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.