At least safe

Trials of CRISPR cancer therapy have begun in the USA

Polina Loseva, N+1

In the USA, the first interim results of clinical trials of CRISPR-a variant of CAR-T therapy for cancer control have appeared. This was reported by the press service of Penn Medical Center at the University of Pennsylvania (Early Results from First-In-U.S. Trial of CRISPR-Edited Immune Cells for Cancer Patients Suggest Safety of Approach).

Three patients received injections of edited cells, they took root in their bloodstream and did not cause deterioration. However, the response of patients to therapy has not yet been recorded by doctors.

Despite the fact that CRISPR-editing technologies are devoting more and more scientific research, none of its applications in medicine has yet been officially approved. There are only a few known clinical trials in which CRISPR-edited cells were injected into patients' bodies: Some were held in China, others in Europe.

Now the pilot tests have reached the USA. At Penn Medical Center, doctors tested CRISPR therapy aimed at fighting cancer. In fact, this is a modification of the CAR-T gene therapy, which was approved for use in 2017.

The original CAR-T technique is based on the modification of the T-lymphocyte genome. They are programmed to fight B-lymphocytes, which multiply in some types of blood cancer. To do this, a gene is injected into T cells using viral vectors, which encodes a receptor for the surface protein of B cells. The modified cells are multiplied and injected back into the body, where they target the tumor.

The CRISPR version of CAR-T is similar to the original only in general principle. T-cells are also taken from patients and their genome is edited. However, in the new method, scientists use CRISPR/Cas9 to remove two genes from the DNA of T cells: one is the PD-1 protein, which blocks the activity of lymphocytes (for its discovery in 2018 was awarded The Nobel Prize). The second is the usual receptor, with which lymphocytes recognize their target. Then, by means of a viral vector, a gene of another receptor is introduced into the cells, which binds only to certain proteins on the surface of the tumor. After such triple editing, the T-lymphocyte gains the ability to selectively recognize a cancer cell, and at the same time acquires resistance to its suppressive action.

According to scientists, three patients took part in the trial: two with multiple myeloma and one with sarcoma. All three received a single injection of edited cells after a short course of chemotherapy. Later, blood tests showed that CAR-T cells had taken root and multiplied in their body. It is too early to judge the effectiveness of the procedure, since doctors have not yet noticed the patients' response to therapy. However, they are already confident about the absence of side symptoms, which is important — one type of CAR-T therapy has already been defeated due to the sudden death of the patient.

In a conversation with the press service of the medical center, the researchers mentioned that editing led to the formation of "different variants" of cells, and among them it is necessary to choose the most active ones. This can mean one of two things: either not all cells manage to make all three changes to the DNA, or in some there are inappropriate corrections. Both can become an obstacle to the further development of this method. More precisely, it will be known in a month, when scientists will present the results of their tests.

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