Not only in oncohematology

CAR T-cell therapy led to remission of a solid tumor for the first time

Svetlana Maslova, Hi-tech+

Previously, this technology was effective only in hematology, but now scientists are showing promising results in the treatment of testicular, ovarian, endometrial and other cancers. The combination with the mRNA vaccine made the treatment effective for tumors that were previously "closed" to immune cells.

CAR T-cell therapy has been used for many years to treat blood cancer. More recently, scientists celebrated 10 years of remission in the first patients. Meanwhile, testing this treatment against solid tumors has been disappointing. Now scientists have presented the first preliminary results of clinical studies of CAR T-cell therapy in combination with an mRNA vaccine against cancer, according to a press release from the American Association for Cancer Research New CAR T-cell Therapy for Solid Tumors Was Safe and Showed Early Efficacy. The effectiveness of the double exposure exceeded their expectations.

"At first I was very skeptical, because therapy had not previously worked with solid tumors. We were very pleased to see how metastases disappear and the condition of patients improves," commented the results of the study author John Haanen. Scientists noted that about 40% of the volunteers had the necessary immune response, and one had a complete remission, which has been maintained for six months. The treatment was tested on 16 patients with testicular, ovarian and endometrial cancer.

Until now, the use of CAR T-cell therapy against solid tumors has been limited mainly by two reasons. The first is that most of the proteins present in solid tumors that could be used as targets are also found in small amounts in normal cells, which makes it difficult to target them. The second problem is that modified T-cells can hardly get inside the tumor to fight it. 

Scientists solved these problems with the help of the tumor-specific antigen claudin-6, which is widely expressed in various types of solid tumors, but is not active in healthy tissues. Now the treatment takes place in two stages.

First, the patient is injected with CAR T cells, and a few days later - an mRNA vaccine carrying claudin–6. As a result, this allows T cells to penetrate into the tumor and not have a toxic effect on healthy tissues.

So far, scientists have not found serious toxicity of the treatment, but some patients have had mild side effects in pancreatic tissue. These results need to be tested on a larger sample in the long run to ensure the safety of the method. Further studies should also assess the safety of increased dosages for the human body. 

Earlier, another group of researchers presented another modification of the CAR T-cell therapy method: they reduced the preparation time of cells from several weeks to several hours. The first results were also very significant and with a long-term effect.

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