Pulmonary pleomorphic carcinoma: A case harboring EGFR mutation treated with EGFR-TKIs

An observational study on the efficacy of targeted therapy for pulmonary sarcomatoid carcinoma

BACKGROUND

Pulmonary sarcomatoid carcinoma is a rare tumor that is resistant to cytotoxic agents. This observational study aimed to evaluate the detection rate of driver gene alteration and the efficacy of targeted therapy for pulmonary sarcomatoid carcinoma.

METHODS

We established a database of patients with pulmonary sarcomatoid carcinoma and their clinical information, including EGFR mutation, ALK fusion gene, ROS1 fusion gene, BRAF mutation, and MET exon 14 skipping mutation. The present study retrieved and analyzed the data of patients with pulmonary sarcomatoid carcinoma in whom driver gene alterations were evaluated, and the survival duration after the initiation of treatment with targeted therapy was examined.

RESULTS

A total of 44 patients were included in the present study. The EGFR mutation, ALK fusion gene, and MET exon 14 skipping mutation were detected in 2/43 patients (4.7%), 2/34 patients (5.9%), and 2/16 patients (12.5%), respectively. The ROS1 fusion gene (0/18 patients) and BRAF mutation (0/15 patients) were not detected. Female patients (P = 0.063, Fisher's exact test) and patients without smoking history (P = 0.025, Fisher's exact test) were the dominant groups in which any driver mutation was detected. Five patients with driver gene alterations were treated with targeted therapy. Progression-free survival (PFS) was 1.3 months and 1.6 months in 2 of the patients treated with gefitinib. Two patients with the ALK fusion gene showed 2.1 and 14.0 months of PFS from the initiation of treatment with crizotinib, and a patient with the MET exon 14 skipping mutation showed 9.7 months of PFS from the initiation of treatment with tepotinib.

CONCLUSION

The EGFR mutation, ALK fusion gene, and MET exon 14 skipping mutation were detected in patients with pulmonary sarcomatoid carcinoma in clinical practice, and some patients achieved long survival times after receiving targeted therapy. Further investigation is necessary to evaluate the efficacy of targeted therapy for pulmonary sarcomatoid carcinoma.

Biological characteristics and clinical treatment of pulmonary sarcomatoid carcinoma: a narrative review

Background and Objective

Pulmonary sarcomatoid carcinoma (PSC) is a subset of non-small cell lung cancer (NSCLC) with highly malignant, aggressive, and heterogeneous features. Patients with this disease account for approximately 0.1-0.4% of lung cancer cases. The absence of comprehensive summaries on the basic biology and clinical treatments for PSC means there is limited systematic awareness and understanding of this rare disease. This paper provides an overview of the biological characteristics of PSC and systematically summarizes various treatment strategies available for patients with this disease.

Methods

For this narrative review, we have searched literature related to the basic biology and clinical treatment approaches of PSC by searching the PubMed database for articles published from July 16, 1990 to August 29, 2023. The following keywords were used: "pulmonary sarcomatoid carcinoma", "genetic mutations", "immune microenvironment", "hypoxia", "angiogenesis", "overall survival", "surgery", "radiotherapy", "chemotherapy", and "immune checkpoint inhibitors".

Key Content and Findings

Classical PSC comprises epithelial and sarcomatoid components, with most studies suggesting a common origin. PSC exhibits a higher tumor mutational burden (TMB) and mutation frequency than other types of NSCLC. The tumor microenvironment (TME) of PSC is characterized by hypoxia, hypermetabolism, elevated programmed cell death protein 1/programmed cell death-ligand 1 expression, and high immune cell infiltration. Treatment strategies for advanced PSC are mainly based on traditional NSCLC treatments, but PSC exhibits resistance to chemotherapy and radiotherapy. The advancement of genome sequencing has introduced targeted therapies as an option for mutation-positive PSC cases. Moreover, due to the characteristics of the immune microenvironment of PSC, many patients positively respond to immunotherapy, demonstrating its potential for the management of PSC.

Conclusions

Although several studies have examined and assessed the TME of PSC, these are limited in quantity and quality, presenting challenges for research into the clinical treatment strategies for PSC. With the emergence of new technologies and the advancement of clinical research, for example, savolitinib's clinical study for MET exon 14 skipping mutations positive PSC patients have shown promising outcomes, more in-depth studies on PSC are eagerly anticipated.

Transformation From Adenocarcinoma to Pleomorphic Carcinoma as an Acquired Resistance to Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors

Pulmonary pleomorphic carcinoma is a very rare histological type of primary lung cancer, and usually provides aggressive clinical courses. A 65-year-old Japanese woman was diagnosed by transbronchial biopsy of the primary tumor as c-stage IV (cT4N3M1b) of adenocarcinoma harboring L858R point mutation in the exon 21 of epidermal growth factor receptor (EGFR). She received EGFR tyrosine kinase inhibitors (TKIs) (gefitinib and erlotinib) and subsequently cytotoxic chemotherapies. Gefitinib achieved partial response, but was switched to erlotinib due to elevated serum aspartate transaminase. After resistance to EGFR-TKIs, the second transbronchial re-biopsy revealed pulmonary pleomorphic carcinoma. Both carcinomatous and sarcomatous components retained the L858R mutation, but did not acquire T790M mutation. This case suggested that the histological transformation to pulmonary pleomorphic carcinoma may be one of mechanisms of drug resistance to EGFR-TKIs.

Pulmonary Pleomorphic Carcinoma Mimicking Primary Sarcoma of the Neck: A Case Report and Literature Review

We describe our challenge in diagnosing an unusual and rapidly progressing case of pulmonary pleomorphic carcinoma (PPC)—a rare, poorly differentiated, or undifferentiated non-small-cell carcinoma that can metastasize locally or distantly and has a poor prognosis. Our patient was an elderly man with a one-month history of abdominal pain, anorexia, and weight loss, diagnosed with atrophic gastritis via endoscopy, and treated medically without improvement. A week later, this patient developed pain in the head, neck, and shoulder area, and further examination revealed a thickening of his left neck and shoulder, with no palpable lymph nodes. Computed tomography (CT) of the neck, chest, and abdomen led us to believe that we might be dealing with primary sarcoma of the neck since no lung mass was evident. Further investigation could not be performed because the patient’s status deteriorated rapidly. An autopsy revealed that soft tissue in the left neck and the mesentery was invaded by poorly differentiated polymorphic malignant cells, which were also seen in the lung lesion. Immunohistochemically, these malignant cells were all positive for AE1/AE3, CAM5.2, TTF-1, Napsin-A, and Vimentin. The cells were also positive for programmed death-ligand 1 staining with a low level of tumor proportion score (over 1%). The final diagnosis was PPC with metastases to soft tissues in the left neck and the mesentery. A review of previous case reports of PPC revealed that soft tissue is an uncommon site for metastasis, and that our CT findings were rather unusual. We hereby present our case and review of published case reports, with the hope that an awareness of the heterogeneous features of PPC could prompt timely biopsy and histological diagnosis.