Ronit Elhasid

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

PURPOSEnRecurrent 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.nnnPATIENTS AND METHODSnWe 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.nnnRESULTSnAll 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.nnnCONCLUSIONnThis 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.

Combined hereditary and somatic mutations of replication error repair genes result in rapid onset of ultra-hypermutated cancers

DNA replication−associated mutations are repaired by two components: polymerase proofreading and mismatch repair. The mutation consequences of disruption to both repair components in humans are not well studied. We sequenced cancer genomes from children with inherited biallelic mismatch repair deficiency (bMMRD). High-grade bMMRD brain tumors exhibited massive numbers of substitution mutations (>250/Mb), which was greater than all childhood and most cancers (>7,000 analyzed). All ultra-hypermutated bMMRD cancers acquired early somatic driver mutations in DNA polymerase ɛ or δ. The ensuing mutation signatures and numbers are unique and diagnostic of childhood germ-line bMMRD (P < 10−13). Sequential tumor biopsy analysis revealed that bMMRD/polymerase-mutant cancers rapidly amass an excess of simultaneous mutations (∼600 mutations/cell division), reaching but not exceeding ∼20,000 exonic mutations in <6 months. This implies a threshold compatible with cancer-cell survival. We suggest a new mechanism of cancer progression in which mutations develop in a rapid burst after ablation of replication repair.

Prophylactic therapy with enoxaparin during L-asparaginase treatment in children with acute lymphoblastic leukemia.

Forty-one consecutive children with acute lymphoblastic leukemia (ALL) received prophylaxis therapy with the low molecular weight heparin (LMWH) enoxaparin during l-asparaginase treatment. Enoxaparin was given every 24 h subcutaneously at a median dose of 0.84 mg/kg per day (range, 0.45–1.33 mg/kg per day) starting at the first dose of l-asparaginase until 1 week after the last dose. Molecular analysis for thrombophilic polymorphisms documented prothrombin G20210A mutation in 3/27 (11%), homozygosity for MTHFR C677T mutation in 5/27 (18.5%, and heterozygosity for factor V Leiden mutation in 5/27 (18.5%) children. There were no thrombotic events during 76 courses of l-asparaginase in 41 patients who had received enoxaparin. One patient suffered brain infarct 7 days after enoxaparin was stopped. There were no bleeding episodes. In a historical control group of 50 ALL children who had not received prophylactic enoxaparin during l-asparaginase treatment, two had thromboembolisms (one deep vein thrombosis and one pulmonary embolism). Enoxaparin is safe and seems to be effective in prevention of thromboembolism in ALL patients during l-asparaginase therapy. This study provides pilot data for a future randomized trial of the use of LMWH during ALL therapy for the prevention of asparaginase-associated thrombotic events.

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 ofxa0patients and families. These data will inform tumor classification, genetic testing, and clinical trial design.

Central Nervous System Involvement in Children with Sarcoma

Objectives: To summarize and analyze the experience in CNS involvement (CNSI) in children with sarcomas treated in the above-mentioned institutions. Patients and Methods: From 1990 to 2001, all medical charts were retrospectively reviewed: 19 sarcoma patients (12 boys and 7 girls) were diagnosed with CNSI (4 osteogenic sarcomas, 11 Ewing sarcomas, 2 rhabdomyosarcomas, 1 alveolar soft part sarcoma and 1 mesenchymal chondrosarcoma). Mean age of all patients at the time of initial diagnosis was 14.9 years (range: 4–24 years), mean age at the time when CNSI was diagnosed was 16.9 years (range: 5.5–27 years). Results: The frequency of CNSI among our patients was 6.17%. The following symptoms and signs (sometimes combined) presented: headache (10 patients), nausea and vomiting (6 patients), seizures (11 patients) and focal neurological signs (9 patients). The mean duration of time elapsed since diagnosis of CNSI till death or last follow-up was 5.2 months (SD: ±5.7 months). Four patients received chemotherapy (CT) alone, 8 CT and radiotherapy (RT), 2 RT alone, 3 supportive treatment only, 1 CT and surgery and 1 surgery alone. Sixteen patients died; there was no significant difference in the duration of survival between those who were treated with RT or surgery (mean ± SD: 6.77 ± 6.56 months) and those who received only CT or supportive treatment (mean ± SD: 2.60 ± 2.94 months) (p = 0.07). Brain disease was the main cause of death in all but 1 patient who died 4 days after autologous bone marrow transplantation from uncontrolled sepsis. In 16 patients, CNSI was part of a metastatic disease. Conclusions: Among children with sarcoma, CNSI is encountered in 6.17% of cases. More effective therapy has to be developed in order to improve their outcome.

