Loss of heterozygosity does not occur in BRCA1/2 mutant pediatric solid and central nervous system tumors.

Utilization of tumor-only sequencing has expanded in pediatric cancer patients, which can lead to identification of pathogenic variants in genes that may be germline and/or have uncertain relevance to the tumor in question, such as the homologous recombination (HR) pathway genes BRCA1/2. We identified patients with pathogenic BRCA1/2 mutations from somatic tumor sequencing, and performed additional germline sequencing to assess for the presence of loss of heterozygosity (LOH). Of seven patients identified, four (57.1%) mutations were found in the germline and none had associated LOH. Our data suggest that BRCA1/2 mutations identified in this context are likely incidental findings.

Real-world experience with low-dose IL-2 for children and young adults with refractory chronic graft-versus-host disease.

The majority of patients with chronic graft-versus-host disease (cGVHD) are steroid refractory (SR), creating a need for safe and effective therapies. Subcutaneous low-dose interleukin-2 (LD IL-2), which preferentially expands CD4+ regulatory T cells (Tregs), has been evaluated in 5 clinical trials at our center with partial responses (PR) in ∼50% of adults and 82% of children by week 8. We now report additional real-world experience with LD IL-2 in 15 children and young adults. We conducted a retrospective chart review of patients with SR-cGVHD at our center who received LD IL-2 from August 2016 to July 2022 not on a research trial. The median age at start of LD IL-2 was 10.4 years (range, 1.2-23.2 years) at a median of 234 days from cGVHD diagnosis (range, 11-542 days). Patients had a median of 2.5 (range, 1-3) active organs at LD IL-2 start and received a median of 3 (range, 1-5) prior therapies. The median duration of LD IL-2 therapy was 462 days (range, 8-1489 days). Most patients received 1 × 106 IU/m2 per day. There were no serious adverse effects. The overall response rate in 13 patients who received >4 weeks of therapy was 85% (complete response, n = 5; PR, n = 6) with responses in diverse organs. Most patients significantly weaned corticosteroids. Tregs preferentially expanded with a median peak fold increase of 2.8 in the ratio of Tregs to CD4+ conventional T cells (range, 2.0-19.8) by 8 weeks on therapy. LD IL-2 is a well-tolerated, steroid-sparing agent with a high response rate in children and young adults with SR-cGVHD.

A single-institution pediatric and young adult interventional oncology collaborative: Novel therapeutic options for relapsed/refractory solid tumors.

BACKGROUND: Pediatric interventional oncology (PIO) is a growing field intended to provide additional or alternative treatment options for pediatric patients with benign or malignant tumors. Large series of patients treated uniformly and subjected to rigorous endpoints for efficacy are not available. METHODS: We designed a collaborative initiative to capture data from pediatric patients with benign and malignant tumors who underwent a therapeutic interventional radiology procedure. Modified Response Evaluation Criteria in Solid Tumors (mRECIST) was utilized as a measure of radiologic response and data were collected regarding improvement in pain and functional endpoints. Cumulative incidence of progressive disease was calculated using both the treated site and the patient as the analytic unit. FINDINGS: Forty patients, 16 with malignant tumors and 24 with benign tumors, underwent a total of 88 procedures. Cryo- and radiofrequency ablation were the most frequently utilized techniques for both cohorts of patients. A complete or partial response, or prolonged disease stability, were achieved in approximately 40% of patients with malignant tumors and 60% of patients with benign tumors. No patients had progressive disease as their best response. Resolution of pain and improved mobility with return-to-baseline activity were demonstrated across patients from both cohorts. Only minor complications were experienced. INTERPRETATION: Interventional radiology-guided interventions can serve as an alternative or complementary approach to the treatment of benign and malignant tumors in pediatric patients. Prospective, multi-institutional trials are required to adequately study utility, treatment endpoints, and durability of response.

Clinical Targeted Next-Generation Panel Sequencing Reveals MYC Amplification Is a Poor Prognostic Factor in Osteosarcoma.

