The most important debate in autoimmune cell therapy is no longer whether deep B cell depletion can reset the immune system, as CAR T therapy has helped settle that question. The harder question is how to deliver and achieve this effect safely, reproducibly, and practically at scale.
Autologous CAR T has produced striking early clinical results, but it requires individualized manufacturing, specialized infrastructure, and a treatment model developed largely for oncology. Allogeneic CAR T aims to overcome these limitations with off-the-shelf products. In vivo CAR T aims to shift the engineering step from the manufacturing facility into patients themselves. T cell engagers offer another off-the-shelf approach by redirecting endogenous T cells toward B cell targets.
All of these strategies are scientifically important. But none of them should be assumed to be the only way to achieve deep B cell depletion. Natural killer (NK) cells offer a fundamentally different therapeutic model. Rather than engineering a patient’s T cells or redirecting endogenous T cells, NK cell approaches can use innate immune effector biology in combination with monoclonal antibodies to eliminate target cells. They are a different immune effector system with different design principles, different manufacturing considerations, and potentially different clinical applications.
Antibodies define the target
One of the most therapeutically important features of NK cells is antibody-dependent cellular cytotoxicity, or ADCC. Through CD16, NK cells recognize the Fc portion of antibodies already bound to target cells, allowing monoclonal antibodies to provide targeting specificity while NK cells deliver the cytotoxic response.
For B cell driven autoimmune diseases, anti-CD20 antibodies provide a well-established targeting mechanism. These antibodies bind CD20 on B cells and have been used for years in autoimmune disease. But antibody therapy alone may not always achieve the depth or consistency of depletion needed to drive durable clinical benefit in the most refractory patients.
Pairing an anti-CD20 antibody with allogeneic NK cells creates a different therapeutic logic. The antibody identifies the target, while the NK cell engages the antibody through CD16 to eliminate the B cell. Rather than relying on engineered receptors or redirecting endogenous T cells, this strategy harnesses the innate cytotoxic machinery of NK cells to amplify the activity of an established antibody.
It also changes modality design. A CD16-mediated NK cell approach can be modular, antibody-directed, and repeat-dosed. It does not require each patient’s cells to be collected, engineered, and returned; nor does it require NK cells to behave like CAR T cells to have therapeutic relevance.
The objective is not to make NK cells behave like T cells, but to exploit the biology that makes them distinct. Their innate immune function, ability to mediate antibody-directed cytotoxicity, controlled activity, and potential for scalable off-the-shelf manufacturing position them as an alternative immune effector system for achieving the same therapeutic goal: deep and sustained B cell depletion.
What drives durability
In cell therapy, persistence is often discussed as though more is always better. In oncology, that assumption has a clear rationale: Long-term expansion and immune surveillance may help prevent relapse. Autoimmune disease, however, raises a different question. What ultimately matters may not be how long therapeutic immune cells persist, but whether they achieve sufficiently deep B cell depletion to reset the immune system.
The recent autologous CAR T experience in autoimmune disease has made that distinction unusually clear. Auto-CAR T cells expand to high levels during the first weeks after infusion, drive deep B cell depletion during that window and are then largely cleared within a few months. Despite that limited persistence, the clinical effect has appeared durable, with responses extending for years in some patients. The implication is straightforward. Once sufficiently deep B cell depletion has been achieved, durability appears to stem from the immune reset itself rather than the continued presence of the therapeutic cells.
That reframes the design question. What matters is not how long an engineered immune cell population persists, but whether the therapy can deliver enough cytotoxic activity, at the right time, to achieve deep depletion and allow a healthier B cell compartment to reconstitute. Doing the job well during a defined window may matter more than staying around afterward.
Antibody-directed NK cell approaches are well-aligned with that task. NK cells deliver potent but time-limited cytotoxic activity, and repeat dosing offers a way to shape exposure and reinforce depth where needed. Rather than relying on prolonged in vivo expansion, the approach combines an established targeting antibody with an off-the-shelf immune effector that can be administered repeatedly and adjusted over time.
That treatment model may also fit the realities of autoimmune care. Unlike haematological malignancies, many autoimmune diseases are managed by rheumatologists, neurologists and gastroenterologists in outpatient settings rather than specialist transplant or cell therapy centres. If clinical trials demonstrate comparable efficacy with an acceptable safety profile, therapies that combine deep immune-cell depletion with repeat dosing, outpatient administration, and less complex delivery could broaden access to transformative immune-reset strategies.
