Phase I Trials of Anti-ENPP3 Antibody-Drug Conjugates in Advanced Refractory Renal Cell Carcinomas

Antibody Drug Conjugates in Urological Cancers: A Review of the Current Landscape

PURPOSE OF REVIEW

Our review delves into the progress across urological malignancies and discusses ongoing challenges and future directions in antibody-drug conjugate (ADC) development, emphasising their transformative potential in cancer care.

RECENT FINDINGS

ADCs have advanced from hematologic to solid tumours, notably in breast cancer, and are now pivotal in metastatic urological cancers as both monotherapies and in combination regimens, underscored by the FDA's approval of enfortumab vedotin and sacituzumab govitecan for metastatic urothelial cancer. Progress in metastatic prostate cancer, particularly with ADCs targeting PSMA and STEAP1, is noteworthy, although renal cell cancer presents ongoing challenges. There is a continual search for agents in the metastatic, relapsed testicular cancer landscape. ADCs have emerged as a pivotal innovation in oncology, blending targeted antibody therapy with potent cytotoxic drugs, significantly advancing treatment options for urological malignancies.

Antibody-drug conjugates in urinary tumors: clinical application, challenge, and perspectives

Urinary tumors primarily consist of kidney, urothelial, and prostate malignancies, which pose significant treatment challenges, particularly in advanced stages. Antibody-drug conjugates (ADCs) have emerged as a promising therapeutic approach, combining monoclonal antibody specificity with cytotoxic chemotherapeutic payloads. This review highlights recent advancements, opportunities, and challenges in ADC application for urinary tumors. We discuss the FDA-approved ADCs and other novel ADCs under investigation, emphasizing their potential to improve patient outcomes. Furthermore, we explore strategies to address challenges, such as toxicity management, predictive biomarker identification, and resistance mechanisms. Additionally, we examine the integration of ADCs with other treatment modalities, including immune checkpoint inhibitors, targeted therapies, and radiation therapy. By addressing these challenges and exploring innovative approaches, the development of ADCs may significantly enhance therapeutic options and outcomes for patients with advanced urinary tumor.

Antibody-Drug Conjugates and Ocular Toxicity

Antibody-drug conjugates (ADCs) are a growing class of chemotherapeutic agents for the purpose of treating cancers that often have relapsed or failed first- and second-line treatments. ADCs are composed of extremely potent cytotoxins with a variety of side effects, one of the most significant being ocular toxicity. The available literature describes these toxicities as varying in severity and in incidence, although with disparate methods of evaluation and management. Some of the most common toxicities include microcyst-like epithelial keratopathy and dry eye. We discuss proposed mechanisms of ocular toxicity and describe the reports that mention these toxicities. We focus on ADCs with the most published literature and the most significant effects on ocular tissue. We propose areas for further investigation and possible ideas of future management. We provide a comprehensive look at the reports of ADCs in current literature to better inform clinicians on an expanding drug class.

Adverse events of antibody-drug conjugates on the ocular surface in cancer therapy

Antibody-drug conjugates consist of a monoclonal antibody attached to a cytotoxic therapeutic molecule by a connector. This association allows a highly specific therapy, which increases their effectiveness and decreases their potential toxicity. This new therapy emerged approximately 20 years ago; since then, numerous combinations have appeared in the field of treatment-related neoplasms as an alternative for patients who do not achieve good results with conventional treatment options. Adverse effects of these drugs on the ocular surface are frequent and varied. Their prevalence ranges from 20 to 90% depending on the drug and administration condition, probably due to multiple receptor-mediated factors or mechanisms not mediated by specific receptors, such as macropinocytosis. These adverse events can greatly limit patients' comfort; thus, the objectives of this article were, in the first place, to compile the information currently available on different types of adverse effects of antibody-drug conjugates on the ocular surface, including pathophysiology, prevalence, and treatment, and in second place, to contribute to the correct identification and management of these events, which will result in a lower rate of cessation of treatment, which is necessary for the survival of candidate patients.

Novel Targeted Therapies for Renal Cell Carcinoma: Building on the Successes of Vascular Endothelial Growth Factor and mTOR Inhibition

Targeted therapies have revolutionized the treatment of renal cell carcinoma (RCC). The VHL/HIF pathway is responsible for the regulation of oxygen homeostasis and is frequently altered in RCC. Targeting this pathway as well as the mTOR pathway have yielded remarkable advances in the treatment of RCC. Here, we review the most promising novel targeted therapies for the treatment of RCC, including HIF2α, MET, metabolic targeting, and epigenomic reprogramming.

Toxicity profiles of antibody-drug conjugates for anticancer treatment: a systematic review and meta-analysis

BACKGROUND

Antibody-drug conjugates are attractive targeted agents in anticancer treatment because of their unique mechanism of action and reduced toxicity. Little is known about the spectrum of adverse events associated with antibody-drug conjugates, despite tens of clinical trials.

METHODS

A systematic review of randomized controlled trials evaluating antibody-drug conjugate efficacy in anticancer treatment was conducted. PubMed, EMBASE, and ClinicalTrial.gov were searched for relevant studies. Meta-analyses assessed the odds ratios (ORs) of 12 treatment-related symptoms and toxicities in patients treated with antibody-drug conjugates compared with those receiving other anticancer agents without antibody-drug conjugates. All-grade and high-grade (grade ≥3) toxicities were examined.