PURPOSE: Osteosarcoma risk stratification, on the basis of the presence of metastatic disease at diagnosis and histologic response to chemotherapy, has remained unchanged for four decades, does not include genomic features, and has not facilitated treatment advances. We report on the genomic features of advanced osteosarcoma and provide evidence that genomic alterations can be used for risk stratification. MATERIALS AND METHODS: In a primary analytic patient cohort, 113 tumor and 69 normal samples from 92 patients with high-grade osteosarcoma were sequenced with OncoPanel, a targeted next-generation sequencing assay. In this primary cohort, we assessed the genomic landscape of advanced disease and evaluated the correlation between recurrent genomic events and outcome. We assessed whether prognostic associations identified in the primary cohort were maintained in a validation cohort of 86 patients with localized osteosarcoma tested with MSK-IMPACT. RESULTS: In the primary cohort, 3-year overall survival (OS) was 65%. Metastatic disease, present in 33% of patients at diagnosis, was associated with poor OS (P = .04). The most frequently altered genes in the primary cohort were TP53, RB1, MYC, CCNE1, CCND3, CDKN2A/B, and ATRX. Mutational signature 3 was present in 28% of samples. MYC amplification was associated with a worse 3-year OS in both the primary cohort (P = .015) and the validation cohort (P = .012). CONCLUSION: The most frequently occurring genomic events in advanced osteosarcoma were similar to those described in prior reports. MYC amplification, detected with clinical targeted next-generation sequencing panel tests, is associated with poorer outcomes in two independent cohorts.

Rare FGFR Oncogenic Alterations in Sequenced Pediatric Solid and Brain Tumors Suggest FGFR Is a Relevant Molecular Target in Childhood Cancer.

PURPOSE: Multiple FGFR inhibitors are currently in clinical trials enrolling adults with different solid tumors, while very few enroll pediatric patients. We determined the types and frequency of FGFR alterations (FGFR1-4) in pediatric cancers to inform future clinical trial design. METHODS: Tumors with FGFR alterations were identified from two large cohorts of pediatric solid tumors subjected to targeted DNA sequencing: The Dana-Farber/Boston Children's Profile Study (n = 888) and the multi-institution GAIN/iCAT2 (Genomic Assessment Improves Novel Therapy) Study (n = 571). Data from the combined patient population of 1,395 cases (64 patients were enrolled in both studies) were reviewed and cases in which an FGFR alteration was identified by OncoPanel sequencing were further assessed. RESULTS: We identified 41 patients with tumors harboring an oncogenic FGFR alteration. Median age at diagnosis was 8 years (range, 6 months-26 years). Diagnoses included 11 rhabdomyosarcomas, nine low-grade gliomas, and 17 other tumor types. Alterations included gain-of-function sequence variants (n = 19), amplifications (n = 10), oncogenic fusions (FGFR3::TACC3 [n = 3], FGFR1::TACC1 [n = 1], FGFR1::EBF2 [n = 1], FGFR1::CLIP2 [n = 1], and FGFR2::CTNNA3 [n = 1]), pathogenic-leaning variants of uncertain significance (n = 4), and amplification in combination with a pathogenic-leaning variant of uncertain significance (n = 1). Two novel FGFR1 fusions in two different patients were identified in this cohort, one of whom showed a response to an FGFR inhibitor. CONCLUSION: In summary, activating FGFR alterations were found in approximately 3% (41/1,395) of pediatric solid tumors, identifying a population of children with cancer who may be eligible and good candidates for trials evaluating FGFR-targeted therapy. Importantly, the genomic and clinical data from this study can help inform drug development in accordance with the Research to Accelerate Cures and Equity for Children Act.

Molecular profiling identifies targeted therapy opportunities in pediatric solid cancer.

