Sarkaria, Jann N.

Abstract Glioblastoma (GBM) is an aggressive brain tumor with poor outcomes due to resistance to radiation and temozolomide (TMZ). Death receptor 5 (DR5), a proapoptotic receptor, induces tumor-selective apoptosis upon activation, is expressed in GBM, and can be upregulated by radiation/TMZ. Ozekibart (INBRX-109), a tetravalent DR5 agonist antibody, has demonstrated tolerability and clinical benefit as monotherapy in chondrosarcoma (PMID: 37265425), prompting a phase 2 trial (NCT04950075), and in combination with irinotecan and TMZ in Ewing’s sarcoma. INBRX-109 was evaluated in GBM using in vitro and in vivo models. DR5 expression in cell lines was determined by flow cytometry and drug sensitivity was measured using CellTiter-Glo®. Efficacy of INBRX-109 as a single agent and in treatment combinations was evaluated in intracranial U87-MG and patient-derived xenograft (PDX) models with activity assessed by survival and tumor imaging. Pharmacodynamic activity was assessed by immunohistochemistry (IHC) for cleaved caspase-3 and PARP. TMZ upregulated DR5 and sensitized U87-MG cells to INBRX-109. GBM cell lines (n=33) exhibited variable sensitivity to INBRX-109 and TMZ as single agents, but a majority showed enhanced sensitivity to combination treatment. In the U87-MG model, combination therapy improved tumor control and survival versus TMZ alone (tumor volume fold increase over baseline 1.1 vs 7.4; median survival 44 vs 36d). IHC staining of tumors indicated INBRX-109 crosses the blood brain barrier and is pharmacologically active. In three PDX models, INBRX-109 improved survival as monotherapy (survival ratios 1.38, 1.47, 1.50). In two models, combination therapy improved survival vs TMZ (survival ratios 1.76 vs 0.93, 2.47 vs 1.94). In summary, TMZ upregulates DR5 and enhances INBRX-109 activity in intracranial GBM models. This combinatorial activity and potential for synergy with radiation/TMZ support clinical evaluation of INBRX-109 in GBM. Moreover, the established clinical safety and activity of INBRX-109 in solid tumors support its development in this indication.

Abstract Despite intensive research over the past two decades, all glioblastoma (GBM) Phase 3 drug trials have been negative. The utility of the preclinical studies used to inform development for 10 Phase 3 trials was evaluated by four criteria: 1) drug distribution to the brain, 2) tumor location (flank vs. intracranial), 3) GBM xenograft source (patient-derived (PD) vs. cell line-derived (CD)), and 4) magnitude of survival extension. For the trials evaluated, no preclinical brain:plasma (B/P) data were reported for enzastaurin, cilengitide, nimotuzumab, Depatux-M, or bevacizumab, although IgG typically has a B/P ≈1%. B/P for imatinib was 1-3% and the other four drugs ranged from 25% to 51%. Except for enzastaurin, all drugs were studied in orthotopic tumor survival studies. The best response for each drug compared to relevant control (relative increase in median survival) was 22% (nimotuzumab), 31% (marizomib), 36% (sunitinib CD) / 5% (sunitinib PD), 63% (bevacizumab/temozolomide), 140% (imatinib), 157% (Depatux-M), 220% (veliparib/temozolomide), 300% (cediranib); median survival was not reached for cilengitide. However, only veliparib and sunitinib were studied in orthotopic PD models, and a single CD model (U87 or D54) was used exclusively for four drugs (enzastaurin, nimotuzumab, sunitinib, marizomib). In summary, 6 of 10 drugs had unknown or very poor brain distribution, 8 of 10 drugs were tested exclusively in CD models, which have questionable translational value, and 3 of 10 drugs had nominal activity (<50% survival prolongation) in preclinical survival studies. The stunning lack of clinical progress in GBM is deeply discouraging, but is consistent with underwhelming preclinical testing and the contextual interpretation of those results. Acknowledging multifaceted reasons for failed clinical trials, a more rigorous and critical approach should be used in preclinical studies, coupled with follow-up surgical window of opportunity studies, to identify and promote only the most promising therapies into advanced clinical testing.