RESULTS

Twenty studies involving 10 075 patients were included. Compared with control groups, antibody-drug conjugates were associated with a higher risk of all-grade fatigue (OR = 1.25, 95% confidence interval [CI] = 1.08 to 1.45), anorexia (OR = 1.36, 95% CI = 1.09 to 1.69), nausea (OR = 1.46, 95% CI = 1.09 to 1.97), and sensory neuropathy (OR = 2.18, 95% CI = 1.27 to 3.76) as treatment-related symptoms. Patients treated with antibody-drug conjugates had a statistically significantly lower risk of all-grade febrile neutropenia (OR = 0.46, 95% CI = 0.22 to 0.96). Conversely, they had a higher risk of thrombocytopenia (OR = 2.07, 95% CI = 1.00 to 4.31), increased alanine aminotransferase (OR = 2.51, 95% CI = 1.84 to 3.40), and increased aspartate aminotransferase (OR = 2.83, 95% CI = 2.04 to 3.93). Subgroup analysis showed a similar toxicity profile when comparing the solid tumors with hematologic malignancy groups and the antibody-drug conjugate vs antibody-drug conjugate plus chemotherapy groups, except for some neurologic and hematologic adverse events.

CONCLUSIONS

This comprehensive profile of adverse events associated with antibody-drug conjugate-based treatment shows an increase in various types of all-grade treatment-related symptoms and adverse events, although no increase in high-grade adverse events was seen.

Antibody-Drug Conjugates for the Treatment of Renal Cancer: A Scoping Review on Current Evidence and Clinical Perspectives

Antibody-drug conjugates (ADCs) are complex chemical structures composed of a monoclonal antibody, serving as a link to target cells, which is conjugated with a potent cytotoxic drug (i.e., payload) through a chemical linker. Inspired by Paul Ehrlich's concept of the ideal anticancer drug as a "magic bullet", ADCs are also highly specific anticancer agents, as they have been demonstrated to recognize, bind, and neutralize cancer cells, limiting injuries to normal cells. ADCs are among the newest pharmacologic breakthroughs in treating solid and hematologic malignancies. Indeed, in recent years, various ADCs have been approved by the Food and Drug Administration and European Medicines Agency for the treatment of several cancers, resulting in a "practice-changing" approach. However, despite these successes, no ADC is approved for treating patients affected by renal cell carcinoma (RCC). In the present paper, we thoroughly reviewed the current literature and summarized preclinical studies and clinical trials that evaluated the activity and toxicity profile of ADCs in RCC patients. Moreover, we scrutinized the potential causes that, until now, hampered the therapeutical success of ADCs in those patients. Finally, we discussed novel strategies that would improve the development of ADCs and their efficacy in treating RCC patients.

Antibody-drug conjugates come of age in oncology

Antibody-drug conjugates (ADCs) combine the specificity of monoclonal antibodies with the potency of highly cytotoxic agents, potentially reducing the severity of side effects by preferentially targeting their payload to the tumour site. ADCs are being increasingly used in combination with other agents, including as first-line cancer therapies. As the technology to produce these complex therapeutics has matured, many more ADCs have been approved or are in late-phase clinical trials. The diversification of antigenic targets as well as bioactive payloads is rapidly broadening the scope of tumour indications for ADCs. Moreover, novel vector protein formats as well as warheads targeting the tumour microenvironment are expected to improve the intratumour distribution or activation of ADCs, and consequently their anticancer activity for difficult-to-treat tumour types. However, toxicity remains a key issue in the development of these agents, and better understanding and management of ADC-related toxicities will be essential for further optimization. This Review provides a broad overview of the recent advances and challenges in ADC development for cancer treatment.

Tusamitamab Ravtansine in Patients with Advanced Solid Tumors: Phase I Study of Safety, Pharmacokinetics, and Antitumor Activity Using Alternative Dosing Regimens

Purpose

Tusamitamab ravtansine is an antibody-drug conjugate that targets carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) and delivers a cytotoxic maytansinoid payload. In a phase I dose-escalation study, the maximum tolerated dose (MTD) was 100 mg/m2 every 2 weeks (Q2W). Here we report results for two alternative schedules.

Experimental Design

Adults ages ≥18 years (range, 34-73) with locally advanced/metastatic solid tumors (N = 43; colon/rectum, 29; stomach, 7; pancreas, 4; other, 3) expressing/likely to express CEACAM5 received intravenous tusamitamab ravtansine 120-170 mg/m2 [loading dose (LD)], then 100 mg/m2 Q2W (Q2W-LD, n = 28), or 120-190 mg/m2 fixed dose [every 3 weeks (Q3W), n = 15]. The primary endpoint was dose-limiting toxicities (DLTs) during cycles 1-2 (Q2W-LD) and cycle 1 (Q3W).

Results

Reversible DLTs were observed in 2 of 9 patients (grade 2 keratopathy; grade 2 keratitis) with 170 mg/m2 in Q2W-LD and in 2 of 3 patients (grade 2 keratopathy; grade 3 transaminase elevation) with 190 mg/m2 in Q3W. Nineteen (67.9%) patients in Q2W-LD and 13 (86.7%) patients in Q3W experienced treatment-related adverse events (AE); 3 of 43 patients discontinued treatment because of AEs. The most common AEs were asthenia, gastrointestinal complaints, keratopathy, keratitis, and peripheral sensory neuropathy. In this small, heavily pretreated population, no confirmed responses were observed; however, stable disease occurred in 35.7% of patients in Q2W-LD and 40.0% of patients in Q3W.

