Background Pancreatic acinar cell carcinoma (PACC) is a rare malignancy, and clinical data on managing bulky hepatic metastases from PACC remain limited. Conventional radiotherapy is restricted by normal tissue tolerance, while stereotactic body radiation therapy (SBRT) leads to prohibitive toxicity when applied to large tumor volumes. Spatially fractionated radiation therapy (SFRT) creates a deliberate non-uniform peak-valley dose distribution, delivering ablative doses to discrete tumor vertices while sparing the surrounding hepatic parenchyma. This approach may enhance local control and antitumor immunity, supporting its use in combination with immunotherapy for large hepatic metastases. Case report A 35-year-old female with metastatic PACC and a solitary 12-cm hepatic metastasis (clinical stage TxN3M1) experienced disease progression despite multiple surgical resections and six lines of systemic chemotherapy. The enlarging hepatic metastasis caused portal vein compression and anasarca. The patient received Lattice SFRT (40 Gy in four fractions) to the hepatic lesion, combined with the PD-1/CTLA-4 bispecific antibody cadonilimab and the multi-targeted tyrosine kinase inhibitor anlotinib. The target lesion decreased by 34% at 1 month and nearly 50% at 5 months, meeting RECIST partial response. No grade ≥3 toxicities were observed. Conclusion This case provides clinical experience supporting the use of SFRT combined with immunotherapy for bulky refractory PACC. The combination of Lattice SFRT, dual immune checkpoint blockade, and targeted therapy appears feasible and well-tolerated in this patient. Further clinical trials are warranted to validate this combined approach.
Fu et al. (Wed,) studied this question.