The extension will run until November 2019 with an option to add another year, to develop utrophin modulators to treat the progressive muscle wasting disorder.
Summit will retain the exclusive rights to any intellectual property resulting from the partnership, and sponsor a drug discovery programme at the university.
DMD is caused by the absence of dystrophin protein, and utrophin modulation, a naturally occurring protein similar to dystrophin, could slow or even stop the progression of DMD.
Glyn Edwards, chief executive, said: “The extension of our alliance will allow us to invest further in utrophin modulation in partnership with the world-leading academic research groups at Oxford.”
Summit’s treatment, SMT C1100, is headed into the next phase of clinical development, and Edwards said it was an “incredibly exciting time for the field of utrophin modulation.”
To date, the collaboration has identified a number of utrophin modulator compounds that are structurally distinct from the clinical candidate SMT C1100, the company said.
Shares rose 1.6% to 118p on Tuesday.