A team of researchers has demonstrated the clinical efficacy and benefits of a vaccine for a type of blood cancer, follicular lymphoma, amongst first time relapse patients. Specialists from two University of Navarre centres – the University Hospital and the Research Centre for Applied Medicine (CIMA) - have worked jointly since 2001 on the research.
According to Dr. Maurizio Bendandi, the team leader, it is the first time that a vaccine against a type of cancer has been able to change the history of the illness.
In Spain more than 5000 persons over 40 are annually diagnosed with this type of cancer. Follicular lymphoma is a tumour of the lymphatic system the cells of which present a surface protein – in fact, an immunoglobuline - that can be used as a target. The vaccine, known as idiotypical, is produced from this protein and its aim is to provoke a reaction from the immune system of the patient. Normally the patient does not react against the protein of the tumour given that, as it is a known element, its immune system does not combat it. By means of laboratory techniques we have managed to adhere to the target protein another protein called KLH, obtained from a mollusc. In this way we managed to get the tumoural protein also to be recognised as foreign.
In the case of follicular lymphoma, this protein is a specific tumour antigen. It is postulated that there are also antigens in other tumours but, for the moment, none has been identified solely and exclusively in the tumour cells and, thus, a vaccine against these would also be damaging to healthy tissues.
Stanford University developed an idiotypical vaccine in the seventies in animals and applied it to humans 15 years ago. In 1992 its biological efficacy was tested: it is capable of stimulating the human immune system. In 1999 Dr. Bendandi and other scientists at the US National Cancer Institute demonstrated that this biological efficacy was also clinical. According to the University of Navarre researcher, the vaccine-stimulated immune system itself is capable of killing some tumour cells that had resisted quimiotherapy. It remains to be demonstrated that this result provides a real benefit to the patient.
With the research work carried out at CIMA and the University Hospital it is known that 50% of the patients treated with quimiotherapy relapse within13 months. Moreover, the duration of the response time tends to be shorter between relapses than between the previous ones.
Our research involved 25 patients over the last four and a half years. Of these, 4 patients did not respond to the vaccine and relapsed in the expected time, with another 3 the study of their illness is yet to finish and 18 responded satisfactorily. None of these 18 has relapsed over the two years vaccination.
This is the first study of this kind or design to investigate the efficacy of the vaccine in patients suffering relapse, although other clinical trials are being undertaken at two centres in the United States.
The vaccine, administered subcutaneously, is especially useful as a complement to quimiotherapy. There have been attempts to apply the vaccine as a first treatment but the results have not been satisfactory.
In general terms, the procedure followed with patients at the University Hospital was to give them conventional quimiotherapy for 6 months in order to reduce the size of the tumour as much as possible. This was followed by a rest period of between 3 and 6 months in order to reconstitute the immune system. Finally, the vaccine was innoculated every month for three or four months, whereupon the frequency of this dosage was gradually reduced.