Study to Determine Optimal Dose, Evaluate the Efficacy and Safety of PRG-N-01 in Patients With Neurofibromatosis Type II

Inclusion Criteria: 1. Male or female subjects aged 18 years or older at screening 2. Subjects diagnosed with NF2 clinically or genetically, according to the I-NF-DC 2022 updated NF2 diagnostic criteria 3. Subjects with tumors due to NF2 who require treatment if they meet one of more of the criteria below but cannot undergo surgical treatment due to high risk of side effects from surgery (e.g., damage to nerve function). (1) Subjects with progressive tumors (VS, non-VS, meningiomas, ependymomas) confirmed on MRI within 36 months prior to screening (2) Subjects with clinical symptoms (decreased function of affected nerves, such as hearing loss, uncontrolled pain, shortness of breath, difficulty swallowing, decreased motor function, and decreased gait) as judged by the investigator 4) Subjects with ECOG performance status 0 - 1 or Karnofsky performance status 70 or higher 5) Subjects who have appropriate hematological, liver, renal, and blood coagulation functions confirmed based on the following criteria at screening: 6) Subjects who have appropriate cardiac and pulmonary functions confirmed based on the following criteria at screening: 7) Subjects who agree to use sunscreen during the clinical study period. 8) Subjects (or the subject's legal representative) who voluntarily consent and provide written informed consent to participate in this clinical study. 9\) (Only for Phase 2a) Subjects with one or more measurable NF2-related tumors confirmed on MRI at screening Exclusion Criteria: 1\) Subjects who have the following past or current medical history confirmed during screening: (1) Malignant tumor requiring treatment (chemotherapy or radiotherapy) or with disease progression within 2 years prior to screening (2) The following heart-related history * Uncontrolled hypertension at screening (DBP ≥100 mmHg or SBP ≥160 mmHg despite treatment) * Acute coronary syndrome (ACS) within 24 weeks of baseline, clinically significant arrhythmia, cardiomyopathy, unstable angina, NYHA II-IV heart failure, or severe valvular heart disease 1. Interstitial lung disease or pulmonary fibrosis 2. Cystitis or urinary obstruction within 12 weeks prior to screening 3. Blood coagulation disorder 4. Severe or active infectious disease requiring antibiotics, antivirals, etc. within 4 weeks prior to screening 5. Gastrointestinal disease that currently makes oral administration difficult or may affect absorption (e.g., celiac disease, Crohn's disease, intestinal resection) 6. Other diseases that are sufficient to affect the clinical study results at the investigator's discretion. 2\) Subjects who have confirmed or need the following drug treatments: 1. Chemotherapy, immunotherapy, or myelosuppressive chemotherapy within 4 weeks prior to screening (but, within 6 weeks prior to screening for nitrosourea agents or mitomycin C) 2. Monoclonal antibody therapy within 12 weeks prior to screening (but, allowing if more than 3 half-lives have elapsed); stem cell transplantation (but, allowing if there is no evidence of active graft-versus-host disease and more than 12 weeks have elapsed since transplantation) 3. Other investigational drugs or devices within 4 weeks prior to screening 4. Corticosteroids such as prednisone and prednisolone within 1 week prior to screening (but, allowing if treated with low doses) 5. Substrate of strong inhibitor, inducer, or transporter (OCT2, MATE1, MATE2-K) of CYP enzymes (CYP2C8, CYP3A) (but, allowing only if more than 5 times the half-life from baseline has elapsed) 3) Subjects who performed a major surgery within 4 weeks prior to screening (but, allowing minor surgical procedures such as catheter replacement therapy and local biopsy). 4\) Subjects who received radiation therapy for the purpose of treating tumors due to NF2 within 24 weeks prior to screening or who require total body irradiation during the clinical study period. 5\) Subjects with prosthetics or orthopedic devices that may interfere with the volumetric analysis of target lesions via MRI. 6\) Subjects with a known severe hypersensitivity to PRG-N-01 or a concomitant medication or the ingredients or a history of allergic reactions to compounds of similar chemical or biological composition. 7\) Female subjects who are pregnant or breastfeeding 8) Women of childbearing potential or men who are unwilling to use an appropriate method of contraception from the date of written consent to 12 weeks after the last dose of PRG-N-01. 9\) Other subjects who are deemed unsuitable for participation in this clinical study at the investigator's discretion