This phase I/II trial tests the safety, side effects and best dose of selinexor given in combination with the usual chemotherapy (temozolomide) and compares the effect of this combination therapy versus the usual chemotherapy alone (temozolomide) in treating patients with glioblastoma that has come back (recurrent). Selinexor is in a class of medications called selective inhibitors of nuclear export (SINE). It works by blocking a protein called CRM1, which may keep cancer cells from growing and may kill them. Temozolomide is in a class of medications called alkylating agents. It works by damaging the cell's deoxyribonucleic acid and may kill tumor cells and slow down or stop tumor growth. Giving selinexor in combination with usual chemotherapy (temozolomide) may shrink or stabilize the tumor better than the usual chemotherapy with temozolomide alone in patients with recurrent glioblastoma.

PRIMARY OBJECTIVES:

I. To determine the maximum tolerated dose of temozolomide followed by selinexor in recurrent glioblastoma patients as determined by dose-limiting toxicities (DLTs) and the total toxicity profile. (Phase I) II. To evaluate the efficacy of sequentially administering temozolomide and selinexor in recurrent glioblastoma as determined by progression-free survival (PFS). (Phase II)

SECONDARY OBJECTIVES:

I. To evaluate overall response rate as determined by Response Assessment in Neuro-Oncology (RANO) response criteria.

II. To evaluate the efficacy of sequentially administering temozolomide and selinexor in recurrent glioblastoma as determined by 6-month PFS (6mPFS) and overall survival (OS).

III. To validate signatures of vulnerability to predict response to selinexor through ribonucleic acid (RNA) sequencing for 6 top-scoring gene pairs, whole exome sequencing, P53, EGFR, and Mcl-1.

OUTLINE: This is a phase I, dose-escalation study of selinexor in combination with fixed dose temozolomide followed by a phase II study that compares selinexor temozolomide combination therapy vs. temozolomide monotherapy. Patients are randomized to 1 of 2 groups for the phase II part of this trial.

GROUP I (Phase II): Patients receive temozolomide orally (PO) once daily (QD) on days 1-5 of each cycle and placebo PO QD on days 8 and 15 of each cycle. Cycles repeat every 28 days in the absence of disease progression or unacceptable toxicity.

GROUP II (Phase I and II): Patients receive temozolomide PO QD on days 1-5 of each cycle and selinexor PO QD on days 8 and 15 of each cycle. Cycles repeat every 28 days in the absence of disease progression or unacceptable toxicity. (Phase I completed as of April 2024)

Patients undergo magnetic resonance imaging (MRI) throughout the study and blood sample collection while on study.

After completion of study treatment, patients are followed up every 2 months up to 2 years.

Inclusion Criteria:

• Patients must have histologically confirmed glioblastoma (IDH wild-type, MGMT promoter methylated) that has undergone resection or biopsy upon first recurrence. Recurrence at site of prior involvement is defined by histopathological evidence of viable neoplastic cells associated with any of the following: mitotic activity, increased proliferation rate, micro-endothelial proliferation, or pseudo-palisading necrosis
• Prior to resection or biopsy, patients must have measurable disease, defined as at least one bi-dimensional contrast-enhancing lesion with clearly defined margins, with 2 perpendicular diameters of at least 10 mm, visible on >= 2 axial slices
• Patients must have received first-line treatment of temozolomide plus radiotherapy
• Patients must not have received any prior therapy aside from resection or biopsy for their recurrent disease
• Age >= 18 years. Because no dosing or adverse event data are currently available on the use of selinexor (KPT-330) in combination with temozolomide in patients < 18 years of age, children are excluded from this study
• Karnofsky performance status >= 60% (Eastern Cooperative Oncology Group [ECOG] =< 2)
• Absolute neutrophil count >= 1,500/mcL
• Platelets >= 100,000/mcL
• Hemoglobin >= 10 g/dL
• Total bilirubin =< 2 x institutional upper limit of normal (ULN)
• Aspartate aminotransferase (AST) (serum glutamic oxaloacetic transaminase [SGOT])/alanine transaminase (ALT) (serum glutamic-pyruvic transaminase [SGPT]) =< 3 x institutional ULN
• Glomerular filtration rate (GFR) >= 30 mL/min/1.73 m^2
• Human immunodeficiency virus (HIV)-infected patients on effective anti-retroviral therapy with undetectable viral load within 6 months are eligible for this trial
• For patients with evidence of chronic hepatitis B virus (HBV) infection, the HBV viral load must be undetectable on suppressive therapy, if indicated
• Patients with a history of hepatitis C virus (HCV) infection must have been treated and cured. For patients with HCV infection who are currently on treatment, they are eligible if they have an undetectable HCV viral load
• Patients with a prior or concurrent malignancy whose natural history or treatment does not have the potential to interfere with the safety or efficacy assessment of the investigational regimen are eligible for this trial
• Patients with known history or current symptoms of cardiac disease, or history of treatment with cardiotoxic agents, should have a clinical risk assessment of cardiac function using the New York Heart Association Functional Classification. To be eligible for this trial, patients should be class 2B or better
• The effects of selinexor (KPT-330) and temozolomide on the developing human fetus are unknown. For this reason and because selective nuclear export inhibitors as well as deoxyribonucleic acid (DNA) alkylating agents are known to be teratogenic, women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for the duration of study participation, and for 180 days after the last dose of temozolomide. Should a woman become pregnant or suspect she is pregnant while she or her partner is participating in this study, she should inform her treating physician immediately. Men treated or enrolled on this protocol must also agree to use adequate contraception prior to the study, for the duration of study participation, and 90 days after completion of study treatment administration
• Ability to understand and the willingness to sign a written informed consent document. Participants with impaired decision-making capacity who have a legally-authorized representative (LAR) and/or family member available will also be eligible

Exclusion Criteria:

• Patients who have had chemotherapy must have full recovery of organ and marrow function following the nadir of the last chemotherapy cycle
• Patients who have not recovered from adverse events due to prior anti-cancer therapy (i.e., have residual toxicities > grade 1) with the exception of alopecia
• Patients who are receiving any other investigational agents
• Patients who have previously received bevacizumab
• History of allergic reactions attributed to compounds of similar chemical or biologic composition to selinexor (KPT-330) or temozolomide
• History of hypersensitivity to dacarbazine (DTIC), since both dacarbazine and temozolomide are metabolized to 5-(3-methyltriazen-1-yl)-imidazole-4-carboxamide (MTIC)
• Patients with uncontrolled intercurrent illness
• Pregnant women are excluded from this study because selinexor (KPT-330) is a selective inhibitor of nuclear export with the potential for teratogenic or abortifacient effects. Because there is an unknown but potential risk for adverse events in nursing infants secondary to treatment of the mother with selinexor (KPT-330), breastfeeding is not allowed for mothers during treatment with selinexor (KPT-330) and for 7 days after the last dose. These potential risks may also apply to other agents used in this study
• Hospitalized patients with severe coronavirus disease of 2019 (COVID-19) who are >= 75 years old, or with a high-risk COVID-GRAM score, or with lactate dehydrogenase (LDH) > 370 (U/L) AND D-Dimer > 600 mcg/L FEU should not receive low-dose selinexor (KPT-330) pending additional results

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