Abstract WSD0922-Fu is an oral, CNS-penetrant, small molecule EGFR inhibitor which potently inhibits EGFR aberrations specific to non-small cell lung cancer (NSCLC) and glioblastoma (GBM). MC1914 (NCT04197934) is a first-in-human phase 1 trial in patients with EGFR aberrant recurrent GBM and NSCLC. After determining the maximum tolerated dose, adults with recurrent GBM were treated in two expansion cohorts: (a) non-surgical cohort (6/12 patients thus far): EGFRvIII mutation, first recurrence; food-effect study included (b) surgical cohort (6/6 patients), any EGFR mutation, any recurrence; window-of-opportunity study (WOO) included. Among these 12 patients, median age = 60 years; 50% female; 58% ECOG 0). All patients received prior radiation and temozolomide. After the WOO or food-effect study, patients were dosed at 120 mg BID (5 days on, 2 days off), and escalated to 160 mg BID (5 days on, 2 days off) based on tolerability. Common adverse events (>40%) are comparable to other EGFR inhibitors (acneiform rash, diarrhea, fatigue, xerosis, pruritis). Treatment-related grade 3+ adverse events were limited to lymphopenia (n = 1). WSD0922-Fu exposure in the fed state exceeded the fasted state (median plasma Cmax and AUC0-24h are 1.6x and 1.3x, respectively) with a delayed Tmax (6.0 vs 1.8 hours). For the WOO, time between last dose administered to tumor collection ranged between 4 - 13.5 hours. Median tumor WSD0922-Fu concentration was 0.76 µg/g; estimated median unbound tumor concentration was 24.9 ng/g and within expectations for pharmacodynamic effect. Median brain/plasma ratio = 0.59; median unbound brain/unbound plasma = 0.88. Enrollment to the non-surgical cohort is ongoing, so formal efficacy data remain immature. However, examples of clinical efficacy will be shown along with data on recurrence patterns. Phase 2 clinical trial development is in progress.

Abstract BACKGROUND High-grade and recurrent meningiomas frequently demonstrate aggressive behavior and therapeutic resistance, with limited treatment options. Dysregulation of the MAPK and FAK pathways drive meningioma progression, but compensatory activation between these pathways could limit single agent efficacy. Recently, a clinical trial (Alliance A071401) showed encouraging efficacy of single-agent FAK inhibition in recurrent/progressive meningioma (Brastianos et al, JCO 2023). This preclinical study aimed to evaluate the therapeutic potential of dual RAF/MEK (avutometinib) and FAK (VS-4718) inhibition in suppressing tumor growth and improving survival in intracranial meningioma models. METHODS Orthotopic intracranial models were established by injecting IOMM-Lee (Fluc-mCherry) or CH157-MN (eGFP-LUC2) cells into nu/nu mice. Mice were randomized into four groups: vehicle, VS-4718 (murine formulation of defactinib, 50 mg/kg, BID), avutometinib (0.3 mg/kg, QD), or combination therapy. Treatments were administered for a 4-week period. Tumor growth was monitored via bioluminescent imaging (BLI) at baseline, midpoint, and study endpoint. Pharmacokinetic (PK) and pharmacodynamic (PD) effects were assessed by intratumoral drug concentrations and Western blotting for p-ERK and p-AKT, respectively. RESULTS In the NF2-mutant CH157-MN model, avutometinib increased median survival from 12.5 to 20.5 days (p=0.001), while combination therapy extended survival further to 22 days (p<0.0001 vs vehicle). Similarly, in the NF2-wildtype IOMM-Lee model, avutometinib raised survival from 27.5 to 33 days (p=0.0237), with combination therapy reaching 34.5 days (p=0.0057 vs vehicle). VS-4718 monotherapy did not extend survival in both models. BLI demonstrated significant inhibition of tumor growth in both avutometinib and combination groups in both tumor models. PK analysis revealed Kp values of 0.26–0.37 for avutometinib and 0.46–0.50 for VS-4718 in orthotopic tumor tissue. Furthermore, combination therapy lowered p-ERK in tumors (p=0.001) compared to vehicle. CONCLUSION Dual RAF/MEK and FAK inhibitor therapy blocks MAPK activation and enhances survival in orthotopic meningioma models, supporting further clinical evaluation for aggressive meningiomas.