To evaluate the clinical impact of molecular tumor profiling (MTP) with targeted sequencing panel tests, pediatric patients with extracranial solid tumors were enrolled in a prospective observational cohort study at 12 institutions. In the 345-patient analytical population, median age at diagnosis was 12 years (range 0-27.5); 298 patients (86%) had 1 or more alterations with potential for impact on care. Genomic alterations with diagnostic, prognostic or therapeutic significance were present in 61, 16 and 65% of patients, respectively. After return of the results, impact on care included 17 patients with a clarified diagnostic classification and 240 patients with an MTP result that could be used to select molecularly targeted therapy matched to identified alterations (MTT). Of the 29 patients who received MTT, 24% had an objective response or experienced durable clinical benefit; all but 1 of these patients received targeted therapy matched to a gene fusion. Of the diagnostic variants identified in 209 patients, 77% were gene fusions. MTP with targeted panel tests that includes fusion detection has a substantial clinical impact for young patients with solid tumors.

Identification of prognostic factors in childhood T-cell acute lymphoblastic leukemia: Results from DFCI ALL Consortium Protocols 05-001 and 11-001.

BACKGROUND/OBJECTIVES: While outcomes for pediatric T-cell acute lymphoblastic leukemia (T-ALL) are favorable, there are few widely accepted prognostic factors, limiting the ability to risk stratify therapy. DESIGN/METHODS: Dana-Farber Cancer Institute (DFCI) Protocols 05-001 and 11-001 enrolled pediatric patients with newly diagnosed B- or T-ALL from 2005 to 2011 and from 2012 to 2015, respectively. Protocol therapy was nearly identical for patients with T-ALL (N = 123), who were all initially assigned to the high-risk arm. End-induction minimal residual disease (MRD) was assessed by reverse transcription polymerase chain reaction (RT-PCR) or next-generation sequencing (NGS), but was not used to modify postinduction therapy. Early T-cell precursor (ETP) status was determined by flow cytometry. Cases with sufficient diagnostic DNA were retrospectively evaluated by targeted NGS of known genetic drivers of T-ALL, including Notch, PI3K, and Ras pathway genes. RESULTS: The 5-year event-free survival (EFS) and overall survival (OS) for patients with T-ALL was 81% (95% CI, 73-87%) and 90% (95% CI, 83-94%), respectively. ETP phenotype was associated with failure to achieve complete remission, but not with inferior OS. Low end-induction MRD (<10-4 ) was associated with superior disease-free survival (DFS). Pathogenic mutations of the PI3K pathway were mutually exclusive of ETP phenotype and were associated with inferior 5-year DFS and OS. CONCLUSIONS: Together, our findings demonstrate that ETP phenotype, end-induction MRD, and PI3K pathway mutation status are prognostically relevant in pediatric T-ALL and should be considered for risk classification in future trials. DFCI Protocols 05-001 and 11-001 are registered at www.clinicaltrials.gov as NCT00165087 and NCT01574274, respectively.

Arming the troops: Post-translational modification of extracellular bacterial proteins.

Protein secretion is almost universally employed by bacteria. Some proteins are retained on the cell surface, whereas others are released into the extracellular milieu, often playing a key role in virulence. In this review, we discuss the diverse types and potential functions of post-translational modifications (PTMs) occurring to extracellular bacterial proteins.

Making the most of small samples: Optimization of tissue allocation of pediatric solid tumors for clinical and research use.

