A systematic literature review of clinical evidence and treatment burden in newly diagnosed high-risk pediatric patients with classical Hodgkin lymphoma.

This systematic literature review evaluated frontline treatment burden in pediatric and adolescent/young adult (AYA) patients with high-risk classical Hodgkin lymphoma (cHL) among studies originating from the United States. Data were extracted from 32 publications (screened: total, n = 3115; full-text, n = 98) representing 12 studies (randomized controlled trials [RCTs], n = 2; non-comparative, non-randomized, n = 7; observational, n = 3). High-risk disease definitions varied across studies. Five-year event-free survival (EFS)/progression-free survival (PFS) was 86%-100% and 79%-94%, and complete response rates were 35%-100% and 5%-64% for brentuximab vedotin (BV)-containing and chemotherapy-alone regimens, respectively. In identified RCTs, BV-containing compared with chemotherapy-alone regimens demonstrated significantly longer 3-year EFS/5-year PFS. Hematological and peripheral neuropathy were the most commonly reported adverse events of interest, although safety data were inconsistently reported. Few studies evaluated humanistic and no studies evaluated economic burden. Results from studies with the highest quality of evidence indicate an EFS/PFS benefit for frontline BV-containing versus chemotherapy-alone regimens for pediatric/AYA patients with high-risk cHL.

Automatic Quantification of Serial PET/CT Images for Pediatric Hodgkin Lymphoma Patients Using a Longitudinally-Aware Segmentation Network.

Purpose: Automatic quantification of longitudinal changes in PET scans for lymphoma patients has proven challenging, as residual disease in interim-therapy scans is often subtle and difficult to detect. Our goal was to develop a longitudinally-aware segmentation network (LAS-Net) that can quantify serial PET/CT images for pediatric Hodgkin lymphoma patients. Materials and Methods: This retrospective study included baseline (PET1) and interim (PET2) PET/CT images from 297 patients enrolled in two Children's Oncology Group clinical trials (AHOD1331 and AHOD0831). LAS-Net incorporates longitudinal cross-attention, allowing relevant features from PET1 to inform the analysis of PET2. Model performance was evaluated using Dice coefficients for PET1 and detection F1 scores for PET2. Additionally, we extracted and compared quantitative PET metrics, including metabolic tumor volume (MTV) and total lesion glycolysis (TLG) in PET1, as well as qPET and ΔSUVmax in PET2, against physician measurements. We quantified their agreement using Spearman's ρ correlations and employed bootstrap resampling for statistical analysis. Results: LAS-Net detected residual lymphoma in PET2 with an F1 score of 0.606 (precision/recall: 0.615/0.600), outperforming all comparator methods (P<0.01). For baseline segmentation, LAS-Net achieved a mean Dice score of 0.772. In PET quantification, LAS-Net's measurements of qPET, ΔSUVmax, MTV and TLG were strongly correlated with physician measurements, with Spearman's ρ of 0.78, 0.80, 0.93 and 0.96, respectively. The performance remained high, with a slight decrease, in an external testing cohort. Conclusion: LAS-Net achieved high performance in quantifying PET metrics across serial scans, highlighting the value of longitudinal awareness in evaluating multi-time-point imaging datasets.

Accelerating pediatric Hodgkin lymphoma research: the Hodgkin Lymphoma Data Collaboration (NODAL).

Data commons have proven to be an indispensable avenue for advancing pediatric cancer research by serving as unified information technology platforms that, when coupled with data standards, facilitate data sharing. The Pediatric Cancer Data Commons, the flagship project of Data for the Common Good (D4CG), collaborates with disease-based consortia to facilitate development of clinical data standards, harmonization and pooling of clinical data from disparate sources, establishment of governance structure, and sharing of clinical data. In the interest of international collaboration, researchers developed the Hodgkin Lymphoma Data Collaboration and forged a relationship with the Pediatric Cancer Data Commons to establish a data commons for pediatric Hodgkin lymphoma. Herein, we describe the progress made in the formation of Hodgkin Lymphoma Data Collaboration and foundational goals to advance pediatric Hodgkin lymphoma research.

Late Cardiac Toxic Effects Associated With Treatment Protocols for Hodgkin Lymphoma in Children.

