The prognostic effect of neoadjuvant chemoradiotherapy on the change of PD-L1 expression in patients with locally advanced rectal adenocarcinoma.

PURPOSE

To evaluate the prognostic effect of neoadjuvant chemoradiotherapy on the change of programmed death ligand 1 (PD-L1) expression in patients with locally advanced rectal adenocarcinoma, by comparing PD-L1 expression in pretreatment biopsies and PD-L1 expression in pathological specimens after neoadjuvant chemoradiotherapy.

METHODS

A total of 25 patients with rectal adenocarcinoma were evaluated. Patients were treated by neoadjuvant chemoradiotherapy (radiotherapy:44Gy normofraxionation; chemotherapy: capecitabine 825 mg/m in two daily doses). Surgery was performed 6-8 weeks after the chemoradiotherapy completion. PD-L1 expression was determined in endoscopic biopsies and in resected specimens with immunohistochemistry.

RESULTS

All 25 patients received radiotherapy without interruption, while concomitant chemotherapy was discontinued prematurely in one patient because of hematological toxicity. In 13 patients sphincter-saving surgery were performed, and 12 patients underwent rectum resection. Downstaging was noticed in 17 patients. Stable disease was found in 5 patients, and progression in 3. The median disease free survival (DFS) was not reached. Three-year DFS was 54.3% (95% CI 34.3-74.2). The median overall survival (OS) was 60 months (95% CI 48-60). Three-year OS was 75 % (95% CI 57.7-92.3). No PD-L1 expression was noticed in pretreatment biopsy and in resected tissue after chemoradiotherapy.

CONCLUSION

No prognostic effect of neoadjuvant chemoradiotherapy on the change of PD-L1 expression was demonstrated in patients with locally advanced rectal adenocarcinoma.