INTRODUCTION: Tissue from pediatric solid tumors is in high demand for use in high-impact research studies, making the allocation of tissue from an anatomic pathology laboratory challenging. We designed, implemented, and assessed an interdepartmental process to optimize tissue allocation of pediatric solid tumors for both clinical care and research. METHODS: Oncologists, pathologists, surgeons, interventional radiologists, pathology technical staff, and clinical research coordinators participated in the workflow design. Procedures were created to address patient identification and consent, prioritization of protocols, electronic communication of requests, tissue preparation, and distribution. Pathologists were surveyed about the value of the new workflow. RESULTS: Over a 5-year period, 644 pediatric solid tumor patients consented to one or more studies requesting archival or fresh tissue. Patients had a variety of tumor types, with many rare and singular diagnoses. Sixty-seven percent of 1768 research requests were fulfilled. Requests for archival tissue were fulfilled at a significantly higher rate than those for fresh tissue (P > .001), and requests from resection specimens were fulfilled at a significantly higher rate than those from biopsies (P > .0001). In an anonymous survey, seven of seven pathologists reported that the process had improved since the introduction of the electronic communication model. CONCLUSIONS: A collaborative and informed model for tissue allocation is successful in distributing archival and fresh tissue for clinical research studies. Our workflows and policies have gained pathologists' approval and streamlined our processes. As clinical and research programs evolve, a thoughtful tissue allocation process will facilitate ongoing research.

Genomic and Immunologic Characterization of INI1-Deficient Pediatric Cancers.

PURPOSE: Several aggressive pediatric cancers harbor alterations in SMARCB1, including rhabdoid tumors, epithelioid sarcoma, and chordoma. As tumor profiling has become more routine in clinical care, we investigated the relationship between SMARCB1 genetic variants identified by next-generation sequencing (NGS) and INI1 protein expression. Therapeutic approaches for INI1-deficient tumors are limited. Early reports suggest a potential role for immune checkpoint inhibition in these patients. Thus, we also investigated PD-L1 and CD8 expression in INI1-negative pediatric brain and solid tumors. EXPERIMENTAL DESIGN: We performed immunohistochemistry (IHC) for INI1 and immune markers (PD-L1, CD8, and CD163) and NGS on tumor samples from 43 pediatric patients who had tumors with INI1 loss on previous IHC or SMARCB1 genomic alterations on prior somatic sequencing. RESULTS: SMARCB1 two-copy deletions and inactivating mutations on NGS were associated with loss of INI1 protein expression. Single-copy deletion of SMARCB1 was not predictive of INI1 loss in tumor histologies not known to be INI1-deficient. In the 27 cases with INI1 loss and successful tumor sequencing, 24 (89%) had a SMARCB1 alteration detected. In addition, 47% (14/30) of the patients with INI1-negative tumors had a tumor specimen that was PD-L1 positive and 60% (18/30) had positive or rare CD8 staining. We report on 3 patients with INI1-negative tumors with evidence of disease control on immune checkpoint inhibitors. CONCLUSIONS: A significant proportion of the INI1-negative tumors express PD-L1, and PD-L1 positivity was associated with extracranial tumor site. These results suggest that clinical trials of immune checkpoint inhibitors are warranted in INI1-negative pediatric cancers.

Recurrent RET gene fusions in paediatric spindle mesenchymal neoplasms.

AIMS: The classification of paediatric spindle mesenchymal tumours is evolving, and the spectrum of so-called 'infantile fibrosarcoma' has expanded to include tumours with NTRK, BRAF and MET gene fusions. RET-rearranged paediatric spindle cell neoplasms are an emerging group; there is sparse literature on their clinical, pathological and genetic features, and their nosological place in the canon of soft tissue tumours is uncertain. In this study, we report five RET-rearranged paediatric spindle cell tumours with fusion partners MYH10, KIAA1217 and CLIP2. METHODS AND RESULTS: The tumours occurred in the pelvic region, paraspinal region, kidney and subcutaneous tissue of hand and abdomen. The patients' ages ranged from 6 months to 13 years (median 1 year). The tumours were composed of monomorphic spindle cells arranged in a fascicular pattern. Lesional cells had minimally atypical ovoid or tapered nuclei and pale cytoplasm with indistinct borders. Necrosis was not identified. Mitoses numbered three to 12 per 10 high-power field. Cases showed inconsistent and variable expression of S100, CD34 and SMA. Clinical behaviour ranged from small lesions potentially cured by simple resection to large lesions exhibiting metastasis, but responsive to kinase inhibitor therapy. CONCLUSIONS: Our findings help to define RET-rearranged spindle cell tumours. Although it is likely that these tumours comprise part of the morphological and clinical spectrum of infantile fibrosarcoma (IFS), identification of RET gene alteration is important for its unique therapeutic implications.

