Phase II clinical trial with metronomic oral vinorelbine and tri-weekly cisplatin as induction therapy, subsequently concomitant with radiotherapy (RT) in patients with locally advanced, unresectable, non-small cell lung cancer (NSCLC). Analysis of survival and value of ctDNA for patient selection.

BACKGROUND: Little progress has been achieved in non-small cell lung cancer (NSCLC) patients with unresectable stage III disease and new drug schemes are warranted. MATERIAL AND METHODS: In this open-label, single-arm, phase II trial 65 treatment-naïve stage III NSCLC deemed surgically unresectable by a multidisciplinary team were treated with 2 cycles of induction cisplatin at 80 mg/m2 every 21 days plus metronomic oral vinorelbine at 50 mg/day every Monday, Wednesday and Friday. During the concomitant treatment with thoracic radiotherapy cisplatin was administered in the same manner but oral vinorelbine was reduced to 30 mg/day. The objective was to administer a total radiotherapy dose of 66 Gy in 33 daily fractions of 2 Gy. The primary endpoint was progression-free survival (PFS). Correlation between circulating tumor DNA (ctDNA) levels and survival was also evaluated. RESULTS: Fifty-five (78.5 %) patients completed treatment. Overall response rate, by RECIST criteria, was 66.2 %. Four (6.2 %) patients had complete response, 39 (60.0 %) partial response and 12 (18.5 %) stable disease. Seven patients (10.8 %) had progressive disease during the induction period. Median follow-up was 29.1 months (m), median PFS was 11.5 m (95 %CI: 9.6-15.4). PFS at 12 m in the intention-to-treat (ITT) population was 47.8 % (95 %CI: 35.1-59.4 %) and median OS was 35.6 m (95 %CI: 24.4-46.8). Grade ≥3 treatment-related adverse events occurred in 14 (21.5 %) patients during induction and in 13 (24.5 %) patients during concomitant treatment with esophagitis occurring in 3% and pneumonitis in 1.5 % of the patients. Patients with undetectable ctDNA after 3 m follow-up had median PFS and OS of 18.1 m (95 %CI: 8.8-NR) and not reached (NR) (95 %CI: 11.3-NR), respectively, compared with 8.0 m (95 %CI: 2.7-NR) and 24.7 m (95 %CI: 5.7-NR) for patients who remained ctDNA positive at that time point. CONCLUSIONS: Metronomic oral vinorelbine and cisplatin obtains similar efficacy results with significantly lower toxicity than the same chemotherapy at standard doses. ctDNA can identify populations with particularly good prognosis.