Efficacy of Nivolumab in Pediatric Cancers with High Mutation Burden and Mismatch Repair Deficiency.

PURPOSE: Checkpoint inhibitors have limited efficacy for children with unselected solid and brain tumors. We report the first prospective pediatric trial (NCT02992964) using nivolumab exclusively for refractory nonhematologic cancers harboring tumor mutation burden (TMB) ≥5 mutations/megabase (mut/Mb) and/or mismatch repair deficiency (MMRD). PATIENTS AND METHODS: Twenty patients were screened, and 10 were ultimately included in the response cohort of whom nine had TMB >10 mut/Mb (three initially eligible based on MMRD) and one patient had TMB between 5 and 10 mut/Mb. RESULTS: Delayed immune responses contributed to best overall response of 50%, improving on initial objective responses (20%) and leading to 2-year overall survival (OS) of 50% [95% confidence interval (CI), 27-93]. Four children, including three with refractory malignant gliomas are in complete remission at a median follow-up of 37 months (range, 32.4-60), culminating in 2-year OS of 43% (95% CI, 18.2-100). Biomarker analyses confirmed benefit in children with germline MMRD, microsatellite instability, higher activated and lower regulatory circulating T cells. Stochastic mutation accumulation driven by underlying germline MMRD impacted the tumor microenvironment, contributing to delayed responses. No benefit was observed in the single patient with an MMR-proficient tumor and TMB 7.4 mut/Mb. CONCLUSIONS: Nivolumab resulted in durable responses and prolonged survival for the first time in a pediatric trial of refractory hypermutated cancers including malignant gliomas. Novel biomarkers identified here need to be translated rapidly to clinical care to identify children who can benefit from checkpoint inhibitors, including upfront management of cancer. See related commentary by Mardis, p. 4701.

[LANGERHANS CELL HISTIOCYTOSIS: A SINGLE CENTER EXPERIENCE IN THE PEDIATRIC HEMATO-ONCOLOGY DIVISION OF THE TEL-AVIV SOURASKY MEDICAL CENTER].

INTRODUCTION: Langerhans cell histiocytosis (LCH) is a histiocytic disorder which is characterized by a wide variety of clinical presentations and is prevalent mostly in children .This is a single center study reviewing experience in the treatment of LCH in a pediatric hemato-oncology ward over 25 years. We summarized the demographics, the locations of the disease, the treatments administered, the reactivations and the survival of the patients. METHODS: A retrospective analysis of files was performed from patients who were referred and treated at the Dana-Dwek Children's hospital in the Tel-Aviv Sourasky Medical Center between the years 1996-2020. RESULTS: One hundred and six patients with LCH were treated during the period 1996-2020 in the Pediatric Hemato-Oncology division. The diagnosis was confirmed by a biopsy from a lesion. The primary location of the disease was single system in 91% of patients (mostly bone lesions) and 9% multisystem disease. Forty-five patients (42.4%) were treated by upfront chemotherapy according to the Histiocyte Society guidelines. Twenty patients (19%) had reactivation of their disease. Ninety percent of the reactivations occurred in the first four years after diagnosis. There was no mortality in this cohort. CONCLUSIONS: This is a single center study summarizing the experience of a Pediatric Hemato-Oncology division in the Tel-Aviv Medical Center in the treatment of 106 patients with LCH over 25 years and is the first review of a large cohort of patients in Israel. The cohort was characterized by abundance of patients with bone disease and paucity of patients with multisystem disease with risk organ involvement. There was overall good response to treatment and all patients survived.

Genomic predictors of response to PD-1 inhibition in children with germline DNA replication repair deficiency.

