For 20 years, monoclonal antibodies (mAbs) have been a standard component of cancer therapy, but there is still much room for improvement. Efforts continue to build better cancer therapeutics based ...on mAbs. Anticancer mAbs function through various mechanisms, including directly targeting the malignant cells, modifying the host response, delivering cytotoxic moieties and retargeting cellular immunity towards the malignant cells. Characteristics of mAbs that affect their efficacy include antigen specificity, overall structure, affinity for the target antigen and how a mAb component is incorporated into a construct that can trigger target cell death. This Review discusses the various approaches to using mAb-based therapeutics to treat cancer and the strategies used to take advantage of the unique potential of each approach, and provides examples of current mAb-based treatments.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SBMB, UILJ, UKNU, UL, UM, UPUK
Cancer immunotherapy has proven to be challenging as it depends on overcoming multiple mechanisms that mediate immune tolerance to self-antigens. A growing understanding of immune tolerance has been ...the foundation for new approaches to cancer immunotherapy. Adoptive transfer of immune effectors such as antitumor mAb and chimeric antigen receptor T cells bypasses many of the mechanisms involved in immune tolerance by allowing for expansion of tumor-specific effectors ex vivo. Vaccination with whole tumor cells, protein, peptide, or dendritic cells has proven challenging, yet may be more useful when combined with other cancer immunotherapeutic strategies. Immunomodulatory approaches to cancer immunotherapy include treatment with agents that enhance and maintain T-cell activation. Recent advances in the use of checkpoint blockade to block negative signals and to maintain the antitumor response are particularly exciting. With our growing knowledge of immune tolerance and ways to overcome it, combination treatments are being developed, tested, and have particular promise. One example is in situ immunization that is designed to break tolerance within the tumor microenvironment. Progress in all these areas is continuing based on clear evidence that cancer immunotherapy designed to overcome immune tolerance can be useful for a growing number of patients with cancer.
Rituximab: mechanism of action Weiner, George J
Seminars in hematology,
04/2010, Letnik:
47, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Rituximab is a mainstay in the therapy for a broad variety of B-cell malignancies. Despite its undeniable therapeutic value, we still do not fully understand the mechanisms of action responsible for ...rituximab's anti-tumor effects. Direct signaling, complement-mediated cytotoxicity (CMC), and antibody-dependent cellular cytotoxicity (ADCC) all appear to play a role in rituximab efficacy. In vitro, animal model and clinical data addressing each of these mechanisms of action are reviewed, as are data speaking to the complexity of interactions between these mechanisms. Taken together, these data suggest different mechanisms are likely important in different scenarios. Study of the complex mechanisms of action that contribute to the clinical efficacy of rituximab have led to novel clinical trials including novel combinations, schedules, and generation of additional antibodies designed to have even greater effect. Such studies need to be accompanied by rigorous correlative analysis if we are to understand the importance of various mechanisms of action of rituximab and use that information to improve on what is already an indispensable component of therapy.
Cancer Immunotherapy Comes of Age TOPALIAN, Suzanne L; WEINER, George J; PARDOLL, Drew M
Journal of clinical oncology,
12/2011, Letnik:
29, Številka:
36
Journal Article
Recenzirano
Odprti dostop
Cancer immunotherapy comprises a variety of treatment approaches, incorporating the tremendous specificity of the adaptive immune system (T cells and antibodies) as well as the diverse and potent ...cytotoxic weaponry of both adaptive and innate immunity. Immunotherapy strategies include antitumor monoclonal antibodies, cancer vaccines, adoptive transfer of ex vivo activated T and natural killer cells, and administration of antibodies or recombinant proteins that either costimulate immune cells or block immune inhibitory pathways (so-called immune checkpoints). Although clear clinical efficacy has been demonstrated with antitumor antibodies since the late 1990s, other immunotherapies had not been shown to be effective until recently, when a spate of successes established the broad potential of this therapeutic modality. These successes are based on fundamental scientific advances demonstrating the toleragenic nature of cancer and the pivotal role of the tumor immune microenvironment in suppressing antitumor immunity. New therapies based on a sophisticated knowledge of immune-suppressive cells, soluble factors, and signaling pathways are designed to break tolerance and reactivate antitumor immunity to induce potent, long-lasting responses. Preclinical models indicate the importance of a complex integrated immune response in eliminating established tumors and validate the exploration of combinatorial treatment regimens, which are anticipated to be far more effective than monotherapies. Unlike conventional cancer therapies, most immunotherapies are active and dynamic, capable of inducing immune memory to propagate a successful rebalancing of the equilibrium between tumor and host.