Importance: Contemporary North American trials for children with Hodgkin lymphoma (HL) have decreased radiation therapy (RT) use and increased pharmacologic cardioprotection but also increased the cumulative doxorubicin dose, making overall treatment consequences for late cardiac toxic effects uncertain. Objective: To estimate the risk of cardiac toxic effects associated with treatments used in modern pediatric HL clinical trials. Design, Setting, and Participants: For this cohort study, Fine and Gray models were fitted using survivors in the Childhood Cancer Survivor Study who were diagnosed with HL between January 1, 1970, and December 31, 1999, and were followed for a median of 23.5 (range, 5.0-46.3) years. These models were applied to the exposures in the study population to estimate the 30-year cumulative incidence of cardiac disease. The study population comprised patients with intermediate-risk or high-risk HL treated in 4 consecutive Children's Oncology Group clinical trials from September 2002 to October 2022: AHOD0031, AHOD0831, AHOD1331, and S1826. Data analysis was performed from April 2020 to February 2023. Exposures: All patients received chemotherapy including doxorubicin, and some patients received mediastinal RT, dexrazoxane, or mediastinal RT and dexrazoxane. Main Outcomes and Measures: Estimated 30-year cumulative incidence of grade 3 to 5 cardiac disease. Results: The study cohort comprised 2563 patients, with a median age at diagnosis of 15 (range, 1-22) years. More than half of the patients were male (1357 [52.9%]). All 2563 patients received doxorubicin, 1362 patients (53.1%) received mediastinal RT, and 307 patients (12.0%) received dexrazoxane. Radiation therapy use and the median mean heart dose among patients receiving RT decreased, whereas the planned cumulative dose of doxorubicin and use of dexrazoxane cardioprotection increased. For patients treated at age 15 years, the estimated 30-year cumulative incidence of severe or fatal cardiac disease was 9.6% (95% CI, 4.2%-16.4%) in the AHOD0031 standard treatment group (enrolled 2002-2009), 8.6% (95% CI, 3.8%-14.9%) in the AHOD0831 trial (enrolled 2009-2012), 8.2% (95% CI, 3.6%-14.3%) in the AHOD1331 trial (enrolled 2015-2019), and 6.2% (95% CI, 2.7%-10.9%) in the S1826 trial (enrolled 2019-2022), whereas the expected rate in an untreated population was 5.0% (95% CI, 2.1%-9.3%). Despite the estimated reduction in late cardiac morbidity, the frequency of recommended echocardiographic screening among survivors will increase based on current guidelines. Conclusions and Relevance: In this cohort study of sequential HL trials, reductions in the proportion of children receiving mediastinal RT and increases in dexrazoxane use were estimated to offset the increased doxorubicin dose and produce a net reduction in late cardiac disease. Further studies on dexrazoxane are warranted to confirm whether its role in reducing cardiac toxic effects is maintained long term. These findings suggest that survivorship follow-up guidelines should be refined to align with the risks associated with treatment.

Distinct Hodgkin lymphoma subtypes defined by noninvasive genomic profiling.

The scarcity of malignant Hodgkin and Reed-Sternberg cells hampers tissue-based comprehensive genomic profiling of classic Hodgkin lymphoma (cHL). By contrast, liquid biopsies show promise for molecular profiling of cHL due to relatively high circulating tumour DNA (ctDNA) levels1-4. Here we show that the plasma representation of mutations exceeds the bulk tumour representation in most cases, making cHL particularly amenable to noninvasive profiling. Leveraging single-cell transcriptional profiles of cHL tumours, we demonstrate Hodgkin and Reed-Sternberg ctDNA shedding to be shaped by DNASE1L3, whose increased tumour microenvironment-derived expression drives high ctDNA concentrations. Using this insight, we comprehensively profile 366 patients, revealing two distinct cHL genomic subtypes with characteristic clinical and prognostic correlates, as well as distinct transcriptional and immunological profiles. Furthermore, we identify a novel class of truncating IL4R mutations that are dependent on IL-13 signalling and therapeutically targetable with IL-4Rα-blocking antibodies. Finally, using PhasED-seq5, we demonstrate the clinical value of pretreatment and on-treatment ctDNA levels for longitudinally refining cHL risk prediction and for detection of radiographically occult minimal residual disease. Collectively, these results support the utility of noninvasive strategies for genotyping and dynamic monitoring of cHL, as well as capturing molecularly distinct subtypes with diagnostic, prognostic and therapeutic potential.

