Clinical Efficacy of ONC201 in H3K27M-Mutant Diffuse Midline Gliomas Is Driven by Disruption of Integrated Metabolic and Epigenetic Pathways

Patients with H3K27M-mutant diffuse midline glioma (DMG) have no proven effective therapies. ONC201 has recently demonstrated efficacy in these patients, but the mechanism behind this finding remains unknown. We assessed clinical outcomes, tumor sequencing, and tissue/cerebrospinal fluid (CSF) correlate samples from patients treated in two completed multisite clinical studies. Patients treated with ONC201 following initial radiation but prior to recurrence demonstrated a median overall survival of 21.7 months, whereas those treated after recurrence had a median overall survival of 9.3 months. Radiographic response was associated with increased expression of key tricarboxylic acid cycle-related genes in baseline tumor sequencing. ONC201 treatment increased 2-hydroxyglutarate levels in cultured H3K27M-DMG cells and patient CSF samples. This corresponded with increases in repressive H3K27me3 in vitro and in human tumors accompanied by epigenetic downregulation of cell cycle regulation and neuroglial differentiation genes. Overall, ONC201 demonstrates efficacy in H3K27M-DMG by disrupting integrated metabolic and epigenetic pathways and reversing pathognomonic H3K27me3 reduction.

SIGNIFICANCE

The clinical, radiographic, and molecular analyses included in this study demonstrate the efficacy of ONC201 in H3K27M-mutant DMG and support ONC201 as the first monotherapy to improve outcomes in H3K27M-mutant DMG beyond radiation. Mechanistically, ONC201 disrupts integrated metabolic and epigenetic pathways and reverses pathognomonic H3K27me3 reduction. This article is featured in Selected Articles from This Issue, p. 2293.

CTNI-61. CLINICAL EFFICACY AND PREDICTIVE BIOMARKERS OF ONC201 IN H3K27M-MUTANT DIFFUSE MIDLINE GLIOMA

Patients with H3K27M-mutated diffuse midline glioma (DMG) have no proven effective therapies beyond radiation. ONC201, a DRD2 antagonist and mitochondrial ClpP agonist, has shown promise in this population. Clinical and genetic variables associated with ONC201 response in H3K27M-mutant DMG continue to be investigated. A combined clinical and genetic study evaluated patients with H3K27M-DMG treated with single-agent ONC201 at the established phase 2 dose. Clinical outcomes of patients treated on two recently completed multi-site clinical studies (NCT03416530 and NCT03134131, n = 75) were compared with historical control data from patients with confirmed H3K27M-DMG (n = 391 total, n = 119 recurrent). Patients treated with ONC201 monotherapy following initial radiation, but prior to recurrence, demonstrated a median overall survival (OS) of 25.6 months from diagnosis and recurrent patients demonstrated a median OS of 16.2 months from recurrence, both of these more than doubling historical outcomes. Using a Cox model to correct for age, gender and tumor location, OS of ONC201-treated patients with H3K27M-mutant tumors remained significantly better than non-ONC201-treated historical controls (p = 0.0001). A survival and radiographic analysis based on tumor location, revealed stronger responses in thalamic patients. In patients with thalamic tumors treated after initial radiation (n = 16), median OS was not reached with median follow up of 22.1 months (historical control median OS of 12.5 months, n = 83, p = 0.0001). Significant correlations were found between baseline cerebral blood flow (CBF) on perfusion imaging and OS (Pearson’s r = 0.75, p = 0.003) and between nrCBF and PFS (r = 0.77, p = 0.002). Baseline tumor sequencing from treated patients (n = 20) demonstrates EGFR mutation (n = 3) and high EGFR expression as a marker of resistance and improved response in tumors with MAPK-pathway alterations (n = 5). In conclusion, ONC201 demonstrates unprecedented clinical and radiographic efficacy in H3K27M-mutant DMG with outcomes enriched in patients with thalamic tumors, treatment prior to recurrence, MAPK-pathway alterations, and patients with relatively high CBF.

Serial H3K27M cell-free tumor DNA (cf-tDNA) tracking predicts ONC201 treatment response and progression in diffuse midline glioma

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.

Overlapping Mental Representations of Self, In-Group, and Partner: Further Response Time Evidence and a Connectionist Model

People’s reports on their own characteristics are facilitated by matches with their relationship partner’s or in-group’s perceived characteristics and inhibited by mismatches. These results suggest that mental representations of the self, partner, and in-groups overlap. A previously untested implication is that judgmental facilitation or inhibition should operate in the reverse direction as well. The authors find that reports on the characteristics of a relationship partner or in-group are facilitated or inhibited by matches or mismatches with the participant’s own characteristics. The size of the effect for the partner is linearly related to perceived relationship closeness. These findings, in combination with the previous ones, suggest that representations of self, other people, and social groups are constructed on-line rather than being stable, static entities, and the authors advance a connectionist model of this construction process.