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.

Therapeutic monitoring of busulfan in pediatric bone marrow transplantation.

The aim of this study was to describe busulfan disposition in a pediatric population who underwent bone marrow transplantation (BMT). Busulfan administered dose was 1 mg/kg every 6 h for 4 days. Plasma determinations were performed after the first dosing at 0, 15, 30, 60, 90, 120, 180, 240, 300, and 360 min. A noncompartment analysis model for extra vascular absorption was used for the pharmacokinetic analysis. To obtain the area under the concentration-timecurve (AUC) within the therapeutic window of 1000-1200 w M 2 minutes a busulfan dose adjustment was performed at the fourth dose. Forty-five busulfan pharmacokinetic analyses were performed in 34 children. Eleven children had their dose adjusted [1.19 ( - 0.14) mg/kg] at the fourth dose and the AUC was monitored at the fifth one. The mean AUC - SD after the fifth dose (998.1 - 189.2 w M 2 min) was different (p = .006) from that after the first dose (1 mg/kg) (687.63 - 166.43 w M 2 min). Six children had their first AUC into the therapeutic window, 17 children had their dose adjusted [1.2 ( - 0.22) mg/kg], but the adjusted AUC was not available. These data suggest that it may be reasonable to recommend a busulfan dose of 1.2 mg/kg to achieve the accepted therapeutic target in children undergoing BMT.

Prompt recovery of recipient hematopoiesis after two consecutive haploidentical peripheral blood SCTs in a child with leukocyte adhesion defect III syndrome.

Prompt recovery of recipient hematopoiesis after two consecutive haploidentical peripheral blood SCTs in a child with leukocyte adhesion defect III syndrome

Policies Designed to Enhance the Quality of Life of Children with Cancer at the End-of-Life

This study evaluated preventive intervention designed to enhance the quality of life of children with cancer at the end-of-life, based on a theoretical model of crises denoted as the Perceived Personal Control Crisis Model. Preventive intervention on the Social Action level consists of introducing policies and services in the pediatric hemato-oncology department designed to enhance the quality of life of children with cancer at the end-of-life.

Glutathione S -transferase T1-null seems to be associated with graft failure in hematopoietic SCT

Hematopoietic SCT (HSCT) from HLA-matched donors is sometimes complicated by GVHD or graft rejection, because of mismatched mHA. This study presents data suggesting the involvement of glutathione S-transferase theta-1 (GSTT1), a phase II detoxifying enzyme encoded by GSTT1, in Ab-mediated rejection of HSCT in children with congenital hemoglobinopathies (CHs). Mismatch of GSTT1, which often features a deletion polymorphism variant, can have major consequences in solid organ transplantation outcome. In liver transplantation, it has been shown to lead to de novo hepatitis, whereas in kidney transplantation, chronic allograft rejection has been documented. In this study on 18 children with CH who underwent HSCT, five cases of graft rejection occurred, all in GSTT1-null patients, four of which featured anti-GSTT1 antibodies. The data suggest that when GSTT1-null patients are transplanted with a GSTT1-positive graft, rejection due to an Ab-mediated immune response against GSTT1 displayed on transplanted stem cells may take place. Thus, it seems that detection of anti-GSTT1 antibodies in patients with a GSTT1-null genotype before transplantation may be predictive of graft rejection in the event of a GSTT1-positive donor.