The present invention relates to a combination therapy of propane-1-sulfonic acid{3-[5-(4-chloro-phenyl)-1H-pyrrolo[2,3-b]pyridine-3-carbonyl-2,4-difluoro-phenyl]-amide}, or a pharmaceutically acceptable salt thereof, and an interferon for treating a patient suffering from a proliferative disorder, in particular a solid tumor, for example, colorectal cancer, melanoma, and thyroid cancer. In particular, the present invention relates to such a therapy wherein the interferon is peginterferon alfa-2a and the disorder is melanoma containing the V600E b-Raf mutation.