Conclusions

Tusamitamab ravtansine had a favorable safety profile with both alternative administration schedules; MTDs were 170 mg/m2 (LD) followed by 100 mg/m2 Q2W, and 170 mg/m2 Q3W as a fixed dose. (NCT02187848).

Significance

The collective results of this phase I dose-escalation study will inform further studies of tusamitamab ravtansine in patients with solid tumors with CEACAM5 expression, including patients with non-small cell lung cancer.

Antibody-Drug Conjugates: Ushering in a New Era of Cancer Therapy

Antibody-drug conjugates (ADCs) have provided new therapeutic options and significant promise for patients with cancer, particularly where existing treatments are limited. Substantial effort in ADC development is underway globally, with 13 ADCs currently approved and many more in development. The therapeutic benefits of ADCs leverage the ability to selectively target cancer cells through antibody binding, resultant relative sparing of non-malignant tissues, and the targeted delivery of a cytotoxic payload. Consequently, this drug class has demonstrated activity in multiple malignancies refractory to standard therapeutic options. Despite this, limitations exist, including narrow therapeutic windows, unique toxicity profiles, development of therapeutic resistance, and appropriate biomarker selection. This review will describe the development of ADCs, their mechanisms of action, pivotal trials, and approved indications and identify common themes. Current challenges and opportunities will be discussed for this drug class in cancer therapeutics at a time when significant developments in antibody therapies, immunotherapy, and targeted agents are occurring.

A Phase 3b Study for Management of Ocular Side Effects in Patients with Epidermal Growth Factor Receptor-Amplified Glioblastoma Receiving Depatuxizumab Mafodotin

INTRODUCTION

The Understanding New Interventions with GBM ThErapy (UNITE) study was designed to assess the effect of prophylaxis for ocular side effects (OSEs) in patients with glioblastoma receiving the antibody-drug conjugate (ADC) depatuxizumab mafodotin. UNITE (NCT03419403) was a phase 3b, open-label, randomized, exploratory study performed at 18 research sites in 5 countries.

METHODS

The study enrolled adult patients with epidermal growth factor receptor-amplified, histologically confirmed, newly diagnosed supratentorial glioblastoma or grade IV gliosarcoma, and a Karnofsky Performance Status ≥70, receiving depatuxizumab mafodotin. All patients were administered depatuxizumab mafodotin during concurrent radiotherapy and temozolomide and with adjuvant temozolomide. Ninety patients were to be randomized (1:1:1) to OSE prophylactic treatments with each depatuxizumab mafodotin infusion: (a) standard steroid eye drops, (b) standard steroid eye drops plus vasoconstrictor eye drops and cold compress, or (c) enhanced steroids plus vasoconstrictor eye drops and cold compress. A Corneal Epitheliopathy Adverse Event (CEAE) scale was devised to capture symptoms, grade OSEs (scale of 0-5), and inform ADC dose modifications. The primary endpoint was the frequency of a required change in OSE management due to inadequate control of OSEs, defined as decline from baseline in visual acuity (using logarithm of the minimum angle of resolution [LogMAR] scale) or a Grade ≥3 CEAE event, in the worst eye in the first 8 weeks of treatment; unless otherwise specified, the treatment period refers to both the chemoradiation and adjuvant phases.

RESULTS

The UNITE study was stopped early after interim analysis of separate phase III trial showed no difference in survival from depatuxizumab mafodotin. Forty patients were randomized (38 received depatuxizumab mafodotin). Overall, 23 patients experienced inadequate control of OSEs that required change in OSE management within 8 weeks of treatment, with 21 (70.0%) experiencing ≥+0.3 change on LogMAR scale in baseline-adjusted visual acuity and 12 reporting a grade ≥3 CEAE. There were no definitive differences among prophylactic treatments.

CONCLUSIONS

The premature cessation of the study precludes definitive conclusions regarding the OSE prophylaxis strategies. No new clinically significant safety findings were noted. Despite these limitations, this study highlights the need for novel assessment tools to better understand and mitigate OSEs associated with ADCs.

Delivery of Drugs into Cancer Cells Using Antibody-Drug Conjugates Based on Receptor-Mediated Endocytosis and the Enhanced Permeability and Retention Effect

Innumerable people worldwide die of cancer every year, although pharmaceutical therapy has actualized many benefits in human health. For background, anti-cancer drug development is difficult due to the multifactorial pathogenesis and complicated pathology of cancers. Cancer cells excrete hydrophobic low-molecular anti-cancer drugs by overexpressed efflux transporters such as multiple drug resistance 1 (MDR1) at the apical membrane. Mutation-driven drug resistance is also developed in cancer. Moreover, the poor distribution of drug to cancer cells is a serious problem, because patients suffer from off-target side effects. Thus, highly selective and effective drug delivery into solid cancer cells across the membrane should be established. It is known that substances (10-100 nm in diameter) such as monoclonal antibodies (mAbs) (approximately 14.2 nm in diameter) or nanoparticles spontaneously gather in solid tumor stroma or parenchyma through the capillary endothelial fenestration, ranging from 200-2000 nm, in neovasculatures due to the enhanced permeability and retention (EPR) effect. Furthermore, cancer antigens, such as HER2, Nectin-4, or TROP2, highly selectively expressed on the surface of cancer cells act as a receptor for receptor-mediated endocytosis (RME) using mAbs against such antigens. Thus, antibody-drug conjugates (ADCs) are promising anti-cancer pharmaceutical agents that fulfill accurate distribution due to the EPR effect and due to antibody-antigen binding and membrane permeability owing to RME. In this review, I introduce the implementation and possibility of highly selective anti-cancer drug delivery into solid cancer cells based on the EPR effect and RME using anti-cancer antigens ADCs with payloads through suitable linkers.

