A novel modified vaccination technique produces IgG antibodies that cause complement-mediated lysis of multiple myeloma cells carrying CD38 antigen

Antibody-initiated beneficial and harmful immune responses

A critical function of the immune system is to maintain tolerance to self by corrective immune responses throughout life, including preventing or correcting changes that may interfere with organ function and architectural integrity. These changes have two broad categories, namely (1) exogenous antigen-induced mishaps (e.g., due to bacterial, viral or fungal infections) and (2) endogenous antigen-caused ailments initiated by modified self-antigens derived from damaged organs following exposure to smoke, certain drugs, chemicals, infectious agents, radiation, etc., resulting in autoimmune diseases or cancer. In some cases, cells of the immune system are unable to respond with a corrective antibody response. For example, presentation of a modified self-antigen can initiate a pathogenic IgG immune response, thereby causing an autoimmune disease. Furthermore, if cancer-associated antigens are not appropriately presented to the cells of the immune system, there is failure to mount a specific pathogenic lytic IgG autoantibody response for recognition and elimination of cancer-associated antigens, and as a consequence, the cancer continues to proliferate.The third vaccination technique that we have developed and designated a modified vaccination technique (MVT) is able to correct these immunological mishaps. The premise of the MVT is that it can prevent both exogenous (infectious and contagious diseases) and endogenous (autoimmune diseases and cancer) antigen-caused diseases, as well as terminate established diseases. Therefore, by exploiting the immune system's natural abilities to make corrective responses, it has both prophylactic and therapeutic actions, with minimal side effects.

The Modified Vaccination Technique

In addition to active and passive immunizations, there is a third method of immunization, the modified vaccination technique, which is based on injecting a combination of target antigens and antibodies against this antigen. The vaccine is essentially comprised of immune complexes with pre-determined immune-inducing components. When such an immune complex (target antigen × antibody against the target antigen) with a slight antigen excess is administered, it evokes a corrective immune response by the production of the same antibody with the same specificity against the target antigen that is present in the immune complex (pre-determined immune response).

CD38: A Target for Immunotherapeutic Approaches in Multiple Myeloma

Multiple Myeloma (MM) is a hematological cancer characterized by proliferation of malignant plasma cells in the bone marrow (BM). MM represents the second most frequent hematological malignancy, accounting 1% of all cancer and 13% of hematological tumors, with ~9,000 new cases per year. Patients with monoclonal gammopathy of undetermined significance (MGUS) and asymptomatic smoldering MM (SMM) usually evolve to active MM in the presence of increased tumor burden, symptoms and organ damage. Despite the role of high dose chemotherapy in combination with autologous stem cell transplantation and the introduction of new treatments, the prognosis of MM patients is still poor, and novel therapeutic approaches have been tested in the last years, including new immunomodulatory drugs, proteasome inhibitors and monoclonal antibodies (mAbs). CD38 is a glycoprotein with ectoenzymatic functions, which is expressed on plasma cells and other lymphoid and myeloid cell populations. Since its expression is very high and uniform on myeloma cells, CD38 is a good target for novel therapeutic strategies. Among them, immunotherapy represents a promising approach. Here, we summarized recent findings regarding CD38-targeted immunotherapy of MM in pre-clinical models and clinical trials, including (i) mAbs (daratumumab and isatuximab), (ii) radioimmunotherapy, and (iii) adoptive cell therapy, using chimeric antigen receptor (CAR)-transfected T cells specific for CD38. Finally, we discussed the efficacy and possible limitations of these therapeutic approaches for MM patients.

Complement as a Biological Tool to Control Tumor Growth

Deposits of complement components have been documented in several human tumors suggesting a potential involvement of the complement system in tumor immune surveillance. In vitro and in vivo studies have revealed a double role played by this system in tumor progression. Complement activation in the cancer microenvironment has been shown to promote cancer growth through the release of the chemotactic peptide C5a recruiting myeloid suppressor cells. There is also evidence that tumor progression can be controlled by complement activated on the surface of cancer cells through one of the three pathways of complement activation. The aim of this review is to discuss the protective role of complement in cancer with special focus on the beneficial effect of complement-fixing antibodies that are efficient activators of the classical pathway and contribute to inhibit tumor expansion as a result of MAC-mediated cancer cell killing and complement-mediated inflammatory process. Cancer cells are heterogeneous in their susceptibility to complement-induced killing that generally depends on stable and relatively high expression of the antigen and the ability of therapeutic antibodies to activate complement. A new generation of monoclonal antibodies are being developed with structural modification leading to hexamer formation and enhanced complement activation. An important progress in cancer immunotherapy has been made with the generation of bispecific antibodies targeting tumor antigens and able to neutralize complement regulators overexpressed on cancer cells. A great effort is being devoted to implementing combined therapy of traditional approaches based on surgery, chemotherapy and radiotherapy and complement-fixing therapeutic antibodies. An effective control of tumor growth by complement is likely to be obtained on residual cancer cells following conventional therapy to reduce the tumor mass, prevent recurrences and avoid disabilities.