Pembrolizumab for advanced urothelial carcinoma: exploratory ctDNA biomarker analyses of the KEYNOTE-361 phase 3 trial.

Circulating tumor DNA (ctDNA) is emerging as a potential biomarker in early-stage urothelial cancer but its utility in metastatic disease remains unknown. In the phase 3 KEYNOTE-361 study, pembrolizumab with and without chemotherapy was compared with chemotherapy alone in patients with metastatic urothelial cancer. The study did not meet prespecified efficacy thresholds for statistical significance. To identify potential biomarkers of response, we retrospectively evaluated association of pre- and post-treatment ctDNA with clinical outcomes in a subset of patients who received pembrolizumab (n = 130) or chemotherapy (n = 130) in KEYNOTE-361. Baseline ctDNA were associated with best overall response (BOR;P = 0.009), progression-free survival (PFS;P < 0.001), and overall survival (OS;P < 0.001) for pembrolizumab, but not chemotherapy (all, P > 0.05). Chemotherapy induced larger ctDNA decreases from baseline to treatment cycle 2 than pembrolizumab; however, change with pembrolizumab (n = 87) were more associated with BOR (P = 4.39 × 10-5) and OS (P = 7.07 × 10-5) versus chemotherapy (n = 102; BOR: P = 1.01 × 10-4; OS: P = 0.018). Tumor tissue-informed versions of ctDNA change metrics were most associated with clinical outcomes but did not show statistically significant independent value for explaining OS beyond radiographic change by RECIST v1.1 when jointly modeled (pembrolizumab P = 0.364; chemotherapy P = 0.823). These results suggest distinct patterns in early ctDNA changes with immunotherapy and chemotherapy and differences in their association with long-term outcomes, which provide preliminary insights on the utility of liquid biopsies for treatment monitoring in metastatic urothelial cancer. Clinical trial registration: NCT02853305.

Systematic review of the incidence and risk factors for cerebral vasculopathy and stroke after cranial proton and photon radiation for childhood brain tumors.

BACKGROUND: The aim of our study is to determine the incidence, timing, and risk factors for cerebral vasculopathy after cranial proton and photon radiation for pediatric brain tumors. METHODS: We performed a single-institution retrospective review of a cohort of children treated with proton radiation for brain tumors. MRA and/or MRI were reviewed for evidence of cerebral vascular stenosis and infarcts. Twenty-one similar studies (17 photon, 4 proton) were identified by systematic literature review. RESULTS: For 81 patients with median follow-up of 3 years, the rates of overall and severe vasculopathy were 9.9% and 6.2% respectively, occurring a median of 2 years post radiation. Dose to optic chiasm greater than 45 Gy and suprasellar location were significant risk factors. Results were consistent with 4 prior proton studies (752 patients) that reported incidence of 5% to 6.7%, 1.5 to 3 years post radiation. With significantly longer follow-up (3.7-19 years), 9 studies (1108 patients) with traditional photon radiation reported a higher rate (6.3%-20%) and longer time to vasculopathy (2-28 years). Significant risk factors were neurofibromatosis type 1 (NF-1; rate 7.6%-60%) and suprasellar tumors (9%-20%). In 10 studies with photon radiation (1708 patients), the stroke rate was 2% to 18.8% (2.3-24 years post radiation). CONCLUSIONS: Childhood brain tumor survivors need screening for vasculopathy after cranial radiation, especially with higher dose to optic chiasm, NF-1, and suprasellar tumors. Prospective studies are needed to identify risk groups, and ideal modality and timing, for screening of this toxicity.

Reevaluating surgery and re-irradiation for locally recurrent pediatric ependymoma-a multi-institutional study.

