Abscopal effect induced by cryoablation in a 55-year-old patient with metastatic dedifferentiated liposarcoma: a case report

Abstract

Background: Metastatic dedifferentiated liposarcoma (DDLPS) is primarily managed with chemotherapy, yet with poor response rate. Locoregional therapies, such as radiotherapy and percutaneous cryoablation, can provide palliation for inoperable metastatic sarcomas. In rare instances, those ablative therapies can elicit an immune-mediated regression of untreated metastases in a process named the abscopal effect. With the growing use of immunotherapy, reports on the abscopal effect have become more frequent during the last decade.

Case description: A 55-year-old patient with no prior medical history was diagnosed with a stage IV DDLPS. The patient was first treated with induction chemotherapy followed by en bloc resection and adjuvant radiotherapy. After two local relapses treated with chemotherapy, the patient developed a systemic disease progression. While progressing on immunochemotherapy, the patient underwent palliative percutaneous cryoablation. Three months after the procedure, the ¹⁸fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸FDG PET/CT) showed regression of the distant metastasis alongside the regression of the cryoablated tumor, suggesting an abscopal effect.

Conclusions: The occurrence of the abscopal effect after progressive disease suggests that cryoablation triggered a systemic immune response, highlighting the potential of this treatment combination. However, it remains a rare phenomenon, and further research and clinical trials are required to determine optimal treatment sequencing.

Keywords: Case report; abscopal effect; immunotherapy; metastatic liposarcoma; percutaneous cryoablation.

Figure 1

Treatment timeline.

Figure 2

Treatment timeline and tumor response ¹⁸FDG PET/CT images showing evolution of left thigh involvement before/during immunotherapy and before/post cryoablation. ¹⁸FDG PET/CT, ¹⁸fluorodeoxyglucose positron emission tomography/computed tomography.

Figure 3

CT-scan images showing cryoablation procedure. Placement of 6 needles into the left thigh lesion (A). The tumor before (B) and after (C) cryoablation showing the formation of the ice ball. CT, computed tomography.

Figure 4

¹⁸FDG PET/CT images showing partial response at distance from the cryoablation site. ¹⁸FDG PET/CT, ¹⁸fluorodeoxyglucose positron emission tomography/computed tomography.

Figure 5

Cryoablation induces tumor cell necrosis and release of tumor antigens, which are taken by dendritic cells. Dendritic cells present tumor antigens to naive T-cell leading to their activation and differentiation into effector T-cells which migrate to the tumor sites. Introduction of checkpoint inhibitors allow the effector T-cells to kill tumor cells, leading to the regression of metastases. MHC, major histocompatibility complex; APC, antigen presenting cell; TCR, T cell receptor.