Stabilization of Metastatic Uterine Leiomyosarcoma Using Pembrolizumab

Treatment With Antitumor Agents Recommended by Cancer Genome Panel for Uterine Leiomyosarcoma

To date, cancer genomic medicine, using cancer gene panel covered by health insurance from June 2019, has been performed for advanced malignant tumors under public medical insurance. In gynecology, the first-line treatment for uterine leiomyosarcomas, which is a mesenchymal uterine tumor, is surgery. In uterine leiomyosarcoma cases, recurrence is observed within 2 years postoperatively; however, to date, clinical trials have not shown efficacy with existing antitumor agents. We noted efficacy in two cases with advanced/recurrent uterine leiomyosarcoma using an antitumor agent selected on the basis of cancer gene panel testing results. Following uterine leiomyosarcoma diagnosis, they underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy as standard surgical treatment. After the surgical treatment, the imaging test revealed recurrent tumors; subsequently, they were treated with doxorubicin alone or doxorubicin combined with Gemzar. However, cancer genome gene panel test was performed because the malignant tumor worsened. Based on the cancer genome gene panel test results, the two cases with advanced uterine leiomyosarcoma were associated with increased tumor mutational burden (TMB) or pathogenic variants (PVs) of AKT serine/threonine kinase 1 (AKT1). Therefore, treatment with pembrolizumab, which is a drug covered by insurance for patients with TMB-high, or treatment with kinase inhibitors for patients with PVs in AKT, was considered. Cancer genomic medicine using cancer gene panel provides a new treatment strategy for intractable malignant tumors. This study aimed to discuss the usefulness of cancer genomic medicine by cancer gene panel testing using the cases of advanced and recurrence uterine leiomyosarcoma and the latest findings.

Expression of immune checkpoint regulators, programmed death-ligand 1 (PD-L1/PD-1), cytotoxic T lymphocyte antigen 4 (CTLA-4), and indolaimine-2, 3-deoxygenase (IDO) in uterine mesenchymal tumors

BACKGROUND

Immune checkpoints including programmed death-ligand 1/programmed death-1/ (PD-L1/PD-1), cytotoxic T lymphocyte antigen 4 (CTLA-4), and indolaimine-2, 3-deoxygenase (IDO) have recently emerged as effective candidates for treatment against a range of human malignancies. We have investigated their expression in the uterine mesenchymal tumors.

METHODS

Sixty-eight mesenchymal tumors were categorized into 6 diagnostic groups. We assessed PD-L1, PD-1, CTLA-4, and IDO expression on paraffin embedded tissue blocks of the uterine tumors using the respective antibodies. Immunohistochemical (IHC) stains were classified as positive when the reactions were present in at least 1% of the cell membranes for PD-L1/PD-1 or in cytoplasm for CTLA-4 and IDO, regardless of intensity. Student's t-test and McNemar's chi-square tests were carried out to analyze the results.

RESULTS

The mesenchymal neoplasms had expressed the immune checkpoints in the tumor and/or the lymphoid cells at the rate of 49% and 54% respectively. The tumor cells were positive in 10 (18%, PD-L1), 0 (0%, PD-1), 18 (32%, CTLA-4), and 13 (23%, IDO) cases while the infiltrating lymphoid cells were positive in 10 (18%, PD-L1), 23 (40%, PD-1), 18 (32%, CTLA-4), and 13 (23%, IDO) cases. Overall, comparison of paired tumor vs lymphoid cells resulted in p-values of ≤ 0.04.

CONCLUSIONS

Nearly 50% of the uterine tumors express at least one of the immune checkpoints in tumor and/or the infiltrating lymphoid cells. However, expression of the proteins in the two cellular components are mutually exclusive. Namely, when tumor cells express an immune checkpoint, the infiltrating lymphoid cells do not, and vice versa. Since the leiomyosarcomas are reportedly resistant to the immunotherapy when PD-L1 is expressed in the tumor cells, it can be posited that presence of the IHC positive lymphoid cells may be a better indicator of response to the treatment.