American scientists have completed the first two phases of clinical trials of a new vaccination method for 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.
Mantle cell lymphoma (MKL) 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 chemo and immunotherapy, often accompanied by transplantation of hematopoietic stem cells 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 MKL based on the tumor cells of the patient himself and have already tested it on mice. It is now reported that the vaccine has successfully passed the first two phases of clinical trials.
In the study, 47 patients with MKL who achieved remission after the standard immuno-chemotherapy complex were vaccinated with their own tumor cells loaded with CpG oligonucleotides – short DNA fragments that mimic bacterial DNA and can elicit an immune response.
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Immune cells were then harvested and stored, and patients received a stem cell transplant. At the final stage, immune cells were transferred back to patients.
The vaccination schedule was safe and did not cause side effects, except for 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 can cause a relapse of the disease.
According to scientists, over 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 formed immune cells that can directly attack and kill cancer cells. These patients were especially well protected from relapses, even if genetic mutations associated with poor prognosis were present in their tumors.
“In general, our data show that CpG-activated whole-cell vaccination against tumors, followed by adoptive transfer of vaccinated immune cells, is feasible, safe and can elicit immune responses that show excellent clinical results,” Ronald Levy, research leader, said in a university press release. (Ronald Levy).
Researchers are now exploring ways to further improve the immune response to tumor cell vaccination.