Where does CAR-T actually show promise in solid tumors?
The most compelling human evidence comes from a randomized phase II trial of a CLDN18.2-directed CAR-T (satricabtagene autoleucel) in advanced gastric or gastroesophageal junction cancer. This trial demonstrated improvements in both progression-free and overall survival compared to physician's choice therapy [4]. This is the only randomized phase II data among the studies reviewed, making it the strongest single piece of evidence.
In glioblastoma, intracranial delivery of CAR-T cells has shown signs of activity. A phase I trial of anti-IL13Rα2 CAR-T cells in 65 patients yielded a 50% disease control rate and 23% one-year survival [1]. Two other phase I studies of multi-target CAR-T products showed early but transient radiological responses [1]. These results are promising but not curative, and survival remains limited to months.
In pediatric solid tumors, GD2-targeted CAR-T cells have shown encouraging results in neuroblastoma. A phase I trial in children and young adults demonstrated feasibility and safety, with some patients showing good CAR-T expansion [9]. Neuroblastoma was one of the first solid tumors evaluated for GD2-targeting CAR-T, and recent results in high-risk, heavily pre-treated patients are promising [8].
What does the overall evidence say about effectiveness?
Across all solid tumors, the overall response rate is low. A meta-analysis of 22 studies with 262 patients found a pooled response rate of just 9% [3]. This means that for every 100 patients treated, only about 9 responded. The same analysis found that CAR-T performed best in neuroblastoma and barely worked in gastrointestinal malignancies [3].
Most clinical trials are early-phase (phase I) and show limited or transient responses. A narrative review of phase I trials noted that clinical responses were often limited to disease stabilization, and efficacy depended on factors like target antigen and the ability to overcome the tumor microenvironment [2]. Another review concluded that durable objective responses are rare with conventional single-agent intravenous CAR-T [4].
The challenges are well-documented: tumor heterogeneity, poor T-cell infiltration, T-cell exhaustion, and an immunosuppressive tumor microenvironment [6][10][11]. These barriers mean that even when CAR-T cells reach the tumor, they often cannot function effectively. As one review put it, 'CAR-T cells have repeatedly failed to achieve curative responses in solid cancers' [10].
Is there reason for cautious optimism?
Yes, but the hype should be tempered. Researchers are actively developing next-generation strategies to overcome the barriers. These include cytokine-armored CAR-T cells (e.g., expressing IL-15), logic-gated systems to improve tumor targeting, and localized delivery directly into tumors [12]. Combination therapies with targeted inhibitors are also being explored to enhance CAR-T infiltration and reduce exhaustion [5].
The evidence base is growing, but it is still early. Most innovative strategies are not yet in clinical trials [10]. The authors of the meta-analysis from 2019 noted that despite unsatisfactory responses, researchers were 'holding an optimistic attitude towards its future efficacy with more modifications' [3]. More recent reviews echo this: CAR-T therapy remains experimental outside of hematological malignancies, and larger randomized trials are needed [2][4].
About These Sources
This answer is built on 12 peer-reviewed studies — published from 2019 to 2026, 10 from 2024 or later, 8 in Q1 journals, collectively cited 391 times — selected as the most relevant from 15 studies that passed quality screening, drawn from 61 papers retrieved from a database of over 500 million.
Sources used in this answer
CAR-T cell therapies are coming after glioblastoma: An overview of early phase clinical trials and future perspectives
In a phase I trial of intracranial IL13Rα2 CAR-T for glioblastoma (65 patients), the disease control rate was 50% and one-year survival was 23%, showing transient activity but not cure.
CAR-T in the Treatment of Solid Tumors—A Review of Current Research and Future Perspectives
This narrative review of phase I trials in solid tumors found promising efficacy mainly in gastrointestinal cancers, but responses were often limited to disease stabilization.
Efficiency of CAR-T Therapy for Treatment of Solid Tumor in Clinical Trials: A Meta-Analysis.
A meta-analysis of 22 studies (262 patients) found an overall response rate of only 9% for CAR-T in solid tumors, with best results in neuroblastoma and poor results in gastrointestinal cancers.
CAR-T Cell Therapy in Solid Tumors: A Systematic Review of Clinical Evidence, Translational Barriers, and Emerging Therapeutic Strategies
This systematic review identifies the strongest evidence as a randomized phase II trial of CLDN18.2-directed CAR-T in gastric cancer, showing improved survival, but notes durable responses are rare otherwise.
CAR-T therapy and targeted treatments: Emerging combination strategies in solid tumors
This review discusses combination strategies of CAR-T with targeted inhibitors to improve infiltration, cytotoxicity, and reduce exhaustion in solid tumors, but notes most evidence is preclinical.
CAR‐T‐cell products in solid tumors: Progress, challenges, and strategies
This review updates clinical trial outcomes for CAR-T in solid tumors, highlighting obstacles like tumor heterogeneity, T-cell exhaustion, and on-target off-tumor toxicity.
Current and Future Roles of Chimeric Antigen Receptor T-Cell Therapy in Neurology
This review states that CAR-T for glioblastoma has not yielded significant success in first-in-human trials, with only limited success in a subset of patients.
Developing CAR T-Cell Therapies for Pediatric Solid Tumors
This review notes that GD2-targeting CAR-T has shown promising results in high-risk pediatric neuroblastoma, but activity remains suboptimal due to tumor heterogeneity and an immunosuppressive microenvironment.
Immune determinants of CAR-T cell expansion in solid tumor patients receiving GD2 CAR-T cell therapy
In a phase I trial of GD2 CAR-T for osteosarcoma and neuroblastoma, good CAR-T expansion was linked to naive T cells in pre-treatment apheresis, while poor expansion was linked to exhausted T cells.
CAR-T Cell Therapy for Solid Tumors
This review states that CAR-T has repeatedly failed to achieve curative responses in solid cancers, and most next-generation strategies are not yet in clinical trials.
CAR-T and CAR-NK as cellular cancer immunotherapy for solid tumors
This review discusses that CAR-T and CAR-NK efficacy against solid tumors is limited due to poor tumor trafficking and an immunosuppressive tumor microenvironment.
Advancing CAR-T Therapy for Solid Tumors: From Barriers to Clinical Progress.
This review highlights next-generation strategies like cytokine-armored CAR-T and logic-gated systems as promising, but notes that second- and third-generation CAR-T have shown restricted efficacy in clinical trials.