Singapore - Johnson & Johnson has dissolved its four-year-old partnership with Geron for cancer drug imetelstat, wiping two-thirds off the biotechs share price at a stroke.

J&Js Janssen Biotech unit said the decision was down to a strategic portfolio evaluation and prioritisation of assets in its pipeline, but nevertheless is a heavy blow to Geron, raising questions about imetelstats potential in particular and the emerging telomerase inhibitor class in general.

Imetelstat has been conspicuously absent from J&Js R&D presentations for some months, raising eyebrows about the state of the programme, but despite this Gerons share price has tripled since the start of the year on expectation that J&J would extend the $935m partnership, signed in 2014.

Geron expects the transition of the complete imetelstat program to occur over approximately 12 months with operational support from Janssen.