Phase 1, first-in-human study of TYRP1-TCB (RO7293583), a novel TYRP1-targeting CD3 T-cell engager, in metastatic melanoma: active drug monitoring to assess the impact of immune response on drug exposure

Introduction

Although checkpoint inhibitors (CPIs) have improved outcomes for patients with metastatic melanoma, those progressing on CPIs have limited therapeutic options. To address this unmet need and overcome CPI resistance mechanisms, novel immunotherapies, such as T-cell engaging agents, are being developed. The use of these agents has sometimes been limited by the immune response mounted against them in the form of anti-drug antibodies (ADAs), which is challenging to predict preclinically and can lead to neutralization of the drug and loss of efficacy.

Methods

TYRP1-TCB (RO7293583; RG6232) is a T-cell engaging bispecific (TCB) antibody that targets tyrosinase-related protein 1 (TYRP1), which is expressed in many melanomas, thereby directing T cells to kill TYRP1-expressing tumor cells. Preclinical studies show TYRP1-TCB to have potent anti-tumor activity. This first-in-human (FIH) phase 1 dose-escalation study characterized the safety, tolerability, maximum tolerated dose/optimal biological dose, and pharmacokinetics (PK) of TYRP1-TCB in patients with metastatic melanoma (NCT04551352).

Results

Twenty participants with cutaneous, uveal, or mucosal TYRP1-positive melanoma received TYRP1-TCB in escalating doses (0.045 to 0.4 mg). All participants experienced ≥1 treatment-related adverse event (TRAE); two participants experienced grade 3 TRAEs. The most common toxicities were grade 1-2 cytokine release syndrome (CRS) and rash. Fractionated dosing mitigated CRS and was associated with lower levels of interleukin-6 and tumor necrosis factor-alpha. Measurement of active drug (dual TYPR1- and CD3-binding) PK rapidly identified loss of active drug exposure in all participants treated with 0.4 mg in a flat dosing schedule for ≥3 cycles. Loss of exposure was associated with development of ADAs towards both the TYRP1 and CD3 domains. A total drug PK assay, measuring free and ADA-bound forms, demonstrated that TYRP1-TCB-ADA immune complexes were present in participant samples, but showed no drug activity in vitro.

Discussion

This study provides important insights into how the use of active drug PK assays, coupled with mechanistic follow-up, can inform and enable ongoing benefit/risk assessment for individuals participating in FIH dose-escalation trials. Translational studies that lead to a better understanding of the underlying biology of cognate T- and B-cell interactions, ultimately resulting in ADA development to novel biotherapeutics, are needed.

Assessment of CYP3A-mediated drug interaction via cytokine (IL-6) elevation for mosunetuzumab using physiologically-based pharmacokinetic modeling

Mosunetuzumab is a CD3/CD20 bispecific antibody. As an on-target effect, transient elevation of interleukin-6 (IL-6) occurs in early treatment cycles. A physiologically-based pharmacokinetic (PBPK) model was developed to assess potential drug interaction caused by IL-6 enzyme suppression on cytochrome P450 3A (CYP3A) during mosunetuzumab treatment. The model's performance in predicting IL-6 CYP3A suppression and subsequent drug-drug interactions (DDIs) was verified using existing clinical data of DDIs caused by chronic and transient IL-6 elevation. Sensitivity analyses were performed for a complete DDI risk assessment. The IL-6 concentration- and time-dependent CYP3A suppression during mosunetuzumab treatment was simulated using PBPK model with incorporation of in vitro IL-6 inhibition data. At clinically approved doses/regimens, the DDI at maximum CYP3A suppression was predicted to be a midazolam maximum drug concentration in plasma (Cmax ) and area under the plasma drug concentration-time curve (AUC) ratio of 1.17 and 1.37, respectively. At the 95th percentile of IL-6 concentration level or when gut CYP3A suppression was considered, the predicted DDI risk for mosunetuzumab remained low (<2-fold). The PBPK-based DDI predictions informed the mosunetuzumab product label to monitor, in early cycles, the concentrations and toxicities for sensitive CYP3A substrates with narrow therapeutic windows.

