This study evaluates the safety, efficacy, and pharmacokinetics (PK) of plerixafor given in addition to granulocyte-colony stimulating factor (G-CSF) for collection of peripheral blood stem cells (PBSCs) for autologous transplantation in patients who would benefit from an autologous stem cell transplant but have failed previous collections or collection attempts with a mobilization regimen of G-CSF alone, chemotherapy and G-CSF, or any other conventional therapy including cytokines, chemotherapy and cytokines and bone marrow harvests.