Bioinformatics analysis of key biomarkers for bladder cancer

Bladder cancer (BC) is one of the most prevalent genitourinary cancers. Despite the growing research interest in BC, the molecular mechanisms underlying its carcinogenesis remain poorly understood. The microarray datasets GSE38264 and GSE61615 obtained from the Gene Expression Omnibus (GEO) database were analyzed and differentially expressed genes (DEGs) were identified, which were then verified using a dataset from The Cancer Genome Atlas (TCGA). By taking the intersection of the two microarray datasets, the common DEGs were identified and these were selected as candidate genes associated with BC. The DEGs were further subjected to Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis, and the protein-protein interaction network was constructed. Further module analysis was performed using STRING and Cytoscape. A total of 362 DEGs were identified, including 13 hub genes, and the GO analysis revealed that these genes were mainly enriched in extracellular matrix organization, positive regulation of cell proliferation, angiogenesis and peptidyl-tyrosine phosphorylation. The expression changes of PTPRC, PDGFRA, CASQ2, TGFBI, KLRD1 and MT1X in the different datasets indicated that these genes were involved in the development of BC. Next, the differential expression of these genes was verified in the TCGA dataset, and ultimately, these 13 genes were determined to be related to the occurrence and development of BC. Finally, the cancer tissues and adjacent tissues of patients with BC were collected and subjected to reverse transcription-quantitative PCR, the results of which were consistent with the bioinformatics prediction. The present findings provide several vital genes for the clinical diagnosis and treatment of BC.

Physician treatment preferences for relapsed/refractory multiple myeloma: a discrete choice experiment

Aim: This study aimed to assess physician preferences for later lines (third to fifth) of therapy in patients with relapsed/refractory multiple myeloma (RRMM) in the USA. Materials & methods: Factors relevant to physicians' treatment preferences for RRMM were identified from a literature search and refined in a qualitative phase. Preferences were quantitatively assessed using a discrete choice experiment. Physicians (n = 227) made choices regarding treatment scenarios for RRMM. Results: Efficacy had the highest mean relative importance, with overall survival valued as most important when making treatment decisions for patients with RRMM. Reduced incidences of keratopathy and thrombocytopenia had similar relative importance in later-line treatment. Conclusion: Greater understanding of physicians' criteria for clinical decision-making may help inform wider adoption of new treatments.

ATP and Adenosine Metabolism in Cancer: Exploitation for Therapeutic Gain

Adenosine is an evolutionary ancient metabolic regulator linking energy state to physiologic processes, including immunomodulation and cell proliferation. Tumors create an adenosine-rich immunosuppressive microenvironment through the increased release of ATP from dying and stressed cells and its ectoenzymatic conversion into adenosine. Therefore, the adenosine pathway becomes an important therapeutic target to improve the effectiveness of immune therapies. Prior research has focused largely on the two major ectonucleotidases, ectonucleoside triphosphate diphosphohydrolase 1/cluster of differentiation (CD)39 and ecto-5'-nucleotidase/CD73, which catalyze the breakdown of extracellular ATP into adenosine, and on the subsequent activation of different subtypes of adenosine receptors with mixed findings of antitumor and protumor effects. New findings, needed for more effective therapeutic approaches, require consideration of redundant pathways controlling intratumoral adenosine levels, including the alternative NAD-inactivating pathway through the CD38-ectonucleotide pyrophosphatase phosphodiesterase (ENPP)1-CD73 axis, the counteracting ATP-regenerating ectoenzymatic pathway, and cellular adenosine uptake and its phosphorylation by adenosine kinase. This review provides a holistic view of extracellular and intracellular adenosine metabolism as an integrated complex network and summarizes recent data on the underlying mechanisms through which adenosine and its precursors ATP and ADP control cancer immunosurveillance, tumor angiogenesis, lymphangiogenesis, cancer-associated thrombosis, blood flow, and tumor perfusion. Special attention is given to differences and commonalities in the purinome of different cancers, heterogeneity of the tumor microenvironment, subcellular compartmentalization of the adenosine system, and novel roles of purine-converting enzymes as targets for cancer therapy. SIGNIFICANCE STATEMENT: The discovery of the role of adenosine as immune checkpoint regulator in cancer has led to the development of novel therapeutic strategies targeting extracellular adenosine metabolism and signaling in multiple clinical trials and preclinical models. Here we identify major gaps in knowledge that need to be filled to improve the therapeutic gain from agents targeting key components of the adenosine metabolic network and, on this basis, provide a holistic view of the cancer purinome as a complex and integrated network.

