Efficacy of Thymosin α1 in Management of Radiation Pneumonitis in Patients With Locally Advanced Non-Small Cell Lung Cancer Treated With Concurrent Chemoradiotherapy: A Phase 2 Clinical Trial (GASTO-1043)

Abstract

Purpose: To evaluate the efficacy of thymosin α1 in management of radiation pneumonitis (RP) in patients with locally advanced non-small cell lung cancer (LANSCLC) treated with concurrent chemoradiotherapy (CCRT).

Methods and materials: This phase 2, single-arm trial enrolled patients with unresectable LANSCLC of 18 to 75 years' old and an Eastern Cooperative Oncology Group performance status of 0 to 1. Eligible patients received definitive CCRT and weekly thymosin α1 from the start of CCRT until 2 months after CCRT. Patients were administered 51 Gy in 17 daily fractions or 40 Gy in 10 daily fractions in the first course followed by a re-evaluation and those patients without disease progression had an adaptive plan of 15 Gy in 5 daily fractions or 24 Gy in 6 daily fractions as a boost. Concurrent chemotherapy consisted of weekly docetaxel (25 mg/m²) and nedaplatin (25 mg/m²) during radiation therapy. The primary endpoint was the incidence of Grade (G) ≥2 RP. Secondary endpoints included the incidence of late pulmonary fibrosis, total lymphocyte count (TLC), serum C-reactive protein (CRP) levels, and the composition of gut microbiota. TLC and CRP data were collected at baseline, 2 to 3 weeks during CCRT, the end of CCRT, 2 and 6 months after CCRT. Fecal samples were collected at baseline and the end of CCRT. Patients treated with CCRT but without thymosin α1 intervention during the same period were selected as the control group by the propensity score matching method.

Results: Sixty-nine patients were enrolled in the study, and another 69 patients were selected as the control group. The incidence of G≥2 RP was lower in the study group compared with control cases (36.2% vs 53.6%, P = .040). G1 late pulmonary fibrosis occurred in 2 (3.7%) patients of the control group compared with no event in the study group (P = .243). Compared with the control group, the incidence of G3 to G4 lymphopenia (19.1% vs 62.1%, P < .001) was lower, and the median TLC nadir (0.51 k/µL vs 0.30 k/µL, P < .001) was higher in the study group. The proportion of patients with maximum CRP ≥100 mg/L was lower in the study group (13.8% vs 29.7% P = .029). The diversity and community composition of the gut microbiota were not significantly different between the 2 groups.

Conclusions: Administration of thymosin α1 during and after CCRT was associated with significant reductions in G≥2 RP and G3 to G4 lymphopenia in patients with LANSCLC compared with historic controls.