(Sharecast News) - Antibiotics developer Summit Therapeutics has entered into a securities purchase agreement for the sale of $25m worth of its US-listed shares in order to extend its cash runway through to January 2020.Summit will issue a total of 78.12m new ordinary shares to Duggan Investments chief executive Robert Duggan at a subscription price of $1.60 each - a 32% premium to its closing price on 14 December.When coupled together with its existing cash resources and funding agreements, Summit believes the funds raised as a result of the placing will extend its cash runway through 31 January 2020 and intends to use the funds to initiate patient enrolment into a Phase 3 clinical programme of ridinilazole for the treatment of Clostridiumdifficile infection.Summit also intends to complete IND-enabling studies for its gonorrhoea treatment and accelerate the development of its discovery assets.Chief executive Glyn Edwards, said: "Mr Duggan is a seasoned healthcare entrepreneur and investor whose proposed investment into our company speaks volumes about the potential that our new mechanism antibiotics have in addressing serious infectious diseases."As of 0910 GMT, Summit's UK shares had shot up 11.11% to 20p.