A case of thoracic SMARCA4-Deficient undifferentiated tumor successfully treated with combination Ipilimumab-Nivolumab

Salvage Surgery for Thoracic SMARCA4-Deficient Undifferentiated Tumor

Thoracic SMARCA4-deficient undifferentiated tumors (SMARCA4-UT) may be effectively managed with immune checkpoint inhibitors; however, the management of posttreatment exacerbations remains uncertain. A 48-year-old man underwent chemotherapy (cisplatin and pemetrexed) along with PD-L1 and CTLA-4 inhibitors, resulting in significant improvement. Subsequently, maintenance therapy was initiated but discontinued because of drug-induced pneumonia. Although prednisone treatment resolved the pneumonia, salvage surgery was performed for exacerbation of an enlarged chest tumor and lymph nodes. No additional postoperative treatment was administered, and the patient has completed 2.5 years of treatment. This case highlights the potential efficacy of salvage surgery in the management of SMARCA4-UT exacerbations.

First-line combination therapy of immunotherapy plus anti-angiogenic drug for thoracic SMARCA4-deficient undifferentiated tumors in AIDS: a case report and review of the literature

Background

Thoracic SMARCA4-deficient undifferentiated tumors (SMARCA4-UT) exhibit a notably aggressive phenotype, which is associated with poor patient survival outcomes. These tumors are generally resistant to conventional cytotoxic chemotherapy, thereby limiting the availability of effective treatment options.

Case presentation

We describe a 69-year-old AIDS patient who initially presented with a fused, enlarged lymph node on the right clavicle and mild, unexplained pain under the right axilla that worsened with severe coughing episodes. An initial chest CT scan revealed multiple nodular and mass shadows in the mediastinum and multiple nodules in both lungs, as well as a small amount of pericardial effusion. Additionally, serum biomarkers of lung cancer were abnormal as follows: carcinoembryonic antigen (CEA) at 13.74 ng/mL, cytokeratin 19 fragment (CYFRA21-1) at 6.82 ng/mL, neuron-specific enolase (NSE) at 25.49 ng/mL, and progastrin-releasing peptide precursor (ProGRP) at 89.35 pg/mL. Subsequent pathology confirmed SMARCA4-deficient undifferentiated tumors. Considering that the weak immune status and intermediate PD-L1 level, the patient was treated with a first-line combination therapy of immunotherapy and anti-angiogenic drug instead of chemo-immunotherapy. The patient responded well to immunotherapy combining anti-angiogenic drugs and achieved an overall survival for more than 22 months.

Conclusion

Our study presented a rare case of thoracic SMARCA4-deficient undifferentiated tumors and AIDS, suggesting that first-line immunotherapy plus anti-angiogenic drugs as a potential therapeutic option for SMARCA4-UT patients under specific conditions.

SMARCA4 and SMARCA2 co-deficiency: An uncommon molecular signature defining a subset of rare, aggressive and undifferentiated malignancies associated with defective chromatin remodeling

Genetic mutations and epigenetic modifications affecting multiple cancer-related genes occur synergistically to drive tumorigenesis. Across a wide spectrum of cancers, pathogenic changes have been identified in members of the SWItch/Sucrose Non-Fermentable complex including its two catalytic subunits, SMARCA4 and SMARCA2. During cancer development, it is not uncommon to lose the function of either SMARCA4 or SMARCA2, however, loss of both together has been reported to be synthetic lethal and therefore unexpected. Co-deficiency of SMARCA4 and SMARCA2 occurs as a pathognomonic feature of the early-onset ovarian cancer Small-cell carcinoma of the ovary, hypercalcemic type. The loss of both catalytic subunits is also described in other rare undifferentiated neoplasms including Thoracic SMARCA4-deficient undifferentiated tumors, Malignant rhabdoid tumors and dedifferentiated or undifferentiated carcinomas, predominantly of lung, gastrointestinal, and endometrial origin. This review provides the first extensive characterization of cancers with concurrent SMARCA4 and SMARCA2 loss through the discussion of shared clinical and molecular features. Further, we discuss the mechanisms triggering the loss of catalytic activity, the cellular processes that are dysfunctional as a consequence, and finally, current therapeutic candidates which may selectively target these cancers.

Thoracic SMARCA4-Deficient Undifferentiated Tumor Mimicking a Pleural Mesothelioma on 18 F-FDG PET/CT

ABSTRACT

A 72-year-old woman, who was a nonsmoker, presented with chest distress persisting for over 10 days. Plain chest CT revealed thickening of the left pleura accompanied by hydrothorax. Subsequent 18 F-FDG PET/CT showed irregular thickening involving the visceral, parietal, and interlobular pleura on the left side, with diffuse high avidity of 18 F-FDG. The left pleural mesothelioma was suspected initially, but pathological examination from biopsied specimen later confirmed a thoracic SMARCA4-deficient undifferentiated tumor.

FDG PET/CT in a Case of Thoracic SMARCA4-Deficient Undifferentiated Tumor

ABSTRACT

Thoracic SMARCA4-deficient undifferentiated tumor is a rare, newly recognized poorly differentiated tumor with poor prognosis. FDG PET/CT findings of thoracic SMARCA4-deficient undifferentiated tumor are rarely reported. We describe FDG PET/CT findings in a case of thoracic SMARCA4-deficient undifferentiated tumor. The tumor presented as a pleural mass, destroyed the adjacent ribs, and showed intense FDG uptake with SUV max of 12.7. This case indicates that thoracic SMARCA4-deficient undifferentiated tumor should be included in the differential diagnosis of FDG-avid pleural lesions.