STARLITE for Unresectable High-Grade Gliomas

Participants will be administered MR-guided Laser Interstitial Thermal Therapy (LITT) as a single procedure, following stereotactic needle biopsy.

Participants will take one 600mg tablet of Abacavir orally once daily, as part of combination antiretroviral therapy (ART).

Participants will take one 300mg tablet of Lamivudine orally once daily, as part of combination antiretroviral therapy (ART)

"Participants will take one tablet of Ritonavir (RTV) orally twice daily, as part of combination antiretroviral therapy (ART), at one of the following dose levels:~* Dose Level 1: 100mg~* Dose Level 2 (starting dose): 300mg~* Dose Level 3: 400mg~* Dose Level 4: 600mg"

Participants will take Temozolomide (TMZ) via capsule orally, during and after focal radiotherapy, as part of standard of care adjuvant therapy. During focal radiotherapy, Temozolomide will be administered at a dose of 75 mg/m2 once daily for six weeks (42 days) on a continuous dosing regimen, including weekends and holidays. After completion of focal radiotherapy, Temozolomide will be administered at 150 mg/m\^2 on days 1 through 5 of Cycle 1, and at 200 mg/m\^2 on days 1 through 5 of Cycles 2 through 6, for a total of six 28-day cycles of maintenance therapy.

Participants will be administered focal radiotherapy for six weeks (42 days), as part of adjuvant therapy, at a total dose of 50-60 grays (Gy) in 1.8-2.0 Gy fractions, depending on prognosis and as determined by the treating radiation oncologist.