Antibody-Drug Conjugate Targets, Drugs and Linkers

Antibody-drug conjugates offer the possibility of directing powerful cytotoxic agents to a malignant tumor while sparing normal tissue. The challenge is to select an antibody target expressed exclusively or at highly elevated levels on the surface of tumor cells and either not all or at low levels on normal cells. The current review explores 78 targets that have been explored as antibody-drug conjugate targets. Some of these targets have been abandoned, 9 or more are the targets of FDA-approved drugs, and most remain active clinical interest. Antibody-drug conjugates require potent cytotoxic drug payloads, several of these small molecules are discussed, as are the linkers between the protein component and small molecule components of the conjugates. Finally, conclusions regarding the elements for the successful antibody-drug conjugate are discussed.

Linkers: An Assurance for Controlled Delivery of Antibody-Drug Conjugate

As one of the major therapeutic options for cancer treatment, chemotherapy has limited selectivity against cancer cells. Consequently, this therapeutic strategy offers a small therapeutic window with potentially high toxicity and thus limited efficacy of doses that can be tolerated by patients. Antibody-drug conjugates (ADCs) are an emerging class of anti-cancer therapeutic drugs that can deliver highly cytotoxic molecules directly to cancer cells. To date, twelve ADCs have received market approval, with several others in clinical stages. ADCs have become a powerful class of therapeutic agents in oncology and hematology. ADCs consist of recombinant monoclonal antibodies that are covalently bound to cytotoxic chemicals via synthetic linkers. The linker has a key role in ADC outcomes because its characteristics substantially impact the therapeutic index efficacy and pharmacokinetics of these drugs. Stable linkers and ADCs can maintain antibody concentration in blood circulation, and they do not release the cytotoxic drug before it reaches its target, thus resulting in minimum off-target effects. The linkers used in ADC development can be classified as cleavable and non-cleavable. The former, in turn, can be grouped into three types: hydrazone, disulfide, or peptide linkers. In this review, we highlight the various linkers used in ADC development and their design strategy, release mechanisms, and future perspectives.

Stepping forward in antibody-drug conjugate development

Antibody-drug conjugates (ADCs) are cancer therapeutic agents comprised of an antibody, a linker and a small-molecule payload. ADCs use the specificity of the antibody to target the toxic payload to tumor cells. After intravenous administration, ADCs enter circulation, distribute to tumor tissues and bind to the tumor surface antigen. The antigen then undergoes endocytosis to internalize the ADC into tumor cells, where it is transported to lysosomes to release the payload. The released toxic payloads can induce apoptosis through DNA damage or microtubule inhibition and can kill surrounding cancer cells through the bystander effect. The first ADC drug was approved by the United States Food and Drug Administration (FDA) in 2000, but the following decade saw no new approved ADC drugs. From 2011 to 2018, four ADC drugs were approved, while in 2019 and 2020 five more ADCs entered the market. This demonstrates an increasing trend for the clinical development of ADCs. This review summarizes the recent clinical research, with a specific focus on how the in vivo processing of ADCs influences their design. We aim to provide comprehensive information about current ADCs to facilitate future development.

Exposure-Response Analyses for Therapeutic Dose Selection of Belantamab Mafodotin in Patients With Relapsed/Refractory Multiple Myeloma

Belantamab mafodotin is an antibody–drug conjugate comprising a humanized anti‐B‐cell maturation antigen (BCMA) monoclonal antibody conjugated to monomethyl auristatin F (MMAF) via a protease‐resistant maleimidocaproyl linker. Single‐agent belantamab mafodotin showed clinically meaningful activity and manageable safety in patients with heavily pretreated relapsed/refractory multiple myeloma (RRMM) in the phase I DREAMM‐1 and phase II DREAMM‐2 studies and is approved by the US Food and Drug Administration and European Medicines Agency for RRMM treatment. To support monotherapy dose selection, the relationship between Cycle 1 exposure (derived using a population pharmacokinetic model) and clinical response (for multiple efficacy and safety end points) was explored. In DREAMM‐2, efficacy end points (probability of response (PoR) and progression‐free survival (PFS)) were associated with exposure in univariate evaluation; however, once disease burden factors were included in the model (e.g., baseline soluble BCMA, ß₂‐microglobulin), exposure was no longer significant. Patients with higher disease burden had lower exposure. In DREAMM‐1, belantamab mafodotin exposure was the only variable to correlate with PoR and PFS. Probability of corneal events (keratopathy), but not dry eye or blurred vision, was strongly associated with belantamab mafodotin exposure (DREAMM‐2). Higher cys‐mcMMAF maximum plasma drug concentration (C_max) and lower baseline platelet count were associated with increased probability of thrombocytopenia (DREAMM‐1 and DREAMM ‐2). In general, safety end points were more strongly associated with belantamab mafodotin exposure than efficacy end points, particularly after disease factors and patient characteristics were taken into account. Overall, these findings supported the monotherapy dose recommendation of belantamab mafodotin as 2.5 mg/kg every 3 weeks in patients with RRMM who have received four or more prior therapies.

