⁃ At least 18 years of age on the day of signing informed consent, with histologically confirmed diagnosis of GBM or astrocytoma Grade 4\^.

⁃ a. For participants with recurrent GBM or astrocytoma grade 4, histological confirmation of primary diagnosis is available i. First occurrence of disease progression with radiological confirmation ≥12 weeks from completion of radiation therapy.

⁃ ii. Where surgical resection of recurrent disease occurred, histological confirmation of GBM or astrocytoma Grade 4 is required.

⁃ b. For participants with newly diagnosed GBM or astrocytoma Grade 4, histological confirmation of diagnosis is required i. Participant, in consultation with their treating clinicians, is willing to delay the commencement of standard of care adjuvant temozolomide until the completion of CMV-specific T cell therapy infusions.

⁃ \^Note: Histological confirmation using the 2016 or 2021 World Health Organization (WHO) Classification of Tumours of the central nervous system (CNS) is acceptable and classification edition will be noted.

⁃ Male participants: Must agree to use contraception during the treatment period and for at least 180 days after the last dose of study treatment and refrain from donating sperm during this period.

⁃ Female participants: Must not be pregnant or undergoing in vitro fertilisation or breastfeeding, and at least one of the following conditions applies:

• Not a woman of childbearing potential (WOCBP) OR

∙ A WOCBP who agrees to follow contraceptive guidance during the treatment period and for at 120 days after the last dose of study treatment.

⁃ Provision of written informed consent for the trial. Approved interpreters will be used for patients who do not have sufficient understanding of English for informed consent to be obtained without an interpreter.

⁃ Participants who have AEs due to previous anti-cancer therapies must have recovered to ≤Grade 1 or baseline. Participants with endocrine-related AEs who are adequately treated with hormone replacement or participants who have ≤Grade 2 neuropathy are eligible. Participants with \>Grade 1 adverse events (AEs) due to previous anti-cancer therapies may be allowed to enrol on a case-by-case basis in discussion with the study Sponsor, if it is determined that it will not put the participant at a higher risk of study-related AEs or interfere with the integrity of the study outcome.

⁃ For participants with disease progression, this should be the first evidence of measureable disease based on modified RANO criteria. Lesions situated in a previously irradiated area are considered measurable if progression has been demonstrated in such lesions.

⁃ CMV-positive serology

⁃ Provision of consent for the use of archival formalin-fixed, paraffin embedded or fresh tumour tissue obtained at the time of surgical resection or excisional biopsy.

⁃ Have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1. Evaluation of ECOG is to be performed within 7 days prior to the first dose of study intervention.

‣ Have a life expectancy of at least 6 months.

‣ Have adequate organ function. Specimens must be collected within 10 days prior to the start of study intervention.

‣ Have availability of an human leukocyte antigen (HLA)-matched batch of allogeneic CMV-specific T cells.

‣ Provision of consent to access to Medicare Benefits Schedule (MBS) and Pharmaceutical Benefits Scheme (PBS) patient/provider health information collected by Services Australia (phase II participants only).

‣ Criteria for known hepatitis B and C positive participants:

⁃ Hepatitis B and C screening tests are not required unless:

• Known history of hepatitis B virus (HBV) or hepatitis C virus (HCV) infection

• As mandated by local health authority

⁃ 1 Hepatitis B-positive participants:

• Participants who are HBsAg positive are eligible if they have received HBV anti-viral therapy for at least 4 weeks and have undetectable HBV viral load prior to enrolment.

• Participants should remain on anti-viral therapy throughout study intervention and follow local guidelines for HBV anti-viral therapy post completion of study intervention

⁃ 2 Participants with history of HCV infection are eligible if HCV viral load is undetectable at screening.

⁃ • Participants must have completed curative anti-viral therapy at least 4 weeks prior to enrolment.