Pharmacyclics, a clinical-stage biopharmaceutical company of Sunnyvale, Calif., announced that the clinical trial, SPARK, of ibrutinib in patients with relapsed or refractory mantle cell lymphoma (MCL) has enrolled its fifth patient, triggering a second $50 million milestone payment obligation from Janssen Biotech.

Janssen Biotech is Pharmacyclics’ worldwide collaborator on ibrutinib in oncology and sponsor of the MCL trial. As Pharmacyclics or Janssen initiate specific clinical trials and enroll the fifth patient, additional milestone payments of $50 million may be triggered up to a total of $250 million.

"We formed this partnership with Janssen, with the intention to broadly expand and propel the clinical development of ibrutinib. The speed at which we have moved into important clinical trials in CLL and now MCL is a validation of this joint venture's ability to convert plans into actualities," said Bob Duggan, chairman and CEO of Pharmacyclics. "We are satisfied with the early progress this partnership is generating and we look forward to providing a material update in December, during the American Society of Hematology Meeting."

The SPARK study is a single-arm, multi-center phase II trial of ibrutinib in MCL patients who received at least one prior rituximab-containing chemotherapy regimen and who progressed after bortezomib therapy. The primary endpoint of the study is overall response rate. The key secondary endpoints include overall survival rate, progression-free survival rate and pharmacokinetic data of ibrutinib. This global study conducted by Janssen is planned to enroll 110 patients worldwide.