 II. To investigate the association between treatment outcome and immunological markers: a Intratumoral expression of programmed cell death 1 PD-1 and programmed cell death-ligand PD-L1 in archived NPC tissues mandatory; b Serum absolute lymphocyte count at baseline and post-treatment mandatory; and c Plasma cytokine levels at baseline and serially during the first 8 weeks of treatment; d Expression of PD-1 in cluster of differentiation CD8 T cells in tumor infiltrating lymphocytes TIL at baseline optional. 