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Researchers at the University of Navarra demonstrate the clinical effectiveness and benefits of an anti-cancer vaccine

A four-year study of 25 patients with follicular lymphoma was presented at the Spanish National Congress of Hematology and Hemotherapy

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FOTO: Manuel Castells
28/10/05 12:12 Mª Pilar Huarte

A team of researchers has demonstrated the effectiveness and clinical benefits of a vaccine against follicular lymphoma, a type of blood cancer, in patients suffering a first relapse. The study has been ongoing since 2001, and has involved researchers from the University Hospital and the Center for Applied Medical Research (CIMA) of the University of Navarra. The study was financed by the Leukemia & Lymphoma Society of New York. The results of the study were presented by Dr. Mercedes Rodríguez Calvillo during the national congress of the Spanish Association of Hematology and Hemotherapy, which was held in Madrid. Dr. Rodríguez Calvillo was awarded the First Prize of 3,000 €.

According to Dr. Maurizio Bendandi, lead scientist for the study, and also head of the laboratory of Immunotherapy of the CIMA and specialist in Hematology at the University Hospital, "This is the first time that a vaccine against a type of cancer has been capable of changing the history of the disease."

More than 5,000 persons diagnosed with this type of tumor each year in Spain

Each year, more than 5,000 persons over 40 years of age are diagnosed with this type of cancer in Spain. Follicular lymphoma is a tumor of the lymphatic system; the tumor cells provide an immunoglobulin protein structure which can be used as a target. The vaccine, which is termed "idiotypic", is produced based on this target protein, and its goal is the production of an immune system reaction in the patient. "Generally the patient does not react against the tumor protein, and since it is a recognized element in the body, the immune system does not combat it. Via laboratory methods we have been able to attach to the target protein another protein called "KLH", which is obtained from a mollusk. By this method we force the immune system to recognize the tumor as a foreign structure."

In the case of follicular lymphoma, this protein is a tumor-specific antigen. "It is believed that there are antigens also in other tumors, but at the moment none has been encountered which occurs solely and exclusively in tumor cells; as a result, a vaccine against these other antigens would also be damaging to healthy tissues."

Stanford University developed the idiotypic vaccine in animals during the 1970"s, and began testing it in humans 15 years ago. In 1992, its biological effectiveness was proved: it is capable of stimulating the human immune system. In 1999, Dr. Bendandi, along with scientists from the U.S. National Cancer Institute, demonstrated that this biological effectiveness is also clinical. According to these scientists, the immune system itself, once stimulated by the vaccine, is capable of killing tumor cells which have resisted chemotherapy. It was, however, necessary to show that this result could translate into a real benefit for the patient.

Longer remission than that expected with chemotherapy alone

From the research performed at the CIMA and at the University Hospital, "it is known that approximately 50% of patients treated with chemotherapy will relapse after 13 months. In addition, each time they relapse, the duration of the following remission tends to be shorter than the preceding remission."

"Our study is based on 25 patients over the last four and a half years. Of these patients, four have not responded to the vaccine, and have relapsed in the expected time period, three are still under study and 18 have responded satisfactorily. None of these 18 have relapsed during the two years of vaccination, and only one of the 18 relapsed (10 months after finishing the two-year vaccine treatment, i.e. nearly a year after we ceased vaccinating the patient; however, even this patient remained 36 months in a second complete remission, compared to a first complete remission of only 13 months). That is to say, all those patients who have responded positively to the vaccine, and with sufficient treatment, have a second remission which is longer than the first. Nearly all of the patients have broken the barrier of 13 months and none of them have relapsed during the vaccination period; this vaccine treatment has easily surpassed the results expected from chemotherapy treatment alone."

Research projects in California, Texas and Navarra

This is the first study of this design which has investigated the effectiveness of the vaccine in patients who have suffered a first relapse, although other clinical efforts are under development in two U.S. centers: that directed by Dr. Larry Kwak in Houston (Texas) and that directed by Dr. Ronald Levy in Stanford (California).

The vaccine, which is administered subcutaneously, has been especially useful as a complement to chemotherapy. "There have been efforts to use the vaccine as a first-line treatment, but the results have not been satisfactory," Dr. Bendandi noted.

In general terms, the procedure followed in the patients treated at the University Hospital consisted in treating the patient with conventional chemotherapy for six months, in order to reduce as much as possible the size of the tumor. This is followed by a rest period of 3 to 6 months, so that the immune system can reconstitute itself. Finally, the patient is inoculated with the vaccine on a monthly basis for four months, later moving to less frequent dosage intervals.

The team of Dr. Bendandi is made up of the following researchers: Susana Inogés, Mercedes Rodríguez Calvillo, Ascensión López Díaz de Cerio, Margarita Legarrea, Silvia Gallego, Elena Soria, Natalia Zabalegui, Helena Villanueva and Fernando Pastor.

The research project has been developed in collaboration with various hospitals in Spain, including those of the Geltamo and Pethema groups. In addition to the 25 persons who have participated in the clinical trials of this vaccine, patients from the U.S.A. have come to the University Hospital at the University of Navarra in order to be treated with this vaccine.