FAPI PET for Response Evaluation and Prognosis Prediction in Liver and Biliary Cancer Patients Treated With PD-1 Combination Therapy

68Ga-FAPI PET for Response Evaluation and Prognosis Prediction in Advanced Liver and Biliary Cancer Patients Treated With PD-1 Based Combination Therapy: A Head-to-head Comparison to 18F-FDG PET

The purpose of this study is to explore the ability of positron emission tomography (PET) with [68Ga]FAPI to detect, evaluate treatment response, and predict prognosis in advanced liver and biliary cancer patients treated with anti-PD-1 antibodies-based combination therapy.

Hepatocellular carcinoma (HCC) and bile tract cancers (BTC) are major health issue worldwide, particularly in Eastern Asia. Anti-PD-1 antibodies-based combination therapy has shown considerable efficacy in advanced HCC and BTC. However, an objective response is only achieved in a portion of patients. Thus, there is an urgent need for better patient selection before immunotherapy as well as accurate evaluation of treatment response.

PET is a noninvasive imaging technique which might be an effective tool for evaluating anti-PD-1 antibody-based combination treatment in liver and biliary cancer. 68Ga-FAPI has been developed as a novel agent targeting fibroblast activation protein (FAP) that is overexpressed in cancer-associated fibroblasts in liver and biliary cancer. Prior studies have shown that FAP-expressing CAF suppresses anti-tumor immunity while suppressing FAP can overcome stromal barriers to immuno-oncological responses. Meanwhile, 68Ga-FAPI PET showed a high detection rate in primary and metastatic lesions in liver and biliary cancer. The aim of this study is to evaluate the ability of positron emission tomography (PET) with [68Ga]FAPI to detect, evaluate treatment response, and predict prognosis in advanced liver and biliary cancer patients treated with anti-PD-1 antibodies-based combination therapy. Our hypothesis is that baseline [68Ga]FAPI PET parameters can predict response and clinical benefit of anti-PD-1 antibodies-based combination therapy and overall survival; that effects of anti-PD-1 antibodies-based combination therapy in liver and biliary cancer can be detected and quantified by [68Ga]FAPI PET after treatment in correlation with other radiological findings and clinical endpoints; that such effects are more prominent with [68Ga]FAPI PET than with the traditional [18F]FDG PET.

Inclusion Criteria:

• locally advanced or metastatic and/or unresectable HCC or BTC
• Child Pugh A or B liver function status
• an ECOG performance status score of 0-2

Exclusion Criteria:

• intolerance to anti-PD-1-based combination therapy
• active or prior autoimmune disease
• concurrent use of immunosuppressive medicaments