Phase II clinical trial of six mercaptopurine (6MP) and methotrexate in patients with BRCA-defective tumors. by Nicum, S, Brooks, C, Wharton, R, Boyle, L, Kaye, S, Gourley, C, Hall, M, Montes, A, Pearson, SR, Julier, P, Midgley, R, Schuh, A, Dutton, S, Grp, 6