Khatua, Soumen

Abstract Background Diffuse Midline Glioma (DMG) with the H3K27M mutation is a lethal childhood brain cancer, with patients rarely surviving 2 years from diagnosis. Methods We conducted a multi-site Phase 1 trial of the imipridone ONC201 for children with H3K27M-mutant glioma (NCT03416530). Patients enrolled on Arm D of the trial (n = 24) underwent serial lumbar puncture for cell-free tumor DNA (cf-tDNA) analysis and patients on all arms at the University of Michigan underwent serial plasma collection. We performed digital droplet polymerase chain reaction (ddPCR) analysis of cf-tDNA samples and compared variant allele fraction (VAF) to radiographic change (maximal 2D tumor area on MRI). Results Change in H3.3K27M VAF over time (“VAF delta”) correlated with prolonged PFS in both CSF and plasma samples. Nonrecurrent patients that had a decrease in CSF VAF displayed a longer progression free survival (P = .0042). Decrease in plasma VAF displayed a similar trend (P = .085). VAF “spikes” (increase of at least 25%) preceded tumor progression in 8/16 cases (50%) in plasma and 5/11 cases (45.4%) in CSF. In individual cases, early reduction in H3K27M VAF predicted long-term clinical response (>1 year) to ONC201, and did not increase in cases of later-defined pseudo-progression. Conclusion Our work demonstrates the feasibility and potential utility of serial cf-tDNA in both plasma and CSF of DMG patients to supplement radiographic monitoring. Patterns of change in H3K27M VAF over time demonstrate clinical utility in terms of predicting progression and sustained response and possible differentiation of pseudo-progression and pseudo-response.

Abstract Background The study aimed to evaluate whether simplified chemotherapy followed by dose-reduced irradiation was effective for treating patients (ages 3–21 years) with localized germinoma. The primary endpoint was 3-year progression-free survival (PFS) rate. Methods Patients with a complete response to chemotherapy with carboplatin and etoposide received 18 Gy WVI + 12 Gy boost to the tumor bed. Patients with partial response proceeded to 24 Gy WVI + 12 Gy. Longitudinal cognitive functioning was evaluated prospectively on ALTE07C1 and was a primary study aim. Results One hundred and fifty-one patients were enrolled; 137 were eligible. Among 90 evaluable patients, 74 were treated with 18 Gy and 16 with 24 Gy WVI. The study failed to demonstrate noninferiority of the 18 Gy WVI regimen compared to the design threshold of 95% 3-year PFS rate, where, per design, patients who could not be assessed for progression at 3 years were counted as failures. The Kaplan-Meier (KM)-based 3-year PFS estimates were 94.5 ± 2.7% and 93.75 ± 6.1% for the 18 Gy and 24 Gy WVI cohorts, respectively. Collectively, estimated mean IQ and attention/concentration were within normal range. A lower mean attention score was observed at 9 months for patients treated with 24 Gy. Acute effects in processing speed were observed in the 18 Gy cohort at 9 months which improved at 30-month assessment. Conclusions While a failure according to the prospective statistical noninferiority design, this study demonstrated high rates of chemotherapy responses, favorable KM-based PFS and OS estimates in the context of reduced irradiation doses and holds promise for lower long-term morbidities for patients with germinoma.

Abstract Diffuse Intrinsic Pontine Glioma (DIPG) is an incurable pediatric brain tumor. An almost ubiquitous dominant negative mutation at lysine (K)-27 in genes encoding histone genes HIST1H3B and H3F3A found in patient tumors is a driver of DIPG development. ONC201, a small molecule DRD2 antagonist and ClpP agonist developed by Chimerix Inc, targets the unfolded protein response (UPR) and integrated stress response (ISR) signaling. It is under clinical investigation in patients with recurrent H3K27M DMGs. In adults, single agent studies have shown durable objective responses when administered orally. A multi-arm, non-randomized multi-institutional Phase I clinical trial (NCT03416530) for pediatric patients with H3K27M DMGs is open and accruing. Preliminary results suggest that the drug has a favorable safety profile and holds promise for patients with DIPGs and other midline gliomas. However, the mechanism of action of ONC201 against DIPGs warrants further study. Here, we show that ONC201 is cytotoxic to DIPGs in vitro and in vivo. RNA Seq analyses revealed cell context specific deployment of PERK-activated UPR and calcium signaling-associated RON tyrosine kinase-macrophage stimulating protein (MSP) signaling in DIPGs. Single cell proteomic assays revealed substantial heterogeneity in the sensitivity of DIPG cells to ONC201, and identified stem-like sub-populations of H3K27M DIPGs with intrinsic insensitivity to the drug. ONC201 treatment, which induces cellular stress, also sensitized DIPG cells to cytolytic activity by ex-vivo expanded and activated innate immune cells, in vitro. Ongoing in vivo experiments are expected to support a novel investigational study in patients with midline gliomas.

