Methyl-guanine-methyl-transferase transgenic bone marrow transplantation allows N, N-bis (2-chloroethyl)-nitrosourea driven donor mixed-chimerism without graft-versus-host disease, and with donor-specific allograft tolerance

Background: Transplant tolerance has been achieved by mixed chimerism in animal models and in a limited number of kidney transplant patients. However, these mixed-chimerism strategies were limited either by loss of long-term mixed chimerism or risk of graft-versus-host disease (GVHD). Selective bone marrow (BM) engraftment using marrow protective strategies are currently reaching clinical use. In this study, we tested the utility of methyl-guanine-methyl-transferase (MGMT)-transgenic-C57BL/6 BM into a major histocompatibility complex mismatched-BALB/c model followed by N,N-bis(2-chloroethyl)-nitrosourea (BCNU) treatment to enhance donor-cell engraftment and then evaluated transplant tolerance induction. Methods: A single-dose of anti-CD8 antibody and busulfan was administered into BALB/c-host-mice at day 1. The BALB/c-mice also received costimulatory blockade through multiple-doses of anti-CD40L antibody. 10 x 106 BM-cells from MGMT-transgenic-mice were transplanted into host BALB/c mice at day 0. The BCNU was administered at 4 time points after BM transplantation (BMT). Heterotopic donor C57BL/6 cardiac allografts were performed at day 243 after BMT. Skin transplantation with third-party CBA, host BALB/c and donor C57BL/6 grafts was performed at day 358 after BMT. Results: The BALB/c-mice showed long-term stable and high-level donor-cell engraftment with MGMT transgenic C57BL/6 BMT after BCNU treatment, demonstrating full reconstitution and donor cardiac-allograft tolerance and no GVHD with expanded donor and host Foxp3+ T regulatory cells. Further, skin grafts from donor, host, and third party showed good immune function with rejection of third-party grafts from all mice and benefit from enhanced chimerism after BCNU with less cell infiltrate and no chronic rejection in the donor skin grafts of BCNU treated mice compared no BCNU treated mice. Conclusions: High-level mixed chimerism without GVHD can be achieved using MGMT transgenic BM in a mixed-chimerism model receiving BCNU across a major histocompatibility complex mismatch. Enhanced mixed chimerism leads to long-term donor-specific allograft tolerance

Biological medicines for diffuse intrinsic pontine glioma (DIPG) eradication (BIOMEDE): Final results of an international randomized phase II platform trial comparing 3 targeted therapies in combination with radiotherapy from ITCC, SIOPE-Brain and ANZCHOG.

International audience10003 Background: DIPG is the most aggressive brain cancer in children and adolescents with a median survival of 9 months. Surgery is not possible due to the invasive nature of the disease in a critical area of the brain; only radiotherapy has shown a transient palliative effect on disease progression and no adjuvant therapy has proven to increase disease control. Methods: We launched a large randomized biomarker-driven platform trial to compare three targeted therapies (erlotinib, everolimus and dasatinib) in combination with 54 Gy radiotherapy, in newly diagnosed patients with DIPG (NCT02233049). A central pathological review was performed prior to study entry to confirm the diagnosis of DIPG with H3K27me3 loss (with or without H3K27M mutation) and assess biomarkers. The randomization was designed so that a drug could not be allocated if the corresponding biomarker was absent in the tumor (EGFR overexpression for erlotinib, mTOR activation for everolimus, no specific biomarker for dasatinib). Tumors underwent whole genome sequencing and RNAseq to evaluate prognostic and theranostic biomarkers. Primary endpoint was overall survival. Results: Among the 279 DIPG patients screened for the randomized trial between October 2014 and September 2019, 233 were enrolled in 45 centers in 7 countries; among the 46 screen failures, the diagnosis of DIPG could not be confirmed in 23 patients. No biopsy- or treatment-related death was reported. Serious adverse events > = 3 unrelated to disease progression were reported in 40% of patients, 34%, 36% and 46%, in the erlotinib, everolimus and dasatinib arms, respectively (p = 0.32). With a median follow-up of 5.3 years, median overall survival (OS) from the date of randomization was 9.0 (95% confidence interval, 7.4-14.4), 11.3 (10.3-13.4) and 9.4 (7.7-10.7) months for erlotinib, everolimus and dasatinib, respectively (p = 0.45). OS were not statistically different from those of a historical biopsy-proven cohort. The molecular profiling with copy number aberrations (CNA) had a strong impact on survival (log-rank test, p = 0.0001) as shown by the preliminary analysis of the first hundred patients identifying a group of tumors with very poor prognosis with a HR for death of 1.96 (1.07-3.64) characterized by TP53 mutations (p = 3.05e-11) associated with more CNA (p < 0.0001). Conclusions: This trial demonstrated the feasibility and safety of a large randomized trial for DIPG based on biomarker information from a stereotactic biopsy at diagnosis in an international multicenter setting and generated new tumor biological insights to further develop innovative therapies. Clinical trial information: NCT02233049

Molecular classification and outcome of children with rare CNS embryonal tumors: results from St. Jude Childrens Research Hospital including the multi-center SJYC07 and SJMB03 clinical trials.

Methylation profiling has radically transformed our understanding of tumors previously called central nervous system primitive neuro-ectodermal tumors (CNS-PNET). While this marks a momentous step toward defining key differences, reclassification has thrown treatment into disarray. To shed light on response to therapy and guide clinical decision-making, we report outcomes and molecular features of children with CNS-PNETs from two multi-center risk-adapted studies (SJMB03 for patients ≥ 3&nbsp;years; SJYC07 for patients &lt; 3&nbsp;years) complemented by a non-protocol institutional cohort. Seventy patients who had a histological diagnosis of CNS-PNET or CNS embryonal tumor from one of the new categories that has supplanted CNS-PNET were included. This cohort was molecularly characterized by DNA methylation profiling (n = 70), whole-exome sequencing (n = 53), RNA sequencing (n = 20), and germline sequencing (n = 28). Clinical characteristics were detailed, and treatment was divided into craniospinal irradiation (CSI)-containing (SJMB03 and SJMB03-like) and CSI-sparing therapy (SJYC07 and SJYC07-like). When the cohort was analyzed in its entirety, no differences were observed in the 5-year survival rates even when CSI-containing therapy was compared to CSI-sparing therapy. However, when analyzed by DNA methylation molecular grouping, significant survival differences were observed, and treatment particulars provided suggestions of therapeutic response. Patients with CNS neuroblastoma with FOXR2 activation (CNS-NB-FOXR2) had a 5-year event-free survival (EFS)/overall survival (OS) of 66.7% ± 19.2%/83.3% ± 15.2%, and CIC rearranged sarcoma (CNS-SARC-CIC) had a 5-year EFS/OS both of 57.1% ± 18.7% with most receiving regimens that contained radiation (focal or CSI) and multidrug chemotherapy. Patients with high-grade neuroepithelial tumor with BCOR alteration (HGNET-BCOR) had abysmal responses to upfront chemotherapy-only regimens (5-year EFS = 0%), but survival extended with salvage radiation after progression [5-year OS = 53.6% ± 20.1%]. Patients with embryonal tumor with multilayered rosettes (ETMR) or high-grade glioma/glioblastoma multiforme (HGG/GBM) did not respond favorably to any modality (5-year EFS/OS = 10.7 ± 5.8%/17.9 ± 7.2%, and 10% ± 9.0%/10% ± 9.0%, respectively). As an accompaniment, we have assembled this data onto an interactive website to allow users to probe and query the cases. By reporting on a carefully matched clinical and molecular cohort, we provide the needed insight for future clinical management