BACKGROUND: The goal of this study was to evaluate extent of surgical resection, and timing and volume of re-irradiation, on survival for children with locally recurrent ependymoma. METHODS: Children with locally recurrent ependymoma treated with a second course of fractionated radiotherapy (RT2) from 6 North American cancer centers were reviewed. The index time was from the start of RT2 unless otherwise stated. RESULTS: Thirty-five patients were included in the study. The median doses for first radiation (RT1) and RT2 were 55.8 and 54 Gy, respectively. Median follow-up time was 5.6 years. Median overall survival (OS) for all patients from RT2 was 65 months. Gross total resection (GTR) was performed in 46% and 66% of patients prior to RT1 and RT2, respectively. GTR prior to RT2 was independently associated with improved progression-free survival (PFS) for all patients (HR 0.41, P = 0.04), with an OS benefit (HR 0.26, P = 0.03) for infratentorial tumors. Median PFS was superior with craniospinal irradiation (CSI) RT2 (not reached) compared to focal RT2 (56.9 months; log-rank P = 0.03). All distant failures (except one) occurred after focal RT2. Local failures after focal RT2 were predominantly in patients with less than GTR pre-RT2. CONCLUSIONS: Patients with locally recurrent pediatric ependymoma should be considered for re-treatment with repeat maximal safe resection (ideally GTR) and CSI re-irradiation, with careful discussion of the potential side effects of these treatments.

Outcomes of BRAF V600E Pediatric Gliomas Treated With Targeted BRAF Inhibition.

PURPOSE: Children with pediatric gliomas harboring a BRAF V600E mutation have poor outcomes with current chemoradiotherapy strategies. Our aim was to study the role of targeted BRAF inhibition in these tumors. PATIENTS AND METHODS: We collected clinical, imaging, molecular, and outcome information from patients with BRAF V600E-mutated glioma treated with BRAF inhibition across 29 centers from multiple countries. RESULTS: Sixty-seven patients were treated with BRAF inhibition (pediatric low-grade gliomas [PLGGs], n = 56; pediatric high-grade gliomas [PHGGs], n = 11) for up to 5.6 years. Objective responses were observed in 80% of PLGGs, compared with 28% observed with conventional chemotherapy (P < .001). These responses were rapid (median, 4 months) and sustained in 86% of tumors up to 5 years while receiving therapy. After discontinuation of BRAF inhibition, 76.5% (13 of 17) of patients with PLGG experienced rapid progression (median, 2.3 months). However, upon rechallenge with BRAF inhibition, 90% achieved an objective response. Poor prognostic factors in conventional therapies, such as concomitant homozygous deletion of CDKN2A, were not associated with lack of response to BRAF inhibition. In contrast, only 36% of those with PHGG responded to BRAF inhibition, with all but one tumor progressing within 18 months. In PLGG, responses translated to 3-year progression-free survival of 49.6% (95% CI, 35.3% to 69.5%) versus 29.8% (95% CI, 20% to 44.4%) for BRAF inhibition versus chemotherapy, respectively (P = .02). CONCLUSION: Use of BRAF inhibition results in robust and durable responses in BRAF V600E-mutated PLGG. Prospective studies are required to determine long-term survival and functional outcomes with BRAF inhibitor therapy in childhood gliomas.

Spontaneous Regression of Atypical Teratoid Rhabdoid Tumor Without Therapy in a Patient With Uncommon Regional Inactivation of SMARCB1 ( hSNF5/INI1).

Atypical teratoid/rhabdoid tumor (ATRT) is a high-grade central nervous system tumor, with poor prognosis despite intensive multimodal therapy. Loss of nuclear immunostaining for INI1 due to inactivation of the hSNF5/INI1 tumor suppressor gene is pathognomonic of ATRT. We present a patient with congenital ATRT, who had spontaneous tumor regression without therapy, and is disease-free 4 years later. Tumor histopathology showed rhabdoid cells characteristic of ATRT, but immunohistochemistry revealed heterogeneous loss of nuclear INI1 staining. The populations of INI1-intact and INI1-deficient cells were separated by laser microdissection, for molecular analysis with DNA sequencing and fluorescence in situ hybridization. The INI1-negative cells were found to harbor a heterozygous deletion and truncating mutation of the hSNF5/INI1 locus, while the INI1-intact cells had 2 copies of the wild-type INI1 gene. To our knowledge, this is the first report of spontaneous regression of ATRT, with molecular heterogeneity for SMARCB1 inactivation, with no radiographic signs of recurrence at 4 years after diagnosis.