Abstract ONC201, an anti-cancer DRD2 antagonist and ClpP agonist, is in Phase II trials for adult H3 K27M-mutant diffuse midline gliomas. The recommended phase 2 dose (RP2D) of 625mg ONC201 once a week has been established as a biologically active dose that is well tolerated in adult and pediatric populations. Radiographic regressions with single agent ONC201 have been reported in recurrent H3 K27M-mutant glioma patients. In another study, twice/week dosing was explored in adult patients and deemed to be safe (no DLTs observed). This warranted exploration of twice/week dosing in pediatric patients and will be discussed in this presentation. This multi-arm, dose-escalation and dose-expansion trial (ONC014; NCT03416530) determined the pediatric RP2D of ONC201 administered once per week and twice per week on two consecutive days. ONC201 was orally administered and scaled by body weight. Dose escalation was performed by a 3 + 3 design beginning with two 125mg capsules less than the adult RP2D equivalent. Twelve children (8 females; 4 males) with H3 K27M-mutant gliomas (pons: 8; thalamus: 2; spinal cord: 2) aged 4-19 years have been treated post-radiation: 3 at dose level -1; 3 at dose level 1; 6 as part of the dose expansion cohort on dose level 2. Median KPS was 90 (range 70-100). One treatment cycle was 21 days (6 doses), which also defined the DLT window. Patients were on-treatment for a median length of 4 cycles (range: 2-11). Twice weekly dosing of ONC201 was tolerated well, as observed with weekly dosing, with no instance of DLT. A total of 4 SAEs were reported, none of which were related to the study drug. The most common AEs (regardless of relatedness) included headache, facial nerve disorder, abducens nerve disorder, nausea, fatigue and ataxia. Additional safety data, PK, and clinical outcomes from this arm will be reported.

AbstractBackgroundAdult medulloblastoma (MB) is rare, and management guidelines are largely based on pediatric clinical trials and retrospective series. Limited data exist with respect to clinical characteristics, prognostic factors, and outcomes based on first-line treatments.MethodsTwo hundred adults with MB seen at a single institution from January 1978 to April 2017 were identified and followed for a median of 8.4 y (7.1, 10.3).ResultsPatient’s median age at diagnosis was 29 y (18, 63). One hundred eleven (55.5%) were standard-risk, 59 (29.5%) were high-risk, and 30 (15.0%) were indeterminate. Most received post-operative radiation (RT) (184 [92.0%]), and 105 (52.5%) received first-line chemotherapy. Median overall survival (OS) was 8.8 y (7.2, 12.2) and median progression-free survival (PFS) was 6.6 y (4.9, 11.2). High-risk patients had inferior OS (Hazard ratio [HR] = 2.5 [1.5, 4.2], P = .0006) and PFS (HR = 2.3 [1.3, 3.9], P = .002) compared to standard-risk patients. Age, sex, and metastatic disease were not associated with survival. After adjusting for risk status, those who received RT plus adjuvant chemotherapy had superior PFS compared to RT plus neoadjuvant chemotherapy [HR = 0.46 (0.22, 0.95), P = .0357]. Within a subgroup for whom detailed clinical data were available, those who received RT plus adjuvant chemotherapy had improved PFS compared to RT only [HR = 0.24 (0.074–0.76), P = .016]. The substitution of cisplatin for carboplatin and the elimination of vincristine did not negatively affect outcomes.ConclusionThis is the largest single-institution retrospective study of adult MB to our knowledge and identifies standard-risk status, first-line RT and adjuvant chemotherapy as factors associated with improved outcomes.

Abstract INTRODUCTION Prospective studies for adult medulloblastoma (MB) are scarce and management guidelines are largely derived from pediatric experience and retrospective data. However, adult MB is a distinct disease for which limited data exist regarding clinical characteristic, prognostic factors, outcome based on upfront treatment, or patterns of recurrence. METHODS 200 patients (≥18 years at diagnosis) were identified from 1978 to 2017. Survival analysis was performed using the Kaplan-Meier method. RESULTS Median age at diagnosis 29 (18–63); 111 (55.5%) standard-risk (SR), 59 (29.5%) high-risk (HR), 30 (15%) unknown. 188 (94%) and 97 (48.5%) underwent radiotherapy and upfront chemotherapy, respectively. Median PFS: 6.28 years (4.9–11.2); median OS: 8.8 (7.8–12.4) years. Median time to first recurrence: 8.2 (5.1-not reached); 5-year recurrence-free rate: 71% in SR and 45% in HR patients. Survival after first recurrence: 2 years (1.64–2.4). Documented recurrence and risk group were associated with survival (HR 30.4, p< 0.0001 and 2.33, p< 0.001), but metastatic status and local vs. distant recurrence were not. The effect of upfront chemotherapy on survival did not reach statistical significance in SR patients. The use of chemotherapy regimens with or without vincristine or containing cisplatin vs. carboplatin, did not alter the survival outcome. In a subgroup of 57 SR patients who were seen at initial diagnosis and for whom complete staging and treatment information were available 3 and 5-year PFS were 94% (88%, 100%) and 76% (66%, 86%); OS at 5 years, 94% (87%, 100%). CONCLUSION No statistically significant difference was noted in outcome of patients treated without vincristine or with carboplatin instead of cisplatin, suggesting attenuated upfront regimens could be considered to reduce toxicity. Adult MB patients recur late and have a poor post-recurrence survival, therefore long-term follow-up, development of molecular risk-adjusted upfront treatment, and optimization of rescue treatments are needed.