Blood cancer specialists have heralded data on Pharmacyclics' ibrutinib, which is partnered with Johnson & Johnson, saying it could significantly change the treatment of chronic lymphocytic leukaemia.
Two studies have been presented at the American Society of Hematology in Atlanta and in the first, a 116-patient Phase Ib/II trial, the overall response rate (ORR) was 68% in elderly treatment-naive patients with a 96% progression-free survival (PFS) rate at 26 months. In patients with relapsed/refractory CLL, including those with high-risk disease, the ORR was 71%, and PFS at 26 months of 75%.
At an ASH press briefing, lead investigator John Byrd of the Ohio State University, noted that "current treatments are unacceptable" for elderly patients. The median age for sufferers is 72 and many cannot tolerate chemotherapy, he noted, and virtually all of them relapse.
However, ibrutinib, a Bruton's tyrosine kinase (BTK) inhibitor taken orally once-a-day, was well-tolerated and most adverse events were grade 1 or 2 in severity. In patients with low blood cell counts at the beginning of the study, sustained improvements of platelet counts (78%) and haemoglobin (82%) were seen after treatment and there was no evidence of cumulative toxicity or long-term safety concerns.
In the second trial, a Phase II study, 40 patients with high-risk CLLtreated with a combination of ibrutinib and Roche's Rituxan (rituximab) reported an ORR of 83%, with 38 of the 40 continuing on therapy without disease progression. Presenting the data, Jan Burger of the MD Anderson Cancer Center in Houston, noted that there was a large and rapid reduction in lymph node and spleen sizes, with 84% of patients experiencing more than a 50% decrease in lymph node size. The combo was well tolerated, with grade 3 or grade 4 toxicities infrequent and transient in nature.
Dr Burger said "We are very excited by the response rates we saw with ibrutinib-rituximab…and believe they emphasise the need for rapid, further development of ibrutinib, especially for patients with high-risk CLL". His views were echoed by Dr Byrd who told journalists at the briefing "this is something that rarely comes along, the quicker we get this over the finishing line the better". A Phase III programme is ongoing.
The moderator at the briefing, Claire Dearden of the Royal Marsden in London, was equally enthusiastic about ibrutinib. She noted that an oral, well-tolerated treatment which is not a chemotherapy and produces positive responses for the elderly and frail has to be welcomed. She added that "I've got patients coming from all over the country" to get onto trials, even though they know they only have a 50% chance of actually receiving ibrutinib.
A year ago, J&J paid $150 million upfront to jointly develop and market ibrutinib in a deal that could be worth close to $1 billion for Pharmacyclics.