Missing the mark? Exploratory analysis of the 10-year-old cutoff as an independent marker of high-risk disease in pediatric B-ALL.

This single-center, retrospective study evaluated age as a risk factor for relapsed/refractory disease and/or death in 153 children with B-cell acute lymphoblastic leukemia. The study sample included children near the 10-year age cutoff for high-risk disease (6.0-13.9 years at diagnosis) and without other high-risk features (high white cell count, unfavorable cytogenetics). Children 10.0-13.9 years treated per high-risk protocols did not have inferior outcomes compared with children aged 6.0-9.9 years initiating treatment per standard-risk protocols. The study indicates that, in the era of cytogenetics, an age threshold of 10 years might not be an independent prognostic marker. Multicenter analyses are needed.

Utilization of cardiac tests in anthracycline-treated cancer survivors differs between young adults and children: A claims-based analysis.

BACKGROUND: The Children's Oncology Group Guidelines recommend a cardiacechocardiogram, or comparable functional imaging, following therapy completion in survivors of childhood/adolescent cancers exposed to anthracyclines. METHODS: Using the 2009-2019 Merative™ MarketScan® Commercial Database, we examined real-world utilization of cardiac testing among 1609 anthracycline-treated survivors of childhood/adolescent cancers. RESULTS: The cumulative incidence of receiving an initial cardiac test by 5.25 years from the index date (six months after end-of-therapy) was 62.3% (95% CI = 57.5%-66.7%), with median time to initial test being 2.7 years (95% CI = 2.5%-3.1%). Young adults (18-28 years) were less likely than children (≤17 years) to receive cardiac testing (hazard ratio [HR] = 0.42, 95% CI = 0.3%-0.49%). More likely to receive cardiac testing were survivors receiving hematopoietic stem cell transplantation versus chemotherapy only (HR = 2.23, 95% CI = 1.63%-3.03%), and survivors with bone or soft tissue versus hematologic cancer (HR = 1.64, 95% CI = 1.30%-2.07%). CONCLUSIONS: Nearly 40% of anthracycline-treated survivors of childhood/adolescent cancers had not received cardiac testing within 5.25 years post-index date, with young adults least likely to receive a test.

Performance of the FACT-GOG-Ntx to assess chemotherapy-induced peripheral neuropathy (CIPN) in pediatric high risk Hodgkin lymphoma: report from the Children's Oncology Group AHOD 1331 study.

BACKGROUND: Chemotherapy-induced peripheral neuropathy (CIPN) is an under-recognized complication of several chemotherapy agents used as part of curative-intent therapy for Hodgkin Lymphoma (HL). In the absence of validated self- or proxy-report measures for children and adolescents, CIPN reporting has relied on clinician rating, with grading scales often restricted to severe manifestations. In a proof-of-concept study, we assessed the feasibility and psychometric performance of the Functional Assessment of Cancer Therapy-Gynecologic Oncology Group-Neurotoxicity (FACT-GOG-Ntx), a unidimensional CIPN symptom scale widely used adults with CIPN, in pediatric HL at risk for CIPN. METHODS: Youth (11+ years) and parents of all children (5-17.9 years) with newly diagnosed high-risk HL enrolled on Children's Oncology Group AHOD1331 (NCT02166463) were invited to complete the FACT-GOG-Ntx and a health-related quality of life (HRQL) measure at pre-treatment (Time 1), and during cycles 2 (Time 2) and 5 (Time 3) of chemotherapy during the first half of study accrual. Clinical grading of CIPN by providers was also assessed using the Balis Pediatric Neuropathy Scale. We evaluated Cronbach's alpha, construct validity, and agreement between raters. Change in FACT-GOG-Ntx scores over time was assessed using a repeated measures model. RESULTS: 306 patients had at least one completed FACT-GOG-Ntx with time-specific completion rates of > 90% for both raters. Cronbach's alpha was > 0.7 for youth and parent-proxy report at all time points. Correlations between FACT-GOG-Ntx and HRQL scores were moderate (0.41-0.48) for youth and parent-proxy raters across all times. Youth and parent-proxy raters both reported worse FACT-GOG-Ntx scores at Time 3 for those who had clinically-reported CIPN compared to those who did not. Agreement between raters was moderate to high. Compared to baseline scores, those at Time 3 were significantly lower for youth (ß = - 2.83, p < 0.001) and parent-proxy raters (ß = - 1.99, p < 0.001). CONCLUSIONS: High completion rates at all time points indicated feasibility of eliciting youth and parent report. Psychometric performance of the FACT-GOG-Ntx revealed acceptable reliability, evidence of validity, and strong inter-rater agreement, supporting the use of this self- or proxy-reported measure of CIPN in youth with high-risk HL exposed to tubulin inhibitors, as part of a Phase 3 clinical trial. CLINICAL TRIAL INFORMATION: Clinical Trials Registry, NCT02166463. Registered 18 June 2014, https://clinicaltrials.gov/ct2/show/study/NCT02166463.