Bispecific antibodies in indolent B-cell lymphomas

The advent of immunotherapy in lymphomas, beginning with Rituximab, have led to paradigm shifting treatments that are increasingly bringing a greater number of affected patients within the ambit of durable disease control and cure. Bispecific antibodies harness the properties of the immunoglobulin antibody structure to design molecules which, apart from engaging with the target tumour associated antigen, engage the host's T-cells to cause tumour cell death. Mosunetuzumab, an anti-CD20 directed bispecific antibody was the first to be approved in follicular lymphoma, this has now been followed by quick approvals of Glofitamab and Epcoritamab in diffuse large B-cell lymphomas. This article reviews contemporary data and ongoing studies evaluating the role of bispecific antibodies in indolent b-cell non Hodgkin lymphomas. This is an area of active research and presents many opportunities in advancing the treatment of indolent lymphomas and potentially forge a chemo-free treatment paradigm in this condition.

Mechanistically modeling peripheral cytokine dynamics following bispecific dosing in solid tumors

Bispecific antibodies exhibit proven clinical benefit, and many bispecifics are currently in clinical development for oncology. Cytokine release syndrome (CRS) is a common clinical adverse effect observed following CD3-based bispecific dosing. However, the pathophysiology of CRS is not fully understood, and no computational model mechanistically describing clinical cytokine dynamics following bispecific dosing in solid tumors exists. Here, a quantitative systems pharmacology (QSP) model describing peripheral clinical cytokine dynamics following bispecific dosing in solid tumors is presented. Using tebentafusp as a case study, a CD3-bispecific approved for uveal melanoma, the model successfully captures the dynamics of five cytokines. The QSP model was shown to predict observed phenomena, such as cytokine maximum concentration suppression using step-up dosing regimens and the importance of on-target off-tumor binding toward CRS and toxicity. Furthermore, the QSP model provides rationale for these biological phenomena based on dynamics of immune cell activation and desensitization in tumors and healthy tissues. Overall, the QSP model structure presented here serves as a basis to infer cytokine dynamics for other CD3-based bispecifics or tumor types by altering model parameters to capture the scenario of interest, supporting applications including dose selection, candidate nomination, and disease area selection.

Mosunetuzumab and the emerging role of T-cell-engaging therapy in follicular lymphoma

Follicular lymphoma (FL) is the most common indolent lymphoma. Since the advent of rituximab, FL has seen a progressive improvement in patient prognosis. While chemotherapy combined with an anti-CD20 monoclonal antibody remains standard first-line therapy, most patients will relapse and require subsequent therapy. T-cell-redirecting therapies can be very potent and are transforming the therapeutic landscape in the relapsed and refractory (R/R) setting. T-cell-dependent bispecific antibodies, of which mosunetuzumab is the first to be approved for R/R FL, are proving to be a highly effective, 'off-the-shelf' option with manageable toxicities. This review covers approved treatments for R/R FL and focuses on preclinical and clinical data available for mosunetuzumab (Lunsumio™), with the goal of determining its role in the treatment of R/R FL.

Strategies for clinical dose optimization of T cell-engaging therapies in oncology

Innovative approaches in the design of T cell-engaging (TCE) molecules are ushering in a new wave of promising immunotherapies for the treatment of cancer. Their mechanism of action, which generates an in trans interaction to create a synthetic immune synapse, leads to complex and interconnected relationships between the exposure, efficacy, and toxicity of these drugs. Challenges thus arise when designing optimal clinical dose regimens for TCEs with narrow therapeutic windows, with a variety of dosing strategies being evaluated to mitigate key side effects such as cytokine release syndrome, neurotoxicity, and on-target off-tumor toxicities. This review evaluates the current approaches to dose optimization throughout the preclinical and clinical development of TCEs, along with perspectives for improvement of these strategies. Quantitative approaches used to aid the understanding of dose-exposure-response relationships are highlighted, along with opportunities to guide the rational design of next-generation TCE molecules, and optimize their dose regimens in patients.

Extending the Continual Reassessment Method to accommodate step-up dosing in Phase I trials

The Continual Reassessment Method (CRM) was developed for Phase I trials to identify a maximum‐tolerated dose of an agent using a design in which each participant is treated with a single administration of the agent. We propose an extension of the CRM in which participants receive multiple administrations of an agent using a so‐called step‐up dosing procedure in which participants receive one or more administrations of lower doses of the agent before they receive their penultimate dose. We use methods developed for the CRM to model the probability of DLT for each administration, which leads to the use of conditional probability models to model the joint probability of DLT across multiple administrations. We compare our approach to two existing methods that use time‐to‐event modeling methods for modeling the probability of DLT. We demonstrate through simulations that our approach has operating characteristics similar to existing methods, but due to its foundations in the CRM, ours is simpler to implement than existing approaches and is therefore more likely to be adopted in practice.

