FDA Approves Blinatumomab for Rare Type of ALL

On December 3, 2014, the US Food and Drug Administration (FDA) announced the approval of Amgen's immunotherapy drug Blincyto (blinatumomab), a bispecific T-cell engager (BiTE) used to treat patients diagnosed with Philadelphia chromosome-negative precursor B-cell acute lymphoblastic leukemia (B-cell ALL).

B-cell ALL is a rapidly growing cancer in which the bone marrow makes too many B-cell lymphoblasts or immature white blood cells. When proteins such as CD19 (found on the surface of most B-cell lymphoblasts) and CD3 (found on the surface of T-cell lymphocytes) are brought together by the unique mechanism of action of blinatumomab, the immune system is activated to fight the cancer--specifically in this case, a rare form of ALL.

Blinatumomab is being approved under the FDA's accelerated approval program for those patients with relapsed or refractory Philadelphia chromosome-negative precursor B-cell ALL. Considering this type of ALL is rare and potentially life-threatening, blinatumomab is being approved 5 months ahead of its original scheduled approval date of May 19, 2015.

Based on clinical data, blinatumomab is showing promise for this particular ALL population. In this phase II, open-label, multicenter, single-arm study, evaluating the efficacy, safety, and tolerability of blinatumomab in adult patients with minimal residual disease (MRD) having received three or more intensive chemotherapy treatments, 78% of patients who received blinatumomab experienced a complete MRD response (a measure of eradication of residual disease at the molecular level) after one treatment cycle. Nearly all complete responses occurred within the first treatment cycle. Furthermore, 80% of patients achieved complete MRD response across all cycles. Initial response to treatment is a crucial factor because for those patients who have persistent or recurrent disease after their first therapy, have a higher risk of relapse than those with no detectable MRD.

As with any good drug come sides effects. Blinatumomab carries a boxed warning alert informing patients and healthcare providers of hypotension and difficulty breathing with the start of the first treatment. The most common side effects reported were pyrexia, febrile neutropenia, headache, peripheral edema, hypokalemia, and gastrointestinal symptoms such as nausea and diarrhea.

The results from the study (abstract #379) will be presented during the 56^th American Society of Hematology (ASH) Annual Meeting and Exposition in an oral session on Monday, December 8, 2014.

Blinatumomab is the first BiTE antibody, single-agent immunotherapy to be approved for the treatment of Philadelphia chromosome-negative relapsed or refractory B-cell precursor ALL. Clinical progress will continue to be monitored and trial data will be collected as required by the FDA.