Single-cell RNA sequencing distinctly characterizes the wide heterogeneity in pediatric mixed phenotype acute leukemia.

BACKGROUND: Mixed phenotype acute leukemia (MPAL), a rare subgroup of leukemia characterized by blast cells with myeloid and lymphoid lineage features, is difficult to diagnose and treat. A better characterization of MPAL is essential to understand the subtype heterogeneity and how it compares with acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). Therefore, we performed single-cell RNA sequencing (scRNAseq) on pediatric MPAL bone marrow (BM) samples to develop a granular map of the MPAL blasts and microenvironment landscape. METHODS: We analyzed over 40,000 cells from nine pediatric MPAL BM samples to generate a single-cell transcriptomic landscape of B/myeloid (B/My) and T/myeloid (T/My) MPAL. Cells were clustered using unsupervised single-cell methods, and malignant blast and immune clusters were annotated. Differential expression analysis was performed to identify B/My and T/My MPAL blast-specific signatures by comparing transcriptome profiles of MPAL with normal BM, AML, and ALL. Gene set enrichment analysis (GSEA) was performed, and significantly enriched pathways were compared in MPAL subtypes. RESULTS: B/My and T/My MPAL blasts displayed distinct blast signatures. Transcriptomic analysis revealed that B/My MPAL profile overlaps with B-ALL and AML samples. Similarly, T/My MPAL exhibited overlap with T-ALL and AML samples. Genes overexpressed in both MPAL subtypes' blast cells compared to AML, ALL, and healthy BM included MAP2K2 and CD81. Subtype-specific genes included HBEGF for B/My and PTEN for T/My. These marker sets segregated bulk RNA-seq AML, ALL, and MPAL samples based on expression profiles. Analysis comparing T/My MPAL to ETP, near-ETP, and non-ETP T-ALL, showed that T/My MPAL had greater overlap with ETP-ALL cases. Comparisons among MPAL subtypes between adult and pediatric samples showed analogous transcriptomic landscapes of corresponding subtypes. Transcriptomic differences were observed in the MPAL samples based on response to induction chemotherapy, including selective upregulation of the IL-16 pathway in relapsed samples. CONCLUSIONS: We have for the first time described the single-cell transcriptomic landscape of pediatric MPAL and demonstrated that B/My and T/My MPAL have distinct scRNAseq profiles from each other, AML, and ALL. Differences in transcriptomic profiles were seen based on response to therapy, but larger studies will be needed to validate these findings.

Single-cell analysis reveals altered tumor microenvironments of relapse- and remission-associated pediatric acute myeloid leukemia.

Acute myeloid leukemia (AML) microenvironment exhibits cellular and molecular differences among various subtypes. Here, we utilize single-cell RNA sequencing (scRNA-seq) to analyze pediatric AML bone marrow (BM) samples from diagnosis (Dx), end of induction (EOI), and relapse timepoints. Analysis of Dx, EOI scRNA-seq, and TARGET AML RNA-seq datasets reveals an AML blasts-associated 7-gene signature (CLEC11A, PRAME, AZU1, NREP, ARMH1, C1QBP, TRH), which we validate on independent datasets. The analysis reveals distinct clusters of Dx relapse- and continuous complete remission (CCR)-associated AML-blasts with differential expression of genes associated with survival. At Dx, relapse-associated samples have more exhausted T cells while CCR-associated samples have more inflammatory M1 macrophages. Post-therapy EOI residual blasts overexpress fatty acid oxidation, tumor growth, and stemness genes. Also, a post-therapy T-cell cluster associated with relapse samples exhibits downregulation of MHC Class I and T-cell regulatory genes. Altogether, this study deeply characterizes pediatric AML relapse- and CCR-associated samples to provide insights into the BM microenvironment landscape.