DLBCL 1L—What to Expect beyond R-CHOP?

Simple Summary

Diffuse large B-cell lymphoma (DLBCL) is the most common aggressive non-Hodgkin’s lymphoma. About two-thirds of patients are cured by the first-line (1L) standard of care (SOC), the R-CHOP (Rituximab, Cyclophosphamide, Doxorubicin, Vincristine and Prednisolone) immunochemotherapy protocol. The profound molecular heterogeneity of DLBCL is the underlying reason why many patients, despite improved next-line options, eventually succumb to the disease. Hence, enhancing the efficacy of 1L treatment is critical for improving long-term outcomes in DLBCL. A plethora of novel treatment options with potential in later lines is currently under evaluation in 1L settings. We summarize here the established and emerging strategies for newly diagnosed DLBCL and emphasize the need for individualized treatment decisions.

Abstract

The R-CHOP immunochemotherapy protocol has been the first-line (1L) standard of care (SOC) for diffuse large B-cell lymphoma (DLBCL) patients for decades and is curative in approximately two-thirds of patients. Numerous randomized phase III trials, most of them in an “R-CHOP ± X” design, failed to further improve outcomes. This was mainly due to increased toxicity, the large proportion of patients not in need of more than R-CHOP, and the extensive molecular heterogeneity of the disease, raising the bar for “one-size-fits-all” concepts. Recently, an R-CHP regimen extended by the anti-CD79b antibody–drug conjugate (ADC) Polatuzumab Vedotin proved superior to R-CHOP in terms of progression-free survival (PFS) in the POLARIX phase III trial. Moreover, a number of targeted agents, especially the Bruton’s tyrosine kinase (BTK) inhibitor Ibrutinib, seem to have activity in certain patient subsets in 1L and are currently being tested in front-line regimens. Chimeric antigen receptor (CAR) T-cells, achieving remarkable results in ≥3L scenarios, are being exploited in earlier lines of therapy, while T-cell-engaging bispecific antibodies emerge as conceptual competitors of CAR T-cells. Hence, we present here the findings and lessons learnt from phase III 1L trials and piloting phase II studies in relapsed/refractory (R/R) and 1L settings, and survey chemotherapy-free regimens with respect to their efficacy and future potential in 1L. Novel agents and their mode of action will be discussed in light of the molecular landscape of DLBCL and personalized 1L perspectives for the challenging patient population not cured by the SOC.

Cytokine Release Syndrome By T-cell-Redirecting Therapies: Can We Predict and Modulate Patient Risk?

T-cell-redirecting therapies are promising new therapeutic options in the field of cancer immunotherapy, but the development of these modalities is challenging. A commonly observed adverse event in patients treated with T-cell-redirecting therapies is cytokine release syndrome (CRS). Its clinical manifestation is a burden on patients, and continues to be a big hurdle in the clinical development of this class of therapeutics. We review different T-cell-redirecting therapies, discuss key factors related to cytokine release and potentially leading to CRS, and present clinical mitigation strategies applied for those modalities. We propose to dissect those risk factors into drug-target-disease-related factors and individual patient risk factors. Aiming to optimize the therapeutic intervention of these modalities, we illustrate how the knowledge on drug-target-disease-related factors, such as target expression, binding affinity, and target accessibility, can be leveraged in a model-based framework and highlight with case examples how modeling and simulation is applied to guide drug discovery and development. We draw attention to the current gaps in predicting the individual patient's risk towards a high-grade CRS, which requires further considerations of risk factors related, but not limited to, the patient's demographics, genetics, underlying pathologies, treatment history, and environmental exposures. The drug-target-disease-related factors together with the individual patient's risk factors can be regarded as the patient's propensity for developing CRS in response to therapy. As an outlook, we suggest implementing a risk scoring system combined with mechanistic modeling to enable the prediction of an individual patient's risk of CRS for a given therapeutic intervention.