Encephalocraniocutaneous Lipomatosis.

A 5-year-old boy presented with worsening headaches for 3 months. On examination, he was found to have a hairless fatty tissue nevus of the scalp (nevus psiloliparus), subcutaneous soft tissue masses on the right side of his face, neck, mandible and right buttock and epibulbar dermoid of the right eye (choristoma) (). Magnetic resonance imaging revealed a large suprasellar mass, which was debulked and found to be a pilocytic astrocytoma. Testing was not performed for the BRAF/KIAA1549 fusion or BRAFV600E mutation. Seven years later, he was started on adjuvant chemotherapy for gradual tumor progression. Over the ensuing 3 years, he had further disease progression despite treatment with 3 frontline chemotherapy regimens: vinblastine, carboplatin/vincristine, and irinotecan/bevacizumab. Targeted sequencing of tissue from the right gluteal mass, revealed a mosaic activating FGFR1 c.1966A>G (p.Lys656Glu) mutation, absent in normal left gluteal tissue, confirming the diagnosis of encephalocraniocutaneous lipomatosis (ECCL), belonging to the family of RASopathies (including neurofibromatosis type I, Noonan syndrome, Costello syndrome), with constitutive activation of the mitogen-activated protein kinase (MAPK) pathway, and an increased risk of developing neoplasms. He was started on trametinib, a MEK inhibitor, off-label, targeting the MAPK pathway downstream from FGFR1, with stable tumor size at last follow-up, after 6 months on therapy.

Meta-analysis of the incidence and patterns of second neoplasms after photon craniospinal irradiation in children with medulloblastoma.

BACKGROUND: Second neoplasms (SNs) are a well-established long-term adverse effect of radiation therapy (RT), but there are limited data regarding their incidence and location relative to the radiation field, specific to medulloblastoma (MB) survivors after craniospinal irradiation (CSI). METHODS: A systematic literature review, per Preferred Reporting Items for Systematic Reviews and Meta-Analyses, identified six studies reporting the incidence and locations of SNs for 1,114 patients with MB, after CSI, with a median follow-up of ∼9 years (7.6-15.4 years). The study-specific cumulative incidence (CI) of SNs, second benign neoplasms (SBNs), and second malignant neoplasms (SMNs) were standardized to a 10-year time frame. Meta-analysis was performed using random effects models, with pooled data from selected studies and an institutional cohort of 55 patients. RESULTS: The 10-year CI was 6.1% for all SNs (excluding skin cancer and leukemia), 3.1% for SBNs, and 3.7% for SMNs. Fifty-eight percent of SNs were malignant; high-grade glioma was the most common SMN (15/33; 45%) and meningioma, the most common SBN (16/24; 67%). Forty percent of SNs occurred outside the target central nervous system (CNS) field, with a majority in areas of exit RT dose. Seventy-four percent of extra-CNS tumors (17/23) were malignant, most commonly thyroid carcinoma (7/17; 41%) and bone and soft-tissue tumors (6/17, 35%). CONCLUSIONS: Survivors of MB are at risk of SNs both within and outside the CNS. A significant proportion of SNs occur in areas of exit RT dose. Studies are needed to determine whether the use of proton therapy, which has no exit RT dose, is associated with a lower incidence of SNs.

Cost-effectiveness and Improved Parent and Provider Satisfaction With Outpatient Management of Pediatric Oncology Patients, With Low-risk Fever and Neutropenia.