Medicaid expansion is associated with treatment receipt, timeliness, and outcomes among young adults with breast cancer.

Female breast cancer is a common cancer in young adults, an age group with the highest uninsured rate. Among 51 675 young adult women (ages 18-39 years) diagnosed with breast cancer between 2011 and 2018 in the National Cancer Database, we estimated changes in guideline-concordant treatment receipt, treatment timeliness, and survival associated with the Affordable Care Act Medicaid expansion. Of young adults with stage I-III estrogen receptor-positive or progesterone receptor-positive breast cancer, Medicaid expansion was associated with a net increase of 2.42 percentage points (95% confidence interval [CI] = 0.56 to 4.28 percentage points) in the percentage receiving endocrine therapy. Among all young adults with stage I-III breast cancer, Medicaid expansion was associated with a net reduction of 1.65 percentage points (95% CI = 0.08 to 3.22 percentage points) in treatment delays defined as treatment initiation of at least 60 days after diagnosis and a net increase of 1.00 percentage points (95% CI = 0.21 to 1.79 percentage points) in 2-year overall survival. Our study provides evidence of benefit in cancer care and outcomes from Medicaid expansion among the young adult population.

Pediatric T-cell acute lymphoblastic leukemia blast signature and MRD associated immune environment changes defined by single cell transcriptomics analysis.

Different driver mutations and/or chromosomal aberrations and dysregulated signaling interactions between leukemia cells and the immune microenvironment have been implicated in the development of T-cell acute lymphoblastic leukemia (T-ALL). To better understand changes in the bone marrow microenvironment and signaling pathways in pediatric T-ALL, bone marrows collected at diagnosis (Dx) and end of induction therapy (EOI) from 11 patients at a single center were profiled by single cell transcriptomics (10 Dx, 5 paired EOI, 1 relapse). T-ALL blasts were identified by comparison with healthy bone marrow cells. T-ALL blast-associated gene signature included SOX4, STMN1, JUN, HES4, CDK6, ARMH1 among the most significantly overexpressed genes, some of which are associated with poor prognosis in children with T-ALL. Transcriptome profiles of the blast cells exhibited significant inter-patient heterogeneity. Post induction therapy expression profiles of the immune cells revealed significant changes. Residual blast cells in MRD+ EOI samples exhibited significant upregulation (P < 0.01) of PD-1 and RhoGDI signaling pathways. Differences in cellular communication were noted in the presence of residual disease in T cell and hematopoietic stem cell compartments in the bone marrow. Together, these studies generate new insights and expand our understanding of the bone marrow landscape in pediatric T-ALL.

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.

Children's Oncology Group's 2023 blueprint for research: Hodgkin lymphoma.

The goal of therapy in pediatric Hodgkin lymphoma (HL) is to maximize overall survival while minimizing the morbidity of curative therapy. Key findings from recent Children's Oncology Group (COG) trials include: (i) superior event-free survival with the addition of brentuximab vedotin (Bv) in frontline regimens for high-risk disease, (ii) successful reduction in myeloablative regimens with demonstrated safety and efficacy of Bv and checkpoint inhibitor therapy in relapsed disease, and (ii) the potential to select a population that can be salvaged after relapse without receiving a stem cell transplant. The COG HL committee will lead a National cancer Institute National Clinical Trials Network phase 3 trial to evaluate the combination of Bv/nivolumab in early-stage disease. Ongoing advances in technology and blood biomarkers are increasing the ability to deliver biologically driven, personalized treatment for HL.

Liver Late Effects in Childhood Cancer Survivors Treated With Radiation Therapy: A PENTEC Comprehensive Review.