Bispecific Antibodies: A Review of Development, Clinical Efficacy and Toxicity in B-Cell Lymphomas

The treatment landscape of B-cell lymphomas is evolving with the advent of novel agents including immune and cellular therapies. Bispecific antibodies (bsAbs) are molecules that recognise two different antigens and are used to engage effector cells, such as T-cells, to kill malignant B-cells. Several bispecific antibodies have entered early phase clinical development since the approval of the CD19/CD3 bispecific antibody, blinatumomab, for relapsed/refractory acute lymphoblastic leukaemia. Novel bsAbs include CD20/CD3 antibodies that are being investigated in both aggressive and indolent non-Hodgkin lymphoma with encouraging overall response rates including complete remissions. These results are seen even in heavily pre-treated patient populations such as those who have relapsed after chimeric antigen receptor T-cell therapy. Potential toxicities include cytokine release syndrome, neurotoxicity and tumour flare, with a number of strategies existing to mitigate these risks. Here, we review the development of bsAbs, their mechanism of action and the different types of bsAbs and how they differ in structure. We will present the currently available data from clinical trials regarding response rates, progression free survival and outcomes across a range of non-Hodgkin lymphoma subtypes. Finally, we will discuss the key toxicities of bsAbs, their rates and management of these adverse events.

TNB-486 induces potent tumor cell cytotoxicity coupled with low cytokine release in preclinical models of B-NHL

The therapeutic potential of targeting CD19 in B cell malignancies has garnered attention in the past decade, resulting in the introduction of novel immunotherapy agents. Encouraging clinical data have been reported for T cell-based targeting agents, such as anti-CD19/CD3 bispecific T-cell engager blinatumomab and chimeric antigen receptor (CAR)-T therapies, for acute lymphoblastic leukemia and B cell non-Hodgkin lymphoma (B-NHL). However, clinical use of both blinatumomab and CAR-T therapies has been limited due to unfavorable pharmacokinetics (PK), significant toxicity associated with cytokine release syndrome and neurotoxicity, and manufacturing challenges. We present here a fully human CD19xCD3 bispecific antibody (TNB-486) for the treatment of B-NHL that could address the limitations of the current approved treatments. In the presence of CD19+ target cells and T cells, TNB-486 induces tumor cell lysis with minimal cytokine release, when compared to a positive control. In vivo, TNB-486 clears CD19+ tumor cells in immunocompromised mice in the presence of human peripheral blood mononuclear cells in multiple models. Additionally, the PK of TNB-486 in mice or cynomolgus monkeys is similar to conventional antibodies. This new T cell engaging bispecific antibody targeting CD19 represents a novel therapeutic that induces potent T cell-mediated tumor-cell cytotoxicity uncoupled from high levels of cytokine release, making it an attractive candidate for B-NHL therapy.

Treatment of Aggressive B Cell Lymphomas: Updates in 2019

PURPOSE OF REVIEW

Recent years have seen the development of gene expression profiling and next-generation sequencing in diffuse large B cell lymphoma (DLBCL), leading to a more defined characterization of this disease into distinct subentities. The genomic era has ushered in the possibility of using precision guided therapy, in part based on targeting genes with somatic mutations. Such precision-targeted therapies will ultimately reduce the need for chemotherapy, induce fewer adverse events, and likely enhance the cure rate for these patients. Here, we discuss emerging therapeutic strategies that have been recently developed for the upfront and relapse setting of DLBCL.

RECENT FINDINGS

Clinical trials exploring precision medicine have showed promising results; however, attempts to enhance frontline immunochemotherapy by adding targeted agents to the R-CHOP backbone did not confirm the expected benefit. The last decade has also seen a revolutionary development of immunotherapy in B cell lymphomas. While cellular immunotherapy demonstrated a striking success of CAR T cells in DLBCL, checkpoint inhibitors have lacked success in B cell lymphomas. A parallel therapeutic expansion has involved bispecific monoclonal antibodies as a powerful tool for redirected T cell therapy independently from costimulatory molecules and major-histocompatibility complex. The landscape of drugs for the treatment of DLBCL has become overwhelmed by the increasing number of targeted and immunological therapies; however, none have enhanced efficacy of frontline therapy. Future direction should focus to redefine therapeutic paradigm and develop mechanism-based combinatorial regimens specifically tailored for DLBCL genetic subgroups.

Current Immunotherapy Approaches in Non-Hodgkin Lymphomas

Non-Hodgkin lymphomas (NHLs) are lymphoid malignancies of B- or T-cell origin. Despite great advances in treatment options and significant improvement of survival parameters, a large part of NHL patients either present with a chemotherapy-refractory disease or experience lymphoma relapse. Chemotherapy-based salvage therapy of relapsed/refractory NHL is, however, capable of re-inducing long-term remissions only in a minority of patients. Immunotherapy-based approaches, including bispecific antibodies, immune checkpoint inhibitors and genetically engineered T-cells carrying chimeric antigen receptors, single-agent or in combination with therapeutic monoclonal antibodies, immunomodulatory agents, chemotherapy or targeted agents demonstrated unprecedented clinical activity in heavily-pretreated patients with NHL, including chemotherapy-refractory cases with complex karyotype changes and other adverse prognostic factors. In this review, we recapitulate currently used immunotherapy modalities in NHL and discuss future perspectives of combinatorial immunotherapy strategies, including patient-tailored approaches.