On the basis of significant evidence for safety, the international pediatric fever and neutropenia committee recommends the identification and management of patients with "low-risk fever and neutropenia" (LRFN), outpatient with oral antibiotics, instead of traditional inpatient management. The aim of our study was to compare the cost-per-patient with these 2 strategies, and to evaluate parent and provider satisfaction with the outpatient management of LRFN. Between March 2016 and February 2017, 17 LRFN patients (median absolute neutrophil count, 90/µL) were managed at a single institution, per new guidelines. Fifteen patients were discharged on presentation or at 24 to 48 hours postadmission on oral levofloxacin, and 2 were inadvertently admitted off protocol. The mean cost of management for the postimplementation cohort was compared with a historic preimplementation control group. Satisfaction surveys were completed by parents and health care providers of LRFN patients. The mean total cost of an LRFN episode was $12,500 per patient preimplementation and $6168 postimplementation, a decrease of $6332 (51%) per patient. All parents surveyed found outpatient follow-up easy; most (12/14) parents and all (16/16) providers preferred outpatient management. Outpatient management of LRFN patients was less costly, and was preferred by a majority of parents and all health care providers, compared with traditional inpatient management.

Dramatic clinical and radiographic response to BRAF inhibition in a patient with progressive disseminated optic pathway glioma refractory to MEK inhibition.

While clinical and radiographic responses to agents targeting the mitogen-activated protein kinases (MAPK) pathway have been repor-ted in pediatric low-grade gliomas (LGG), early phase trials indicate refractoriness to these medications in some of these patients. We report a patient with disseminated LGG with the BRAFV600E mutation, which was refractory to selumetinib, a MEK inhibitor, but subsequently showed immediate clinical and radiographic response to dabrafenib, a BRAF inhibitor, with sustained effect for 9 months prior to clinical progression. In LGGs, treatment resistance to one agent targeting the MAPK pathway might not imply refractoriness to other agents targeting this pathway.

From One to Many: Further Refinement of Medulloblastoma Subtypes Offers Promise for Personalized Therapy.

There is significant intertumoral heterogeneity within the four molecular subgroups of medulloblastoma. In this issue of Cancer Cell, Cavalli et al. apply similarity network fusion to gene expression and DNA methylation data to identify 12 medulloblastoma subtypes with distinct molecular and clinical profiles, making an important step toward molecularly tailored therapy.

Integrated tumor and germline whole-exome sequencing identifies mutations in MAPK and PI3K pathway genes in an adolescent with rosette-forming glioneuronal tumor of the fourth ventricle.

The integration of genome-scale studies such as whole-exome sequencing (WES) into the clinical care of children with cancer has the potential to provide insight into the genetic basis of an individual's cancer with implications for clinical management. This report describes the results of clinical tumor and germline WES for a patient with a rare tumor diagnosis, rosette-forming glioneuronal tumor of the fourth ventricle (RGNT). Three pathogenic gene alterations with implications for clinical care were identified: somatic activating hotspot mutations in FGFR1 (p.N546K) and PIK3CA (p.H1047R) and a germline pathogenic variant in PTPN11 (p.N308S) diagnostic for Noonan syndrome. The molecular landscape of RGNT is not well-described, but these data are consistent with prior observations regarding the importance of the interconnected MAPK and PI3K/AKT/mTOR signaling pathways in this rare tumor. The co-occurrence of FGFR1, PIK3CA, and PTPN11 alterations provides further evidence for consideration of RGNT as a distinct molecular entity from pediatric low-grade gliomas and suggests potential therapeutic strategies for this patient in the event of tumor recurrence as novel agents targeting these pathways enter pediatric clinical trials. Although RGNT has not been definitively linked with cancer predisposition syndromes, two prior cases have been reported in patients with RASopathies (Noonan syndrome and neurofibromatosis type 1 [NF1]), providing an additional link between these tumors and the mitogen-activated protein kinase (MAPK) signaling pathway. In summary, this case provides an example of the potential for genome-scale sequencing technologies to provide insight into the biology of rare tumors and yield both tumor and germline results of potential relevance to patient care.

Applications of Genomic Sequencing in Pediatric CNS Tumors.

