C: Syntheses of Peptides and conjugates (Specific aims 1,2,3) Peptides will be synthesized using solid-phase chemistry. In the first stage of the project, the two peptides specific for A20 mouse leukemic cells already identified will be synthesized, namely HIS SER THR PRO SER SER PRO (Peptide 1) and ASP SER SER LEU PHE ALA LEU (Peptide 2). In later stages (see below), selected human CLL specific peptides will be synthesized as their sequences become available. Only peptides will multiple repeat reads (>5) (see B above) will be selected (maximum of 3 per patient) as these represent phage clones with greater propensity to induce uptake into cells. Peptides will be synthesized both as fluorescent dye- and drug-conjugates based on our previous work with targeted multi-drug conjugates (21). We will employ drugs with differing mechanisms of action, such as the nitrogen mustard Chlorambucil used to treat elderly CLL patients, and the microtubule inhibitor Combretastatin 4A, known to induce apoptosis in CLL cells (25). Purity and composition of the products will be verified by HPLC and LC/MS. Syntheses will be carried out by an external supplier.