Cancers arising from germline DNA mismatch repair deficiency or polymerase proofreading deficiency (MMRD and PPD) in children harbour the highest mutational and microsatellite insertion-deletion (MS-indel) burden in humans. MMRD and PPD cancers are commonly lethal due to the inherent resistance to chemo-irradiation. Although immune checkpoint inhibitors (ICIs) have failed to benefit children in previous studies, we hypothesized that hypermutation caused by MMRD and PPD will improve outcomes following ICI treatment in these patients. Using an international consortium registry study, we report on the ICI treatment of 45 progressive or recurrent tumors from 38 patients. Durable objective responses were observed in most patients, culminating in a 3 year survival of 41.4%. High mutation burden predicted response for ultra-hypermutant cancers (>100 mutations per Mb) enriched for combined MMRD + PPD, while MS-indels predicted response in MMRD tumors with lower mutation burden (10-100 mutations per Mb). Furthermore, both mechanisms were associated with increased immune infiltration even in 'immunologically cold' tumors such as gliomas, contributing to the favorable response. Pseudo-progression (flare) was common and was associated with immune activation in the tumor microenvironment and systemically. Furthermore, patients with flare who continued ICI treatment achieved durable responses. This study demonstrates improved survival for patients with tumors not previously known to respond to ICI treatment, including central nervous system and synchronous cancers, and identifies the dual roles of mutation burden and MS-indels in predicting sustained response to immunotherapy.

Tramadol Treatment for Chemotherapy-induced Mucositis Pain in Children.

Mucositis, a painful and debilitating condition, is a common side effect of chemotherapy. The role of tramadol in the treatment of mucositis in pediatric patients has not yet been determined. In this retrospective study, we evaluate whether tramadol as single agent achieved a reduction of pain intensity among oncologic children admitted for mucositis. In total, 34 of 54 (63%) episodes were treated with tramadol alone and achieved adequate pain relief. Tramadol's side effects were mild and manageable.

Survival Benefit for Individuals With Constitutional Mismatch Repair Deficiency Undergoing Surveillance.

PURPOSE: Constitutional mismatch repair deficiency syndrome (CMMRD) is a lethal cancer predisposition syndrome characterized by early-onset synchronous and metachronous multiorgan tumors. We designed a surveillance protocol for early tumor detection in these individuals. PATIENTS AND METHODS: Data were collected from patients with confirmed CMMRD who were registered in the International Replication Repair Deficiency Consortium. Tumor spectrum, efficacy of the surveillance protocol, and malignant transformation of low-grade lesions were examined for the entire cohort. Survival outcomes were analyzed for patients followed prospectively from the time of surveillance implementation. RESULTS: A total of 193 malignant tumors in 110 patients were identified. Median age of first cancer diagnosis was 9.2 years (range: 1.7-39.5 years). For patients undergoing surveillance, all GI and other solid tumors, and 75% of brain cancers were detected asymptomatically. By contrast, only 16% of hematologic malignancies were detected asymptomatically (P < .001). Eighty-nine patients were followed prospectively and used for survival analysis. Five-year overall survival (OS) was 90% (95% CI, 78.6 to 100) and 50% (95% CI, 39.2 to 63.7) when cancer was detected asymptomatically and symptomatically, respectively (P = .001). Patient outcome measured by adherence to the surveillance protocol revealed 4-year OS of 79% (95% CI, 54.8 to 90.9) for patients undergoing full surveillance, 55% (95% CI, 28.5 to 74.5) for partial surveillance, and 15% (95% CI, 5.2 to 28.8) for those not under surveillance (P < .0001). Of the 64 low-grade tumors detected, the cumulative likelihood of transformation from low-to high-grade was 81% for GI cancers within 8 years and 100% for gliomas in 6 years. CONCLUSION: Surveillance and early cancer detection are associated with improved OS for individuals with CMMRD.

MRI-based diagnosis and treatment of pediatric brain tumors: is tissue sample always needed?

Traditional management of newly diagnosed pediatric brain tumors (PBTs) consists of cranial imaging, typically magnetic resonance imaging (MRI), and is frequently followed by tissue diagnosis, through either surgical biopsy or tumor resection. Therapy regimes are typically dependent on histological diagnosis. To date, many treatment regimens are based on molecular biology. The scope of this article is to discuss the role of diagnosis and further treatment of PBTs based solely on MRI features, in light of the latest treatment protocols. Typical MRI findings and indications for surgical biopsy of these lesions are described.

