Blood vessel invasion is a major feature and a factor of poor prognosis in sarcomatoid carcinoma of the lung

'Inflammatory myofibroblastic tumour'-like dedifferentiation of anaplastic lymphoma kinase-rearranged lung adenocarcinoma

AIMS

Anaplastic lymphoma kinase (ALK) functions as an oncogenic driver in a subset of haematopoietic, epithelial and mesenchymal neoplasms. Activation of ALK most commonly occurs through gene fusion events, the presence of which predicts response to ALK-targeted inhibitors in some tumour types. Echinoderm microtubule-associated protein-like 4 (EML4)-ALK fusions represent the majority of ALK rearrangements in lung adenocarcinomas and were, until recently, thought to be exclusive to that tumour type. However, recent work has identified EML4-ALK fusions in ~20% of inflammatory myofibroblastic tumours (IMTs), particularly in those arising in the lung. Here, we present a patient with an ALK-rearranged poorly differentiated lung adenocarcinoma with a predominant sarcomatoid component that was morphologically indistinguishable from IMT.

METHODS AND RESULTS

Targeted next-generation sequencing revealed EML4-ALK rearrangements in both components, with identical fusion sequences. Copy number analysis demonstrated focal gain of the MYC gene in the IMT-like component. The findings support a diagnosis of ALK-rearranged lung adenocarcinoma with IMT-like dedifferentiation.

CONCLUSIONS

Our findings suggest that ALK-driven epithelial and mesenchymal neoplasms exist on a morphological spectrum, and emphasize the need to consider translocation testing in pulmonary tumours with unusual sarcomatoid morphology.

[Pulmonary sarcomatoid carcinoma]

Pulmonary sarcomatoid carcinomas are a rare group of tumors accounting for about one percent of non-small cell lung carcinoma (NSCLC). In 2015, the World Health Organization classification united under this name all the carcinomas with sarcomatous-like component with spindle cell or giant cell appearance, or associated with a sarcomatous component sometimes heterologous. There are five subtypes: pleomorphic carcinoma, spindle cell carcinoma, giant cell carcinoma, carcinosarcoma and pulmonary blastoma. Clinical characteristics are not specific from the other subtypes of NSCLC. Epithelial to mesenchymal transition pathway may play a key role. Patients, usually tobacco smokers, are frequently symptomatic. Tumors are voluminous more often peripherical than central, with strong fixation on FDG TEP CT. Distant metastases are frequent with atypical visceral locations. These tumors have poorer prognosis than the other NSCLC subtypes because of great aggressivity, and frequent chemoresistance. Here we present pathological description and a review of literature with molecular features in order to better describe these tumors and perhaps introduce new therapeutics.

Definitive Chemoradiotherapy for Advanced Pulmonary Sarcomatoid Carcinoma

Pulmonary sarcomatoid carcinoma is a rare subtype of non-small cell lung cancer with a poor prognosis. We herein report on a case of pulmonary sarcomatoid carcinoma that was treated successfully by concurrent chemoradiotherapy. A 65-year-old man was diagnosed to have pulmonary pleomorphic carcinoma (clinical T4N2M0 stage IIIB). He received concurrent chemoradiotherapy (60 Gy of radiotherapy in 30 fractionations and two courses of chemotherapy with carboplatin and paclitaxel). After chemoradiotherapy, a significant reduction of the tumor size was observed. Two courses of adjuvant chemotherapy were performed. He is currently alive at 15 months after the first treatment without any recurrence or metastasis.

Histomolecular profiling of pleomorphic, spindle cell, and giant cell carcinoma of the lung for targeted therapies

In pleomorphic, spindle cell, and giant cell carcinoma (PSCGC) of the lung, we wondered if an integrated diagnosis including morphological and immunohistochemical features could be related to molecular status. We performed immunohistochemistry on 35 PSCGCs against TTF1, napsin A, p40, ALK, ROS1, and c-MET. Mutational status regarding EGFR, KRAS, BRAF, HER2, and PIK3CA genes was established. Of 18 PSCGCs with adenocarcinomatous or "undifferentiated" carcinoma differentiation, 8 were mutated for EGFR (n = 1), KRAS (n = 2), BRAF (n = 1), HER2 (n = 3), and PIK3CA (n = 1). No PSCGC (0/4) with only squamous cell or adenosquamous (0/2) differentiation was mutated. c-MET overexpression was only seen in PSCGC with adenocarcinomatous or undifferentiated component (n = 5) without squamous cell component. ROS1 and ALK were negative. The presence of a "targetable mutation" was correlated to the presence of morphological or immunohistochemical adenocarcinomatous differentiation (P = .0137). Integrated diagnosis of an adenocarcinomatous component in PSCGC could be associated with the presence of targetable gene mutation. Because only PSCGC with adenocarcinomatous or undifferentiated carcinoma harbors mutations, whereas PSCGC with only squamous or adenosquamous differentiation does not in our study, this might represent a prescreening for patients with PSCGC to be tested for molecular targets. Our results emphasize that careful morphological examination and the use of immunohistochemistry might be useful for the selection of PSCGC tested for a mutational target.

Next-Generation Sequencing of Pulmonary Sarcomatoid Carcinoma Reveals High Frequency of Actionable MET Gene Mutations

PURPOSE

To further understand the molecular pathogenesis of pulmonary sarcomatoid carcinoma (PSC) and develop new therapeutic strategies in this treatment-refractory disease.

MATERIALS AND METHODS

Whole-exome sequencing in a discovery set (n = 10) as well as targeted MET mutation screening in an independent validation set (n = 26) of PSC were performed. Reverse transcriptase polymerase chain reaction and Western blotting were performed to validate MET exon 14 skipping. Functional studies for validation of the oncogenic roles of MET exon 14 skipping were conducted in lung adenosquamous cell line H596 (MET exon 14 skipped and PIK3CA mutated) and gastric adenocarcinoma cell line Hs746T (MET exon 14 skipped). Response to MET inhibitor therapy with crizotinib in a patient with advanced PSC and MET exon 14 skipping was evaluated to assess clinical translatability.

RESULTS

In addition to confirming mutations in known cancer-associated genes (TP53, KRAS, PIK3CA, MET, NOTCH, STK11, and RB1), several novel mutations in additional genes, including RASA1, CDH4, CDH7, LAMB4, SCAF1, and LMTK2, were identified and validated. MET mutations leading to exon 14 skipping were identified in eight (22%) of 36 patient cases; one of these tumors also harbored a concurrent PIK3CA mutation. Short interfering RNA silencing of MET and MET inhibition with crizotinib showed marked effects on cell viability and decrease in downstream AKT and mitogen-activated protein kinase activation in Hs746T and H596 cells. Concurrent PIK3CA mutation required addition of a second agent for successful pathway suppression and cell viability effect. Dramatic response to crizotinib was noted in a patient with advanced chemotherapy-refractory PSC carrying a MET exon 14 skipping mutation.

CONCLUSION

Mutational events of MET leading to exon 14 skipping are frequent and potentially targetable events in PSC.