The US Food and Drug Administration (FDA) has approved Pharmacyclics, Inc's Imbruvica (ibrutinib) as a single agent for the treatment of patients with chronic lymphocytic leukaemia (CLL) who have received at least one prior therapy. This indication is based on overall response rate (ORR). An improvement in survival or disease-related symptoms has not been established.

Imbruvica is the first oncedaily, single-agent, oral kinase inhibitor for patients with CLL who have received one prior therapy and is being jointly developed and commercialized by Pharmacyclics and Janssen Biotech, Inc.

“Rarely does a drug come along with so much potential to help CLL patients,” said John C Byrd, MD, director, Division of Hematology, The Ohio State University Comprehensive Cancer Centre – Arthur G James Cancer Hospital & Richard J Solove Research Institute and lead investigator for the pivotal CLL trial PCYC-1102-CA. “I have been impressed with the promising and durable response rates we have seen in patients. It is particularly gratifying to see the difference that Imbruvica has made for patients in the clinical trials.”

CLL is a slow-growing blood cancer of the white blood cells (lymphocytes), most commonly B-cells.

“Today’s approval of Imbruvica is the first major milestone in the CLL clinical development plan, which includes seven Phase III trials, four of which are company sponsored, and covers all lines and various combinations of treatments,” said Bob Duggan, CEO and chairman of the Board of Pharmacyclics. “I would like to thank the patients and physicians for their trust and participation in our clinical trials. We are also thankful to the FDA for their collaboration and support, and a very big ‘thank you’ to the entire Pharmacyclics and Janssen teams who are tirelessly advancing our mission to serve for the betterment of patients.”

Imbruvica inhibits the function of Bruton’s tyrosine kinase (BTK). BTK is a key signaling molecule of the B-cell receptor signaling complex that plays an important role in the survival and spread of malignant B-cells.

Imbruvica blocks signals that stimulate malignant B-cells to grow and divide uncontrollably. The approval was based on the results of a Phase Ib/II, open-label, multi-centre, international, single-arm trial of 48 patients with relapsed or refractory CLL who received 420mg of Imbruvica daily.  The primary endpoint was safety and a secondary 3 PRC-00275 endpoint was ORR, which was assessed by a modified version of the International Working Group on CLL (IWCLL) criteria by an Independent Review Committee.

The efficacy results demonstrated a 58.3 per cent ORR (95% confidence interval (CI) (%), 43.2, 72.4), all partial responses. The duration of response (DOR) ranged from 5.6 to 24.2+ months. The median DOR was not reached. Safety was evaluated in the same 48 patients, with a median treatment duration of 15.6 months.  The Warnings and Precautions listed in the Prescribing Information include hemorrhage, infections, myelosuppression, renal toxicity, second primary malignancies and embryo-fetal toxicity.

Pharmacyclics is a biopharmaceutical company focused on developing and commercializing innovative small-molecule drugs for the treatment of cancer and immune mediated diseases.