Fibroblast Activating Protein (FAP) PET/CT in Adults With Tuberculosis

Most participants will be receiving care at the clinical practices of the University of Pennsylvania or through City of Philadelphia TB Control Program (named the Flick clinic). Patients may participate in this study if they are at least 21 years of age and will be approached about study participation regardless of race or ethnic background. The study anticipates enrolling up to 10 participants who meet eligibility requirements for this study. Accrual is estimated to occur over approximately 2 years.

Investigators propose to use Fibroblast Activating Protein (FAP) PET/computed tomography (CT) to define the extent and location of FAP signals in lungs of TB patients at the time of TB treatment initiation and after TB cure. These timepoints are chosen as they could be utilized to deliver treatments designed to prevent, predict, or treat Post-transplant Lymphoproliferative Disorder (PTLD). The overarching hypothesis is that greater FAP signals in lungs of adult TB patients are associated with greater imaging manifestations of PTLD after cure. This is important, as radiographic findings in TB are associated with mortality.

This longitudinal study will perform FAP PET/CT and high-resolution CT (HRCT) within 6 weeks of TB treatment initiation and again within 6 months after TB cure to evaluate the hypothesis that change in total pulmonary FAP signal during treatment is associated with change in a measure of total lung structural damage previously validated in TB. It is expected that patients with less decrease in FAP lung signals will have less improvement in lung structural damage despite curative TB treatment.

After injection of [F-18]-FAPI-74, patients will undergo a vertex to mid-thigh scan, starting at approximately 30 minutes (± 5 min) post injection. PET/CT imaging sessions will include an injection of ≤ 8.0 mCi (expected range of doses is expected to be 6.0-8.0 mCi) of [F-18]-FAPI-74 intravenously. Data will be collected to evaluate uptake of [F-18]-FAPI-74 in the lung.

Inclusion criteria

• Participants will be ≥ 21 years of age
• Diagnosed with microbiologically confirmed (culture or Xpert MTB/RIF PCR positive on at least one respiratory sample) pTB
• Be currently on or able to initiate standard drug-sensitive pTB treatment according to IDSA guidelines.
• Have initiated or planning to initiate TB treatment prior to screening and enrollment.
• Have a Timika CXR score indicating cavitary disease
• Be able and willing to provide written informed consent to participate in the study

Exclusion criteria

• Diagnosed with TB that is resistant to rifampin per medical record review or have only extrapulmonary TB.
• Women of childbearing potential may not be pregnant or breast-feeding. A negative pregnancy test will be required before [F-18]-FAPI-74 injection.
• Inability to tolerate imaging procedures in the opinion of an investigator or treating physician
• Any current medical condition, illness, or disorder as assessed by medical record review and/or self-reported that is considered by a physician investigator to be a condition that could compromise participant safety or successful participation in the study, including completion of the study follow-up or TB treatment.
• History of major alternative pulmonary disease such as asthma, chronic obstructive pulmonary disease (COPD), or interstitial lung disease as per medical record review or patient self-report. "Major" is defined as potentially resulting in pulmonary radiographic abnormalities that could interfere with interpretation of PET-CT scan data.
• Have been administered at least 7 days of corticosteroids or any duration of another systemic investigational agent within 3 months of enrollment per medical record review or patient self-report
• Have symptoms or signs that, in the opinion of the investigative team, are suggestive of active TB at the time of pre-screening per patient self-report