The Next Chapter of B7-H3: From Systemic Disease to the Brain

Early Data for T-MAXIMUM's B7-H3 Allogeneic CAR-T in Brain Metastases Presented at WCLC 2026

BEIJING, Sept. 21, 2026 /PRNewswire/ -- As B7-H3 ADCs reshape the second-line treatment landscape for small cell lung cancer at WCLC, a more specific question comes into focus: systemic disease now has new answers — but what about brain metastases?

In September 2026, the IASLC World Conference on Lung Cancer (WCLC 2026) was held in Seoul, South Korea. Two B7-H3-targeted ADCs reported positive Phase III results on the same day, validating B7-H3 as a therapeutic target. At the same meeting, T-MAXIMUM presented early clinical data for MT027, its allogeneic, off-the-shelf B7-H3-targeted CAR-T, in refractory brain metastases from lung cancer. Unlike ADCs, which work "outside-in" and depend on systemic circulation for delivery, MT027 takes a different route — "inside-out" — using intracerebroventricular and other local delivery approaches to bring an engineered cell therapy directly to the vicinity of intracranial lesions. One target, two solutions. The next chapter of B7-H3 may be moving from systemic disease into the brain.

Early Data: Tumor Shrinkage and Disease Control Observed in Patients with Refractory Brain Metastases

This is a prospective, investigator-initiated trial (IIT; registration no. ChiCTR2500107346) with a dose-escalation design. The study evaluates the safety and preliminary efficacy of MT027 in patients with brain metastases from lung cancer who have failed prior standard therapy.

As of the data cutoff for the conference abstract, 5 patients had completed treatment. All had received multiple prior lines of therapy and had no remaining guideline-recommended treatment options. Of these, 3 patients had measurable disease and were evaluable for response:

• 2 patients achieved a partial response (PR), with tumor shrinkage of approximately 80%;
• 1 patient achieved stable disease (SD).

Based on the company's follow-up through September 2026, of the two patients with PR, one has survived more than 11 months and the other more than 13 months from their first MT027 dose. All 3 evaluable patients remain alive.

More important than any single efficacy figure is whether the clinical pathway is feasible. In this study, MT027 demonstrated three key features:

• Local delivery: Administered via intracerebroventricular or lumbar intrathecal routes, exploring delivery of therapeutic cells into the cerebrospinal fluid (CSF) compartment and close to intracranial lesions.
• Allogeneic, off-the-shelf: Derived from healthy-donor T cells and manufactured in advance, providing a foundation for exploring scheduled dosing and repeat administration.
• Early safety: Among the 5 patients in this study, no drug-related Grade ≥3 adverse events or graft-versus-host disease (GvHD) were observed; adverse reactions were predominantly Grade 1–2 immune-inflammatory reactions.

Taken together, these early observations support the continued clinical investigation of locally delivered allogeneic CAR-T for intracranial lesions. Larger studies with longer follow-up will be needed to further characterize its safety and efficacy.

Brain Metastases: The "Second Half" for ADCs, the "Home Turf" for Cell Therapy

Brain metastases are a major challenge in the treatment of advanced lung cancer, breast cancer and other solid tumors. As systemic therapies continue to improve and patients live longer, control of intracranial disease, preservation of neurological function, and quality of life are increasingly becoming key determinants of long-term benefit.

ADCs and bispecific antibodies have transformed the treatment of systemic disease, but in the brain they share a common physical obstacle: the blood–brain barrier. These drugs rely on systemic circulation for delivery, and the blood–brain barrier substantially limits how efficiently large-molecule drugs reach the central nervous system. For patients who have already developed brain metastases, systemic disease may be under control while intracranial lesions continue to progress — the hardest part of treatment today.

Why Deliver CAR-T Locally, Rather Than ADCs?

