FDA Approval: Venetoclax (Venclexta) for Leukemia

The approval, in specifics

On April 11, 2016, the FDA approved venetoclax, sold as Venclexta, for people with chronic lymphocytic leukemia carrying a 17p deletion, detected by an FDA-approved test, who had already received at least one prior therapy.

The evidence was a phase 2, single-arm trial. Single-arm means everyone got the drug and there was no comparison group. It enrolled 106 patients with the 17p deletion who had a median of 2.5 prior treatments, with a range of 1 to 10. The main outcome was overall response rate, judged by an independent review committee.

The response rate was 80 percent, with a 95 percent confidence interval of 71 to 87 percent. Complete remission was 8 percent. The 17p deletion was found using an FDA-approved fluorescence in situ hybridization probe kit, usually called FISH.

That is a narrow, precise approval. It is not a statement about leukemia in general.

What venetoclax is approved for now

Labels grow. NCI currently lists venetoclax as approved for two settings.

The first is chronic lymphocytic leukemia, or CLL, and small lymphocytic lymphoma, or SLL, in adults. It may be given alone, or with obinutuzumab or rituximab.

The second is newly diagnosed acute myeloid leukemia in adults aged 75 and older, or in adults who cannot take intensive induction chemotherapy. There it is combined with azacitidine, decitabine, or low-dose cytarabine.

Venetoclax blocks a protein called BCL-2. BCL-2 keeps cells from dying on schedule. Blocking it lets the leukemia cells complete a death program they had been dodging.

What CLL is

CLL is a cancer of the blood and bone marrow in which the marrow makes too many lymphocytes, a kind of white blood cell. It usually gets worse slowly. It is one of the most common leukemias in adults, and it rarely occurs in children.

At the start, CLL often causes nothing at all. It is frequently picked up on a routine blood test.

When to get checked

NCI lists these signs. Check with a doctor if you have:

• Painless swelling of lymph nodes in the neck, underarm, stomach, or groin.
• Weakness, or feeling tired.
• Pain or a feeling of fullness below the ribs.
• Fever and infection.
• Easy bruising or bleeding.
• Petechiae, which are flat pinpoint dark-red spots under the skin caused by bleeding.
• Weight loss for no known reason.
• Drenching night sweats.

There is no screening program for CLL. A raised lymphocyte count on a complete blood count is usually the first clue.

The blood tests that define CLL

Diagnosis rests on blood tests. A complete blood count with differential measures red cells, platelets, hemoglobin, and the number and type of white cells. Further blood testing identifies the cell type and looks for the gene changes that guide treatment, including the 17p deletion.

Staging runs from stage 0 to stage IV, based on how far the leukemia cells have spread from blood and marrow into lymph nodes, liver, and spleen. Chest X-ray and CT scans help map that. Doctors also describe CLL as asymptomatic, symptomatic or progressive, recurrent, or refractory, and that description often drives the plan more than the stage number.

From watchful waiting to targeted pills

For CLL without symptoms, the standard option is watchful waiting. That is active monitoring, not neglect, and it can go on for years.

For symptomatic or progressive CLL, NCI lists watchful waiting, targeted therapy with a tyrosine kinase inhibitor such as acalabrutinib, zanubrutinib, or ibrutinib, venetoclax with obinutuzumab or rituximab, chemotherapy with rituximab, immunotherapy with lenalidomide, and trials of stem cell transplantation.

NCI adds an honest caveat. These treatments have not been compared head to head, so it is not possible to say one is better. Choice rests on test results, age, general health, and side effects. Our overview of targeted therapy explains how drugs like these are matched to a tumor's biology, and biomarker testing covers the tests that find markers like the 17p deletion.

The specific risk this drug carries

Venetoclax works fast, and that creates its own problem. When many leukemia cells die at once, their contents flood the blood. This is tumor lysis syndrome, or TLS, and it can damage the kidneys and disturb heart rhythm.

The label instructs clinicians to anticipate TLS and assess risk in every patient. Prevention includes drugs that lower uric acid, adequate hydration, and, as risk rises, intravenous fluids, frequent lab monitoring, and hospital admission. This is why the drug is started at a low dose and increased in weekly steps, a schedule called the ramp-up.

Other labeled warnings include neutropenia, meaning low white cell counts, and infections. Live attenuated vaccines should not be given before, during, or after treatment until B cells recover.

Call the team promptly for fever of 100.4 degrees Fahrenheit or higher, chills, reduced urine output, muscle cramps, an irregular heartbeat, or confusion during the first weeks of dosing.

The numbers behind a 17p diagnosis

SEER figures describe the whole US population, not one person.

For chronic lymphocytic leukemia, five-year relative survival is 90.2 percent for cases from 2016 to 2022. Median age at diagnosis is 71. The American Cancer Society projects 22,760 new cases and 4,350 deaths in the United States for 2026, a figure SEER republishes.

CLL is not staged like a solid tumor, so SEER does not publish a stage breakdown for it. The 17p deletion has historically marked a harder-to-treat group, which is exactly why a drug approved specifically for that group mattered. Our page on leukemia covers the wider family of these diseases.

What this trial cannot tell you

A single-arm trial with 106 patients shows that tumors respond. It does not show how long people live compared with another option. Response rate is a surrogate endpoint. Whether venetoclax suits one person depends on their disease, prior treatments, kidney function, other medicines, and what they want from treatment.

Sources

• FDA, Venetoclax (Venclexta) Tablets approval notification — https://www.fda.gov/drugs/resources-information-approved-drugs/venetoclax-venclexta-tablets
• NCI, Venetoclax — https://www.cancer.gov/about-cancer/treatment/drugs/venetoclax
• NCI Cancer Currents, venetoclax for chronic lymphocytic leukemia — https://www.cancer.gov/news-events/cancer-currents-blog/2016/venetoclax-cll
• DailyMed, VENCLEXTA (venetoclax) label — https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=b118a40d-6b56-cee3-10f6-ded821a97018
• NCI PDQ, Chronic Lymphocytic Leukemia Treatment (Patient Version) — https://www.cancer.gov/types/leukemia/patient/cll-treatment-pdq
• SEER Cancer Stat Facts, Chronic Lymphocytic Leukemia — https://seer.cancer.gov/statfacts/html/clyl.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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