The role of obinutuzumab in the management of follicular lymphoma

Improved Therapy of B-Cell Non-Hodgkin Lymphoma by Obinutuzumab-Dianthin Conjugates in Combination with the Endosomal Escape Enhancer SO1861

Immunotoxins do not only bind to cancer-specific receptors to mediate the elimination of tumor cells through the innate immune system, but also increase target cytotoxicity by the intrinsic toxin activity. The plant glycoside SO1861 was previously reported to enhance the endolysosomal escape of antibody-toxin conjugates in non-hematopoietic cells, thus increasing their cytotoxicity manifold. Here we tested this technology for the first time in a lymphoma in vivo model. First, the therapeutic CD20 antibody obinutuzumab was chemically conjugated to the ribosome-inactivating protein dianthin. The cytotoxicity of obinutuzumab-dianthin (ObiDi) was evaluated on human B-lymphocyte Burkitt’s lymphoma Raji cells and compared to human T-cell leukemia off-target Jurkat cells. When tested in combination with SO1861, the cytotoxicity for target cells was 131-fold greater than for off-target cells. In vivo imaging in a xenograft model of B-cell lymphoma in mice revealed that ObiDi/SO1861 efficiently prevents tumor growth (51.4% response rate) compared to the monotherapy with ObiDi (25.9%) and non-conjugated obinutuzumab (20.7%). The reduction of tumor volume and overall survival was also improved. Taken together, our results substantially contribute to the development of a combination therapy with SO1861 as a platform technology to enhance the efficacy of therapeutic antibody-toxin conjugates in lymphoma and leukemia.

Molecular Aspects of Resistance to Immunotherapies-Advances in Understanding and Management of Diffuse Large B-Cell Lymphoma

Despite the unquestionable success achieved by rituximab-based regimens in the management of diffuse large B-cell lymphoma (DLBCL), the high incidence of relapsed/refractory disease still remains a challenge. The widespread clinical use of chemo-immunotherapy demonstrated that it invariably leads to the induction of resistance; however, the molecular mechanisms underlying this phenomenon remain unclear. Rituximab-mediated therapeutic effect primarily relies on complement-dependent cytotoxicity and antibody-dependent cell cytotoxicity, and their outcome is often compromised following the development of resistance. Factors involved include inherent genetic characteristics and rituximab-induced changes in effectors cells, the role of ligand/receptor interactions between target and effector cells, and the tumor microenvironment. This review focuses on summarizing the emerging advances in the understanding of the molecular basis responsible for the resistance induced by various forms of immunotherapy used in DLBCL. We outline available models of resistance and delineate solutions that may improve the efficacy of standard therapeutic protocols, which might be essential for the rational design of novel therapeutic regimens.

Spinal anesthesia in a patient on monoclonal antibody treatment: a poisoned chalice? A case report

BACKGROUND

Paraplegia is a rare complication of spinal anesthesia.

CASE PRESENTATION

We report a case of a 68-year-old man who developed postoperative paraplegia and hypoesthesia after spinal anesthesia for an otherwise uncomplicated transurethral resection of the prostate. Acute transverse myelitis was diagnosed based on urgent MRI. A prior history of similar though less severe neurological symptoms after obinutuzumab treatment for follicular lymphoma suggested a potential causative role for obinutuzumab, a novel monoclonal antibody that has not been associated with such devastating neurological side effects yet. High-dose steroid treatment partially attenuated the symptoms, but debilitating hypoesthesia and motor deficit remained present 3 months postoperatively.

CONCLUSION

The presented case warrants caution when performing neuraxial anesthesia in patients on monoclonal antibody therapies.

Murlentamab, a Low Fucosylated Anti-Müllerian Hormone Type II Receptor (AMHRII) Antibody, Exhibits Anti-Tumor Activity through Tumor-Associated Macrophage Reprogrammation and T Cell Activation

Simple Summary

AMHRII, the anti-Müllerian hormone receptor, is selectively expressed in normal sexual organs in healthy adults but is also re-expressed in ovarian, colorectal and lung cancers. In this context, we developed murlentamab, a humanized glyco-engineered anti-AMHRII monoclonal antibody, currently in clinical trial. Preliminary data suggest that murlentamab anti-tumor activity involves immune response activation. Thus, in vitro experiments were performed to precisely characterize the murlentamab effect on the human immune system. We show that murlentamab treatment is associated with evidences of innate and adaptive immune cell activation in cancer patient samples. Moreover, we demonstrate that the murlentamab opsonization of AMHRII-expressing ovarian tumor cells promotes a polarization switch of both naïve and tumor-associated macrophages towards an anti-tumor M1-like phenotype. Our work also supports that, through macrophage reeducation, murlentamab activates an anti-tumor adaptive immune response. Finally, the combination of murlentamab with pembrolizumab confirmed novel clinical perspectives of murlentamab association with checkpoint inhibitors and other immuno-modulators.