Recent advances in genome-scale sequencing methods have resulted in a significant increase in our understanding of the biology of human cancers. When applied to pediatric central nervous system (CNS) tumors, these remarkable technological breakthroughs have facilitated the molecular characterization of multiple tumor types, provided new insights into the genetic basis of these cancers, and prompted innovative strategies that are changing the management paradigm in pediatric neuro-oncology. Genomic tests have begun to affect medical decision making in a number of ways, from delineating histopathologically similar tumor types into distinct molecular subgroups that correlate with clinical characteristics, to guiding the addition of novel therapeutic agents for patients with high-risk or poor-prognosis tumors, or alternatively, reducing treatment intensity for those with a favorable prognosis. Genomic sequencing has also had a significant impact on translational research strategies in pediatric CNS tumors, resulting in wide-ranging applications that have the potential to direct the rational preclinical screening of novel therapeutic agents, shed light on tumor heterogeneity and evolution, and highlight differences (or similarities) between pediatric and adult CNS tumors. Finally, in addition to allowing the identification of somatic (tumor-specific) mutations, the analysis of patient-matched constitutional (germline) DNA has facilitated the detection of pathogenic germline alterations in cancer genes in patients with CNS tumors, with critical implications for genetic counseling and tumor surveillance strategies for children with familial predisposition syndromes. As our understanding of the molecular landscape of pediatric CNS tumors continues to advance, innovative applications of genomic sequencing hold significant promise for further improving the care of children with these cancers.

Diagnostic Yield of Clinical Tumor and Germline Whole-Exome Sequencing for Children With Solid Tumors.

IMPORTANCE: Whole-exome sequencing (WES) has the potential to reveal tumor and germline mutations of clinical relevance, but the diagnostic yield for pediatric patients with solid tumors is unknown. OBJECTIVE: To characterize the diagnostic yield of combined tumor and germline WES for children with solid tumors. DESIGN: Unselected children with newly diagnosed and previously untreated central nervous system (CNS) and non-CNS solid tumors were prospectively enrolled in the BASIC3 study at a large academic children's hospital during a 23-month period from August 2012 through June 2014. Blood and tumor samples underwent WES in a certified clinical laboratory with genetic results categorized on the basis of perceived clinical relevance and entered in the electronic health record. MAIN OUTCOMES AND MEASURES: Clinical categorization of somatic mutations; frequencies of deleterious germline mutations related to patient phenotype and incidental medically-actionable mutations. RESULTS: Of the first 150 participants (80 boys and 70 girls, mean age, 7.4 years), tumor samples adequate for WES were available from 121 patients (81%). Somatic mutations of established clinical utility (category I) were reported in 4 (3%) of 121 patients, with mutations of potential utility (category II) detected in an additional 29 (24%) of 121 patients. CTNNB1 was the gene most frequently mutated, with recurrent mutations in KIT, TSC2, and MAPK pathway genes (BRAF, KRAS, and NRAS) also identified. Mutations in consensus cancer genes (category III) were found in an additional 24 (20%) of 121 tumors. Fewer than half of somatic mutations identified were in genes known to be recurrently mutated in the tumor type tested. Diagnostic germline findings related to patient phenotype were discovered in 15 (10%) of 150 cases: 13 pathogenic or likely pathogenic dominant mutations in adult and pediatric cancer susceptibility genes (including 2 each in TP53, VHL, and BRCA1), 1 recessive liver disorder with hepatocellular carcinoma (TJP2), and 1 renal diagnosis (CLCN5). Incidental findings were reported in 8 (5%) of 150 patients. Most patients harbored germline uncertain variants in cancer genes (98%), pharmacogenetic variants (89%), and recessive carrier mutations (85%). CONCLUSIONS AND RELEVANCE: Tumor and germline WES revealed mutations in a broad spectrum of genes previously implicated in both adult and pediatric cancers. Combined reporting of tumor and germline WES identified diagnostic and/or potentially actionable findings in nearly 40% of newly diagnosed pediatric patients with solid tumors.

Multimodality Treatment of Pediatric Esthesioneuroblastoma.

