Inclusion Criteria
* Either newly diagnosied, suspected lower grade glioma per radiographic features, or radiographic recurrence of a histologically confirmed grade II or III IDH-mutant glioma.
* Patient must be a candidate for surgical resection
* At least 18 years of age.
* Karnofsky ≥ 70%
* Adequate bone marrow and organ function as defined below:
* Absolute neutrophil count ≥ 1.5 K/cumm (patient may not use G-CSF or GM-CSF to achieve this ANC level)
* Platelets ≥ 100 K/cumm
* Hemoglobin ≥ 9 g/dL (patient may not receive transfusion or use erythropoietin to obtain this Hgb level)
* Total bilirubin ≤ 1.5 x IULN (or ≤ 3 x IULN for patients with known Gilbert's syndrome)
* AST(SGOT)/ALT(SGPT) ≤ 3.0 x IULN
* International normalized ratio (INR), prothrombin time (PT), partial thromboplastin time (PTT), or activated partial thromboplastin time (aPTT) ≤1.5 x ULN. The use of anticoagulants is permitted as long as the PT/(a)PTT is within therapeutic limits (according to the local institution standard) and the patient has been on a stable anticoagulant regimen for at least 2 weeks prior to Day 1.
* Creatinine Clearance of ≥40 mL/min per Cockroft-Gault formula or by a 24 hour urine.
* If a patient is using an antiepileptic medication, the patient is on a stable dose and without seizures for 14 days prior to Day 1. The antiepileptic medication used must not fall under any prohibited therapy category as defined in the protocol.
* If the patient is receiving corticosteroids at baseline, the dose administered is stable or decreasing for at least 5 days prior to Day 1. A higher stable dose of corticosteroids, if used as hormone replacement therapy, may be allowed upon discussion with the sponsor-investigator.
* The effects of DSP-0390 on the developing human fetus are unknown. For this reason, women of childbearing potential and men must agree to use adequate contraception (2 forms of acceptable contraception, including one barrier method) prior to study entry, for the duration of study participation, and for 6 months after the last dose of DSP-0390. Should a woman become pregnant or suspect she is pregnant while participating in this study, she must inform her treating physician immediately.
* Ability to understand and willingness to sign an IRB approved written informed consent document.
Exclusion Criteria
* Patient has had prior therapy with bevacizumab or other anti-vascular endothelial growth factor (VEGF) treatments within 3 months prior to Day 1.
* Patient has multifocal disease, leptomeningeal metastasis, or extracranial metastasis.
* Patient has a clinically significant abnormal ECG, including those where QT prolongation is determined by the Fridericia formula (QTcF \>450 msec for males and \>470 msec for females); and/or the patient has a history of Torsade de Pointes.
* Patient is known to have dysphagia, short-gut syndrome, gastroparesis, or other condition that may limit the ingestion or gastrointestinal absorption of drugs administered orally.
* Patient is known to have active Crohn's or other inflammatory bowel disease.
* A history of other malignancy for which all treatment was completed at least 2 years before Day 1 and the patient has no evidence of disease. Exceptions include non-melanoma skin cancer, cervical carcinoma in situ, and superficial bladder cancer that has been removed or curatively treated.
* On active treatment for other, unrelated malignancy or currently receiving any other investigational agents.
* A history of allergic reactions attributed to compounds of similar chemical or biologic composition to DSP-0390.
* Patient has taken concurrent use of prohibited medications: carbamazepine, phenytoin, phenobarbital, and other strong or moderate CYP3A4 inhibitors or inducers, and strong CYP2D6 inhibitors within 1 week or 5 half-lives (whichever is greater) prior to Day 1 or expects to use them during the study. Note both oral and IV ondansetron at doses ≤ 8mg q6 hours are permitted.
* The presence of any active retinal abnormality determined by screening ophthalmologic examination.
* Patient has significant cardiovascular disease, including New York Heart Association (NYHA) Class III or IV congestive heart failure, myocardial infarction, unstable angina, pectoris, clinically significant cardiac arrhythmias, or stroke in the preceding 6 months prior to Day 1.
* Uncontrolled intercurrent illness including, but not limited to, psychiatric illness/social situations that would limit compliance with study requirements, disorders associated with significant immunocompromised state, or ongoing or active infection.
* Pregnant and/or breastfeeding. Women of childbearing potential must have a negative serum pregnancy test within 7 days prior to the first dose of DSP-0390.
* Patients with HIV are eligible unless their CD4+ T-cell counts are \<350 cells/mcL or they have a history of AIDS-defining opportunistic infection within the 12 months prior to registration. Concurrent treatment with effective ART according to DHHS treatment guidelines is recommended, as long as the ART agents do not fall under exclusion #8.
* Patient has a known detectable viral load for hepatitis C, or evidence of a hepatitis B surface antigen.
* Patient has had a major non-neurologic surgical procedure, surgical resection, open biopsy, or significant traumatic injury within 4 weeks prior to Day 1 or anticipates needing a major surgical procedure during the course of the study.
* Patient has had a minor surgical procedure, fine needle aspirations, or core biopsies within 7 days prior to Day 1.
* Patient has received chemotherapy or investigational anticancer therapy within 4 weeks (except 6 weeks for nitrosoureas and immunotherapy, or 8 weeks for an implanted nitrosoureas wafer) prior to Day 1.
* Patient has had radiotherapy within 12 weeks prior to Day 1, unless relapse is confirmed by tumor biopsy.