Effect of interferon-alpha on immunoglobulin synthesis by human B cells

We have investigated the effect of human recombinant interferon-alpha (IFN-alpha) on mitogen-induced immunoglobulin (Ig) production by peripheral blood mononuclear cells from normal individuals. Low concentrations (1 to 100 IU/ml) of IFN-alpha enhanced pokeweed mitogen-stimulated Ig production. In contrast, high concentrations of IFN-alpha (10(5) IU/ml) suppressed pokeweed mitogen-induced Ig production. Irradiation of T cells did not ablate the high dose suppression, indicating that suppression was not due to a radiation-sensitive T cell. Kinetic experiments revealed that IFN-alpha needed to be added to 10 day cultures within the first 72 hr for either enhancement or suppression to be noted. Preincubation of purified B cells with IFN-alpha suppressed Ig production as completely as when unfractionated mononuclear cells were incubated with IFN-alpha. On the other hand, preincubation of T cells or monocytes with IFN-alpha had no effect on subsequent Ig production in reconstituted mononuclear cell cultures. Mitogen-induced proliferation of purified B cells was not affected by IFN-alpha at any concentration, but Ig production by purified B cells stimulated with Staphylococcus aureus Cowan I or anti-mu and B cell differentiation factors responded to IFN-alpha with low concentration enhancement and high concentration suppression. Studies of Ebstein-Barr virus-transformed B cell lines showed that IFN-alpha caused a similar effect on the CESS line as on peripheral blood B cells, with low dose enhancement and high dose suppression of Ig production. Thus one IFN-alpha effect is to modulate Ig production, and this appears to be a direct effect on B cells. Combined with the data in the accompanying paper, the effects of IFN-alpha on B cell function are similar in vivo and in vitro.

Effect of interferon-alpha on immunoglobulin synthesis by human B cells

We have investigated the effect of human recombinant interferon-alpha (IFN-alpha) on mitogen-induced immunoglobulin (Ig) production by peripheral blood mononuclear cells from normal individuals. Low concentrations (1 to 100 IU/ml) of IFN-alpha enhanced pokeweed mitogen-stimulated Ig production. In contrast, high concentrations of IFN-alpha (10(5) IU/ml) suppressed pokeweed mitogen-induced Ig production. Irradiation of T cells did not ablate the high dose suppression, indicating that suppression was not due to a radiation-sensitive T cell. Kinetic experiments revealed that IFN-alpha needed to be added to 10 day cultures within the first 72 hr for either enhancement or suppression to be noted. Preincubation of purified B cells with IFN-alpha suppressed Ig production as completely as when unfractionated mononuclear cells were incubated with IFN-alpha. On the other hand, preincubation of T cells or monocytes with IFN-alpha had no effect on subsequent Ig production in reconstituted mononuclear cell cultures. Mitogen-induced proliferation of purified B cells was not affected by IFN-alpha at any concentration, but Ig production by purified B cells stimulated with Staphylococcus aureus Cowan I or anti-mu and B cell differentiation factors responded to IFN-alpha with low concentration enhancement and high concentration suppression. Studies of Ebstein-Barr virus-transformed B cell lines showed that IFN-alpha caused a similar effect on the CESS line as on peripheral blood B cells, with low dose enhancement and high dose suppression of Ig production. Thus one IFN-alpha effect is to modulate Ig production, and this appears to be a direct effect on B cells. Combined with the data in the accompanying paper, the effects of IFN-alpha on B cell function are similar in vivo and in vitro.

Dynamic gravimetry in studying the adsorption of proteins onto metal surfaces: analysis and limitations

The paper describes the physical and mathematical fundamentals of dynamic gravimetry in liquid phase. First, a relation is developed to calculate the apparent weight of a vertical thin cylinder partially immersed Into a liquid. It emphasizes the magnitude of buoyancy forces and surface-tension forces (which act upon fine threads used to suspend a solid object completely immersed into a liquid). Next, the basic relation of dynamic gravimetry is derived to estimate the absolute mass of adsorbed material onto the surface of a submerged solid object. This relation encompasses, apart from the term related to the measured output signal of the balance, three correction terms which originate from the surface tension effects, buoyancy effect of the submerged object, and buoyancy effect due to the adsorbed material.The following sections address adsorption at the air-liquid interface as well as the molecular diffusion process (both being intermingled with concentration and density gradients in the system). Special attention is given to the errors connected with a series of relaxation processes in which the external menisci, the plate-beam system, and the surface tension are involved once their equilibrium conditions are disturbed. The time constants of these relaxation processes can not be exactly predicted. The paper concludes with an experimental illustration of dynamic gravimetry, with the adsorption of beta-lactoglobulin onto stainless steel plates. The validity of predictions based upon the physico-mathematical fundamentals is reconciled with the analytical and technical aspects and difficulties specific to dynamic gravimetry.