The invention provides cell permeable peptides and peptide agents that inhibit anti-apoptotic processes in cancer cells to promote tumor cell death, as well as a method for providing therapeutic treatment for cancer. The composition may be delivered in conjunction with a conventional chemotherapeutic agent to provide a synergistic effect that significantly increases the effectiveness of the chemotherapeutic agent to destroy cancer cells. The invention also provides kits or systems for cancer therapy, comprising at least one peptide agent for inhibiting the anti-apoptotic effects of NF-kB and at least one chemotherapeutic agent for stimulating the cellular apoptotic pathway.