This clinical trial aims to determine if FG001 can assist surgeons in identifying the difference between tumor and healthy tissue during surgery in participants with newly diagnosed high-grade glioma. The scheduled neurosurgical tumor resection will occur under NIR fluorescence guidance and support the surgeons in achieving complete removal of the cancer.

FG001 is a 'fluorescent imaging agent,' which is a dye that glows under a special light to help doctors see certain tissues.

The main questions it aims to answer are:

1. To see how well a special light (called NIR fluorescence imaging) can show the difference between the tumor and the nearby healthy tissue during surgery. This difference is measured by comparing how bright the tumor looks to how bright the normal tissue looks.
2. Another goal is to find out how many patients have almost all the tumor removed. This is checked by looking at MRI scans, taken within 48 hours after surgery, to see if the leftover tumor is smaller than 0.175 cubic centimeters.

Participants will receive FG001 before tumor resection surgery and will participate in follow-up visits during the six months after surgery. Follow-up visits may include brain MRI, bloodwork, physical assessments, vital signs, assessment of functional and neurologic status, quality-of-life assessments, adverse event monitoring, and review of concomitant medications.

INVESTIGATIONAL PLAN This is a prospective, multicenter, Phase 2 dose confirmation study of FG001 (0.45 mg/kg) with diagnostic purpose (optimal imaging agent) and a single group under NIR fluorescence imaging with FG001. Dosage will be 0.45 mg/kg FG001, single dose, intravenous injection, 12 to 19 hours before surgery. Neurosurgical tumor resection will be supported by NIR fluorescence imaging with FG001. Evaluation of MR imaging and histopathology will be conducted by central neuroradiologists and neuropathologists, respectively.

Overall Design The overall trial design is an open-label assessment of FG001 to confirm the acceptability of the dose selected (0.45 mg/kg administered within 12-19 hours of surgery).

Trial Schedule

Eligible subjects will undergo the following sequence of events:

• Screening (to be completed ≤30 days before surgery)

• Pre-operative MRI (obtained within 48 hours) prior to surgery

• Pretreatment (conducted in accordance with local institution practice)

• Pre-dose Anti-drug antibody (ADA) sampling

• Administration of FG001 12-19 hours prior to surgery

• Pre-operative assessments (1 hour and 3-12 hours following IP administration)

• Neurosurgical intervention with planned study assessments

  • Surgical Phase I: Dura View
  • Surgical Phase II: Cortex View
  • Surgical Phase III: Tumor View
  • Surgical Phase IV: Tumor Margin View
  • Surgical Phase V: Tumor Cavity View

• Postoperative Assessments

  • Day 0 (±12 hours): Laboratory assessments, tumor characterization labs (including IDH and MGMT), and adverse events
  • Within 48 hours: MRI
  • Over 72 hours post-operative: collection of FG001 urine excretion metabolites

• Over 48 hours post-operative: PK analysis

• Day 3 (±12 hours): physical exam, vital signs, NANO scale, ECG and AEs

• Post-operative Assessments:

• Day 7 (±1 day): physical examination, safety assessments, Karnofsky Performance Status, Neurologic Assessment in Neuro-Oncology Scale, neurocognitive assessment, serum chemistries and hematology, anti-drug antibody sampling, ECG, adverse event monitoring, and concomitant medication review.

• Week 6 (±1 week): follow-up assessments, including Karnofsky Performance Status, Neurologic Assessment in Neuro-Oncology Scale, neurocognitive assessment, quality-of-life assessment, adverse event monitoring, concomitant medication review, steroid use documentation, temozolomide compliance, and anti-drug antibody sampling.

• 3 Months (±2 weeks): follow-up assessments, including MRI, Karnofsky Performance Status, Neurologic Assessment in Neuro-Oncology Scale, neurocognitive assessment, quality-of-life assessment, adverse event monitoring, concomitant medication review, temozolomide compliance, steroid use documentation, and disease progression and survival assessment.

• 6 Months (±2 weeks): final follow-up assessments, including physical examination, vital signs, MRI, Karnofsky Performance Status, Neurologic Assessment in Neuro-Oncology Scale, neurocognitive assessment, quality-of-life assessment, adverse event monitoring, concomitant medication review, temozolomide compliance, steroid use documentation, and disease progression and survival assessment, as applicable.

Inclusion Criteria:

1. Age 18 and older

2. Radiological evidence of a unifocal, contrast-enhancing brain lesion consistent with HGG, characterized by ring-enhancing or heterogeneously enhancing tumor with central hypointensity suggestive of necrosis, based on preoperative contrast-enhanced T1-weighted MRI.

