Autoimmune R&D Series 02 | The Competition Is Just Beginning

Originally published in Chinese on September 8, 2026. This commentary reflects information available as of September 8, 2026.

HKeyBio’s take. Autoimmune TCEs already have a growing pipeline; the next challenge is to establish clinically validated product standards. The optimal target, treatment course, tissue-depletion objective, and model of care are still being defined. Efficacy, safety, patient acceptability, and commercial access all need to be validated. For biotech and large pharmaceutical companies, it is not too late to enter, provided they compete with a clearly defined target product profile.

Summary. On September 1, 2026, Simcere Zaiming announced a global licensing agreement with Roche for SIM0660, a preclinical CD79a/CD19/CD3 trispecific antibody. Potential payments total up to US$1.53 billion, including US$75 million upfront, with additional royalties on future sales. The announcement describes opportunities across B-cell-mediated diseases, including autoimmune disease. Earlier, GSK announced an agreement to acquire global rights to CMG1A46, a dual CD19/CD20-targeting T-cell engager (TCE), for US$300 million upfront. In 2026, CLN-978 also reported early clinical data in systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). As deals and clinical progress accelerate, more teams are asking the same question: Is it already too late to enter autoimmune TCE development?

Quite the opposite. Autoimmune TCE development is still at an early stage, and the competition is just beginning. The number of programs and the value of deals show that the field is gaining momentum; the product standards that will define success are still taking shape.

01 Why the autoimmune TCE competition is just beginning

Many teams are concerned that several high-value deals and multiple programs already in development may leave little room for new entrants. A crowded pipeline alone, however, does not establish that a field is saturated. The more important question is whether product standards have converged. As of September 8, 2026, there was no consensus on the optimal target, immune-reset regimen, clinical endpoint package, or model of care for autoimmune TCEs. Most programs remained preclinical or in early clinical development, and the key parameters of competition were still taking shape. Disease-specific clinical endpoints exist; how best to combine them with measures of immune reset remains an active development question.

· The target landscape is not yet settled. CD19, CD20, BCMA, CD79a, and dual- or multi-target approaches each cover different cell populations. Which approach best balances disease indication, cellular coverage, and treatment risk remains an open question.

· The treatment-course strategy is not yet settled. Can a single or limited induction course achieve immune reset, or will intermittent maintenance be needed? Different diseases may require very different exposure strategies.

· Clinical endpoints for immune reset are not yet settled. Peripheral B-cell depletion provides an important initial PD readout. Integrating it with tissue depletion, background-therapy reduction or withdrawal, drug-free remission, organ protection, and time to relapse can provide a fuller assessment of immune reset.

· The model of treatment delivery is not yet settled. Subcutaneous administration, outpatient treatment, first-dose monitoring, step-up dosing, infection management, and reimbursement have yet to converge on a reproducible standard.

For biotech companies, it is not too late to enter, and a clearly defined target product profile (TPP) provides a strong starting point. For CD19 × CD3 programs, differentiation can be strengthened through a coordinated strategy for patient selection in a specific disease, tissue-level pharmacology, treatment duration, low-dose regimens, and an outpatient pathway.

For large pharmaceutical companies, a deal can shorten the time needed to enter the field, while clinical development remains essential. High-value transactions reflect confidence in the platform’s potential and provide resources for further development. Clinical studies will progressively define the magnitude, durability, and safety of patient benefit. Subsequent value depends on linking molecular engineering, translational models, clinical pharmacology, rheumatology and immunology expertise, and global delivery capabilities into a complete development pathway.

02 The four product gates for autoimmune TCEs

Autoimmune TCEs must satisfy all four product requirements, from efficacy through commercial access. These requirements are connected and should be assessed in parallel as development progresses.

Gate 1 Efficacy in the right tissues and cellular compartments

The question extends beyond whether a molecule can lower B-cell counts to whether it can deplete the relevant cells in the right sites. A decline in peripheral-blood B cells is one of the most accessible pharmacodynamic (PD) readouts. Immune reset may depend on whether pathogenic cells in lymph nodes, synovium, kidneys, skin, muscle, or bone marrow are reached; how long depletion lasts; whether B-cell reconstitution produces a healthier repertoire; and whether autoantibodies, complement, tissue inflammation, and disease activity improve together.

Target selection determines which cells are eliminated. CD20 mainly covers mature B cells. CD19 spans a broader range of B-cell stages, including many plasmablasts and some plasma cells. BCMA is associated with antibody-secreting cells, including long-lived plasma cells, but is not restricted to that population. Multi-target designs such as CD19/CD20, CD19/CD79a, and CD19/BCMA may broaden depletion while adding complexity to molecular architecture, dose selection, and safety optimization.

