Isatuximab and Elotuzumab in Myeloma

Two antibody medicines used in multiple myeloma, and in nothing else. Isatuximab targets CD38 on myeloma plasma cells. Elotuzumab targets a different protein, SLAMF7, and works largely by activating natural killer cells. Both are given by drip, always alongside other myeloma drugs. Both are immunotherapy, though patients are rarely told so.

These two sit in the shadow of daratumumab, which most Indian myeloma patients hear about first. They are worth understanding as a pair, because they answer two different questions. Isatuximab answers “is there another CD38 antibody?” Elotuzumab answers “is there an antibody that works a different way altogether?”

The second one is the more interesting of the two. SLAMF7 sits on myeloma plasma cells and on natural killer cells, the immune cells that patrol for and destroy abnormal cells. Elotuzumab attaches to both. It flags the myeloma cell as a target and, through the same protein, switches on the immune cell that comes to attack it. That is immunotherapy in the most literal sense available in myeloma — and it is almost never described that way on a discharge summary, which simply says “antibody” or “targeted therapy”.

Isatuximab is daratumumab’s close relative; elotuzumab is not. Isatuximab uses the same CD38 target, attaches to a different part of it, and does a similar job in the same disease. Elotuzumab uses a different target, has no useful effect on its own, and does not disturb blood cross-matching. Daratumumab is the one actually marketed in India.

That table is not a ranking. There is no published head-to-head trial that settles isatuximab against daratumumab in the same patients, and NCCN and ESMO myeloma guidance builds regimens around each of them rather than declaring one the winner. What actually decides the choice is narrower and more practical: the diagnosis, what regimen came before, which partner drug is planned, what the treating unit can obtain, and what the family can sustain.

For most Indian patients that arithmetic ends at daratumumab, simply because it is here. Daratumumab: Uses, Cost and Side Effects in Myeloma covers that molecule in full, including the subcutaneous form.

Adults with multiple myeloma, in defined combinations, and no one else. Isatuximab is used in relapsed or refractory myeloma, and in newly diagnosed myeloma in people not eligible for a transplant. Elotuzumab is used in relapsed disease, with lenalidomide or pomalidomide. Neither has any role in solid tumours, lymphoma or leukaemia.

Labels differ a little between regulators, and what follows reflects the United States and European labels, since those are the ones these products are supplied against.

Anyone who does not have multiple myeloma. Isatuximab needs CD38 in quantity and elotuzumab needs SLAMF7, and in practice both proteins mean myeloma plasma cells. If the diagnosis is something else, neither antibody has anything useful to attach to, and no amount of import effort or cost help changes that.

Concretely, these are not treatments for solid tumours — breast, lung, colorectal, prostate, head and neck, cervical or ovarian cancer. They are not lymphoma or leukaemia medicines; those diseases are treated with antibodies aimed at different markers. And they are not alternatives to a checkpoint inhibitor, which acts on an entirely different part of the immune system in entirely different diseases.

They are also not for everyone with a plasma-cell disorder. MGUS and most smouldering myeloma are watched rather than treated. And elotuzumab in particular is not for a patient who cannot take an immunomodulatory drug, because without lenalidomide or pomalidomide alongside it there is very little left of its effect — it is not a gentler antibody to fall back on when the partner drug is stopped.

Within myeloma that does need treatment, neither is given during an active severe infection, or to anyone who has had a severe reaction to that antibody before. Hepatitis B screening is done before the first dose, since these medicines can wake a dormant infection. Live vaccines are avoided during treatment. Contraception is advised during treatment and for a period after the last dose — five months after isatuximab, per its labelling — and that conversation belongs before the first cycle rather than after it.

There is one more group these are not for, and it is a practical one rather than a medical one: a family who cannot sustain a repeated import. Both medicines are given for months, not once. A route that works for the first dose and fails at the fourth is worse than a regimen built on something obtainable locally.

Both by drip, in day care, after premedication. Each is dosed on body weight, weekly at first and less often later. The early risk is a reaction while the medicine is going in. The longer risk is a fall in white cells and the infections that follow. Neither needs admission on its own.

The first visit follows the same sequence in most units, and knowing it in advance removes a good deal of the anxiety.

1. Before the first dose. Blood counts, kidney and liver tests, hepatitis B screening, and — for isatuximab, as for daratumumab — a type-and-screen sample for the blood bank while the result is still clean.
2. Premedication, 45 to 90 minutes ahead. A corticosteroid, an antihistamine, an acid-blocker and paracetamol. This is what keeps most first-dose reactions mild.
3. The drip starts slowly. Elotuzumab begins at a rate of about 0.5 mg a minute and is stepped up over later cycles if it is well tolerated. Isatuximab is stepped up the same way.
4. Observation at each step-up. Blood pressure, pulse and temperature. Reactions declare themselves at exactly these moments, and almost always on the first dose.
5. Home the same day. These are day-care treatments. Admission is needed only if something else in the regimen calls for it.

