Gazyva (obinutuzumab) is an immunotherapy, not chemotherapy. It is a monoclonal antibody, a type of targeted cancer treatment that works with your immune system to destroy cancer cells. However, Gazyva is almost always given alongside chemotherapy drugs, which is likely where the confusion comes from.
How Gazyva Works
Gazyva belongs to a class of drugs called anti-CD20 monoclonal antibodies. CD20 is a protein found on the surface of certain white blood cells called B lymphocytes, including the cancerous B cells involved in leukemia and lymphoma. Gazyva is designed to lock onto that protein like a key fitting into a lock.
Once Gazyva attaches to a cancer cell, it kills that cell in three ways. First, it flags the cell so your immune system’s natural killer cells can find and destroy it. Second, it triggers internal death signals within the cancer cell itself. Third, it activates a chain reaction of immune proteins called the complement cascade that punches holes in the cell’s outer membrane. This multi-pronged attack is what makes it an immunotherapy: it recruits and amplifies your own immune defenses rather than poisoning cells with toxic chemicals.
Traditional chemotherapy, by contrast, uses cytotoxic drugs that kill rapidly dividing cells throughout the body. Chemotherapy doesn’t distinguish well between cancer cells and healthy cells, which is why it causes side effects like hair loss and nausea. Gazyva is far more selective because it only targets cells displaying the CD20 protein.
Why It’s Often Paired With Chemotherapy
Even though Gazyva itself is not chemotherapy, your treatment plan will likely include chemotherapy drugs given at the same time. The FDA has approved Gazyva for use in combination with several chemotherapy regimens, not as a standalone replacement for them. For chronic lymphocytic leukemia (CLL), Gazyva is approved in combination with chlorambucil. For follicular lymphoma, it can be paired with bendamustine, or with multi-drug chemotherapy regimens known as CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) or CVP (cyclophosphamide, vincristine, and prednisone).
In more recent treatment approaches for CLL, Gazyva is increasingly combined with newer targeted drugs rather than traditional chemotherapy. Current national guidelines list venetoclax plus Gazyva as a preferred first-line regimen. Venetoclax is a targeted therapy that blocks a protein cancer cells use to survive. This combination represents a shift toward “chemo-free” regimens for CLL, though Gazyva itself has been part of the treatment landscape since its initial approval.
What Gazyva Is Approved to Treat
Gazyva has three FDA-approved uses. It treats previously untreated CLL, the most common type of leukemia in adults. It treats follicular lymphoma that has come back after or stopped responding to a prior treatment containing rituximab, a related anti-CD20 antibody. And it treats previously untreated advanced-stage follicular lymphoma (stage II bulky, III, or IV) in combination with chemotherapy, followed by Gazyva alone as maintenance therapy for patients who achieve at least a partial response.
How Treatment Is Given
Gazyva is delivered as an intravenous infusion, meaning it drips slowly into a vein through an IV line. It cannot be given as a quick injection. The first cycle is the most intensive: you receive a small 100 mg dose on day 1, then 900 mg on day 2, followed by full 1,000 mg doses on days 8 and 15. This split dosing on the first two days is deliberate, designed to reduce the risk of a reaction by introducing the drug gradually. After cycle 1, each subsequent cycle typically involves a single 1,000 mg infusion, with treatment running in 28-day cycles.
After the combination phase ends, some patients with follicular lymphoma continue receiving Gazyva alone as maintenance therapy for up to two years.
Infusion Reactions and Side Effects
The most notable side effect of Gazyva is infusion-related reactions, which occur in roughly 25% of patients. The vast majority of these reactions (about 94%) are mild to moderate, involving symptoms like fever, chills, nausea, or flushing during or shortly after the infusion. Severe reactions are uncommon, occurring in about 1.5% of patients in one multicenter study.
Most patients who experience a reaction can still continue treatment. In that same study, about 71% of patients who had a reaction completed their infusion the same day after symptoms improved. Another 24% were successfully re-treated at a later date. Only one patient out of 68 had to stop Gazyva entirely because of a reaction. The first infusion carries the highest risk, which is why the dose is split across two days and why medical teams monitor you closely during that initial session.
Because Gazyva destroys B cells (both cancerous and some healthy ones), it can lower your body’s ability to fight infections. This is different from the broad immune suppression caused by chemotherapy, but it still requires monitoring. If you’re receiving Gazyva alongside chemotherapy drugs, you’ll experience side effects from both, and the chemotherapy component is typically responsible for the more familiar effects like fatigue, low blood counts, and nausea.
Gazyva vs. Rituximab
If you’ve researched blood cancer treatments, you’ve likely come across rituximab (Rituxan), an older anti-CD20 monoclonal antibody that has been a cornerstone of lymphoma and CLL treatment for decades. Gazyva was engineered to bind to a different part of the CD20 protein and was designed to trigger stronger immune cell killing. Both are immunotherapies in the same drug class, but Gazyva represents a newer generation of the approach. Your oncologist may choose one over the other based on your specific diagnosis, treatment history, and the combination regimen being used.