Hrachova, Maya

Abstract BACKGROUND Selinexor (SEL) is a first-in-class XPO1 inhibitor with potent antitumor activity through the nuclear retention and reactivation of tumor suppressor proteins, reduced translation of oncogenes, and decreased expression of anti-apoptotic proteins. As a single agent, SEL has demonstrated brain penetration and clinically relevant responses in glioblastoma. We seek to enhance the effect and benefit of SEL by priming with temozolomide (TMZ). METHODS Through an NCI Project Team, we developed a multi-institutional phase I/II clinical trial which opened across the NCI Experimental Therapeutics Clinical Trial Network. Eligibility included histologically confirmed 1st recurrent MGMT promoter methylated glioblastoma. We evaluated safety, tolerability, and dose finding with an IQ 3 + 3 design of TMZ 150mg/m2 on days 1-5 of a 28-day cycle plus SEL on days 8 and 15. RESULTS From October 2022 to March 2024, we enrolled 12 patients (n=11 evaluable) into phase I of the study. Patient characteristics included 82% male, median age 62 (range 50-77), 64% white. The median number of cycles administered was 6 (range 1-12). Two dose levels (SEL 60mg and SEL 80mg) were evaluated. No dose-limiting toxicities (DLTs) were observed. The most common treatment related adverse events were nausea (58%), decreased platelet count (50%), fatigue (50%), constipation (42%), vomiting (25%), decreased lymphocyte count (25%), and decreased neutrophil count (25%). Grade 3+ treatment related adverse events included nausea, grade 3 (n=1); decreased lymphocyte count, grades 3-4 (n=2); and anorexia, grade 3 (n=1). Phase I has completed enrollment and the recommended phase II dose will be SEL 80mg. Additional results will be presented. CONCLUSION Results suggest that a sequential dosing regimen of SEL+TMZ is feasible, well-tolerated, and may minimize the cumulative toxicity of SEL. The phase II randomized portion of this trial is enrolling nationwide and will investigate efficacy and candidate molecular signatures of vulnerability (NCI #10505, NCT05432804).

Abstract BACKGROUND Treatment of high-grade glioma (HGG) remains a challenge. Several groups have developed ex vivo drug sensitivity assays to evaluate susceptibility of the tumor tissue to specific chemotherapeutics. This tool, in addition to molecular analysis of tumors might provide another layer of confidence in choosing treatments for patients with high-grade gliomas. METHODS 3D PredictTM platform (Kiyatec, Greenville, SC, USA) was tested at three academic medical centers in the United States. Twelve patients with newly diagnosed and recurrent HGGs were included. Tumor spheroids created ex vivo were exposed to twelve pre-selected drugs. Responses were reported as: no response, moderate response and response. We analyzed: demographics, histopathology, stage of disease, success rate and results of the ex vivo assay and clinical implications. RESULTS Majority of patients were women (67%). Median age was 58.5. Histology: GBM-83%, HGGs-17%. Eighty three percent of the samples represented recurrent disease. Sixty percent represented first recurrence while the remaining 40% represented 2nd or 3rd recurrence. Eight out of 12 tissue samples (67%) were successfully tested ex vivo. In six cases (75%), the information was used for immediate clinical decision making. In 2 cases, the decision was deferred until the next progression of the disease. The drugs chosen for treatment based on assay results included: olaparib (the assay was positive for response to rucaparib), temozolomide, lomustine, carboplatin and irinotecan. CONCLUSIONS This platform is easy to use in a standard clinical setting, the success rate for creating viable spheroids for drug sensitivity testing is high and the information obtained can be useful in clinical practice. Addition of other agents to the assay, correlation with molecular testing of the tumor tissue and attempt to assess response to drug combinations should be considered in further development of this technology. Prospective clinical trial is needed to validate this approach for routine clinical use.