PURPOSE: A pediatric normal tissue effects in the clinic (PENTEC) comprehensive review of patients with childhood cancer who received radiation therapy (RT) to the liver was performed to develop models that may inform RT dose constraints for the liver and improve risk forecasting of toxicities. METHODS AND MATERIALS: A systematic literature search was performed to identify published data on hepatic toxicities in children. Treatment and outcome data were extracted and used to generate normal tissue complication probability (NTCP) models. Complications from both whole and partial liver irradiation were considered. For whole liver irradiation, total body irradiation and non-total body irradiation treatments were considered, but it was assumed that the entire liver received the prescribed dose. For partial liver irradiation, only Wilms tumor flank field RT could be analyzed. However, a prescribed dose assumption could not be applied, and there was a paucity of analyzable liver dosimetry data. To associate the dose-volume exposures with the partial volume complication data from flank irradiation, liver dose-volume metrics were reconstructed for Wilms tumor flank RT using age-specific computational phantoms as a function of field laterality and superior extent of the field. RESULTS: The literature search identified 2103 investigations pertaining to hepatic sinusoidal obstructive syndrome (SOS) and liver failure in pediatric patients. All abstracts were screened, and 241 articles were reviewed in full by the study team. A model was developed to calculate the risk of developing SOS after whole liver RT. RT dose (P = .006) and receipt of nonalkylating chemotherapy (P = .01) were significant. Age <20 years at time of RT was borderline significant (P = .058). The model predicted a 2% risk of SOS with zero RT dose, 6.1% following 10 Gy, and 14.5% following 20 Gy to the whole liver (modeled as the linear-quadratic equivalent dose in 2-Gy fractions [α/ß = 3 Gy]). Patients with Wilms tumor treated with right flank RT had a higher observed rate of SOS than patients receiving left flank RT, but data were insufficient to generate an NTCP model for partial liver irradiation. From the phantom-based dose reconstructions, mean liver dose was estimated to be 2.16 ± 1.15 Gy and 6.54 ± 2.50 Gy for left and right flank RT, respectively, using T10-T11 as the superior field border and a prescription dose of 10.8 Gy (based on dose reconstruction). Data were sparse regarding rates of late liver injury after RT, which suggests low rates of severe toxicity after treatment for common pediatric malignancies. CONCLUSIONS: This pediatric normal tissue effects in the clinic (PENTEC) review provides an NTCP model to estimate the risk of hepatic SOS as a function of RT dose following whole liver RT and quantifies the range of mean liver doses from typical Wilms tumor flank irradiation fields. Patients treated with right flank RT had higher rates of SOS than patients treated with left flank RT, but data were insufficient to develop a model for partial liver irradiation. Risk of SOS was estimated to be approximately ≤6% in pediatric patients receiving whole liver doses of <10 Gy.

Siglec-15 Promotes Evasion of Adaptive Immunity in B-cell Acute Lymphoblastic Leukemia.

Siglec-15 (Sig15) has been implicated as an immune checkpoint expressed in solid tumor-infiltrating macrophages and is being targeted in clinical trials with mAbs to normalize the tumor immune microenvironment and stimulate antitumor immunity. However, the role of Sig15 in hematologic malignancies remains undefined. Sig15 mRNA and protein expression levels in hematologic malignancies were determined from publicly available databases, cell lines, and primary patient samples. Human B-cell acute lymphoblastic leukemia (B-ALL) cell lines were used to identify signaling pathways involved in the regulation of Sig15 expression. Secreted/soluble Sig15 and cytokine levels were measured from the plasma of children with leukemia and healthy controls. Knockdown and knockout of Siglec15 in a murine model of B-ALL was used to evaluate the effect of leukemia-derived Sig15 on the immune response to leukemia. We observed pathologic overexpression of Sig15 in a variety of hematologic malignancies, including primary B-ALL samples. This overexpression was driven by NFκB activation, which also increased the surface localization of Sig15. Secreted/soluble Sig15 was found to circulate at elevated levels in the plasma of children with B-ALL and correlated with an immune-suppressive cytokine milieu. Genetic inhibition of Sig15 in murine B-ALL promoted clearance of the leukemia by the immune system and a marked reversal of the immune-privileged leukemia bone marrow niche, including expanded early effector CD8+ T cells and reduction of immunosuppressive cytokines. Thus, Sig15 is a novel, potent immunosuppressive molecule active in leukemia that may be targeted therapeutically to activate T lymphocytes against leukemia cells. Significance: We demonstrate that Sig15 is overexpressed in hematologic malignancies driven by NFκB, is required for immune evasion in a mouse model of leukemia, and, for the first time, that it circulates at high levels in the plasma of children with leukemia.

