The US Food and Drug Administration (FDA) has approved Amgen's supplemental Biologics License Application (sBLA) for Blincyto (blinatumomab) to include overall survival (OS) data from the phase 3 TOWER study. The approval converts Blincyto's accelerated approval to a full approval. The sBLA approval also included data from the phase 2 ALCANTARA study supporting the treatment of patients with Philadelphia chromosome-positive (Ph+) relapsed or refractory B-cell precursor acute lymphoblastic leukemia (ALL). The approval expands the indication of Blincyto for the treatment of relapsed or refractory B-cell precursor ALL in adults and children.

"For researchers and physicians, overall survival is the primary goal of treatment and the gold standard of outcomes, demonstrating a clear value to patients," said Anthony Stein, M.D., study investigator and co-director of the Gehr Family Center for Leukemia Research, City of Hope, Duarte, Calif. "Data from the TOWER study support the use of this single agent bispecific T cell engager immunotherapy, the first to demonstrate superior overall survival in patients with Philadelphia chromosome-negative relapsed or refractory B-cell precursor ALL, offering a much needed alternative with significantly improved outcomes over standard of care chemotherapy."

Blincyto, the first single-agent immunotherapy to treat patients with Philadelphia chromosome-negative (Ph-) relapsed or refractory B-cell precursor ALL, was previously granted breakthrough therapy designation and accelerated approval. It is also the first-and-only FDA-approved CD19-directed CD3 bispecific T cell engager (BiTE) immunotherapy, and the first bispecific antibody construct from Amgen's BiTE platform.

"Relapsed or refractory ALL is often a lethal disease, with a median overall survival of just four months on standard of care chemotherapy," said Bijal D. Shah, M.D., medical oncologist, Moffitt Cancer Center, Tampa, Fla. "As a physician, my goal is to identify treatments that improve response rates in patients with aggressive hematologic malignancies. Blincyto is an option that has been shown to help these high-risk patients fight their disease."

The approval is based on results from the TOWER study, which found that Blincyto demonstrated a superior improvement in median OS over standard of care (SOC) chemotherapy, nearly doubling median OS. The study showed that median OS was 7.7 months (95 percent CI: 5.6, 9.6) for Blincyto versus four months (95 percent CI: 2.9, 5.3) for SOC (hazard ratio for death=0.71; p=0.012). The approval is also based on data from the phase 2 ALCANTARA study, which evaluated the efficacy of Blincyto in adult patients with Ph+ relapsed or refractory B-cell precursor ALL.

"We are pleased that the FDA has granted full approval for Blincyto, marking a significant milestone for certain patients with relapsed or refractory ALL," said Sean E. Harper, M.D., executive vice president of Research and Development at Amgen. "This approval supports the use of Blincyto in a broader spectrum of patients, including those with few options to date, such as Philadelphia chromosome-positive patients, and reinforces the potential of the BiTE platform as a novel approach to immuno-oncology."

The FDA-approved prescribing information for Blincyto includes a boxed warning for cytokine release syndrome and neurologic toxicities. Blincyto is also under a risk evaluation and mitigation strategy (REMS) program in the US.

Safety results among patients who received Blincyto were comparable to those seen in the phase 2 studies in adult patients with Ph- relapsed or refractory B-cell precursor ALL. For the most common adverse events (greater than or equal to 10 percent incidence rate) in the Blincyto arm, six events (pyrexia, infusion-related reaction, cough, cytokine release syndrome, tremor, decreased immunoglobulins) occurred at an incidence rate that was at least five percent higher for Blincyto compared to SOC chemotherapy.

On May 3, 2017, the FDA also approved the sBLA for the administration of Blincyto to be infused over seven days with preservative, adding to the previously approved administration options for infusion over 24 and 48 hours preservative-free, and allowing physicians to customize a treatment plan to fit the needs of their patients. The Blincyto intravenous bag for a seven-day infusion contains Bacteriostatic 0.9 percent Sodium Chloride, USP (containing 0.9 percent benzyl alcohol), which permits continuous intravenous infusion of Blincyto at 28 mcg/day or 15 mcg/m2/day for a total of seven days. The seven-day infusion is not recommended for patients weighing less than 22 kg due to the risk of serious and sometimes fatal adverse events associated with benzyl alcohol in pediatric patients. Please see the full prescribing information for Blincyto for more information.

ALL is a rare and rapidly progressing cancer of the blood and bone marrow.1,2 Currently, there is no broadly accepted standard treatment regimen for adult patients with relapsed or refractory ALL beyond chemotherapy.3 Adults with relapsed or refractory ALL typically have a very poor prognosis, with a median OS of three to five months.4 In adult ALL, approximately 75 percent is B-cell precursor ALL, of which 75-80 percent is Ph- and roughly half will be refractory to treatment or experience relapse.5

The TOWER study was a phase 3, randomized, active-controlled, open-label study investigating the efficacy of Blincyto versus SOC chemotherapy in 405 adult patients with Ph- relapsed or refractory B-cell precursor ALL. The study enrolled a difficult-to-treat patient population which included patients from several stages of relapse. In the Blincyto arm, this included 35 percent of patients that had relapsed post-allogenic hematopoietic stem cell transplant (alloHSCT), and excluded those with late first relapse (=12 months after initial remission). Patients were randomized in a 2:1 ratio to receive Blincyto (n=271) or treatment with investigator choice of SOC chemotherapy (n=134). The determination of efficacy was based on OS. Per the recommendation of an independent data monitoring committee, Amgen ended the study early for evidence of superior efficacy in the Blincyto arm versus SOC chemotherapy. These results were published in The New England Journal of Medicine.

The ALCANTARA study was a phase 2, single-arm, multicenter, open-label study investigating the efficacy of Blincyto in 45 adult patients with Ph+ B-cell precursor ALL, who had relapsed after or were refractory to at least one second-generation or later tyrosine kinase inhibitor (TKI), or were intolerant to second-generation or later TKIs and intolerant or refractory to imatinib. Blincyto was administered in 28-day cycles by continuous intravenous infusion. Efficacy was based on the complete remission rate, duration of complete remission and proportion of patients with an MRD-negative complete remission or complete remission with partial hematologic recovery within two cycles. Results of the study, one of the largest conducted in this patient population, were published in the Journal of Clinical Oncology.