Background: Post-treatment prognosis and monitoring are critical for determining the timing of salvage treatment in glioblastoma patients but has been challenging due to difficulties differentiating progression from treatment effects in conventional images. This exploratory study aimed to establish the correlation of radiomics image features from time series of amino acid tracer 18F-DOPA PET images, with outcomes, using machine learning and dimension reduction analysis. Methods: 18F-DOPA PET images were collected for a patient cohort with wild-type IDH and unmethylated MGMT who underwent dose-escalated radiation therapy. Quantitative features were derived from the high uptake region (T/N > 2.0) in pre- and post-radiation therapy follow-up 18F-DOPA PET images. A customized workflow was utilized for pre-selecting predictive features, followed by manifold learning. Machine learning algorithms were employed to establish associations between imaging features and remaining survival (RS), defined as the time between a follow-up scan and date of death. Results: The ML models exhibited 81–83% ROC_AUC in predicting RS evaluated on an independent test dataset. A RS map is proposed for monitoring tumor alterations through serial 18F-DOPA PET scans, demonstrating superior sensitivity and better correlation with survival compared to the RANO criteria. Conclusions: Our study demonstrates that ML models utilizing FU 18F-DOPA PET images have the potential to effectively predict future survival outcomes in patients with glioblastoma treated with dose-escalated radiation therapy. The capability to assess changes in tumor over time through imaging can potentially assist in patient stratification and the selection of salvage treatments, while also aiding in distinguishing treatment effects from genuine tumor progression.

