CD4 and neoplasm: Pre-depletion of 98% of NK cells resulted in 3/6 complete regressions, but with only 1/6 durable; 100% pre-depletion of CD4+ T cells resulted in 1/6 transient or durable regressions; 92% pre-depletion of CD8+ T cells resulted in 2/6 tumor regressions, with only 1/6 durable; and 100% pre-depletion of both CD4+ and CD8+ T cells prevented all tumor regressions/responses.