Protection against relapses
A vaccine against one of the types of cancer has passed the first clinical trials
American scientists have completed the first two phases of clinical trials of a new method of vaccination against incurable mantle cell lymphoma. The vaccine is based on the patient's own tumor cells.
The results of the study are published in the Journal of Experimental Medicine (Frank et al., Autologous tumor cell vaccine induces antitumor T cell immune responses in patients with mantle cell lymphoma: A phase I/II trial).
Mantle cell lymphoma (MCL) is an aggressive form of lymphoma in which white blood cells, known as B cells, become malignant and form tumors in the lymph nodes and other parts of the body. The disease is usually treated with a combination of chemotherapy and immunotherapy, often accompanied by hematopoietic stem cell transplantation to restore the body's ability to form normal, healthy blood cells. But cancer usually returns, and the average survival time for patients with MCL is five to seven years.
Biologists from Stanford University have developed a vaccine against relapses of MCL based on the tumor cells of the patient himself and have previously tested it on mice. Now it is reported that the vaccine has successfully passed the first two phases of clinical trials.
During the study, 47 patients with MCL who achieved remission after a standard complex of immuno- and chemotherapy were vaccinated with their own tumor cells loaded with CpG oligonucleotides – short DNA fragments that mimic bacterial DNA and can cause an immune response.
The immune cells were then collected and stored, and the patients received a stem cell transplant. At the final stage, the immune cells were transferred back to the patients.
The vaccination regimen proved to be safe and did not cause side effects other than those usually associated with stem cell transplantation. The results showed that the vaccine is able to induce the immune system to attack any tumor cells that may cause a relapse of the disease.
According to the observations of scientists, during the next year after vaccination, 89 percent of the observed had no minimal residual markers of MCL. This means that their blood contained too few cancer cells to form new tumors.
40 percent of patients have developed immune cells capable of directly attacking and killing cancer cells. These patients were particularly well protected from relapses of the disease, even if their tumors had genetic mutations associated with a poor prognosis.
"In general, our data show that CpG-activated whole–cell vaccination against tumors with subsequent adoptive transfer of vaccinated immune cells is feasible, safe and can cause immune responses that show excellent clinical results," Ronald Levy, the head of the study, said in a press release from the university.
Now researchers are considering ways to further improve the immune response to vaccination with tumor cells.
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