Discovery of potent nucleotide pyrophosphatase/phosphodiesterase3 (NPP3) inhibitors with ancillary carbonic anhydrase inhibition for cancer (immuno)therapy

Nucleotide pyrophosphatase/phosphodiesterase3 (NPP3) catalyzes the hydrolysis of extracellular nucleotides. It is expressed by immune cells and some carcinomas, e.g. of kidney and colon. Together with ecto-5'-nucleotidase (CD73), NPP3 produces immunosuppressive, cancer-promoting adenosine, and has therefore been proposed as a target for cancer therapy. Here we report on the discovery of 4-[(4-methylphthalazin-1-yl)amino]benzenesulfonamide (1) as an inhibitor of human NPP3 identified by compound library screening. Subsequent structure-activity relationship (SAR) studies led to the potent competitive NPP3 inhibitor 2-methyl-5-{4-[(4-sulfamoylphenyl)amino]phthalazin-1-yl}benzenesulfonamide (23, K i 53.7 nM versus the natural substrate ATP). Docking studies predicted its binding pose and interactions. While 23 displayed high selectivity versus other ecto-nucleotidases, it showed ancillary inhibition of two proposed anti-cancer targets, the carbonic anhydrases CA-II (Ki 74.7 nM) and CA-IX (Ki 20.3 nM). Thus, 23 may act as multi-target anti-cancer drug. SARs for NPP3 were steeper than for CAs leading to the identification of potent dual CA-II/CA-IX (e.g. 34) as well as selective CA-IX inhibitors (e.g. 31).

Antibody-Based Targeted Interventions for the Diagnosis and Treatment of Skin Cancers

BACKGROUND

Cutaneous malignancies most commonly arise from skin epidermal cells. These cancers may rapidly progress from benign to a metastatic phase. Surgical resection represents the gold standard therapeutic treatment of non-metastatic skin cancer while chemo- and/or radiotherapy are often used against metastatic tumors. However, these therapeutic treatments are limited by the development of resistance and toxic side effects, resulting from the passive accumulation of cytotoxic drugs within healthy cells.

OBJECTIVE

This review aims to elucidate how the use of monoclonal Antibodies (mAbs) targeting specific Tumor Associated Antigens (TAAs) is paving the way to improved treatment. These mAbs are used as therapeutic or diagnostic carriers that can specifically deliver cytotoxic molecules, fluorophores or radiolabels to cancer cells that overexpress specific target antigens.

RESULTS

mAbs raised against TAAs are widely in use for e.g. differential diagnosis, prognosis and therapy of skin cancers. Antibody-Drug Conjugates (ADCs) particularly show remarkable potential. The safest ADCs reported to date use non-toxic photo-activatable Photosensitizers (PSs), allowing targeted Photodynamic Therapy (PDT) resulting in targeted delivery of PS into cancer cells and selective killing after light activation without harming the normal cell population. The use of near-infrared-emitting PSs enables both diagnostic and therapeutic applications upon light activation at the specific wavelengths.

CONCLUSION

Antibody-based approaches are presenting an array of opportunities to complement and improve current methods employed for skin cancer diagnosis and treatment.

Development of Marine-Derived Compounds for Cancer Therapy

Cancer has always been a threat to human health with its high morbidity and mortality rates. Traditional therapy, including surgery, chemotherapy and radiotherapy, plays a key role in cancer treatment. However, it is not able to prevent tumor recurrence, drug resistance and treatment side effects, which makes it a very attractive challenge to search for new effective and specific anticancer drugs. Nature is a valuable source of multiple pharmaceuticals, and most of the anticancer drugs are natural products or derived from them. Marine-derived compounds, such as nucleotides, proteins, peptides and amides, have also shed light on cancer therapy, and they are receiving a fast-growing interest due to their bioactive properties. Their mechanisms contain anti-angiogenic, anti-proliferative and anti-metastasis activities; cell cycle arrest; and induction of apoptosis. This review provides an overview on the development of marine-derived compounds with anticancer properties, both their applications and mechanisms, and discovered technologies.

Potential New Therapeutic Approaches for Renal Cell Carcinoma

Renal cell carcinoma (RCC) is increasing in incidence and one third of newly diagnosed cases already are metastatic. The metastatic spread of solid tumors renders RCC incurable by surgical resection and consequently more difficult to treat. New molecular-targeted therapies have played a pivotal role in RCC treatment. Unfortunately, tumors frequently develop resistance to these targeted therapies by activating bypass pathways in which alternative signaling or biochemical pathways are activated in response to targeted inhibition of a signaling pathway, allowing cancer cells to continue to survive. Although the advent of immunotherapy with checkpoint inhibitors has led to significant changes in the treatment landscape for advanced RCC, many issues remain to be resolved. For these reasons, there is an urgent need to develop novel therapies and new treatment paradigms for patients with RCC. Much research has been performed thus far in identifying novel targets and treatment strategies in RCC and many of these currently are under investigation and/or in clinical trials. In this article, we discuss therapeutic options in the management of RCC with a focus on the new therapeutic approaches currently investigated in research and for use in the clinic. We divide these potential novel therapies into five groups: nonbiologics, small-molecule drugs, biologics, immunomodulatory therapies, and peptide drugs. We also present some therapeutics and treatment paradigms.