TCEs are not inherently less potent than CAR-T. Building on encouraging clinical signals, the next task is to define the depth of tissue depletion and durability of drug-free disease control achievable with a single or limited TCE course. Efficacy therefore remains the first product requirement. CAR-T experience offers a useful reference, with cross-study comparisons accounting for differences in disease, patient selection, conditioning, and maintenance therapy. [1–3]

Gate 2 Safety while preserving effective target-cell killing

The aim is to reduce peak T-cell activation while preserving a sufficient range of exposure for effective killing. Patients with autoimmune disease differ from oncology populations in target-cell burden, inflammatory background, prior immunosuppression, and T-cell status. Cytokine release syndrome (CRS), neurotoxicity, infections, cytopenias, and hypogammaglobulinemia therefore remain relevant risks to assess. [4,5,10,11]

Clinical development needs to explore starting dose, step-up dosing, dosing intervals, premedication, and monitoring. Molecular engineering must balance CD3 affinity and valency, target affinity, Fc effector function where applicable, half-life, and route of administration. Alongside control of peak activation, safety evaluation should characterize the predictability and monitorability of activation, the options for managing associated toxicities, and longer-term effects on immune function.

Gate 3 Patient acceptability and adherence in routine care

Off-the-shelf availability is a structural advantage of TCEs over autologous CAR-T. Patient-cell collection and individualized cell engineering are unnecessary, and lymphodepleting conditioning may be avoidable, depending on the product and regimen. Subcutaneous dosing, short courses, and adjustable exposure may also reduce the burden on treatment centers.

These advantages need to be considered alongside the patient experience. First-dose hospitalization, prolonged observation after every dose, frequent step-up visits, or intensive long-term maintenance can all add substantial burden. The competitive question is broader than intravenous versus subcutaneous administration: can a complete pathway be established that is manageable in outpatient care, has a clinically justified treatment duration, and allows retreatment after relapse?

Gate 4 Commercial access and affordability

Off-the-shelf manufacturing offers opportunities for standardization and scale. The resulting affordability and access will also depend on the resources required across the full treatment pathway: dose, dosing frequency, cold chain, premedication, infusion or injection facilities, observation time, infection management, and long-term immunoglobulin replacement when needed.

Reimbursement for chronic autoimmune disease also differs from that for advanced cancer. Scalable production can translate into affordability when total treatment costs are commensurate with the value of drug-free remission, organ protection, or reduced relapse. Commercial access therefore needs to be assessed across the full treatment pathway.

The four product gates in study design

Table 1. Key questions, required evidence, and design options

HKeyBio’s perspective

Preclinical evaluation should address the biological and dosing questions underlying all four product gates in parallel. Human cell and tissue systems should establish target coverage, effector-cell dependence, the threshold for target-cell killing, and the exposure range associated with cytokine release. Disease models aligned with the target and effector pathway should assess blood and tissue depletion, disease readouts, and relapse where the model supports it.

Pharmacologically relevant nonhuman primate (NHP) studies can connect pharmacokinetics and pharmacodynamics (PK/PD), step-up dosing, immunoglobulins, cytokines, indicators of infection susceptibility, and histopathology. Relevance requires functional engagement of both CD3 and the target antigen and appropriate effector biology. Clinical follow-up is needed to establish infection frequency and severity in patients.

Models help strengthen the evidence supporting each product requirement and inform clinical development decisions. Clinical studies remain essential for establishing patient benefit and safety, while clinical, manufacturing, and health-economic studies provide complementary evidence on patient acceptability and access.

03 Applying oncology TCE experience to autoimmune disease

CD3-directed TCEs bind CD3 on T cells and an antigen on target cells simultaneously, bringing endogenous T cells into contact with the target and triggering cell killing. Oncology has demonstrated that these molecules can be manufactured, administered, and produce clinical benefit. It has also generated substantial engineering and clinical experience with step-up dosing, premedication, CRS management, routes of administration, and half-life design. [10,11]

This experience provides a valuable foundation for autoimmune development, with treatment strategies adapted to each disease setting. In advanced cancers with limited alternatives, disease urgency and acceptable treatment risk may be higher. Intense short-term immune activation, hospitalization for monitoring, or continuous infusion may be acceptable in some oncology settings. Autoimmune diseases often require long-term management, and multiple immunosuppressants and biologics are available. An oncology TCE therefore needs a fresh benefit–risk assessment for each autoimmune indication, taking account of severity, organ involvement, and unmet need.