Pineal region tumors: an entity with crucial anatomical nuances.

PURPOSE: Intra-axial "pineal region" tumors include pineal, tectal, and aqueductal tumors. All three tumor subgroups cause obstruction of the aqueduct; however, they differ in radiological nuances, pathology, differential diagnosis, and treatment. The goal of this manuscript is to describe the radiological, clinical, and pathological nuances that differentiate between these subgroups. METHODS: All patients with intra-axial pineal region tumors were analyzed retrospectively, including demographics, radiological characteristics, pathology, treatment, and outcome. RESULTS: Forty-nine patients (1-69 years of age) were included: 19 pineal, 10 tectal, 10 aqueductal, 4 periaqueductal, and 6 complex. The 3 main subgroups differed in various radiological and anatomical nuances. Age and gender did not differ between groups. Other factors that did not differ between groups included T1 and T2 signals, presence of blood products, a normally located (non-displaced) tectum, anterior tectal displacement, thalamic involvement, and presence of hydrocephalus. The pathological spectrum differed between the 3 main subgroups, as well as the surgical treatment, and outcome. CONCLUSIONS: Despite sharing a close anatomical location, as well as all causing obstruction of the aqueduct with secondary hydrocephalus, the differential diagnosis, diagnostic methods, and possible treatment and surgical options differ between the various subgroups. Anatomical nuances are described to better delineate the various tumor subgroups and recommend specific treatment approaches.

Mesothelioma in children and adolescents: the European Cooperative Study Group for Pediatric Rare Tumors (EXPeRT) contribution.

INTRODUCTION: Very little is known about the characteristics of mesothelial tumours in the paediatric population. In adults with malignant mesothelioma, the pemetrexed-based regimen with cytoreductive surgery (CRS) is a standard of care in limited tumours, but long-term survival is uncommon. MATERIAL AND METHODS: The European Cooperative Study Group on Pediatric Rare Tumors (EXPeRT) retrospectively reviewed children, adolescents and young adults (≤21 year) diagnosed with mesothelial tumours treated between 1987 and 2018. RESULTS: Thirty-three patients were identified, 15 male and 18 female patients. One patient's exposure to asbestos was documented. Primary tumour was mainly in the peritoneum (23 patients). Histology was multicystic mesothelioma of the peritoneum (MCM) (six patients) or malignant mesothelioma (MM) (27 patients). Among MM, the first-line treatment comprised preoperative chemotherapy (14 cases), surgery only (three cases), chemotherapy only (five cases), adjuvant chemotherapy (three cases) or palliative treatment (two cases). The response rate to cisplatin-pemetrexed was 50% (6/12 cases). CRS with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) was performed in 19 patients (upfront in three, after neoadjuvant therapy in 12, or after tumour progression in six patients, including three twice). After a median follow-up of 6.7 years (range, 0-20), five-year overall and event-free survivals were 82.3% (95% CI, confidential interval ((CI), 67.8-99.9) and 45.1% (95% CI, 28.4-71.7), respectively. All patients with MCM are alive after surgery (five patients) and CRS-HIPEC (one patient). CONCLUSIONS: Paediatric mesothelioma is exceptional and seems to be different from its adult counterpart with few asbestos exposures, more peritoneal primary, and a better outcome. The cisplatin-pemetrexed regimen showed promising efficacy. Relapses could be salvaged with active therapy including CRS-HIPEC.

Functional Repair Assay for the Diagnosis of Constitutional Mismatch Repair Deficiency From Non-Neoplastic Tissue.

