Radioimmunotherapy in follicular lymphoma: some like it hot…

Radioimmunotherapy in Oncology: Overview of the Last Decade Clinical Trials

Simple Summary

Monoclonal antibody-bearing radionuclides have been under clinical investigation over the last two decades for their use in theranostic (diagnostic and therapeutic) applications in cancer. However, despite the numerous trials that have been conducted, only two radioimmunotherapies (RIT) have been approved by the FDA for the targeted therapy of hematologic tumors expressing CD20 antigens. Moreover, RIT applications for solid cancers faced major issues—such as radiotoxicity due to low antibodies penetrance requiring substantial curative dose—where new discoveries concerning antibody engineering or radionuclides are trying to overcome. Here, we performed an overview of the last 11-year clinical trials involving RIT for solid and non-solid cancers conducted either with full antibodies or antibody fragments. We discussed the low-to-moderate efficiency of RIT compared to conventional therapies and described the last advances in clinic for antibodies carriers (F(ab′)₂, Fab′, ScFv). Finally, we discussed about the complexity of RIT as a therapy and depicted both the issues and the prospects of such a strategy.

Abstract

The specific irradiation of tumors with selective radiolabeled antibodies constitutes an attractive therapeutic approach. Consequent preclinical research has been conducted by both biologists to identify pertinent targets and to select corresponding antibodies (mAb) and by radiochemists to radiolabel mAbs. These numerous preclinical investigations have ascertained the therapeutic interest of radioimmunotherapy (RIT) protocols in mice models. Here, we summarize the clinical studies that have been performed the last decade, including clinical trials (phases I, II, and III), prospective and retrospective studies, and cases series. We thereby reported 92 clinical studies. Among them, 62 concern the treatment of hematological malignancies, and 30 concern solid tumors. For hematologic diseases, the analysis was complex due to the high discrepancy of therapeutic strategies (first-line therapy, consolidation, stem cell transplantation conditioning) as well as the high variety of malignancies that were treated. The clinical studies from the last decade failed to expand anti-CD20 RIT indications but confirmed that RIT using radiolabeled anti-CD20 remains a pertinent choice for patients with relapse follicular lymphomas. For solid tumors, the positive benefit of RIT is more mitigated, apart for few malignancies that can be treated locally. Clinical trials also demonstrated the potential of some antibody formats, such as F(ab′)₂, which has already been approved by the China State FDA under the trend name Licartin®. Despite disparate results, mAb fragments are an interesting prospect for the improvement of RIT efficiency as well as for pretargeted strategies that delay the injection of radioactive treatments from the mAb ones.

Therapeutic Activity of Lenalidomide in Mantle Cell Lymphoma and Indolent Non-Hodgkin's Lymphomas

Mantle cell lymphoma (MCL) comprises 3–10% of NHL, with survival times ranging from 3 and 5 years. Indolent lymphomas represent approximately 30% of all NHLs with patient survival largely dependent on validated prognostic scores. High response rates are typically achieved in these patients with current first-line chemoimmunotherapy. However, most patients will eventually relapse and become chemorefractory with poor outcome. Alternative chemoimmunotherapy regimens are often used as salvage strategy and stem cell transplant remains an option for selected patients. However, novel approaches are urgently needed for patients no longer responding to conventional chemotherapy. Lenalidomide is an immunomodulatory drug with activity in multiple myeloma, myelodisplastic syndrome and chronic lymphoproliferative disorders. In phase II studies of indolent NHL and MCL lenalidomide has shown activity with encouraging response rates, both as a single agent and in combination with other drugs. Some of these responses may be durable. Optimal dose of lenalidomide has not been defined yet. The role of lenalidomide in the therapeutic armamentarium of patients with indolent NHL or MCL will be discussed in the present paper.

Antibody-radionuclide conjugates for cancer therapy: historical considerations and new trends

When delivered at a sufficient dose and dose rate to a neoplastic mass, radiation can kill tumor cells. Because cancer frequently presents as a disseminated disease, it is imperative to deliver cytotoxic radiation not only to the primary tumor but also to distant metastases, while reducing exposure of healthy organs as much as possible. Monoclonal antibodies and their fragments, labeled with therapeutic radionuclides, have been used for many years in the development of anticancer strategies, with the aim of concentrating radioactivity at the tumor site and sparing normal tissues. This review surveys important milestones in the development and clinical implementation of radioimmunotherapy and critically examines new trends for the antibody-mediated targeted delivery of radionuclides to sites of cancer.