3. Suspected HGG based on imaging, later confirmed as WHO Grade 3 or 4 glioma postsurgery. Eligible histologies (WHO CNS5) upon intraoperative or postoperative confirmation are:

   • Glioblastoma, IDH-wildtype (CNS WHO Grade 4)
   • Astrocytoma, IDH-mutant (CNS WHO Grade 3 or 4)
   • Oligodendroglioma, IDH-mutant, 1p/19q-codeleted (CNS WHO Grade 3)
   • Ependymoma (CNS WHO Grade 3)

4. No prior tumor-specific treatment, including surgery, chemotherapy, radiotherapy, or investigational therapy (i.e., newly diagnosed, treatment-naïve HGG).

5. Subject is scheduled to undergo first neurosurgical intervention with the intent of GTR of the contrast-enhancing lesion.

6. Surgery must be clinically anticipated to allow GTR, defined as removal of ≥98% of contrast-enhancing tumor, based on neurosurgeon assessment and preoperative imaging.

7. Indication for surgical tumor resection. The anatomical location of the contrast agent-accumulating tumor allows the possibility of complete resection. Resectability and EOR will be retrospectively assessed by an independent blinded centralized review of preoperative and postoperative MRI.

8. KPS ≥70, as assessed within 14 days prior to study treatment. Subject must not previously have received the trial drug (FG001).

9. Male subjects must commit to use barrier contraception (e.g., condom) during the trial and for 30 days after the end-of-trial visit and avoid sperm donation during this period.

10. Women of childbearing potential must agree to use highly effective method of contraception during the trial and for 30 days after the end-of-trial visit. Acceptable methods of contraception include intrauterine device or hormonal contraception (oral contraceptive pill, depot injections or implant, transdermal depot patch or vaginal ring). To be considered sterilized or infertile, females must have undergone surgical sterilization (bilateral tubectomy, hysterectomy or bilateral ovariectomy) or be post-menopausal (defined as at least 12 months amenorrhea; may be confirmed with FSH test if there is doubt).

11. Subject is capable of understanding and giving written informed consent

Exclusion Criteria:

1. Tumor location in the midline, basal ganglia, cerebellum, or brainstem where resection is not safely achievable or is considered high-risk.
2. Tumors judged by the PI to infiltrate critical motor pathways.
3. Multifocal disease, defined as:

3a. More than one contrast-enhancing lesion; or 3b. Additional contrast-enhancing lesions unrelated to the primary tumor; or 3c. Evidence of extracerebral metastases

4. Substantial non-contrast-enhancing tumor areas suggestive of low-grade glioma with malignant transformation, as assessed by preoperative MRI. Defined as ≥50% of non-CE volume in relation to CE tumor volume.

5. Tumor location is not amenable to GTR based on neuro-surgeon assessment.

6. Application of iMRI or intraoperative ultrasound guidance during surgical resection is prohibited to avoid bias in resection outcome measurement.

7. Medical contraindications to MRI (e.g., pacemaker).

8. Any known allergy or hypersensitivity to: 8a. ICG or any component of the IP 8b. Gadolinium-based contrast agents

9. Pre-existing severe chronic renal impairment, defined as: 9a. Estimated indexed and non-indexed glomerular filtration rate (eGFR ≤30 mL/min/1.73 m² AND (eGFR ≤30 mL/min) 9b. Assessed within 30 days prior to enrollment

10. Pre-existing hepatic insufficiency, defined as: 10a. AST and alanine transaminase ALT >3 times the upper limit of normal; or 10b. Total bilirubin >1.5 times the upper limit of normal unless the elevation is attributable to Gilbert's syndrome.

10c. Assessed within 30 days prior to enrollment

11. Abnormal coagulation profile, defined as any: 11a. Platelets < 100,000 11b. aPTT >1.5x upper limit of normal, or 11c. INR > 1.7 11d. Assessed within 30 days prior to enrollment

12. QTc will be assessed using Fridericia's correction (QTcF); thresholds for exclusion is > 470 ms or subjects with QTcF > 470 ms will be excluded.

13. History of malignant tumor in any body site (excluding adequately treated basal cell carcinoma of the skin).

14. Unwilling or unable to follow the protocol requirements.

15. Prior history of serious gastrointestinal perforation, diverticulitis, and/or peptic ulcer disease.

16. Existing or planned pregnancy or lactation, or unwillingness/inability to use effective contraception during the study.

17. Inability to provide informed consent due to significant language barrier, cognitive impairment, or dysphasia.

18. Simultaneous participation in another interventional clinical trial or trial participation in any other clinical study 30 days prior to enrollment.

19. Subjects enrolled that are later determined to have non-high-grade gliomas will be considered a screen failure (e.g., Excluded Population), including but not limited to: 19a. IDH-mutant oligodendroglioma, or astrocytoma 19b. Metastasis 19c. Lymphoma

Individual participant data will not be shared with other researchers in order to protect participant privacy and confidentiality. Aggregate study results will be reported as required.