Synthesis and biological evaluation of 1,2-disubsubstituted 4-quinolone analogues of Pseudonocardia sp. natural products.

A series of analogues of Pseudonocardia sp. natural products were synthesized, which have been reported to possess potent antibacterial activity against Helicobacter pylori and induce growth defects in Escherichia coli and Staphylococcus aureus. Taking inspiration from a methodology used in our total synthesis of natural products, we applied this methodology to access analogues possessing bulky N-substituents, traditionally considered to be challenging scaffolds. Screening of the library provided valuable insights into the structure-activity relationship of the bacterial growth defects, and suggested that selectivity between bacterial species should be attainable. Furthermore, a structurally related series of analogues was observed to inhibit production of the virulence factor pyocyanin in the human pathogen Pseudomonas aeruginosa, which may be a result of their similarity to the Pseudomonas quinolone signal (PQS) quorum sensing autoinducer. This provided new insights regarding the effect of N-substitution in PQS analogues, which has been hitherto underexplored.

Precision medicine in pediatric oncology.

PURPOSE OF REVIEW: The current review describes recent advances and unique challenges in precision medicine for pediatric cancers and highlights clinical trials assessing the clinical impact of targeted therapy matched to molecular alterations identified by tumor profiling. RECENT FINDINGS: Multiple prospective clinical sequencing studies in pediatric oncology have been reported in the last 2 years. These studies demonstrated feasibility of sequencing in the clinic and revealed a rate of actionable variants that justifies the development of precision trials for childhood cancer. A number of precision medicine trials are recently completed, underway or in development and these will be reviewed herein, with a focus on highlighting aspects of precision medicine trial design relevant to pediatric oncology. SUMMARY: The primary results of the first round of pediatric precision oncology clinical trials will provide us with a greater understanding of the clinical impact of linking tumor profiling to selection of targeted therapies. The aggregation of sequencing and clinical data from these trials and the results of biologic investigations linked to these trials will drive further discoveries and broaden opportunities for precision medicine for children with cancer.

Evaluation of SMN protein, transcript, and copy number in the biomarkers for spinal muscular atrophy (BforSMA) clinical study.

BACKGROUND: The universal presence of a gene (SMN2) nearly identical to the mutated SMN1 gene responsible for Spinal Muscular Atrophy (SMA) has proved an enticing incentive to therapeutics development. Early disappointments from putative SMN-enhancing agent clinical trials have increased interest in improving the assessment of SMN expression in blood as an early "biomarker" of treatment effect. METHODS: A cross-sectional, single visit, multi-center design assessed SMN transcript and protein in 108 SMA and 22 age and gender-matched healthy control subjects, while motor function was assessed by the Modified Hammersmith Functional Motor Scale (MHFMS). Enrollment selectively targeted a broad range of SMA subjects that would permit maximum power to distinguish the relative influence of SMN2 copy number, SMA type, present motor function, and age. RESULTS: SMN2 copy number and levels of full-length SMN2 transcripts correlated with SMA type, and like SMN protein levels, were lower in SMA subjects compared to controls. No measure of SMN expression correlated strongly with MHFMS. A key finding is that SMN2 copy number, levels of transcript and protein showed no correlation with each other. CONCLUSION: This is a prospective study that uses the most advanced techniques of SMN transcript and protein measurement in a large selectively-recruited cohort of individuals with SMA. There is a relationship between measures of SMN expression in blood and SMA type, but not a strong correlation to motor function as measured by the MHFMS. Low SMN transcript and protein levels in the SMA subjects relative to controls suggest that these measures of SMN in accessible tissues may be amenable to an "early look" for target engagement in clinical trials of putative SMN-enhancing agents. Full length SMN transcript abundance may provide insight into the molecular mechanism of phenotypic variation as a function of SMN2 copy number. TRIAL REGISTRY: Clinicaltrials.gov NCT00756821.