Abstract

AMHRII, the anti-Müllerian hormone receptor, is selectively expressed in normal sexual organs but is also re-expressed in gynecologic cancers. Hence, we developed murlentamab, a humanized glyco-engineered anti-AMHRII monoclonal antibody currently in clinical trial. Low-fucosylated antibodies are known to increase the antibody-dependent cell-mediated cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) potency of effector cells, but some preliminary results suggest a more global murlentamab-dependent activation of the immune system. In this context, we demonstrate here that the murlentamab opsonization of AMHRII-expressing ovarian tumor cells, in the presence of unstimulated- or tumor-associated macrophage (TAM)-like macrophages, significantly promotes macrophage-mediated ADCC and shifts the whole microenvironment towards a pro-inflammatory and anti-tumoral status, thus triggering anti-tumor activity. We also report that murlentamab orients both unstimulated- and TAM-like macrophages to an M1-like phenotype characterized by a strong expression of co-stimulation markers, pro-inflammatory cytokines and chemokines, favoring T cell recruitment and activation. Moreover, we show that murlentamab treatment shifts CD4⁺ Th1/Th2 balance towards a Th1 response and activates CD8⁺ T cells. Altogether, these results suggest that murlentamab, through naïve macrophage orientation and TAM reprogrammation, stimulates the anti-tumor adaptive immune response. Those mechanisms might contribute to the sustained clinical benefit observed in advanced cancer patients treated with murlentamab. Finally, the enhanced murlentamab activity in combination with pembrolizumab opens new therapeutic perspectives.

Novel Therapy Approaches to Follicular Lymphoma

Follicular lymphoma (FL) is the most common form of indolent non-Hodgkin lymphoma. It is a disease characterised by a long median overall survival and high response rates to currently available chemotherapy and anti-CD20 monoclonal antibody therapy combinations. However, for a sub-group of patients the disease behaves aggressively, fails to respond adequately to initial therapy or relapses early. For others, the disease becomes resistant following multiple lines of therapy, and despite recent advances the main cause of death for patients with FL remains their lymphoma. A wide landscape of novel therapies is emerging and the role of individual agents in the FL treatment paradigm is still being established. Some agents, including the cereblon modulator lenalidomide, the phosphatidylinositol 3-kinase inhibitors idelalisib, copanlisib and duvelisib, and the EZH2 inhibitor tazemetostat have received regulatory approval in the USA or European Union and have entered clinical practice for relapsed FL. Other developments, such as the emergence of immunotherapies including CAR-T cell therapy and bispecific antibodies, are expected to fundamentally change the approach to FL treatment in the future.

Therapeutic Monoclonal Antibodies in Clinical Practice against Cancer

The importance of monoclonal antibodies in oncology has increased drastically following the discovery of Milstein and Kohler. Since the first approval of the monoclonal antibody, i.e. Rituximab in 1997 by the FDA, there was a decline in further applications but this number has significantly increased over the last three decades for various therapeutic applications due to the lesser side effects in comparison to the traditional chemotherapy methods. Presently, numerous monoclonal antibodies have been approved and many are in queue for approval as a strong therapeutic agent for treating hematologic malignancies and solid tumors. The main target checkpoints for the monoclonal antibodies against cancer cells include EGFR, VEGF, CD and tyrosine kinase which are overexpressed in malignant cells. Other immune checkpoints like CTLA-4, PD-1 and PD-1 receptors targeted by the recently developed antibodies increase the capability of the immune system in destroying the cancerous cells. Here, in this review, the mechanism of action, uses and target points of the approved mAbs against cancer have been summarized.

Immunomodulatory Agents in Follicular Lymphoma

New treatment strategies in follicular lymphoma (FL) are driven by a deeper understanding of microenvironmental cues supporting lymphomagenesis, chemoresistance, and immuno-escape. These immune-mediated signaling pathways contribute to initial learnings and clinical successes with lenalidomide, the first, oral, non-chemotherapeutic immunomodulatory drug, combined with anti-CD20 antibodies. This combination of lenalidomide with rituximab showed similar efficacy to chemoimmunotherapy (CIT) in first-line patients requiring therapy, and is approved in relapsed/refractory FL. We review the biology supporting the rationale for adequate inhibitory receptor/ligand pathways targeting the tissue immune microenvironment of FL cells, and potential immunomodulating combinations to replace CIT in the near future.