Importance of Central Imaging Review in a Pediatric Hodgkin Lymphoma Trial Using Positron Emission Tomography Response Adapted Radiation Therapy.

PURPOSE: We investigated the effects of central review of the interim fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) scan response (iPET) assessment on treatment allocation in the risk-based, response-adapted, Children's Oncology Group study AHOD1331 (ClinicalTrials.gov identifier: NCT02166463) for pediatric patients with high-risk Hodgkin lymphoma. METHODS AND MATERIALS: Per protocol, after 2 cycles of systemic therapy, patients underwent iPET, with visual response assessment by 5-point Deauville score (DS) at their treating institution and a real-time central review, with the latter considered the reference standard. An area of disease with a DS of 1 to 3 was considered a rapid-responding lesion, whereas a DS of 4 to 5 was considered a slow-responding lesion (SRL). Patients with 1 or more SRLs were considered iPET positive, whereas patients with only rapid-responding lesions were considered iPET negative. We conducted a predefined exploratory evaluation of concordance in iPET response assessment between institutional and central reviews of 573 patients. The concordance rate was evaluated using the Cohen κ statistic (κ > 0.80 was considered very good agreement and κ > 0.60-0.80, good agreement). RESULTS: The concordance rate (514 of 573 [89.7%]) had a κ of 0.685 (95% CI, 0.610-0.759), consistent with good agreement. In terms of the direction of discordance, among the 126 patients who were considered iPET positive by institutional review, 38 (30.2%) were categorized as iPET negative by central review, preventing overtreatment with radiation therapy. Conversely, among the 447 patients who were considered iPET negative by institutional review, 21 patients (4.7%) were categorized as iPET positive by the central review and would have been undertreated without radiation therapy. CONCLUSIONS: Central review is integral to PET response-adapted clinical trials for children with Hodgkin lymphoma. Continued support of central imaging review and education about DS are needed.

Survival in Young Adults With Cancer Is Associated With Medicaid Expansion Through the Affordable Care Act.

PURPOSE: Medicaid expansion through the Affordable Care Act (ACA) has been shown to improve insurance coverage and early diagnosis of cancer in young adults (YAs); whether these improvements translate to survival benefits remains unknown. We examined the association between Medicaid expansion under the ACA and 2-year overall survival among YAs with cancer. METHODS: Using the National Cancer Database, we identified 345,413 YAs (age 18-39 years) diagnosed with cancer in 2010-2017. We applied the difference-in-differences (DD) method to estimate changes in 2-year overall survival after versus before Medicaid expansion in expansion versus nonexpansion states. RESULTS: Among all YAs, 2-year overall survival increased more in expansion states (90.39% pre-expansion to 91.85% postexpansion) than in nonexpansion states (88.98% pre-expansion to 90.07% postexpansion), resulting in a net increase of 0.55 percentage points (ppt; 95% CI, 0.13 to 0.96). The expansion-associated survival benefit was concentrated in patients with female breast cancer (DD, 1.20 ppt; 95%CI, 0.27 to 2.12) when stratifying by cancer type and in patients with stage IV disease (DD, 2.56; 95%CI, 0.36 to 4.77) when stratifying by stage. In addition, greater survival benefit associated with Medicaid expansion was observed among racial and ethnic minoritized groups (DD, 1.01 ppt; 95% CI, 0.14 to 1.87) as compared with non-Hispanic White peers (DD, 0.41 ppt; 95% CI, -0.06 to 0.87) and among patients with a Charlson comorbidity score of ≥ 2 (DD, 6.48 ppt; 95% CI, 0.81 to 12.16) than those with a comorbidity score of 0 (DD, 0.44 ppt; 95% CI, 0.005 to 0.87). CONCLUSION: Medicaid expansion under the ACA was associated with an improvement in overall survival among YAs with cancer, with survival benefits most pronounced among patients of under-represented race and ethnicity and patients with high-risk diseases.