Off-the-shelf manufacturing steps in
Allogeneic NK cell therapy is often described as “off the shelf,” but that phrase understates the development challenge. Off-the-shelf cell therapy is not simply a logistics advantage; it is central to the product concept.
An allogeneic NK cell product must be manufactured consistently, released in batches, cryopreserved, shipped, thawed and administered while preserving the biological properties that matter clinically. For an antibody-directed NK cell therapy, that means preserving viability, phenotype, cytotoxic function, and CD16-mediated ADCC activity in the final clinical-use product.
Sourcing matters as much as process. Because NK cells can be derived from umbilical cord units or healthy peripheral blood donors, developers can select starting material with attributes that drive potency — most notably the high-affinity CD16 (158V/V) genotype associated with stronger antibody-dependent cellular cytotoxicity. Donor selection builds those properties into the product upstream rather than engineering them in later, reducing manufacturing complexity and keeping the biology closer to what a healthy immune system already does well.
That is a very different model from autologous cell therapy. Autologous CAR T begins with the individual patient and requires patient-specific manufacturing. Allogeneic NK cell therapy is designed to decouple manufacturing from the patient, enabling centralized production and broader distribution.
In autoimmune disease, that distinction matters. Large patient populations, community-based treatment patterns, and chronic disease management demand therapies that are not only potent but scalable and practical — judged less by whether cells can kill in a laboratory assay than by whether the product can be manufactured consistently, delivered reliably, and administered in real-world clinical settings.
Moving away from T cell only story
Recently disclosed clinical data from industry-sponsored trials show that allogeneic NK cell therapy combined with rituximab has been administered to dozens of autoimmune patients across a broad network of community-based clinical sites, with all treatment delivered in the outpatient setting.
Across multiple autoimmune indications, initial data have shown deep and consistent B cell depletion, B cell reconstitution consistent with an immune reset and clinical improvements across multiple disease activity measures. These early results appear consistent with the clinical activity reported with autologous CAR T approaches in autoimmune disease, though additional follow-up will be required to assess the durability of response.
The biological data are equally important. Uniform peripheral B cell depletion has been reported across evaluated patients receiving low-dose cyclophosphamide/fludarabine, allogeneic NK cells and rituximab, with complete depletion confirmed on high-sensitivity assays. B cell reconstitution has shown a predominance of naïve/transitional B cells, consistent with the hypothesized B cell reset mechanism.
The safety and treatment-setting observations are equally relevant. Neither cytokine release syndrome nor immune effector cell-associated neurotoxicity syndrome (ICANS) has been reported. No treatment discontinuations or serious adverse events related to the NK cell therapy have been described, and Grade 3 or higher infection rates have remained low. During the initial 28-day post-treatment period, no patients were hospitalized for infection, and hospitalizations for treatment-emergent adverse events have been rare and unrelated to the NK cell therapy.
These data are early and require confirmation in larger studies. Even so, they suggest that the future of immune-reset therapies may not hinge on a single modality. If antibody-directed allogeneic NK cell therapies can achieve sufficiently deep B cell depletion, they could offer a more scalable route to immune reset while retaining practical advantages such as off-the-shelf availability, repeat dosing, outpatient administration, and compatibility with community-based specialty care.
The importance of therapy fit
Autologous CAR T, in vivo CAR T, T cell engagers and NK cell therapies each ask different biological and clinical questions. The question for antibody-directed NK cell therapy is whether innate immune effector cells, combined with established monoclonal antibodies, can achieve sufficiently deep target-cell depletion in a treatment model that is both scalable and practical.
For autoimmune disease, the ideal therapy will need to do more than produce a strong biological effect. It must match the disease setting, patient population, treatment infrastructure, and safety expectations of chronic, non-malignant disease, while being potent enough to change the course of disease, but practical enough to reach patients beyond a small number of highly specialized centers.
The next phase of cell therapy will not be defined by a single modality. It will be defined by matching the right immune effector strategy to the right disease biology, target, safety profile, and treatment setting. For deep B cell depletion in autoimmune disease, antibody-directed allogeneic NK cell therapy deserves to be part of that conversation.