Candidate proteins, metabolites and transcripts in the Biomarkers for Spinal Muscular Atrophy (BforSMA) clinical study.

BACKGROUND: Spinal Muscular Atrophy (SMA) is a neurodegenerative motor neuron disorder resulting from a homozygous mutation of the survival of motor neuron 1 (SMN1) gene. The gene product, SMN protein, functions in RNA biosynthesis in all tissues. In humans, a nearly identical gene, SMN2, rescues an otherwise lethal phenotype by producing a small amount of full-length SMN protein. SMN2 copy number inversely correlates with disease severity. Identifying other novel biomarkers could inform clinical trial design and identify novel therapeutic targets. OBJECTIVE: To identify novel candidate biomarkers associated with disease severity in SMA using unbiased proteomic, metabolomic and transcriptomic approaches. MATERIALS AND METHODS: A cross-sectional single evaluation was performed in 108 children with genetically confirmed SMA, aged 2-12 years, manifesting a broad range of disease severity and selected to distinguish factors associated with SMA type and present functional ability independent of age. Blood and urine specimens from these and 22 age-matched healthy controls were interrogated using proteomic, metabolomic and transcriptomic discovery platforms. Analyte associations were evaluated against a primary measure of disease severity, the Modified Hammersmith Functional Motor Scale (MHFMS) and to a number of secondary clinical measures. RESULTS: A total of 200 candidate biomarkers correlate with MHFMS scores: 97 plasma proteins, 59 plasma metabolites (9 amino acids, 10 free fatty acids, 12 lipids and 28 GC/MS metabolites) and 44 urine metabolites. No transcripts correlated with MHFMS. DISCUSSION: In this cross-sectional study, "BforSMA" (Biomarkers for SMA), candidate protein and metabolite markers were identified. No transcript biomarker candidates were identified. Additional mining of this rich dataset may yield important insights into relevant SMA-related pathophysiology and biological network associations. Additional prospective studies are needed to confirm these findings, demonstrate sensitivity to change with disease progression, and assess potential impact on clinical trial design. TRIAL REGISTRY: Clinicaltrials.gov NCT00756821.

Proteinuria is associated with elevated tricuspid regurgitant jet velocity in children with sickle cell disease.

BACKGROUND: Sickle cell disease (SCD) affects multiple organ systems. Complications of SCD such as pulmonary hypertension (PHT) and sickle cell nephropathy (SCN) are associated with an increased mortality. Both PHT and SCN have some common risk factors. In adults, PHT has been found to be associated with albuminuria, a manifestation of SCN. There is no data on this association in children. We conducted a study to determine if elevated pulmonary artery systolic pressures estimated on echocardiogram was associated with proteinuria in children with SCD. METHODS: A detailed retrospective chart review was conducted on a cohort of sickle cell patients screened with echocardiograms from June 2005 to July 2010. Patients who had an initial screening echocardiogram and urine analysis within 1 year were included. Longitudinal data from all subsequent echocardiograms and urine analyses were collected. RESULTS: Eighty-five patients were included. On initial echocardiograms 32.9% had an elevated tricuspid regurgitant jet velocity (TRV) ≥2.5 m/second. On follow up, in the 28 patients with elevated TRV, 49.27% of all repeat echocardiograms showed persistent elevation. In the 57 patients with normal baseline TRV, 73.6% of all repeat echocardiograms continued to have normal TRV. On initial screening 7.14% of patients with elevated TRV had proteinuria compared to 1.75% without elevated TRV. On follow up, 19.08% of repeat urinalysis had proteinuria in patients with elevated baseline TRV compared to 12.35% in patients with normal baseline TRV (P = 0.04). CONCLUSIONS: Elevated TRV ≥ 2.5 m/second is significantly associated with proteinuria on longitudinal follow up in children with SCD.