FDA Approval: Blinatumomab (Blincyto) for Leukemia

The approval, in the label's own words

The FDA approved blinatumomab, sold as Blincyto, on December 3, 2014, under biologics licence 125557 held by Amgen. It was a priority review.

The 2014 label names a narrow group: Philadelphia chromosome-negative relapsed or refractory B-cell precursor acute lymphoblastic leukemia. Unpacked, that means ALL that started in immature B cells. It has either come back or never responded. And it does not carry the Philadelphia chromosome, a swap between chromosomes 9 and 22. That swap creates a fusion gene called BCR::ABL1, and it opens a different set of drug options.

It came through accelerated approval. The label says so plainly. Continued approval "may be contingent upon verification of clinical benefit in subsequent trials." That verification arrived later. NCI reported the change to a full approval in 2017, based on a randomized trial called TOWER.

A drug that holds two cells together

Blinatumomab is a bispecific T-cell engager. It is a small protein with two grips. One grabs CD19, a marker on the surface of B cells, including leukemic ones. The other grabs CD3 on a T cell, part of the patient's own immune system.

The drug does not kill anything itself. It drags a T cell into contact with a leukemia cell and lets the T cell do the work. That was new in 2014. Blincyto was the first bispecific antibody of its kind the FDA approved. Our explainer on immunotherapy versus chemotherapy covers the difference in approach.

The trial that supported it

The evidence was a single-arm, open-label study. Everyone got the drug. There was no comparison group. That is common in accelerated approvals for a group with few options, and it limits what can be concluded.

The study treated 185 patients, all aged 18 or over. The median age was 39. Thirty-four percent had already had a stem cell transplant. Another 17.3% had been through more than two prior salvage treatments.

The main measure was complete remission, or complete remission with partial recovery of blood counts, within two cycles. Seventy-seven of 185 patients, 41.6%, reached it. Most of those responses, 81%, came in the first cycle.

The label defines complete remission. It means 5% or fewer blast cells in the bone marrow, no other sign of disease, and blood counts back to normal. The partial-recovery version accepts lower platelet and white cell counts.

What taking it actually involves

This is not a clinic visit. A cycle is four weeks of continuous infusion into a vein, run through a pump at a constant rate, then two weeks off. A full course is up to two cycles to induce remission and three more to consolidate it.

The label recommends hospitalization for the first nine days of cycle one and the first two days of cycle two. Patients take dexamethasone an hour before certain doses. The label warns against flushing the infusion line, because doing so can deliver an accidental overdose.

The two boxed warnings

Blincyto carries the FDA's strongest warning, and it carries two.

The first is cytokine release syndrome, a storm of immune signalling that follows the T cells being switched on. The label says it may be life-threatening or fatal. Associated events include fever, headache, nausea, weakness, low blood pressure and abnormal liver tests.

The second is neurological toxicity. The label reports that some neurological effect occurred in roughly 50% of patients in trials. The median time to onset was seven days. Severe, life-threatening or fatal versions occurred in about 15%. Those included encephalopathy, seizures, speech problems, confusion and loss of balance. Most resolved when the drug was stopped for a time.

The most common side effects overall, at 20% or more, were fever, headache, swelling in the limbs, febrile neutropenia, nausea, low potassium, tremor, rash and constipation.

Why a second option mattered here

ALL moves fast. NCI states it usually gets worse quickly without treatment. It is diagnosed from blood and bone marrow. The tests include a complete blood count, immunophenotyping to read the markers on a cell surface, and cytogenetic analysis to find changes such as the Philadelphia chromosome. Our page on ALL pathology and molecular results explains the report.

Standard treatment runs in phases: induction to force remission, then consolidation to kill what is left. NCI notes that central nervous system prophylaxis is given during each phase, because ordinary chemotherapy doses do not reach leukemia cells hiding in the brain and spinal cord.

The American Cancer Society projects 6,250 new US cases of acute lymphocytic leukemia in 2026 and 1,600 deaths; SEER publishes those numbers but NCI does not generate them. Five-year relative survival, an NCI SEER measurement based on people diagnosed between 2016 and 2022, is 73.2%. That figure is lifted by children, who do far better than adults. In 2014, relapsed adult ALL was a situation with very little to offer.

When to get checked

NCI notes that early ALL can look like flu. Take these to a doctor:

• Weakness or fatigue that is new and does not lift
• Fever, or night sweats that soak the sheets
• Bruising easily, or bleeding from gums or nose
• Petechiae, meaning flat pinpoint red spots under the skin
• Bone pain, or pain and fullness below the ribs
• Painless lumps in the neck, underarm, stomach or groin
• Infections that keep coming back

Unexplained bruising together with fatigue and fever deserves a blood count within days, not weeks. A complete blood count is a cheap test that settles the question quickly.

What this does not mean

• The 2014 approval covered Philadelphia chromosome-negative relapsed or refractory B-cell precursor ALL. It said nothing about newly diagnosed disease or other leukemias.
• A 41.6% remission rate came from a study with no comparison group. It cannot tell you how blinatumomab compares with anything else.
• Complete remission is not the same as cure. Many patients went on to further treatment.
• Accelerated approval means the FDA accepted an early measure of benefit while further evidence was gathered.
• The 2014 label quoted here is not the current one. Blinatumomab has since been approved in wider settings.

Sources

• FDA, BLINCYTO (blinatumomab) prescribing information, BLA 125557, approved 3 December 2014 — https://www.accessdata.fda.gov/drugsatfda_docs/label/2014/125557lbl.pdf
• FDA openFDA Drugs@FDA API record for BLA 125557 — https://api.fda.gov/drug/drugsfda.json?search=openfda.brand_name:%22BLINCYTO%22&limit=2
• NCI Cancer Currents, Blinatumomab Receives Full FDA Approval for ALL — https://www.cancer.gov/news-events/cancer-currents-blog/2017/blinatumomab-all-fda-full-approval
• NCI PDQ, Adult Acute Lymphoblastic Leukemia Treatment (Patient Version) — https://www.cancer.gov/types/leukemia/patient/adult-all-treatment-pdq
• SEER Cancer Stat Facts, Acute Lymphocytic Leukemia — https://seer.cancer.gov/statfacts/html/alyl.html

How this article was prepared

An AI-assisted editorial system helped prepare this page. No named medical reviewer has reviewed it unless one is listed.

The National Cancer Information Foundation publishes Cancer Explained. This page is for learning. It is not medical advice and does not suggest a test or treatment.

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