Quantifying morphologic variations as an alternate to standard response criteria for unresectable primary liver tumors after checkpoint inhibition therapy.

Purpose: The aim of this study was to assess the feasibility of quantifying morphologic changes in tumors during immunotherapy, as a reflection of response or survival.

Methods And Materials: A retrospective single-center analysis was performed in patients with unresectable liver cancer previously enrolled in clinical trials combining immunotherapy (tremelimumab ± durvalumab) and locoregional treatment (either ablation or transarterial chemoembolization). Conventional response (RECIST 1.1) was assessed at 6-month follow-up. For morphologic assessment, the largest target lesion was manually segmented on axial slices in two dimensions using contrast-enhanced CT. Solidity and circularity of tumors were calculated at baseline, 3-month follow-up, and at 6-months follow-up. Survival analysis was performed.

Results: From the 68 patients enrolled in clinical trials, 28 did not have target lesions separate from lesions treated by locoregional therapies, and 3 had no follow-up imaging. Thirty-seven patients (9 with biliary cancer and 28 with hepatocellular carcinoma) were included. Shape features and shape variation were not correlated with RECIST 1.1 status at 6-month follow-up. However, patients with low solidity tumors at 6-month follow-up showed poorer prognosis compared with patients with high solidity tumors at 6-month follow-up (p = 0.01). Solidity variation analysis confirmed that a decrease of tumor solidity at 6-month follow-up was associated with poorer prognosis (p = 0.01). No association was found between shape features at baseline or shape features at 3-month follow-up with overall survival.

Conclusion: Evolution and variation of tumor morphology during treatment may reflect or correlate with outcomes and contribute toward adapted response criteria.