CD4 and neoplasm: Subsequent studies using dual blockade of CSF1R and PD-1 or CTLA-4 profoundly increased both CD4 and CD8 infiltration of tumors and resulted in tumor regression, including complete regression in about 30 percent of mice.97 This strategy has now led to a national phase Ia/b clinical trial (NCT02526017) incorporating αPD-1 blockade and cabiralizumab, an antibody against CSF1R.