The available clinical signals provide a strong rationale for continued TCE development. In compassionate-use cases reported in Nature Medicine in 2026, CD19 × CD3 blinatumomab was used in five patients with refractory antisynthetase syndrome and BCMA × CD3 teclistamab in five with refractory systemic sclerosis. Reductions in target cells in affected tissues, together with clinical and serological improvements, were observed. The treatment strategies included subsequent rituximab maintenance, which is important when interpreting sustained disease control. CRS reached grade 3, and six of the ten patients developed respiratory infections treated with antibiotics. [4]

Early phase 1 CLN-978 data in SLE and RA also showed peripheral B-cell depletion, lymph-node and synovial depletion in RA, and preliminary remission signals. Cullinan’s June 2026 disclosure included safety data for 29 patients at the May 15 cutoff, with smaller subsets evaluable for PD and efficacy. Most CRS events were grade 1; one grade 3 event occurred at the 45 μg target dose. [5,6]

These small, non-randomized studies with limited follow-up provide a foundation for further evaluation of durable immune reset. Prospective studies should clarify whether a single or finite course can sustain drug-free benefit and how maintenance therapy or retreatment affects the outcome. Interpretation of a “single target dose” should account for any preceding priming dose. Reporting disease-specific remission and drug-free remission separately will also help clarify the nature and durability of benefit.

Representative evidence for autoimmune TCEs

Table 2. Evidence available as of September 8, 2026, and questions for further development

Competition in autoimmune TCEs has begun, but it is still far from over. CAR-T provides a benchmark for deep B-cell depletion, while oncology TCEs offer tools for molecular engineering and risk management. The next stage will depend on translating both sets of experience into products that meet the benefit–risk requirements of autoimmune disease. For biotech and large pharmaceutical companies entering now, it is not too late, provided they start with all four product requirements and adapt oncology experience to the autoimmune setting.

HKeyBio quick poll

What evidence is most important for determining whether an autoimmune TCE has the potential to be a truly next-generation product?

A. A rapid decline in peripheral-blood B cells is sufficient to prove immune reset.

B. Demonstrate target-cell depletion in both tissues and peripheral blood, clinical benefit and durability, and a linked evidence chain covering CRS, infections, healthcare burden, and total cost of delivery.

C. Subcutaneous administration alone means that patient adherence and commercial access have been solved.

D. A high-value license deal with a multinational company (MNC) is sufficient to establish clinical efficacy.

Suggested answer: B. Biological activity, durable patient benefit, safety, treatment burden, and total delivery cost need to be considered together.

References

[1] Müller F, et al. CD19 CAR T-Cell Therapy in Autoimmune Disease — A Case Series with Follow-up. N Engl J Med. 2024;390(8):687–700. doi:10.1056/NEJMoa2308917

[2] Mackensen A, et al. Anti-CD19 CAR T cell therapy for refractory systemic lupus erythematosus. Nat Med. 2022;28:2124–2132. doi:10.1038/s41591-022-02017-5

[3] Müller F, et al. CD19 CAR-T cells for treatment-refractory autoimmune diseases: the phase 1/2 CASTLE basket trial. Nat Med. 2026;32(3):1142–1151. doi:10.1038/s41591-025-04185-6

[4] Düsing C, et al. Bispecific T cell engagers for treatment-refractory autoimmune connective tissue diseases. Nat Med. 2026;32:1530–1542. doi:10.1038/s41591-026-04238-4

[5] Cullinan Therapeutics. Initial clinical data for CLN-978 at EULAR 2026. June 6, 2026. Company disclosure of early, non-randomized clinical data. Source

[6] ClinicalTrials.gov. OUTRACE SLE (NCT06613360) and OUTRACE RA (NCT06994143). Source

[7] GSK. Agreement to acquire CMG1A46 from Chimagen Biosciences. October 29, 2024. Source

[8] GSK Study Register. ELEVATE-1, study 300134 (NCT07371468): GSK5926371 in B-cell-driven autoimmune rheumatic diseases. Source

[9] Simcere Zaiming. Exclusive global license agreement with Roche for SIM0660. September 1, 2026. Source

[10] U.S. Food and Drug Administration. BLINCYTO (blinatumomab) U.S. prescribing information. Version cited: 2022. Source

[11] U.S. Food and Drug Administration. LUNSUMIO and LUNSUMIO VELO (mosunetuzumab-axgb) U.S. prescribing information for intravenous and subcutaneous use. Version cited: 2025. Source