Anti‐CD20 mAb is an effective therapy for most B‐cell malignancies. Checkpoint blockade has been used to enhance T‐cell‐mediated antitumor response. Little is known about the biologic significance of ...immune checkpoints expressed by NK cells in anti‐CD20‐based therapy. To investigate the role of checkpoints in anti‐CD20‐mediated NK cell biology, Raji B‐cell lymphoma cells, and PBMCs from normal donors were cocultured with rituximab (RTX), obinutuzumab (OBZ), or trastuzumab as a control mAb for between 20 h and 9 d. RTX and OBZ induced a dose‐dependent NK cell up‐regulation of T‐cell immunoreceptor with Ig and ITIM domain (TIGIT) and T‐cell immunoglobulin mucin‐3 (TIM3), but not PD1, CTLA4, or LAG3. Resting CD56dim NK had higher TIGIT and TIM3 expression than resting CD56bright NK although TIGIT and TIM3 were up‐regulated on both subsets. NK cells with the CD16 158VV single nucleotide polymorphism had greater TIM3 up‐regulation than did NK from VF or FF donors. TIGIT+ and TIM3+ NK cells degranulated, produced cytokines, and expressed activation markers to a greater degree than did TIGIT– or TIM3– NK cells. Blockade of TIGIT, TIM3, or both had little impact on RTX‐induced NK cell proliferation, degranulation, cytokine production, or activation. Taken together, TIGIT and TIM3 can serve as markers for anti‐CD20‐mediated NK cell activation, but may not serve well as targets for enhancing the anti‐tumor activity of such therapy.
Graphical
Activation by anti‐CD20 mAb upregulates NK cell TIGIT and TIM3 expression but has minimal effect on NK cell phenotype or function.
The immunologic and therapeutic effects of intratumoral (IT) delivery of a novel virus-like particle as a lymphoma immunotherapy were evaluated in preclinical studies with human cells and a murine ...model. CMP-001 is a virus-like particle composed of the Qβ bacteriophage capsid protein encapsulating an immunostimulatory CpG-A oligodeoxynucleotide TLR9 agonist. In vitro, CMP-001 induced cytokine production, including IFN-α from plasmacytoid dendritic cells, but only in the presence of anti-Qβ Ab. In vivo, IT CMP-001 treatment of murine A20 lymphoma enhanced survival and reduced growth of both injected and contralateral noninjected tumors in a manner dependent on both the ability of mice to generate anti-Qβ Ab and the presence of T cells. The combination of IT CMP-001 with systemic anti-PD-1 enhanced antitumor responses in both injected and noninjected tumors. IT CMP-001 alone or combined with anti-PD-1 augmented T cell infiltration in tumor-draining lymph nodes. We conclude IT CMP-001 induces a robust antitumor T cell response in an anti-Qβ Ab-dependent manner and results in systemic antitumor T cell effects that are enhanced by anti-PD-1 in a mouse model of B cell lymphoma. Early-phase clinical evaluation of CMP-001 and anti-PD-1 combination therapy in lymphoma will begin shortly, based in part on these results.
We examined the utility of post-therapy surveillance imaging in a large, prospectively enrolled cohort of patients with diffuse large B-cell lymphoma (DLBCL) from the United States and confirmed our ...results in an independent cohort of patients from France.
Patients with newly diagnosed DLBCL and treated with anthracycline-based immunochemotherapy were identified from the Molecular Epidemiology Resource (MER) of the University of Iowa/Mayo Clinic Lymphoma Specialized Program of Research Excellence and the Léon Bérard Cancer Center, Lyon, France. In those with relapse, details at relapse and outcomes were abstracted from records.
680 individuals with DLBCL were identified from the MER, 552 (81%) of whom achieved remission after induction. 112 of the 552 patients (20%) suffered a relapse. The majority (64%) of relapses were identified before a scheduled follow-up visit. Surveillance imaging detected DLBCL relapse before clinical manifestations in nine out of 552 patients (1.6%) observed after therapy. In the Lyon cohort, imaging identified asymptomatic DLBCL relapse in four out of 222 patients (1.8%). There was no difference in survival after DLBCL relapse in patients detected at scheduled follow-up versus before scheduled follow-up in both the MER (P = .56) and Lyon cohorts (P = .25).