Abstract BACKGROUND Selinexor (SEL) is a first-in-class XPO1 inhibitor with potent antitumor activity via tumor suppressor protein nuclear localization and reactivation, oncoprotein translation suppression, and DNA repair inhibition. As a single agent, SEL has demonstrated adequate brain penetration and clinically relevant responses in glioblastoma. We seek to enhance the effect and benefit of SEL by priming with temozolomide (TMZ). METHODS We developed in vitro and in vivo studies to rationally design a phase I/II trial to evaluate the safety and efficacy of the sequential combination of SEL+TMZ. Sequential treatment of U87 cells and intracranial mouse xenografts demonstrated superior DNA damage (ɣH2A.X, cleaved PARP) and overall survival compared to combination or single-agent therapy (HR 0.25 [95% CI, 0.07-0.84]; p = 0.01, log-rank). We used the top-scoring pair method to identify a 6 gene-pair RNAseq signature associated with response to SEL. RESULTS Based on preclinical findings, we developed and opened a multi-institutional phase I/II clinical trial in October 2022. Eligibility includes histologically confirmed 1st recurrent MGMT promoter methylated glioblastoma. Primary objectives are safety and preliminary efficacy. Secondary objectives are overall response rate, efficacy, and prospective validation of a molecular signature of response. Phase I dose finding by IQ 3 + 3 (n = 12) involves TMZ 150mg/m2 on days 1-5 of a 28-day cycle plus SEL on days 8 and 15. Phase II will involve randomization (n = 72) to the RP2D of SEL+TMZ versus monotherapy TMZ. Using proportional hazards regression, RHR 0.5 with p < 0.1 will demonstrate sufficient efficacy. We have enrolled 3 participants in dose level 1 (SEL 60mg) with no dose-limiting toxicities (DLTs) observed. Additional preliminary results will be presented. CONCLUSION Preliminary results suggest that a sequential dosing regimen of SEL+TMZ is feasible and initial dose is well-tolerated and may minimize the cumulative toxicity of SEL. The trial is currently enrolling nationwide (NCI #10505, NCT05432804).

Abstract INTRODUCTION Leptomeningeal carcinomatosis (LC) is an end-stage sequela of metastatic cancer that commonly leads to severe neurological symptoms due to hydrocephalus and commonly treated with surgery or radiation. As these procedures are invasive and have associated risks, chemotherapy could be a great alternative. We report a case of a hydrocephalus related to LC in a patient with Stage IV breast cancer that resolved after the administration of HD-MTX and intrathecal cytarabine. CASE A 64-year-old right-handed woman with Stage IV ER positive, PR positive, HER2 negative invasive lobular carcinoma of the left breast on chemotherapy with palbociclib and alpelisib who presented with mild occipital headaches, diplopia and imbalance. Imaging revealed an extensive abnormal leptomeningeal enhancement withing the posterior fossa compatible with leptomeningeal carcinomatosis. CSF cytology was consistent with metastatic adenocarcinoma. Liquid biopsy detected circulating tumor cells. During the admission for the cycle 1 of systemic chemotherapy with HD-MTX and intrathecal cytarabine, neurological status deteriorated as she became stuporous due to the newly developed moderate obstructive and communicating hydrocephalus. Surgical innervation was considered but given her response to serial Ommaya taps and dexamethasone, we proceeded with observation. Symptomatic improvement was noted within few days and confirmed on imaging showing the resolution of previously seen hydrocephalus. DISCUSSION This case highlights the role of non-invasive combination of systemic and intrathecal chemotherapy in patients with LC-related hydrocephalus aimed to preserve patient’s quality of life. No relevant disclosures.

Abstract Background Advanced age is a major risk factor for the development of many diseases including those affecting the central nervous system. Wild-type isocitrate dehydrogenase glioblastoma (IDHwt GBM) is the most common primary malignant brain cancer and accounts for ≥90% of all adult GBM diagnoses. Patients with IDHwt GBM have a median age of diagnosis at 68–70 years of age, and increasing age is associated with an increasingly worse prognosis for patients with this type of GBM. Methods The Surveillance, Epidemiology, and End Results, The Cancer Genome Atlas, and the Chinese Glioma Genome Atlas databases were analyzed for mortality indices. Meta-analysis of 80 clinical trials was evaluated for log hazard ratio for aging to tumor survivorship. Results Despite significant advances in the understanding of intratumoral genetic alterations, molecular characteristics of tumor microenvironments, and relationships between tumor molecular characteristics and the use of targeted therapeutics, life expectancy for older adults with GBM has yet to improve. Conclusions Based upon the results of our analysis, we propose that age-dependent factors that are yet to be fully elucidated, contribute to IDHwt GBM patient outcomes.