FDA expanded the approved use of ibrutinib (Imbruvica, Pharmacyclics and Janssen Biotech) as a single-agent, oral kinase inhibitor for chronic lymphocytic leukemia (CLL) patients who have received at least 1 previous therapy.
CLL is a type of cancer that starts from white blood cells (lymphocytes) in the bone marrow. CLL mainly affects older adults, and accounts for about one-third of all leukemias. According to the American Cancer Society, estimates for leukemia in the United States for 2014 are:
Ibrutinib works by blocking the enzyme that allows cancer cells to grow and divide. In November 2013, FDA granted ibrutinib accelerated approval to treat patients with mantle cell lymphoma, a rare and aggressive type of blood cancer, if those patients received at least one prior therapy.
Ibrutinib for CLL also received priority review and orphan-product designation because the drug demonstrated the potential to offer significant improvement in safety or effectiveness in the treatment of a serious condition and is intended to treat a rare disease, respectively.
FDA’s accelerated approval of ibrutinib for CLL is based on a clinical study of 48 previously treated participants. On average, participants were diagnosed with CLL 6.7 years prior to the study and had received four previous therapies. All study participants received a 420-mg orally administered dose of ibrutinib until the treatment reached unacceptable toxicity or the disease progressed. Nearly 58% of participants had their cancer shrink after treatment (overall response rate), results showed. At the time of the study, the duration of response ranged from 5.6 to 24.2 months. An improvement in survival or disease-related symptoms has not been established.
In the clinical study, the most common side effects observed include thrombocytopenia, diarrhea, bruising, neutropenia, anemia, upper respiratory tract infection, fatigue, musculoskeletal pain, rash, pyrexia, constipation, peripheral edema, arthralgia, nausea, stomatitis, sinusitis, and dizziness.
“The clinical data on Imbruvica for the treatment of chronic lymphocytic leukemia includes only ‘surrogate’ end points-in this case, cancer shrinkage versus increases in survival or life years,” said John E. Schneider, PhD, CEO, Avalon Health Economics LLC. “The drug will still have to prove itself in terms of survival, but FDA, for the time being, is of the opinion that the cancer shrinkage data is sufficient to warrant getting this to patients who need it.
The approval of Imbruvica was long anticipated, according to Andrew Schorr, founder, PatientPower, a Seattle-based company devoted to helping the cancer patient or survivor and their family through knowledge, to get the best medicine and return to or maintain good health.
“As a pill that can help a wide range of CLL patients, even some with the most aggressive form, this is a big deal,” said Schorr, himself a 18-year CLL survivor. “While it will mean patients may have to take an expensive oral therapy for life, for some patients where a risky transplant was their only option, this is welcome news.”
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