PURPOSE: Constitutional mismatch repair deficiency (CMMRD) is a highly penetrant cancer predisposition syndrome caused by biallelic mutations in mismatch repair (MMR) genes. As several cancer syndromes are clinically similar, accurate diagnosis is critical to cancer screening and treatment. As genetic diagnosis is confounded by 15 or more pseudogenes and variants of uncertain significance, a robust diagnostic assay is urgently needed. We sought to determine whether an assay that directly measures MMR activity could accurately diagnose CMMRD. PATIENTS AND METHODS: In vitro MMR activity was quantified using a 3'-nicked G-T mismatched DNA substrate, which requires MSH2-MSH6 and MLH1-PMS2 for repair. We quantified MMR activity from 20 Epstein-Barr virus-transformed lymphoblastoid cell lines from patients with confirmed CMMRD. We also tested 20 lymphoblastoid cell lines from patients who were suspected for CMMRD. We also characterized MMR activity from patients with neurofibromatosis type 1, Li-Fraumeni syndrome, polymerase proofreading-associated cancer syndrome, and Lynch syndrome. RESULTS: All CMMRD cell lines had low MMR activity (n = 20; mean, 4.14 ± 1.56%) relative to controls (n = 6; mean, 44.00 ± 8.65%; P < .001). Repair was restored by complementation with the missing protein, which confirmed MMR deficiency. All cases of patients with suspected CMMRD were accurately diagnosed. Individuals with Lynch syndrome (n = 28), neurofibromatosis type 1 (n = 5), Li-Fraumeni syndrome (n = 5), and polymerase proofreading-associated cancer syndrome (n = 3) had MMR activity that was comparable to controls. To accelerate testing, we measured MMR activity directly from fresh lymphocytes, which yielded results in 8 days. CONCLUSION: On the basis of the current data set, the in vitro G-T repair assay was able to diagnose CMMRD with 100% specificity and sensitivity. Rapid diagnosis before surgery in non-neoplastic tissues could speed proper therapeutic management.

Significant correlation between peripheral blood CD34+ cell count in children prior to aphaeresis and CD34+ cell yield following aphaeresis: A single-center experience.

Numerous adults' studies demonstrated that preaphaeresis CD34+ cells significantly correlate with the number of CD34+ cells collected by the aphaeresis procedure. Equivalent studies in children are scarce. We studied retrospectively 92 aphaeresis procedures performed following chemotherapy (44) or in steady state (48) in 60 pediatric patients (40 males, 20 females), median age of 7.5 years. Aphaeresis procedures were performed using a SPECTRA Optica (TERUMOBCT) continuous flow cell separator. CD34+ cell concentrations were assessed using flow cytometry. A highly significant correlation between peripheral CD34 cell count on the day of aphaeresis and CD34 cell yield per kg (R2  = .824, P < .0001) was demonstrated. A higher preaphaeresis CD34 cell count was demonstrated in patients with higher preaphaeresis white blood cell count, in patients with brain tumors, and in patients who received chemotherapy as part of their mobilization protocol. A threshold number of 20 peripheral CD34+ cell/µL was found to predict harvesting of 3 × 106 stem cells/kg, and 30 peripheral CD34+ cell/µL for harvesting of 5 × 106 stem cells/kg. This significant correlation between peripheral CD34 cell count and CD34 cell yield, and the threshold number of peripheral CD34 found to predict adequate harvesting can be useful in planning the optimal time for aphaeresis in children.

Lessons From an Outbreak of Varicella Infection in Pediatric Hemato-oncology Patients.

BACKGROUND: Immunocompromised patients exposed to varicella may experience significant morbidity and a 7% mortality rate. Management and outcome of an outbreak of varicella infection among hospitalized pediatric hemato-oncology patients using the guidelines of the American Academy of Pediatrics Committee on Infectious Diseases are presented. METHODS: This retrospective study describes an outbreak of varicella infection between February 2011 and June 2011. Data were retrieved from the patients' files. Positive polymerase chain reaction results for varicella zoster virus from vesicular skin lesions were used for the diagnosis of varicella infection. RESULTS: Twelve pediatric hemato-oncology patients experienced 13 episodes of varicella infection, 11 underwent 1 episode each and 1 patient had 2 episodes. All exposed patients without immunity received varicella zoster immune globulins or intravenous immunoglobulin and were isolated as recommended by the guidelines. Infected patients received intravenous acyclovir. One patient with acute lymphoblastic leukemia at induction chemotherapy died. All the other patients survived. CONCLUSIONS: Our experience in the management of hospitalized immunocompromised patients exposed to varicella was that a positive IgG serology did not confer protection after exposure to varicella infection and thus can not serve as a marker for immunity. Unlike the isolation period sufficient for immunocompetent patients, crusted lesions can be contagious and thus require extended isolation for immunocompromised patients. Patients receiving rituximab are at greater risk of having persistent or recurrent disease. Studies with a larger sample size should be performed to better assess the management of immunocompromized patients exposed to varicella.

