Furthermore, intra-tumoral SD-101 (CpG-C ODN) administration in combination with low-dose radiation in a phase 1/2 trial promoted the generation of tumor-specific CD8+ and CD4+ effector T-cells, and reduced the abundance of T regulatory cells (Tregs) in the tumor microenvironment, which in turn led to complete tumor regression in both treated and untreated tumor sites 23. The gene discussed is CD4; the disease is neoplasm.