Berlin – Advances in immunotherapy for solid tumors, including bispecific antibodies, CAR-T cell therapies, and cancer vaccines, were key discussion points at the 37th German Cancer Congress (Deutscher Krebskongress – DKK) held in Berlin February 18-21, 2026. While immunotherapy has revolutionized treatment for blood cancers, extending those successes to solid tumors remains a significant challenge. Researchers presented data on ongoing trials and emerging strategies aimed at overcoming the unique hurdles posed by these more complex cancers.
The potential of immunotherapy to transform cancer care is undeniable, but realizing that potential requires addressing the limitations that currently hinder its effectiveness against solid tumors. Experts at the DKK emphasized the need for innovative approaches to enhance immune cell penetration, overcome immunosuppressive tumor microenvironments, and minimize treatment-related toxicity. The congress highlighted a shift towards more personalized and combination-based strategies, tailoring treatments to the specific characteristics of both the patient and their cancer.
The German Cancer Congress, the largest and oldest oncology congress in the German-speaking world, brought together thousands of experts from across the globe, as reported by the official congress website. The event, co-hosted by the Deutsche Krebsgesellschaft (German Cancer Society) and the Stiftung Deutsche Krebshilfe (German Cancer Aid), focused on improving cancer prevention, diagnosis, therapy, and aftercare, as well as showcasing the latest research findings, according to a press release from the German Cancer Aid.
Bispecific Antibodies: Expanding Roles in Solid Tumors
Bispecific antibodies (bsAbs) are gaining traction in solid tumor treatment, according to Dr. Maria-Elisabeth Goebler of the University Hospital Würzburg. These antibodies are designed to bind to two different targets simultaneously, bridging cancer cells and immune cells to enhance the immune response. Dr. Goebler noted that bsAbs now account for a significant portion of clinical trials and newly approved antibody therapies for solid tumors.
Tarlatamab, a T-cell engager, has demonstrated promising results in minor cell lung cancer (SCLC), inducing substantial response rates and durable remissions. However, its efficacy in neuroendocrine prostate cancer has been less consistent, underscoring the importance of careful patient selection. Other bsAbs in development include Cadonilimab, a dual checkpoint inhibitor currently approved in China, and Zanidatamab, which targets HER2 and received European Medicines Agency (EMA) approval in July 2025. Zenocutuzumab, targeting both HER2 and HER3, is approved by the FDA for NRG1-fusion tumors.
Despite these advances, challenges remain. Dr. Goebler highlighted the immunosuppressive tumor microenvironment, tumor heterogeneity, potential antigen loss, toxicity, and physical barriers within the tumor stroma as key obstacles. Researchers are exploring strategies to overcome these hurdles, including designing bsAbs as masked pro-drugs or incorporating them into nanocarrier systems to improve selectivity and therapeutic index.
CAR-T Cell Therapy: Boosting Solid Tumor Penetration
While CAR-T cell therapy has shown remarkable success in hematologic malignancies, its application to solid tumors has been limited by poor tumor infiltration and an immunosuppressive microenvironment, explained Prof. Claudia Rössig of the University Hospital Münster. Enhancing CAR-T cell penetration and persistence within the tumor is crucial for improving efficacy.
One promising approach involves combining CARs with cytokine secretion triggered by antigen contact. IL-15-enhanced CAR-T cells have demonstrated improved expansion and initial clinical activity. At Münster, researchers are testing a construct combining a GD2-specific CAR with IL-18 (GD2IL18CART) in a Phase I study involving patients with relapsed or refractory neuroblastoma, osteosarcoma/Ewing syndrome, and breast cancer. Preliminary data indicate good manufacturing feasibility, moderate inflammatory toxicity at lower doses, significant in vivo expansion, and initial complete remissions.
T-Cell Receptor Therapy: Targeting Intracellular Antigens
T-cell receptor (TCR)-modified T-cells (TCR-T) offer a distinct advantage over CAR-T cells by recognizing intracellular tumor antigens, a key benefit in solid tumors. However, TCR-T therapy is highly dependent on the patient’s HLA type, noted Prof. Martin Wermke of the University Hospital Dresden.
PRAME (Preferentially Expressed Antigen in Melanoma) is a prominent target for TCR-T therapy. The Phase I IMA203-101 study, utilizing Anzutresgene Autoleucel, treated patients with HLA-A*02:01-positive melanoma who had exhausted other treatment options. The study demonstrated a favorable safety profile with no Grade 4 or 5 toxicities. Over 50% of patients achieved an objective response, with many experiencing long-lasting remissions. Cytokine release syndrome (CRS) was generally mild and early-onset, and neurotoxicity was rare. The therapy has received FDA approval, though at a substantial cost.
Tumor-infiltrating lymphocyte (TIL) therapy represents another approach. TILs are extracted from the patient’s tumor, expanded ex vivo, and then reinfused. This method leverages the patient’s own T-cells, potentially targeting multiple antigens. The FDA has also approved TIL therapy (Lifileucel).
Cancer Vaccines: Harnessing the Power of Peptides
Peptide-based cancer vaccines are showing promise as a way to stimulate tumor-specific T-cell responses. Dr. Jens Bauer of the University Hospital Tübingen explained that identifying suitable antigens involves mass spectrometry analysis of naturally presented HLA peptides. This approach expands the range of potential targets beyond mutated neoantigens to include non-mutated tumor-associated antigens, cryptic peptides, therapy-induced antigens, and soluble HLA ligands.
Formulating peptides with a potent adjuvant, such as XS15, is crucial for eliciting a robust immune response. The vaccine is administered subcutaneously with minimal side effects. In the iVAC-XS15-CLL01 study, this approach induced a robust T-cell response in 90-95% of patients with chronic lymphocytic leukemia (CLL) in minimal residual disease (MRD) status. Significant MRD reduction correlated with the strength of the immune response.
Looking Ahead
The data presented at the German Cancer Congress suggest that newer immunotherapies are achieving clinically relevant progress even in solid tumors. However, ongoing research is essential to optimize existing therapies and develop new approaches. A consensus emerged among presenters that the future of solid tumor treatment lies in combining different immunotherapeutic strategies. The next steps will involve refining patient selection criteria, identifying predictive biomarkers, and designing clinical trials that evaluate synergistic combinations of therapies.
This rapidly evolving field offers hope for improved outcomes for patients with solid tumors. Share your thoughts and experiences with cancer treatment in the comments below.
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