A first aspect of the invention relates to a method of treating a proliferative disorder in a subject, said method comprising administering to the subject a therapeutically effective amount of (i) sapacitabine, or a metabolite thereof and (ii) seliciclib in accordance with a dosing regimen comprising at least one first treatment cycle and at least one second treatment cycle, wherein said first treatment cycle comprises: (a) administering a therapeutically effective amount of sapacitabine, or a metabolite thereof, for 3 to 5 consecutive days for 2 weeks, starting on day d, where d is the first day of treatment with sapacitabine, or the metabolite thereof, in said first treatment cycle and (b) optionally administering a therapeutically effective amount of seliciclib for 3 to 5 consecutive days for 2 weeks, starting on day (d−1) relative to the administration of sapacitabine or the metabolite thereof, in said first treatment cycle followed by a rest period of at least 2 weeks, or until treatment-related toxicities are resolved, whichever is longer and wherein said second treatment cycle comprises: (a) administering a therapeutically effective amount of sapacitabine, or a metabolite thereof, for 3 to 5 consecutive days for 2 weeks, starting on day d, where d is the first day of treatment with sapacitabine, or the metabolite thereof, in said second treatment cycle and (b) administering a therapeutically effective amount of seliciclib for 3 to 5 consecutive days for 2 weeks, starting on day (d−1) relative to the administration of sapacitabine or the metabolite thereof, in said second treatment cycle followed by a rest period of at least 2 weeks, or until treatment-related toxicities are resolved, whichever is longer. Further aspects of the invention relate to a kit of parts, and corresponding uses.