Beyond conventional immune-checkpoint inhibition - novel immunotherapies for renal cell carcinoma

The management of advanced-stage renal cell carcinoma (RCC) has been transformed by the development of immune-checkpoint inhibitors (ICIs). Nonetheless, most patients do not derive durable clinical benefit from these agents. Importantly, unlike other immunotherapy-responsive solid tumours, most RCCs have only a moderate mutational burden, and paradoxically, high levels of tumour CD8+ T cell infiltration are associated with a worse prognosis in patients with this disease. Building on the successes of antibodies targeting the PD-1 and CTLA4 immune checkpoints, multiple innovative immunotherapies are now in clinical development for the treatment of patients with RCC, including ICIs with novel targets, co-stimulatory pathway agonists, modified cytokines, metabolic pathway modulators, cell therapies and therapeutic vaccines. However, the successful development of such novel immune-based treatments and of immunotherapy-based combinations will require a disease-specific framework that incorporates a deep understanding of RCC immunobiology. In this Review, using the structure provided by the well-described cancer-immunity cycle, we outline the key steps required for a successful antitumour immune response in the context of RCC, and describe the development of promising new immunotherapies within the context of this framework. With this approach, we summarize and analyse the most encouraging targets of novel immune-based therapies within the RCC microenvironment, and review the landscape of emerging antigen-directed therapies for this disease.

A Randomized Phase II Study of AGS-16C3F Versus Axitinib in Previously Treated Patients with Metastatic Renal Cell Carcinoma

LESSONS LEARNED

The primary endpoint of this phase II study that evaluated the efficacy and safety of the investigational compound, AGS-16C3F, versus axitinib in previously treated patients with metastatic renal cell carcinoma (mRCC) was not met. Median progression-free survival, the primary endpoint, was 2.9 months with AGS-16C3F and 5.7 months with axitinib (HR, 1.676; 95% CI, 1.107-2.537; p = .015), per investigator assessment The safety profile for each study drug was as expected, with the most commonly reported adverse events being fatigue (53%) and nausea (47%) in the AGS-16C3F arm and fatigue (57%) and diarrhea (48%) in the axitinib arm. These results provide a benchmark for axitinib use in heavily pretreated patients with mRCC.

BACKGROUND

AGS-16C3F is a novel antibody-drug conjugate that targets cell-surface ectonucleotide pyrophosphatase/phosphodiesterase 3 (ENPP3) and is conjugated to a microtubule disruptive agent. Here we present findings from a phase II study of AGS-16C3F versus axitinib in metastatic renal cell carcinoma (mRCC).

METHODS

Patients with mRCC of any histology and disease progression during or after their last treatment regimen were randomized 1:1 to intravenous AGS-16C3F 1.8 mg/kg every 3 weeks or oral axitinib 5 mg twice daily (starting dose). The primary objective was investigator-assessed progression-free survival (PFS) of AGS-16C3F versus axitinib (RECIST version 1.1).

RESULTS

In the total population (N = 133), 63% (n = 84) of patients had completed the study at data cutoff (August 21, 2019). Median PFS was 2.9 months with AGS-16C3F and 5.7 months with axitinib (hazard ratio [HR], 1.676; 95% confidence interval [CI], 1.107-2.537; p = .015). There were no significant differences between arms in secondary efficacy endpoints, including overall survival (13.1 months, AGS-16C3F and 15.4 months, axitinib; HR, 1.079; 95% CI, 0.681-1.707; p = .747). In the safety population (n = 131), the most commonly reported adverse events were fatigue (53%) and nausea (47%) in the AGS-16C3F arm and fatigue (57%) and diarrhea (48%) in the axitinib arm. The incidence of diarrhea was lower in the AGS-16C3F arm than in the axitinib arm (17% vs. 48%), and ocular toxicities were more frequent in the AGS-16C3F arm than in the axitinib arm (44% vs. 26%).

CONCLUSION

The investigational compound, AGS-16C3F, did not meet the primary endpoint of this trial. These study results provide a benchmark for axitinib use in heavily pretreated patients with mRCC.

Adenosine metabolism in the vascular system

The concept of extracellular purinergic signaling was first proposed by Geoffrey Burnstock in the early 1970s. Since then, extracellular ATP and its metabolites ADP and adenosine have attracted an enormous amount of attention in terms of their involvement in a wide range of immunomodulatory, thromboregulatory, angiogenic, vasoactive and other pathophysiological activities in different organs and tissues, including the vascular system. In addition to significant progress in understanding the properties of nucleotide- and adenosine-selective receptors, recent studies have begun to uncover the complexity of regulatory mechanisms governing the duration and magnitude of the purinergic signaling cascade. This knowledge has led to the development of new paradigms in understanding the entire purinome by taking into account the multitude of signaling and metabolic pathways involved in biological effects of ATP and adenosine and compartmentalization of the adenosine system. Along with the "canonical route" of ATP breakdown to adenosine via sequential ecto-nucleoside triphosphate diphosphohydrolase-1 (NTPDase1/CD39) and ecto-5'-nucleotidase/CD73 activities, it has now become clear that purine metabolism is the result of concerted effort between ATP release, its metabolism through redundant nucleotide-inactivating and counteracting ATP-regenerating ectoenzymatic pathways, as well as cellular nucleoside uptake and phosphorylation of adenosine to ATP through complex phosphotransfer reactions. In this review I provide an overview of key enzymes involved in adenosine metabolic network, with special emphasis on the emerging roles of purine-converting ectoenzymes as novel targets for cancer and vascular therapies.

Belantamab mafodotin in the treatment of relapsed or refractory multiple myeloma

Multiple myeloma remains an incurable disease, with a large proportion of patients in the relapsed/refractory setting often unable to achieve durable responses. Novel, well-tolerated and highly effective therapies in this patient population represent an unmet need. Preclinical studies have shown that B-cell maturation antigen is nearly exclusively expressed on normal and malignant plasma cells, thereby identifying it as a highly selective target for immunotherapeutic approaches. Belantamab mafodotin (GSK2857916, belamaf) is a first-in-class antibody-drug conjugate directed at B-cell maturation antigen and has shown promising activity in clinical trials. In this review, we provide an overview of belantamab mafodotin as a compound and present the available clinical efficacy and safety data in the treatment of relapsed/refractory multiple myeloma.

