Primary lung sebaceous carcinoma successfully treated with radiotherapy and pembrolizumab: A case report.

Sebaceous carcinoma is a rare cutaneous malignant tumor, usually occurring on the eyelids, head, neck, and trunk. There have been few reports about sebaceous carcinoma with primary lung cancer, for which optimal therapy has not yet been established. A 70-year-old man presented with a mass in the left iliac bone and tumor of the lower left lung. The morphological characteristics of the iliac bone biopsy pathology and immunostaining results showed sebaceous gland differentiation. After systemic examination, we diagnosed a primary lung sebaceous carcinoma with intrapulmonary and bone metastases. PD-L1 was positive in 1%-24% of tumor cells, and microsatellites were stable. We detected protein kinase B (AKT1) mutations using the Oncomine Dx target test. Palliative radiotherapy (RT) of a total of 45 Gy was provided in 15 fractions to the left iliac region, which resulted in a 25% reduction in the tumor size. Subsequently, four courses of first-line pembrolizumab led to a 30% reduction in the total tumor count. RT and pembrolizumab may be treatment options for certain rare primary sebaceous carcinomas of the lungs. A synergistic effect from RT and subsequent administration of immune checkpoint inhibitors may have contributed to tumor reduction.

Heterogeneous tumor-immune microenvironments between primary and metastatic carcinoid tumors differentially respond to anti-PD-L1 antibody therapy.

A pulmonary carcinoid tumor is a rare tumor that lacks a validated therapeutic approach for unresectable disease. Understanding the intersite tumor-immune heterogeneity is essential to harness the immune system for cancer therapy. However, little is known about the tumor-immune microenvironment (TIME). Here, we describe a patient who had heterogeneous TIME between primary and metastatic carcinoid tumors which differentially responded to chemoimmunotherapy. A 72-year-old man was diagnosed with an advanced pulmonary carcinoid tumor. CT-guided biopsies of lung and scapular tumors confirmed typical carcinoid (PD-L1, 1%-24%) and atypical carcinoid tumors (PD-L1, negative), respectively. Although the primary lung carcinoid tumor showed a partial response, the scapular tumor was significantly enlarged after two cycles of anti-PD-L1 antibody therapy in combination with carboplatin plus etoposide. We performed quantitative pathology imaging analysis with fluorescent multiplex immunohistochemistry. CD8+ T cell infiltration was detected in the PD-L1-positive primary lung tumor nest; however, it was mostly restrained in the stroma in a PD-L1-negative metastatic scapular tumor. Treg infiltrations into both tumor nests and stroma were detected in the lung tumor, which were not detected in the metastatic scapular tumor. This study provides the first evidence of coexistence of heterogeneous TIME within a single individual with a pulmonary carcinoid tumor. This study may provide new insights into the mechanism of primary resistance to chemoimmunotherapy in pulmonary carcinoid tumors.