Credit: Steven Harbour
The European Commission has granted marketing approval for the Bruton’s tyrosine kinase inhibitor ibrutinib (Imbruvica) in the European Union (EU).
The drug is now approved to treat adult patients with relapsed or refractory mantle cell lymphoma (MCL), adults with chronic lymphocytic leukemia (CLL) who have received at least one prior therapy, and first-line CLL patients who have 17p deletion or TP53 mutation and are unsuitable for chemotherapy.
In the EU and all other countries except the US, ibrutinib is marketed by Janssen Pharmaceutical Companies. In the US, the drug is being jointly developed and commercialized by Pharmacyclics and Janssen Biotech, Inc.
The EU approval of ibrutinib was based on data from a phase 2 study (PCYC-1104) in patients with MCL, the phase 3 RESONATE trial (PCYC-1112-CA) in CLL and small lymphocytic lymphoma (SLL), and a phase 1b/2 study (PCYC-1102) in CLL/SLL.
PCYC-1104: Ibrutinib in MCL
Results of this trial were presented at ASH 2012 and published in NEJM in 2013. The NEJM data included 111 patients who received ibrutinib at 560 mg daily in continuous, 28-day cycles until disease progression.
The overall response rate was 68%, with a complete response rate of 21% and a partial response rate of 47%. With an estimated median follow-up of 15.3 months, the estimated median response duration was 17.5 months.
The estimated progression-free survival was 13.9 months, and the overall survival was not reached. The estimated rate of overall survival was 58% at 18 months.
Common nonhematologic adverse events included diarrhea (50%), fatigue (41%), nausea (31%), peripheral edema (28%), dyspnea (27%), constipation (25%), upper respiratory tract infection (23%), vomiting (23%), and decreased appetite (21%). The most common grade 3, 4, or 5 infection was pneumonia (6%).
Grade 3 and 4 hematologic adverse events included neutropenia (16%), thrombocytopenia (11%), and anemia (10%). Grade 3 bleeding events occurred in 5 patients.
RESONATE: Ibrutinib in CLL/SLL
Results of the RESONATE trial were reported at EHA 2014 and published in NEJM in July. This trial was stopped early after an interim analysis showed that ibrutinib-treated patients experienced a 78% reduction in the risk of disease progression or death.
The trial included 391 patients with relapsed or refractory CLL or SLL who were randomized to receive ibrutinib (n=195) or ofatumumab (n=196). Patients in the ofatumumab arm were allowed to cross over to ibrutinib if they progressed (n=57). The median time on study was 9.4 months.
The best overall response rate was higher in the ibrutinib arm than the ofatumumab arm, at 78% and 11%, respectively. And ibrutinib significantly prolonged progression-free survival. The median was 8.1 months in the ofatumumab arm and was not reached in the ibrutinib arm (P<0.0001).
Ibrutinib significantly prolonged overall survival as well. The median overall survival was not reached in either arm, but the hazard ratio was 0.434 (P=0.0049).
Adverse events occurred in 99% of patients in the ibrutinib arm and 98% of those in the ofatumumab arm. Grade 3/4 events occurred in 51% and 39% of patients, respectively.
Atrial fibrillation, bleeding-related events, diarrhea, and arthralgia were more common in the ibrutinib arm. Infusion-related reactions, peripheral sensory neuropathy, urticaria, night sweats, and pruritus were more common in the ofatumumab arm.
PCYC-1102: Ibrutinib in CLL/SLL
Results of this phase 1b/2 trial were published in The Lancet Oncology in January. The trial enrolled 29 patients with previously untreated CLL and 2 with SLL.
They received 28-day cycles of once-daily ibrutinib at 420 mg or 840 mg. The 840 mg dose was discontinued after enrollment had begun because the doses showed comparable activity.
After a median follow-up of 22.1 months, 71% of patients achieved an objective response. Four patients (13%) had a complete response. The median time to response was 1.9 months.
Study investigators did not establish whether ibrutinib confers improvements in survival or disease-related symptoms.
Common adverse events included diarrhea (68%), nausea (48%), fatigue (32%), peripheral edema (29%), hypertension (29%), dizziness (26%), dyspepsia (26%), upper respiratory tract infection (26%), arthralgia (23%), constipation (23%), urinary tract infection (23%), and vomiting (23%).
Grade 3 adverse events included diarrhea (13%), fatigue (3%), hypertension (6%), dizziness (3%), urinary tract infection (3%), headache (3%), back pain (3%), and neutropenia (3%). One patient (3%) had grade 4 thrombocytopenia.
