Molecular, clinicopathological characteristics and surgical results of resectable SMARCA4-deficient thoracic tumors.

PURPOSE

SMARCA4-deficient thoracic tumors are rapid aggressive malignancies, often diagnosed at an advanced and inoperable stage. The value of pulmonary resection for resectable SMARCA4-deficient thoracic tumors is largely unknown.

METHODS

In this observational study, we included 45 patients who received surgery for stage I-III SMARCA4-deficient tumors. We compared the molecular, clinicopathological characteristics and survival between SMARCA4-dNSCLC and SMARCA4-deficient undifferentiated tumor (SMARCA4-dUT) patients.

RESULTS

Thirty-four SMARCA4-dNSCLC and 11 SMARCA4-dUT patients were included in this study. Molecular profiles were available in 33 out of 45 patients. The most common mutated gene was TP53 (21, 64%), and followed by STK11 (9, 27%), KRAS (5, 15%), FGFR1 (4, 12%) and ROS1 (4, 12%). There were 3 patients that harbored ALK mutation including 1 EML4-ALK rearrangement. There were 2 patients that harbored EGFR rare site missense mutation. SMARCA4-dUT patients had significance worse TTP (HR = 4.35 95% CI 1.77-10.71, p = 0.001) and OS (HR = 4.27, 95% CI 1.12-16.35, p = 0.022) compared to SMARCA4-dNSCLC patients. SMARCA4-dUT histologic type, stage II/III, R1/2 resection and lymphovascular invasion were independent poor prognostic predictors for both TTP and OS. There were 8 patients who received immunotherapy, the objective response rate was 50%. The SMARCA4-dNSCLC patient with ALK rearrangement was treated with crizotinib as second-line therapy, and achieved stable disease for 9.7 months.

CONCLUSION

Patients with SMARCA4-deficient tumors have a high probability of early recurrence after surgery, except for stage I patients. Immunotherapy seems to be a valuable strategy to treat recurrence.