One laboratory point separates the two, and it matters at the worst possible moment. Isatuximab, like every anti-CD38 antibody, coats red blood cells and makes the indirect Coombs test positive for months, so a myeloma patient who is anaemic and arrives at an emergency department at night can be hard to cross-match unless the blood bank is told. Elotuzumab does not do this at all. Both, being IgG kappa antibodies themselves, can show up as a faint band on immunofixation and be misread as leftover myeloma protein — which is a reason to have the report read by the treating haematologist rather than by the family.

Once home, a temperature of 38 °C or more, new breathlessness or a spreading rash means going to the emergency department the same day. Carry the day-care record: the molecule, the brand, the batch number and the date of the last dose are the first three things the receiving doctor will want.

Not as ordinary hospital-pharmacy stock, as far as can be confirmed. Neither molecule could be confirmed as holding a CDSCO marketing authorisation for routine sale in India in August 2026. Both appear on Indian speciality-pharmacy listings only as imported medicines supplied on request. Treat the regulatory status as unconfirmed rather than settled either way.

That distinction is not pedantic. A locally registered medicine has an Indian licence holder, a printed MRP, a supply chain a hospital can order against, and a manufacturer answerable here. A named-patient import has none of those. The haematologist writes a prescription for one identified patient, an importer brings in that quantity for that patient, and the paperwork, freight, customs clearance and validated cold chain all sit on the family’s timeline and the family’s bill.

• There is no Indian MRP to check against. Any figure quoted is a landed cost, not a printed price, and it moves with the exchange rate, duty and freight. For reference only: Sanofi’s published United States list price at launch was USD 650 for a 100 mg vial and USD 3,250 for a 500 mg vial, as reported by Reuters on 2 March 2020. That is a United States figure from six years ago and is not an Indian price. All costs on this page are indicative only, as of August 2026.
• There is no Indian biosimilar of either molecule. As of August 2026 there is no cheaper same-molecule version to ask for, unlike rituximab or trastuzumab. The molecules that do have Indian biosimilars are set out in Immunotherapy Medicines Explained.
• Insurance and scheme cover is harder, not merely dearer. Policies and government scheme ceilings are written against approved protocols and locally registered products. An imported, unregistered medicine often falls outside both. Ask for the position in writing before the first cycle, not after it.
• The cold chain is the whole product. These are refrigerated biologics, and an import route has more handoffs than a local one. Insist on documented temperature control, an unbroken chain of custody and original packaging, and keep the batch number for every dose.
• Time is a real variable. Myeloma treatment runs to a schedule. A route that takes weeks to arrange for dose one has to be able to repeat for dose eight, on time, before the regimen is built around it.

None of this makes an import wrong. For a patient who has exhausted the locally available options, it can be entirely reasonable, and it is a route Indian haematologists use. It does mean the conversation has to be honest about cost, delay and cover before the first vial is ordered, and it means a locally marketed alternative deserves to be considered first on its merits rather than dismissed as second best.

Regulatory status changes, sometimes quickly. Anything on this page about approval or availability should be re-checked with the treating haematologist and against the current CDSCO record before it is relied on.

They are the middle generation. Elotuzumab and the CD38 antibodies flag a myeloma cell and leave the immune system to act. The newer bispecific antibodies physically drag a T cell onto the myeloma cell instead. Same broad family, a considerable step up in both effect and risk, and a different set of access problems in India.

Understanding that ladder helps a family read a treatment plan. An antibody that marks a target depends on the patient’s remaining immune function to finish the job — which is exactly why elotuzumab needs lenalidomide beside it. A bispecific antibody does not wait for that; it brings the killer cell itself, which is why it works later in the disease and why it carries cytokine release syndrome as a risk that these two do not. Teclistamab, Talquetamab and Myeloma Bispecifics covers that group and what it takes to be considered for one.

The same generational step happened in lymphoma, and the parallel is worth reading if the family is comparing notes across diagnoses — Glofitamab, Mosunetuzumab and Epcoritamab in Lymphoma sets it out. And “antibody medicine” is a wider word than either: Sacituzumab Govitecan in Triple-Negative Breast Cancer describes an antibody used as a delivery vehicle for chemotherapy in a solid tumour, which is a third idea again and has nothing to do with myeloma.

• Daratumumab: Uses, Cost and Side Effects in Myeloma — the CD38 antibody that is actually marketed in India.
• Teclistamab, Talquetamab and Myeloma Bispecifics — the generation that brings a T cell rather than flagging a target.
• Glofitamab, Mosunetuzumab and Epcoritamab in Lymphoma — the same step, in a different blood cancer.
• Sacituzumab Govitecan in Triple-Negative Breast Cancer — an antibody used as a delivery vehicle, in a solid tumour.
• Immunotherapy Medicines Explained — the index of antibodies, checkpoint inhibitors and biosimilars.
• Immunotherapy at a glance — what this family of treatments does, and what it does not.

Editorial information about prescription-only medicines — not an offer, a price list, or a recommendation to use any named product, and no comparative quality claim between manufacturers. Clinical statements follow product labelling and published NCCN, ESMO and International Myeloma Foundation patient-education material; regulatory and pricing statements are indicative and dated to August 2026, are drawn from published sources, and can change. Whether isatuximab or elotuzumab applies to a particular patient, in which regimen, is a decision for the treating haematologist or medical oncologist.