Understanding the differences between CAR T-cell therapy and Bispecific antibody therapy

Recent advances in immunotherapy are creating new treatment options for patients whose cancer has returned or has not responded to standard treatments. Two of the most important developments in this area are CAR T-cell therapy and bispecific antibody treatment.

Both therapies are designed to help the immune system recognise and attack cancer cells more effectively. Both are used in certain blood cancers, including lymphoma and myeloma, and both can offer new options when other treatments have failed. However, although they share similar goals, they work in very different ways.

Understanding these differences can help patients feel more informed when discussing treatment options with their specialist team.

At GenesisCare, CAR T-cell therapy is provided through a dedicated partnership with Cambridge University Hospitals NHS Foundation Trust, and bispecific antibody treatment is delivered through specialist care pathways with Cambridge University Hospitals NHS Foundation Trust and other leading centres, supported by experienced multidisciplinary teams. For selected patients GenesisCare provide a complete ambulatory bispecific pathway, which allows patients to receive treatment and monitoring at GenesisCare while spending the time between treatments at home rather than staying in hospital overnight. Careful assessment, monitoring and personalised treatment planning help ensure each patient receives the most appropriate treatment for their individual situation.

CAR T-cell therapy is a personalised cellular therapy made using a patient’s own immune cells. T cells are collected from the blood, genetically modified in a laboratory to become CAR (Chimeric Antigen Receptor) T cells that better recognise cancer cells, and then returned to the body.

Bispecific antibody treatment is an immunotherapy that uses specially engineered antibodies to bring immune cells and cancer cells into direct contact. Unlike CAR T-cell therapy, it does not involve collecting or modifying a patient’s cells.

Although both treatments activate the immune system, the way they are created, delivered and maintained within the body is very different.

One of the biggest differences between the treatments is how they are produced.

CAR T-cell therapy is individually designed and manufactured for each patient. T cells are collected using a procedure called apheresis, then genetically modified in a specialist laboratory to produce what is called a chimeric antigen receptor (CAR) that recognises specific proteins on cancer cells.

Once modified, the cells are expanded into millions of copies before undergoing extensive quality and safety testing. Only once this process is complete can the cells be returned to the patient.

Because every treatment is created from an individual patient’s cells, CAR T-cell therapy is highly personalised. However, this also means the manufacturing process is more complex and can take several weeks. During this time, some patients may require additional treatment, known as bridging therapy, to help control the cancer while the CAR T cells are being prepared.

Rather than being manufactured individually for each patient, bispecific antibodies are produced in advance as off-the-shelf therapies. These antibodies are specially engineered to bind to both a cancer cell and an immune cell at the same time.

Because there is no need for cell collection, genetic modification or laboratory expansion of immune cells, bispecific antibody treatment can often begin more quickly than CAR T-cell therapy.

This difference in manufacturing is one of the key reasons why one treatment may be recommended over another, particularly if treatment needs to start urgently.

Although both CAR T-cell therapy and bispecific antibody treatment are designed to activate the immune system against cancer, the way they work is fundamentally different.

CAR T-cell therapy works by permanently modifying a patient’s own T cells so they can independently recognise and attack cancer cells. CAR T-cell therapy overcomes immune evasion by genetically engineering the T cells with a receptor specifically designed to recognise a protein on the surface of the cancer cell.

Once the modified cells are returned to the body, they begin identifying and attacking cancer cells directly. These CAR T cells can also continue expanding and multiplying inside the body over time. In some cases, they may remain active for months or even years, continuing to monitor for cancer cells long after treatment has finished.

This means CAR T-cell therapy has the potential to create a deep and long-lasting immune response from a single treatment process.

Rather than permanently changing immune cells, bispecific antibodies act as a bridge between T cells and cancer cells while the treatment is present in the bloodstream.

One part of the antibody binds to a protein on the cancer cell, while the other binds to the T cell. This physically brings the immune cell and cancer cell together, helping activate the immune response against the cancer.

Unlike CAR T-cell therapy, bispecific antibodies do not genetically modify the immune cells themselves. Instead, they repeatedly recruit and redirect the patient’s existing immune cells during each treatment cycle.

As treatment continues, the antibodies keep guiding T cells towards cancer cells, helping maintain an active but more controlled immune response over time.

Because of these differences, CAR T-cell therapy is often viewed as a highly personalised cellular therapy designed to create a long-term immune response, while bispecific antibody treatment is generally considered a more flexible and adjustable immunotherapy approach that can often be started more quickly.

The way these therapies are delivered is also very different.

CAR T-cell therapy is usually delivered as a one-off treatment process. Before receiving the modified cells, patients typically receive a short course of chemotherapy to prepare the immune system. The CAR T cells are then returned through a single intravenous infusion.

Because the immune response can become very active shortly after treatment, patients require close monitoring by their specialist team during the early recovery period. Patients are also typically required to have a carer stay with them at home and remain within approximately one hour of the treating hospital so that urgent medical care can be accessed quickly if needed.

Bispecific antibody treatment is usually delivered as a series of treatments over time rather than a single infusion. Depending on the specific treatment, it may be given through an intravenous infusion or as an injection under the skin.

Treatment often begins with step-up dosing, where smaller doses are given initially and gradually increased over the first few treatments to help reduce the risk of immune-related side effects.

At GenesisCare, selected myeloma and lymphoma patients receiving bispecific antibody treatment may also be suitable for ambulatory care pathways which allows patients to receive treatment and monitoring at GenesisCare while spending the time between treatments at home rather than staying in hospital overnight.

For many patients, this can mean less time in hospital while still maintaining close specialist supervision and rapid access to clinical support if needed. Being able to spend more time at home can help patients maintain greater independence, remain closer to family and familiar surroundings, and reduce some of the disruption that prolonged hospital stays can have on day-to-day life, while still benefiting from careful monitoring by specialist teams.

Because both therapies activate the immune system, they can cause similar immune-related side effects.

The two most important side effects associated with both treatments are cytokine release syndrome (CRS) and neurological side effects known as ICANS. Although both treatments can cause these side effects, the timing and intensity may differ.

With CAR T-cell therapy, side effects often occur shortly after the single infusion and may require intensive hospital-based monitoring during the early recovery period.

With bispecific antibody treatment, side effects are often most likely during the first few step-up doses. In many cases, they become less frequent or less severe as treatment continues and the body adapts.

At GenesisCare, selected patients receiving bispecific antibody treatment may be supported through structured ambulatory monitoring pathways. Patients and carers are provided with home monitoring equipment, symptom guidance and access to 24-hour specialist advice lines to help identify side effects early and manage them safely.

Both CAR T-cell therapy and bispecific antibody treatment are highly specialised therapies that should be delivered within experienced immunotherapy and cellular therapy programmes.

At GenesisCare UK, patients are supported by haematology experts, oncology teams, specialist nurses and multidisciplinary teams experienced in delivering advanced immunotherapies safely and effectively.

Patients benefit from coordinated care, personalised treatment planning and access to innovative therapies supported by robust monitoring and expert clinical oversight.

The decision to recommend CAR T-cell therapy or bispecific antibody treatment depends on several factors, including the type of cancer, previous treatments, how quickly treatment is needed, and a patient’s overall health and individual circumstances.

For some patients, CAR T-cell therapy may be recommended because of its potential to create a deep and long-lasting immune response from a single treatment process. For others, bispecific antibody treatment may be more appropriate because it can often be started more quickly and delivered in a more flexible way.

Professor Karthik Ramasamy, MBBS, PhD, FRCP, FRCPath

Consultant Haematologist