FDA Approves Subcutaneous Isatuximab for Multiple Myeloma Indications

A change in route, not in drug

On July 9, 2026, FDA approved isatuximab-irfc for injection under the skin. The brand name for this form is Sarclisa Escena.

The drug itself is not new. What changed is how it gets into the body. Until now it went in through a vein, over a long chair-side infusion. Now it can be given as an injection under the skin. The medical word for that is subcutaneous.

For someone on a myeloma regimen, that is not a small detail. It is the difference between a long clinic appointment and a short one.

What the drug does

Isatuximab is a monoclonal antibody. That means a lab-made protein built to lock onto one target. Its target is CD38, a molecule on the surface of plasma cells.

Myeloma is a cancer of plasma cells. Those are the white cells that normally make antibodies. They carry a lot of CD38. So an antibody aimed at CD38 sticks mainly to myeloma cells. It then marks them for the immune system to destroy.

That is why this drug is always given with partners. It clears cells the rest of the regimen has already weakened. Our page on immunotherapy explains how antibody drugs differ from chemotherapy.

The three approved settings

FDA's notice is precise about who this covers, and precision matters here.

The first pairing is with pomalidomide and dexamethasone. That is for adults who have had at least one prior line of therapy. It had to include lenalidomide and a proteasome inhibitor.

The second is with carfilzomib and dexamethasone. That is for adults with relapsed or refractory myeloma after one to three prior lines.

The third is with bortezomib, lenalidomide and dexamethasone. That is for adults with newly diagnosed myeloma who cannot have a stem cell transplant using their own cells.

That last group matters. Transplant is standard for many people with new myeloma. But age or other health problems rule it out for many others. Our page on treatment by stage covers how that call is made.

What the trials actually measured

This is the part that gets flattened in headlines, so here it is straight from FDA's notice.

The main study was IRAKLIA, registry number NCT05405166. The registry lists it as a phase 3 trial with 531 people enrolled. It randomly assigned them to get isatuximab either under the skin, through an on-body device, or into a vein. Both arms also got pomalidomide and dexamethasone.

It was a non-inferiority trial. That design does not ask whether the new route is better. It asks whether it is not meaningfully worse.

The overall response rate was 71.1 percent for the injection and 70.5 percent for the infusion. Drug levels in the blood before the next dose came out slightly higher with the injection.

Two smaller studies backed the other settings. IZALCO tested the injection with carfilzomib and dexamethasone in 74 patients with relapsed or refractory disease. The response rate was 79.7 percent. IsaSocut was a single-arm study of 74 newly diagnosed patients who could not have a transplant. Its response rate was 97.3 percent.

Note what those two are. Small, and in IsaSocut's case with no comparison group at all. A single-arm response rate cannot tell you what would have happened without the drug.

What the label warns about

FDA lists warnings for hypersensitivity and other reactions to the way the drug is given. Also neutropenia, meaning a shortage of the white cells that fight bacteria. Also serious infections, and second primary cancers. Also interference with laboratory tests, and harm to a developing fetus.

The laboratory interference is worth understanding. The label explains that isatuximab binds CD38 on red blood cells as well. That can produce a false positive on the indirect antiglobulin test, also called the indirect Coombs test. It was positive in 68 percent of tested patients on one intravenous regimen. So patients are typed and screened before starting, and blood banks are told.

The recommended dose is 1,400 mg given by subcutaneous injection.

Signs that need a call during treatment

Anyone on a CD38 antibody should have a clear threshold for contacting the team. Ask what yours is, and then act on it.

• A temperature at or above 100.4°F (38°C), or shaking chills. With a low white count that is an emergency, not a wait-and-see.
• Swelling, redness, pain, or a lump at the injection site that is spreading or not settling.
• Breathlessness, wheeze, throat tightness, rash, or dizziness during or shortly after a dose.
• A cough, sore throat, burning on passing urine, or any new infection symptom.
• Unusual bruising or bleeding.
• Before any planned transfusion, tell the team you are taking this drug.

What this does not mean

• This is a new route, not a new drug and not a new indication. The disease settings it covers were already treated with isatuximab.
• Non-inferiority is the claim. The evidence supports the injection working about as well as the infusion. It does not show it works better.
• Two of the three settings rest on small single-arm or phase 2 data. Response rate is not survival.
• Fewer hours in a chair is a real benefit for quality of life. It does not change how the cancer behaves.
• Side effects are not reduced by changing the route, and injection-site and hypersensitivity reactions still occur.
• SEER, the federal cancer surveillance program, estimates about 36,000 new myeloma cases in the United States in 2026. Five-year relative survival is 63.7 percent. That is a group average from people diagnosed years ago. It describes populations, not individuals.

Sources

• FDA: FDA approves isatuximab-irfc for subcutaneous injection for multiple myeloma indications
• ClinicalTrials.gov API v2 record for NCT05405166 (IRAKLIA)
• DailyMed: SARCLISA ESCENA prescribing information (SPL)
• NCI PDQ: Plasma Cell Neoplasms (Including Multiple Myeloma) Treatment (Health Professional Version)
• NCI SEER Cancer Stat Facts: Myeloma

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.

Cancer Explained is published by the National Cancer Information Foundation. It is not medical advice and does not suggest a test or treatment.

See an error, old source, or unclear wording? Tell us.