Abstract Failure to repair radiation (RT)-induced DNA damage results in cell lethality, and combined treatment with DNA repair inhibitors can markedly enhance tumor control achieved with radiation. These inhibitors also can potentiate acute RT toxicities by suppressing DNA repair. Capitalizing on this normal tissue radiosensitizing effect, we determined effective radiosensitizing dosing regimens in mice for the ATM inhibitor WSD0628 and the DNAPK inhibitor WNC0901 in mice. Drugs were administered via oral gavage prior to each RT dose, and RT was delivered using an anterior/posterior 225 kVp beam. In an initial iteration of this model, various combinations of WSD0628 and RT were administered to cohorts of mice (n=5/group) and body weight was followed for 2 weeks. The resulting data were modeled to define the total dose of radiation estimated to cause 50% of mice to lose >20% body weight (D50). There was an inverse relationship between the WSD0628 and D50 doses: 0 mg/kg WSD0628/24.0 Gy (95% confidence interval (CI) 24.5–24.7); 0.25 mg/kg/19.2 Gy (95% CI 16.7–21.8); 1 mg/kg/13.7 Gy (95% CI 13.2–14.2); 2.5 mg/kg/11.0 Gy (95% CI 10.5–11.5); 5 mg/kg/11.3 Gy (95% CI 6.7–15.9) and 7.5 mg/kg/7.8 Gy (95% CI 7.8–7.9). Histological review of tongues from animals treated with 15 Gy RT (5Gy x 3) + 7.5 mg/kg WSD0628 demonstrated epithelial denudation and acute inflammation consistent with oral mucositis, while these features were not seen with the same dose as RT alone. Similar WSD0628 doses were evaluated in combination with 8 Gy supratentorial RT (via lateral beams) in orthotopic GBM43 PDX tumors. By treatment arm, the median time to a moribund state was: sham (29 days (d)), RT (39d), 1 mg/kg (42d), 2.5 mg/kg (49d), 5 mg/kg (65d), and 10 mg/kg (123d, overall p<0.0001). A second mucositis model was used for evaluation of WNC0901. Cohorts of 5 mice/group were treated with a set dose of RT (4Gy x 3) to the oral cavity alone and in combination with various doses of WNC0901, and the fraction of mice with >20% weight loss within 2 weeks was determined. The results of this study are as follows: placebo (0 of 5 mice with >20% weight loss); 15 mg/kg (3 of 5 mice); 25, 50, or 100 mg/kg (5 of 5 mice). Based on these data, we defined 25 mg/kg WNC0901 as the minimally effective dose and predicted that 50 mg/kg would provide robust radiosensitization. Consistent with this prediction, co-treatment of B16 melanoma flank tumor xenografts with RT (8Gy x 1) and WNC0901 (50 mg/kg) more than doubled the median tumor control duration (median 42 [range 24-45] days; time from implantation for tumor to exceed 1500 mm3) as compared to RT alone (24 [13-30] days) or sham treatment (17 [13-17] days; overall p<0.0001). This study describes how a radiation-induced oral mucositis model can be used to identify effective radiosensitizing regimens faster and with fewer resources than relying on tumor control studies alone. Citation Format: Danielle Burgenske, Darwin Garcia, Jiayan Le, Wenjuan Zhang, Sneha Rathi, Katrina K. Bakken, Lauren L. Ott, Zeng Hu, Brett L. Carlson, Ann Mladek, Jessica L. Abraham, Paul A. Decker, Matthew L . Kosel, Jeanette E. Eckel-Passow, William F. Elmquist, Wei Zhong, Jann N. Sarkaria. Radiation-induced oral mucositis to rapidly determine effective radiosensitizing dosing regimens for ATM and DNAPK inhibitors [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2025 Oct 22-26; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2025;24(10 Suppl):Abstract nr B090.

IDH1/2 mutations (IDH mut ) increase methylation of DNA and histones in gliomas. IDH mut inhibitors are effective against low-grade IDH mut gliomas, but new strategies against high-grade IDH mut gliomas are needed. Although histone deacetylase inhibitors (HDACi) are ineffective against IDH wt glioblastoma (GBM), their potential in IDH mut gliomas has not been extensively studied. We previously established that IDH mut gliomas are more sensitive to HDACi than IDH wt GBM. Here we show that IDH mut is associated with greater sensitivity to HDACi only in glioma, not in IDH mut chondrosarcoma or cholangiocarcinoma. While HDACi induced more histone acetylation and gene regulation in IDH mut glioma than in IDH wt GBM, such acetylation was mostly within gene deserts, whereas IDH mut glioma promoters paradoxically lost histone acetylation. Two mediators of HDACi resistance, YAP and TAZ, were methylated and suppressed in IDH mut gliomas but not in other IDH mut cancers. Inducing YAP or TAZ expression in IDH mut gliomas conferred resistance to HDACi. Finally, belinostat extended in vivo survival only in IDH mut glioma models, not in IDH mut GBM models. Our findings provide a mechanistic rationale for further studies of HDACi in patients with IDH mut glioma, as well as the potential use of YAP/TAZ as a biomarker of HDACi sensitivity in cancers.