Preliminary results of immune modulating antibody MDV9300 (pidilizumab) treatment in children with diffuse intrinsic pontine glioma.

Diffuse intrinsic pontine glioma (DIPG) is an incurable disease with a median overall survival of 10 months. Immune modulating antibodies have recently emerged as a highly promising treatment modality in multiple cancer types. We present results from the first study to evaluate the immune modulating antibody MDV9300 (pidilizumab) in pediatric patients with DIPG. All patients aged 3 years and older, diagnosed with DIPG between February 2014 and June 2015 in Israel, were offered to participate in the study. Enrolled patients were started on biweekly 6 mg/kg MDV9300 after radiation completion. Treatment was continued until disease progression on imaging. Patients were followed biweekly for the occurrence of neurological deficit toxicities and side effects. Secondary endpoints were event free survival and overall survival. Of 13 children diagnosed with DIPG during the study period, nine were enrolled in the study. The patients underwent radiotherapy and none had chemotherapy. A total of 83 cycles of MDV9300 (range 2-16) were applied. The main side effects were neutropenia (CTCAE grade 1-3), mild to moderate fatigue, and acute elevation of blood pressure. Four patients died within 1 year of the diagnosis, another three died within 2 years and two children are still alive nearly 30 months from diagnosis, with stable disease. The median event free survival is 9.3 months (range 6.8-24) and the median overall survival is 15.6 months (range 6.9-28). Preliminary results demonstrate that MDV9300 treatment is safe and may be effective in the treatment of children with DIPG.

Comprehensive Analysis of Hypermutation in Human Cancer.

We present an extensive assessment of mutation burden through sequencing analysis of >81,000 tumors from pediatric and adult patients, including tumors with hypermutation caused by chemotherapy, carcinogens, or germline alterations. Hypermutation was detected in tumor types not previously associated with high mutation burden. Replication repair deficiency was a major contributing factor. We uncovered new driver mutations in the replication-repair-associated DNA polymerases and a distinct impact of microsatellite instability and replication repair deficiency on the scale of mutation load. Unbiased clustering, based on mutational context, revealed clinically relevant subgroups regardless of the tumors' tissue of origin, highlighting similarities in evolutionary dynamics leading to hypermutation. Mutagens, such as UV light, were implicated in unexpected cancers, including sarcomas and lung tumors. The order of mutational signatures identified previous treatment and germline replication repair deficiency, which improved management of patients and families. These data will inform tumor classification, genetic testing, and clinical trial design.

Intracystic interferon-alpha in pediatric craniopharyngioma patients: an international multicenter assessment on behalf of SIOPE and ISPN.