The fundamental reason lies in the different nature of the two drug modalities. As large-molecule antibody drugs, ADCs are generally thought to reach brain tissue mainly by passive diffusion, which may limit penetration and distribution; the local behavior of linkers and payloads within the central nervous system is also not yet well characterized. CAR-T cells, by contrast, are "living cells" designed to actively migrate toward tumors, with the potential to persist in the CSF and sustain antitumor activity. Simply put, an ADC must be carried to the lesion, whereas CAR-T is designed to seek out the lesion on its own. On this rationale, CAR-T may be well suited to local delivery for intracranial disease, while local delivery of ADCs remains at an early exploratory stage. No head-to-head clinical comparison between these approaches has been conducted. This is the niche that allogeneic CAR-T aims to address in intracranial solid tumors.

Allogeneic CAR-T offers a different way to solve the problem. Derived from healthy-donor T cells and manufactured in advance, MT027 is delivered locally — for example, via intracerebroventricular administration — so that the cell therapy enters the CSF circulation directly and acts near the lesions, in principle bypassing the physical wall of the blood–brain barrier. The expression of B7-H3 across multiple solid tumors provides the biological rationale for investigating this strategy in intracranial solid tumors regardless of the primary tumor of origin.

In this study, some patients were not included in the measurable-disease efficacy analysis due to overall disease progression or changes in clinical condition. These clinical courses suggest that further development of local intracranial therapy will need to be closely integrated with systemic disease management. ADCs for systemic disease, CAR-T for the brain — the two may prove complementary.

From Glioma to Brain Metastases: One Pipeline, Validating a Multi-Indication Development Path

Although gliomas and brain metastases differ in origin, the experience gained in local administration, repeat dosing, safety monitoring and clinical execution can be accumulated and carried across both. These early first-in-human observations extend the exploration of MT027 from primary brain tumors to metastatic brain tumors.

In recurrent glioblastoma, MT027 has been cleared by the U.S. FDA to conduct a Phase II clinical study and has received Fast Track Designation (FTD) for this indication; the company previously announced that it has also received Orphan Drug Designation (ODD) in high-grade glioma. Under T-MAXIMUM's current plans, a global multicenter Phase II study of MT027 in recurrent glioma is underway.

According to T-MAXIMUM's leadership, the company will continue to build clinical data and prepare for further development in brain metastases, maintain communication with regulatory authorities within a compliant framework, and steadily advance its subsequent clinical research plans. T-MAXIMUM will continue to drive development through product supply, clinical execution and the generation of key data, always putting patients' needs first.

About the Conference

WCLC, hosted by the International Association for the Study of Lung Cancer (IASLC), is the world's largest and most influential multidisciplinary meeting dedicated to lung cancer and other thoracic malignancies. This year's conference took place September 12–15, 2026, at the COEX Convention & Exhibition Center in Seoul, South Korea, under the theme "Science Without Boundaries: Uniting the World Against Thoracic Cancer." It brought together more than 7,000 clinicians, researchers and industry professionals from over 100 countries, featuring more than 2,300 abstracts and over 130 scientific sessions.

About T-MAXIMUM

T-MAXIMUM is a clinical-stage cell therapy company focused on developing allogeneic (off-the-shelf) CAR-T products for intracranial solid tumors with high unmet medical need, including recurrent glioblastoma and brain metastases. The company is committed to exploring more accessible treatment approaches that support repeat dosing through engineered cell therapy, local delivery strategies and clinical research. Its lead program has received FDA clearance to advance into Phase 2 clinical development and has been granted ODD and FTD.

MT027 is an investigational therapy. It has not been approved by the U.S. FDA or any other regulatory authority for any indication, and its safety and efficacy have not been established.

Forward-Looking Statements

This press release contains forward-looking statements, including statements regarding the clinical development, regulatory pathway, therapeutic potential and anticipated milestones of MT027 and T-MAXIMUM's other programs. These statements are based on the company's current expectations and assumptions and involve known and unknown risks and uncertainties, including, without limitation, risks related to the initiation, enrollment, conduct and results of clinical trials; the fact that early or interim data from small numbers of patients may not be predictive of results in later or larger studies; regulatory review and decisions; manufacturing and product supply; financing; and competitive developments. Actual results may differ materially from those expressed or implied. Forward-looking statements speak only as of the date of this release, and T-MAXIMUM undertakes no obligation to update them except as required by law.

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SOURCE T-MAXIMUM PHARMACEUTICAL