It looks like the end of a long and painful journey for Dendreon after the maker of the prostate cancer immunotherapy Provenge filed for Chapter 11 bankruptcy protection.

The firm has come to an agreement with senior lenders ahead of having to pay off $620 million in convertible debt, due early in 2016. A restructuring has been agreed with holders representing 84% of that debt and Dendreon is now looking for a buyer and if that fails, the note holders will convert their debt interest into equity and Dendreon will become a privately-held company.

The picture is all so different from when Provenge (sipuleucel-T) was approved by the US Food and Drug Administration in April 2010. Dendreon’s shares soared and the immunotherapy was lauded as a revolutionary treatment.

However,  Provenge cost a whopping $93,000 for a course of treatment that improved median survival by just over four months. Any chance of gaining traction in the market was scuppered by the advent of more conventional but highly-effective prostate cancer treatments - Johnson & Johnson’s Zytiga (abiraterone) and Medivation and Astellas’ Xtandi (enzalutamide).

Dendreon has implemented a number of restructuring and cost-saving plans, and has also sought buyers to no avail. News of the bankruptcy saw its stock sink 81% in after-hours trading to just $0.18.