Context: with the arrival of immunotherapy in cancer care, it is no longer the drug that will destroy the tumour, but the patient himself, thanks to his immune system. We do, however, encounter two important problems. Why do only 20 to 30% of patients respond to this treatment? Why do some patients switch to autoimmunity. Method: by studying the exact immune mechanisms involved in immunotherapy, we sought, respecting the principle of similarity, homeopathic medicines able to support and modulate the immune responses induced by immunotherapy. Results: of course, Silicea is the traditional and reliable immune modulator, but there is also a new interesting medicine which belongs to the Lanthanides group: Dysprosium metallicum. In medium dilution they appear to be the two best medicine-candidates. The constitutional remedy of the patient, when it is known, can also be considered in this situation. Clinically, we obtained good preliminary results on the immune response and less autoimmune side effects compared to the figures expected in scientific literature. Conclusion: the challenge of a good response and a good tolerance to immunotherapy is real. This should prompt us to propose innovative homeopathic support protocols, such as Silicea and Dysprosium metallicum, which can encourage the mechanisms of action of immunotherapy, while preventing side effects. Clinical studies are now needed to evaluate our work.