BACKGROUND: Esthesioneuroblastoma (ENB) is a rare cancer of the nasal cavity in children. Radical surgery followed by postoperative radiation is considered the standard of care in adults. A similar approach in children can lead to significant long-term morbidity. PROCEDURE: A retrospective multi-institutional review of patients less than 21 years of age diagnosed with ENB between 1990 and 2014 was performed. Clinical features, treatment, and outcome were obtained from the medical records. RESULTS: Twenty-four patients were identified with a median age of 14 years (range 0.6-20 years) at diagnosis. The majority (75%) were females. Headache was the most common presenting symptom, followed by nasal obstruction and epistaxis. Eight patients had Kadish stage B tumors and 16 had Kadish stage C tumors. Nine patients had metastatic disease. Gross total resection was achieved at diagnosis in eight patients and after neoadjuvant chemotherapy in four patients. Twenty-one patients received radiation therapy (45-68.4 Gy). Thirteen patients received neoadjuvant chemotherapy with 84% objective response rate. Seven patients experienced disease progression or relapse-five in central nervous system, one local, and one in cervical lymph node. Fifteen patients were alive at the last follow-up. The 5-year disease-free survival and overall survival were 74% and 73%, respectively. Late effects were observed in 78% of long-term survivors. Four patients developed subsequent malignant neoplasms. CONCLUSIONS: Pediatric ENB is a chemosensitive disease. Preoperative chemotherapy-based multimodal approach should be used in patients with advanced stage disease. Radiation therapy is effective for local control, but lower doses should be considered in children.

Recurrent internal tandem duplications of BCOR in clear cell sarcoma of the kidney.

The X-linked BCL-6 co-repressor (BCOR) gene encodes a key constituent of a variant polycomb repressive complex (PRC) that is mutated or translocated in human cancers. Here we report on the identification of somatic internal tandem duplications (ITDs) clustering in the C terminus of BCOR in 23 of 27 (85%) pediatric clear cell sarcomas of the kidney (CCSK) from two independent cohorts. We profile CCSK tumours using a combination of whole-exome, transcriptome and targeted sequencing. Identical ITD mutations are found in primary and relapsed tumour pairs but not in adjacent normal kidney or blood. Mutant BCOR transcripts and proteins are markedly upregulated in ITD-positive tumours. Transcriptome analysis of ITD-positive CCSKs reveals enrichment for PRC2-regulated genes and similarity to undifferentiated sarcomas harbouring BCOR-CCNB3 fusions. The discovery of recurrent BCOR ITDs defines a major oncogenic event in this childhood sarcoma with significant implications for diagnostic and therapeutic approaches to this tumour.

Impact of long-term erythrocytapheresis on growth and peak height velocity of children with sickle cell disease.

BACKGROUND: Children with sickle cell disease (SCD) lag in weight and height and have a delayed growth spurt compared to normal children. We studied the effect of long-term erythrocytapheresis (LTE) on the growth of children with SCD and the age at which they attained peak height velocity. PROCEDURE: A retrospective chart review was performed recording weight, height, and body mass index (BMI) measurements of 36 patients with SCD who received LTE every 3-5 weeks for an average duration of 5 years. The z-scores for weight, height, and BMI of these patients were compared with that of patients with SCD from the Cooperative Study of Sickle Cell Disease (CSSCD) and a sub-set of 64 controls matched for age, sex, and initial growth parameter z-scores at the start of LTE. RESULTS: The z-scores for all parameters improved significantly for our patients on LTE compared to match controls from CSSCD and the entire pediatric CSSCD cohort (P-value: <0.01). Peak height velocity was achieved 2 months earlier for females (P-value: 0.94) and 11 months earlier for males (P-value: 0.02), who started LTE before 14 years of age, compared to matched CSSCD controls. The study subjects who had not been on regular simple transfusions prior to starting LTE had a mean serum ferritin of 681 ng/ml after LTE for an average duration of 63 months. CONCLUSION: LTE improves the growth of children with SCD without the risk of iron overload.