BACKGROUND: Craniopharyngiomas are frequent hypothalamo-pituitary tumors in children, presenting predominantly as cystic lesions. Morbidity from conventional treatment has focused attention on intracystic drug delivery, hypothesized to cause fewer clinical consequences. However, the efficacy of intracystic therapy remains unclear. We report the retrospective experiences of several global centers using intracystic interferon-alpha. METHODS: European Société Internationale d'Oncologie Pédiatrique and International Society for Pediatric Neurosurgery centers were contacted to submit a datasheet capturing pediatric patients with cystic craniopharyngiomas who had received intracystic interferon-alpha. Patient demographics, administration schedules, adverse events, and outcomes were obtained. Progression was clinical or radiological (cyst reaccumulation, novel cysts, or solid growth). RESULTS: Fifty-six children (median age, 6.3 y) from 21 international centers were identified. Median follow-up from diagnosis was 5.1 years (0.3-17.7 y). Lesions were cystic (n = 22; 39%) or cystic/solid (n = 34; 61%). Previous progression was treated in 43 (77%) patients before interferon use. In such cases, further progression was delayed by intracystic interferon compared with the preceding therapy for cystic lesions (P = 0.0005). Few significant attributable side effects were reported. Progression post interferon occurred in 42 patients (median 14 mo; 0-8 y), while the estimated median time to definitive therapy post interferon was 5.8 (1.8-9.7) years. CONCLUSIONS: Intracystic interferon-alpha can delay disease progression and potentially offer a protracted time to definitive surgery or radiotherapy in pediatric cystic craniopharyngioma, yet demonstrates a favorable toxicity profile compared with other therapeutic modalities-important factors for this developing age group. A prospective, randomized international clinical trial assessment is warranted.

Combined plerixafor and granulocyte colony-stimulating factor for harvesting high-dose hematopoietic stem cells: Possible niche for plerixafor use in pediatric patients.

PB is a source of HSC, especially for autologous HCT in solid tumors. However, there is a risk of failing to achieve the target number of SC after mobilization with growth factors alone in patients who were heavily pretreated with chemotherapy or those in need for tandem transplants. SC were harvested from seven pediatric patients with solid tumors who were in need of autologous HCT following combination GCSF and plerixafor. Six of them received plerixafor after failing to achieve enough SC with GCSF only, while the seventh patient received the combined protocol upfront. All seven patients achieved the target number of SC according to their treatment protocol. There were no adverse events. All patients underwent autologous HCT using the harvested HSC and achieved full engraftment. A protocol for harvesting autologous HCT using GCSF and plerixafor is feasible and safe in children with solid tumors who had been heavily pretreated with chemotherapy or needed tandem transplants.

Immune Checkpoint Inhibition for Hypermutant Glioblastoma Multiforme Resulting From Germline Biallelic Mismatch Repair Deficiency.

PURPOSE: Recurrent glioblastoma multiforme (GBM) is incurable with current therapies. Biallelic mismatch repair deficiency (bMMRD) is a highly penetrant childhood cancer syndrome often resulting in GBM characterized by a high mutational burden. Evidence suggests that high mutation and neoantigen loads are associated with response to immune checkpoint inhibition. PATIENTS AND METHODS: We performed exome sequencing and neoantigen prediction on 37 bMMRD cancers and compared them with childhood and adult brain neoplasms. Neoantigen prediction bMMRD GBM was compared with responsive adult cancers from multiple tissues. Two siblings with recurrent multifocal bMMRD GBM were treated with the immune checkpoint inhibitor nivolumab. RESULTS: All malignant tumors (n = 32) were hypermutant. Although bMMRD brain tumors had the highest mutational load because of secondary polymerase mutations (mean, 17,740 ± standard deviation, 7,703), all other high-grade tumors were hypermutant (mean, 1,589 ± standard deviation, 1,043), similar to other cancers that responded favorably to immune checkpoint inhibitors. bMMRD GBM had a significantly higher mutational load than sporadic pediatric and adult gliomas and all other brain tumors (P < .001). bMMRD GBM harbored mean neoantigen loads seven to 16 times higher than those in immunoresponsive melanomas, lung cancers, or microsatellite-unstable GI cancers (P < .001). On the basis of these preclinical data, we treated two bMMRD siblings with recurrent multifocal GBM with the anti-programmed death-1 inhibitor nivolumab, which resulted in clinically significant responses and a profound radiologic response. CONCLUSION: This report of initial and durable responses of recurrent GBM to immune checkpoint inhibition may have implications for GBM in general and other hypermutant cancers arising from primary (genetic predisposition) or secondary MMRD.

Gastrointestinal Findings in the Largest Series of Patients With Hereditary Biallelic Mismatch Repair Deficiency Syndrome: Report from the International Consortium.

