutation in PDGFRA, p.D842N, and used an integrated structural modeling and molecular biology approach to characterize mutations at D842 to guide therapeutic targeting. We conducted a preclinical study of avapritinib in a mouse patient-derived xenograft (PDX) model of FIP1L1-PDGFRA and PDGFRA p.D842N leukemia. RESULTS: Two patients with T-ALL in the LEAP cohort (14%) had targetable genomic alterations affecting PDGFRA, a FIP1-like 1 protein/PDGFRA (FIP1L1-PDGFRA) fusion and a novel mutation in PDGFRA, p.D842N. The D842N mutation resulted in PDGFRA activation and sensitivity to tested PDGFRA inhibitors. In a T-ALL PDX model, avapritinib treatment led to decreased leukemia burden, significantly prolonged survival, and even cured a subset of mice. Avapritinib treatment was well tolerated and yielded clinical benefit in a patient with refractory T-ALL. CONCLUSIONS: Refractory T-ALL has not been fully characterized. Alterations in PDGFRA or other targetable kinases may inform therapy for patients with refractory T-ALL who otherwise have limited treatment options. Clinical genomic profiling, in real time, is needed for fully informed therapeutic decision making.