Quantitative Clinical Pharmacology of T-Cell Engaging Bispecifics: Current Perspectives and Opportunities

T-cell directing/engaging bispecifics (TDBs) enable a powerful mode of action by activating T-cells through the creation of artificial immune synapses. Their pharmacological response involves the dynamic inter-relationships among T-cells, tumor cells, and TDBs. This results in complex and challenging issues in understanding pharmacokinetics, tissue distribution, target engagement, and exposure-response relationship. Dosing strategy plays a crucial role in determining the therapeutic window of TDBs because of the desire to maximize therapeutic efficacy in the context of known mechanism-related adverse events, such as cytokine release syndrome and neurological adverse events. Such adverse events are commonly reported as the most prominent events during the initial treatment cycles and dissipate over time. Therefore, the kinetic characterization of the inter-relationships between exposure/target engagement and safety/efficacy outcomes is crucial in designing the optimal dosing regimen to maximize the benefit/risk of TDB agents. In this review, we discuss the key clinical pharmacological considerations in drug discovery and development for TDBs and provide a summary of TDBs currently in clinical development. We also propose forward-looking perspectives and opportunities to derive insights through quantitative clinical pharmacology approaches.

Novel Therapies Potentially Available for Pediatric B-Cell Non-Hodgkin Lymphoma

Burkitt lymphoma, diffuse large B-cell lymphoma (DLBCL), and primary mediastinal B-cell lymphoma are the most common aggressive pediatric mature B-cell non-Hodgkin lymphomas (B-NHLs). Despite excellent survival with current chemotherapy regimens, therapy for Burkitt lymphoma and DLBCL has a high incidence of short- and long-term toxicities. Patients who experience relapse generally have a very poor prognosis. Therefore, novel approaches using targeted therapies to reduce toxicities and improve outcomes in the relapse setting are needed. The addition of rituximab, a monoclonal antibody against CD20, to upfront therapy has improved survival outcomes for high-risk patients and may allow decreased total chemotherapy in those with low-risk disease. Antibody-drug conjugates have been combined with chemotherapy in relapsed/refractory (R/R) NHL, and multiple antibody-drug conjugates are in development. Additionally, bispecific T-cell-engaging antibody constructs and autologous CAR T-cells have been successful in the treatment of R/R acute leukemias and are now being applied to R/R B-NHL with some successes. PD-L1 and PD-L2 on tumor cells can be targeted with checkpoint inhibitors, which restore T-cell-mediated immunity and antitumor responses and can be added to conventional chemotherapy and immune-directed therapies to augment responses. Lastly, trials of small molecule inhibitors targeting cell signaling pathways in NHL subtypes are underway. This article reviews many of the targeted therapies under development that could be considered for future trials in R/R pediatric mature B-NHL.

Polatuzumab vedotin for the treatment of adults with relapsed or refractory diffuse large B-cell lymphoma

INTRODUCTION

Polatuzumab vedotin is an antibody-drug conjugate comprised of an anti-CD79b monoclonal antibody conjugated to monomethyl auristatin (MMAE), a microtubule-disrupting cytotoxin. CD79b is almost exclusively expressed on normal and malignant B-cells, making it an appealing target for novel therapeutics.

AREAS COVERED

This article reviews the current literature on polatuzumab vedotin, including its pharmacology, as well as summarizing the results of clinical trials in relapsed/refractory diffuse large B-cell lymphoma (DLBCL) as a single agent and in combination with other chemotherapies and chemoimmunotherapies. The current landscape of approved therapies for relapsed and refractory DLBCL, as well as other promising novel approaches, is discussed.

EXPERT OPINION

The recent approval of polatuzumab vedotin in combination with bendamustine and rituximab (BR) offers another option to patients with DLBCL who are not eligible for autologous hematopoietic cell transplant or chimeric antigen receptors (CAR)-T cell therapy. In younger patients and those without serious comorbidities, polatuzumab vedotin-BR may serve as bridging therapy to more intensive therapies with reasonable efficacy and tolerability. Polatuzumab vedotin is currently being studied in a randomized trial in the front line setting in combination with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP).