Significance of changes in tumor markers in patients treated with durvalumab plus tremelimumab combination therapy as a surrogate marker for tumor response to unresectable hepatocellular carcinoma.

Aim: When evaluating response to immune checkpoint inhibitor therapy, the tumor sometimes initially swells before shrinking and ultimately responding, also called pseudo-progression. In this study, we analyzed whether tumor markers were useful for reflecting the treatment response.

Methods: Thirty-three patients who were treated with durvalumab plus tremelimumab combination therapy (Dur + Tre) were enrolled. Their functional reserve was Child-Pugh grade A. Their tumor markers α-fetoprotein (AFP), des-γ-carboxy prothrombin (DCP), or AFP-Lectin 3 fraction (AFP-L3) were positive. Tumor markers were evaluated before treatment and at 1, 4, and 8 weeks after the start of treatment. The first radiological evaluation was carried out at 4 weeks and the second evaluation at 8-12 weeks. The responders included those with complete response and partial response and the nonresponders included those with stable disease (SD) and progression disease at best response evaluated by Response Evaluation Criteria in Solid Tumors.

Results: In the responder group, the change ratio of AFP, DCP, and AFP-L3 specifically decreased at 8 weeks. In the nonresponder group, the change ratio of DCP specifically increased at 4 weeks. The optimal cut-off value to divide responders and nonresponders at 4 weeks was approximately -40%. The ratio of responders was 72.7% in the patients whose AFP or DCP decreased over 40% at 4 weeks.

Conclusions: The change in tumor markers is a more useful predicter of tumor response to Dur + Tre than imaging evaluation alone.