Abstract BACKGROUND Adamantinomatous craniopharyngiomas (ACPs) are rare, partially cystic central nervous system tumors driven by the WNT/β-catenin pathway. As they grow, ACPs compress the surrounding pituitary gland, optic chiasm, and third ventricle. ACPs are highly morbid tumors with enormous quality of life impact on patients, often early in life. Thus, better treatments are needed. Current ACP treatment consists of maximally safe surgical resection with radiation for residual disease. Complete surgical resection is challenging, and recurrence is common. Targeted systemic chemotherapy is not routinely used for ACP treatment. Interleukin-6 (IL-6) levels are elevated within ACPs compared to normal brain tissue, making IL-6 an intriguing therapeutic target. Treatment response of ACP to tocilizumab alone or in combination with bevacizumab has been reported in children. MATERIAL AND METHODS We retrospectively reviewed the medical records of three adults with recurrent ACP who received combination treatment with bevacizumab and tocilizumab on a compassionate basis between June 2022 and April 2025 at Mayo Clinic in Rochester, MN. We collected demographic, clinical, treatment, radiologic, and outcome data. RESULTS All three patients were male and median age at initial ACP diagnosis was 38 years (range: 32-42 years). All patients underwent subtotal resection followed by radiation therapy. One patient had repeat surgical resection and two patients required interventions for hydrocephalus. At the time of ACP recurrence, all patients had visual impairment, endocrine dysfunction, and headaches. All patients received bevacizumab (7.5 mg/kg q3 weeks) and tocilizumab (8 mg/kg q3 weeks [n=2] or 4 mg/kg q4 weeks [n=1]). While receiving combination therapy, ACP tumor volume decreased on magnetic resonance imaging for all three patients (64%, 68%, and 29% reduction). None exhibited tumor growth since starting combination therapy. One patient had a small intraparenchymal hemorrhage, suspected secondary to radiation-induced cavernous malformation, so bevacizumab was discontinued, and he remains on tocilizumab alone. The other two patients continue combination therapy (for 344 and 351 days). Two patients experienced improvement in vision, and one had improvement in cognition. Possible adverse effects of treatment included sinus infections, fatigue, neutropenia, and hypertension. CONCLUSION Treatment with combination bevacizumab and tocilizumab was associated with shrinkage of ACP tumors and clinical improvements and obviated the need for further surgery or radiation in all three patients. This combination of medications may reprogram the tumor microenvironment, leading to ACP involution. This well-tolerated regimen provides a noninvasive option for treatment of recurrent ACP, and potentially initial ACP treatment, and may improve quality of life for patients.

Abstract Background Disruption of the blood–brain barrier (BBB) in high-grade brain tumors is characterized by contrast accumulation on diagnostic imaging. This window of opportunity study correlates contrast imaging features with the tumor distribution of BBB-permeable (levetiracetam) and -impermeable (cefazolin) drugs. Methods Patients with a clinical diagnosis of a high-grade brain tumor underwent MRI for surgical planning. Cefazolin and levetiracetam were administered prior to skin incision, and serial plasma and image-registered tumor samples were collected during the operation. Drug levels were measured by LC-MS/MS, tissue drug levels were corrected for residual blood, and tumor-to-plasma concentration ratios were calculated. Intraoperative microdialysis was performed in a subset of patients to measure the same two drugs. Results Tumor (n = 125) and plasma (n = 261) samples were available for analysis from 42 operative cases. Across all samples, the tumor-to-plasma ratio was significantly lower for cefazolin (marginal mean [MM]: 0.15, 95% CI: 0.11–0.19) as compared to levetiracetam (MM: 0.70, 95% CI: 0.64–0.75; P < .001). When compared between contrast-enhancing and non-enhancing regions, tumor-to-plasma ratios for cefazolin varied by 4.4-fold (0.27, 95% CI: 0.20–0.35 vs. 0.06, 95% CI: 0.04–0.08, respectively; P < .001), and varied for levetiracetam by 1.4-fold (0.88, 95% CI: 0.78–0.97 vs. 0.61, 95% CI: 0.55–0.66, respectively; P < .001). These results were confirmed with the intra-operative microdialysis and a population pharmacokinetic analysis. Conclusions This study demonstrates significant inter- and intra-tumoral heterogeneity in drug delivery for both levetiracetam and cefazolin within high-grade brain tumors that is not necessarily predicted by clinical MR imaging and may reflect tumor-induced changes in both perfusion and BBB integrity.