OBJECTIVES: Hereditary biallelic mismatch repair deficiency (BMMRD) is caused by biallelic mutations in the mismatch repair (MMR) genes and manifests features of neurofibromatosis type 1, gastrointestinal (GI) polyposis, and GI, brain, and hematological cancers. This is the first study to characterize the GI phenotype in BMMRD using both retrospective and prospective surveillance data. METHODS: The International BMMRD Consortium was created to collect information on BMMRD families referred from around the world. All patients had germline biallelic MMR mutations or lack of MMR protein staining in normal and tumor tissue. GI screening data were obtained through medical records with annual updates. RESULTS: Thirty-five individuals from seven countries were identified with BMMRD. GI data were available on 24 of 33 individuals (73%) of screening age, totaling 53 person-years. The youngest age of colonic adenomas was 7, and small bowel adenoma was 11. Eight patients had 19 colorectal adenocarcinomas (CRC; median age 16.7 years, range 8-25), and 11 of 18 (61%) CRC were distal to the splenic flexure. Eleven patients had 15 colorectal surgeries (median 14 years, range 9-25). Four patients had five small bowel adenocarcinomas (SBC; median 18 years, range 11-33). Two CRC and two SBC were detected during surveillance within 6-11 months and 9-16 months, respectively, of last consecutive endoscopy. No patient undergoing surveillance died of a GI malignancy. Familial clustering of GI cancer was observed. CONCLUSIONS: The prevalence and penetrance of GI neoplasia in children with BMMRD is high, with rapid development of carcinoma. Colorectal and small bowel surveillance should commence at ages 3-5 and 8 years, respectively.

Management of Acute Myeloblastic Leukemia in a Child With Biallelic Mismatch Repair Deficiency.

Germline biallelic mismatch repair deficiency (bMMRD) results in a unique cancer predisposition syndrome in which the affected children are susceptible to the development of malignancies, especially brain, gastrointestinal, and lymphoid cancers. Acute myeloblastic leukemia is rarely reported in this syndrome. Here we report the decision-making challenges in a bMMRD child with acute myeloblastic leukemia. Our experience should alert physicians to include bMMRD in the differential diagnosis of a child with hyper/hypopigmented spots and leukemia. Furthermore, the presence of the above and consanguinity emphasizes the need to rule out bMMRD when an allogeneic bone marrow transplant is considered and to enable the surveillance of other family members for earlier detection of cancers in these children.

The effect of chemotherapy on optic pathway gliomas and their sub-components: A volumetric MR analysis study.

BACKGROUND: Optic pathway gliomas (OPG) represent 5% of pediatric brain tumors and compose a major therapeutic dilemma to the treating physicians. While chemotherapy is widely used for these tumors, our ability to predict radiological response is still lacking. In this study, we use volumetric imaging to examine in detail the long-term effect of chemotherapy on the tumor as well as its various sub-components. PROCEDURE: The tumors of 15 patients with OPG, treated with chemotherapy, were longitudinally measured using our novel, previously described volumetric method. Patients were treated with up to five lines of chemotherapy. Sufficient follow-up imaging data, and patient's numbers, allowed for analysis of two treatment lines. Volumetric measurements of the tumors were segmented into solid-non-enhancing, solid-enhancing, and cystic components. Outcome analysis was done per specific treatment line and for the overall follow-up period. RESULTS: An average reduction of 9.7% (±23%) in the gross-total-solid volume (GTSV) was noted following treatment with vincristine and carboplatin. The cystic component grew under therapy by an average of 12.6% (±39%). When measured over the course of the whole study period, the cystic component grew by an average of 35% (±100%) and the GTSV increased by 12% (±35%). CONCLUSION: Initial treatment with vincristine and carboplatin seems to have a minimal initial effect, mostly on the solid components. The cystic component in itself seems to be unaffected by chemotherapy, and contributes to the subsequent growth of the total volume. During the overall treatment period, both solid and cystic components grew regardless of combined treatment methods.