The majority of DLBCL relapses are detected outside of planned follow-up, with no difference in outcome in patients with DLBCL detected at a scheduled visit compared with patients with relapse detected outside of planned follow-up. These data do not support the use of routine surveillance imaging for follow-up of DLBCL.
Patients with advanced melanoma that is resistant to PD-1 blockade therapy have limited treatment options. Vidutolimod (formerly CMP-001), a virus-like particle containing a CpG-A Toll-like receptor ...9 (TLR9) agonist, may reverse PD-1 blockade resistance by triggering a strong IFN response to induce and attract antitumor T cells. In the dose-escalation part of this phase Ib study, vidutolimod was administered intratumorally at escalating doses with intravenous pembrolizumab to 44 patients with advanced melanoma who had progressive disease or stable disease on prior anti-PD-1 therapy. The combination of vidutolimod and pembrolizumab had a manageable safety profile, and durable responses were observed in 25% of patients, with tumor regression in both injected and noninjected lesions, including visceral lesions. Patients who responded to vidutolimod and pembrolizumab had noninflamed tumors at baseline and induction of an IFNγ gene signature following treatment, as well as increased systemic expression of the IFN-inducible chemokine CXCL10.
In this phase Ib study in patients with advanced melanoma, intratumoral TLR9 agonist vidutolimod in combination with pembrolizumab had a manageable safety profile and showed promising clinical activity, supporting the further clinical development of vidutolimod to overcome PD-1 blockade resistance through induction of an IFN response. See related commentary by Sullivan, p. 2960. This article is highlighted in the In This Issue feature, p. 2945.
Anti-CD20 monoclonal antibody (mAb) therapy is a mainstay of therapy for B cell malignancies, however many patients fail to respond or eventually develop resistance. The current understanding of ...mechanisms responsible for this resistance is limited. When peripheral blood mononuclear cells of healthy donors were cultured with Raji cells for 7 days, rituximab (RTX) induced NK cell-mediated antibody-dependent cellular cytotoxicity (ADCC), enhanced NK cell viability and increased or maintained NK expression of CD56, CD16, CD57 and KIR. T cells, mainly CD4
+
, mediated these changes in a contact-dependent manner, with local T cell production of IL2 playing a central role. Similar findings were found when autologous B cells were used as target cells demonstrating the need for T cell help was not due to allogenic reaction. Results with other anti-CD20 and anti-EGFR antibodies were consistent. Small numbers of T cells activated by anti-CD3/CD28 beads or bispecific antibody enhanced RTX-mediated NK cell ADCC, viability and phenotypical changes. Pathway analysis of bulk NK cell mRNA sequencing after activation by RTX with and without T cells was consistent with T cells maintaining the viability of the activated NK cells. These findings suggest T cell help, mediated in large part by local production of IL2, contributes to NK cell ADCC and viability, and that activating T cells in the tumor microenvironment, such as through the use of anti-CD3 based bispecific antibodies, could enhance the efficacy of anti-CD20 and other mAb therapies where NK-mediated ADCC is a primary mechanism of action.
Cancers often arise as the end stage of inflammation in adults, but not in children. As such there is a complex interplay between host immune cells during neoplastic development, with both an ability ...to promote cancer and limit or eliminate it, most often complicit with the host. In humans, defining inflammation and the presence of inflammatory cells within or surrounding the tumor is a critical aspect of modern pathology. Groups defining staging for neoplasms are strongly encouraged to assess and incorporate measures of the presence of apoptosis, autophagy, and necrosis and also the nature and quality of the immune infiltrate. Both environmental and genetic factors enhance the risk of cigarette smoking, Helicobacter pylori, hepatitis B/C, human papilloma virus, solar irradiation, asbestos, pancreatitis, or other causes of chronic inflammation. Identifying suitable genetic polymorphisms in cytokines, cytokine receptors, and Toll-like receptors among other immune response genes is also seen as high value as genomic sequencing becomes less expensive. Animal models that incorporate and assess not only the genetic anlagen but also the inflammatory cells and the presence of microbial pathogens and damage-associated molecular pattern molecules are necessary. Identifying micro-RNAs involved in regulating the response to damage or injury are seen as highly promising. Although no therapeutic strategies to prevent or treat cancers based on insights into inflammatory pathways are currently approved for the common epithelial malignancies, there remains substantial interest in agents targeting COX2 or PPARgamma, ethyl pyruvate and steroids, and several novel agents on the horizon.
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