Corneal Epithelial Findings in Patients with Multiple Myeloma Treated with Antibody-Drug Conjugate Belantamab Mafodotin in the Pivotal, Randomized, DREAMM-2 Study

INTRODUCTION

Patients with relapsed or refractory multiple myeloma (RRMM) represent an unmet clinical need. Belantamab mafodotin (belamaf; GSK2857916) is a first-in-class antibody-drug conjugate (ADC; or immunoconjugate) that delivers a cytotoxic payload, monomethyl auristatin F (MMAF), to myeloma cells. In the phase II DREAMM-2 study (NCT03525678), single-agent belamaf (2.5 mg/kg) demonstrated clinically meaningful anti-myeloma activity (overall response rate 32%) in patients with heavily pretreated disease. Microcyst-like epithelial changes (MECs) were common, consistent with reports from other MMAF-containing ADCs.

METHODS

Corneal examination findings from patients in DREAMM-2 were reviewed, and the clinical descriptions and accompanying images (slit lamp microscopy and in vivo confocal microscopy [IVCM]) of representative events were selected. A literature review on corneal events reported with other ADCs was performed.

RESULTS

In most patients receiving single-agent belamaf (72%; 68/95), MECs were observed by slit lamp microscopy early in treatment (69% had their first event by dose 4). However, IVCM revealed hyperreflective material. Blurred vision (25%) and dry eye (15%) were commonly reported symptoms. Management of MECs included dose delays (47%)/reductions (25%), with few patients discontinuing due to MECs (1%). The first event resolved in most patients (grade ≥2 MECs and visual acuity [each 77%], blurred vision [67%], and dry eye [86%]), with no reports of permanent vision loss to date. A literature review confirmed that similar MECs were reported with other ADCs; however, event management strategies varied. The pathophysiology of MECs is unclear, though the ADC cytotoxic payload may contribute to on- or off-target effects on corneal epithelial cells.

CONCLUSION

Single-agent belamaf represents a new treatment option for patients with RRMM. As with other ADCs, MECs were observed and additional research is warranted to determine their pathophysiology. A multidisciplinary approach, involving close collaboration between eye care professionals and hematologist/oncologists, is needed to determine appropriate diagnosis and management of these patients.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier, NCT03525678.

Safety and efficacy of CDX-014, an antibody-drug conjugate directed against T cell immunoglobulin mucin-1 in advanced renal cell carcinoma

CDX-014 is an antibody-drug conjugate directed against TIM-1, a surface marker highly expressed in renal cell carcinoma (RCC) and ovarian carcinoma. This phase I, first-in-human trial was conducted to evaluate the safety and preliminary activity of CDX-014 in patients with advanced refractory RCC, following a dose-escalation and dose expansion design. CDX-014 was administered intravenously at doses ranging from 0.15 to 2.0 mg/kg every 2 or 3 weeks until progression or unacceptable toxicity. Sixteen patients received at least one dose of CDX-014. The maximum tolerated dose was not identified. Most frequent adverse grade 1 or 2 adverse events included nausea (38%), fatigue, alopecia, elevation of AST and decreased appetite (25% each). Adverse events of grade 3 or more included hyperglycemia (19%), urosepsis (6%), and one multi-organ failure (6%) responsible for one treatment-related death. Two patients discontinued therapy for adverse events including fatigue grade 2 and urosepsis grade 4. CDX-014 showed antitumor activity with one prolonged partial response and a clinical benefit rate (objective response or stable disease >6 months) of 31%. The two patients that exhibited the most marked tumor shrinkage had high TIM-1 expression on tumor tissue. Overall, CDX-014 exhibited a manageable toxicity profile and early signs of activity, supporting further evaluation of antibody-drug conjugates in patients with advanced RCC and potentially other TIM-1 expressing cancers. Trial registration https://clinicaltrials.gov/ct2/show/NCT02837991 NCT02837991; July 20, 2016.

Advances in Antibody–Drug Conjugate Design: Current Clinical Landscape and Future Innovations

The targeted delivery of potent cytotoxic molecules into cancer cells is considered a promising anticancer strategy. The design of clinically effective antibody–drug conjugates (ADCs), in which biologically active drugs are coupled through chemical linkers to monoclonal antibodies, has presented challenges for pharmaceutical researchers. After 30 years of intensive research and development activities, only seven ADCs have been approved for clinical use; two have received fast-track designation and two breakthrough therapy designation from the Food and Drug Administration. There is continued interest in the field, as documented by the growing number of candidates in clinical development. This review aims to summarize the most recent innovations that have been applied to the design of ADCs undergoing early- and late-stage clinical trials. Discovery and rational optimization of new payloads, chemical linkers, and antibody formats have improved the therapeutic index of next-generation ADCs, ultimately resulting in improved clinical benefit for the patients.

Current State of Systemic Therapies for Advanced Renal Cell Carcinoma

PURPOSE OF REVIEW

Due to the rapidly changing field of kidney cancer therapeutics, addressing the state of the art systemic therapy regimens, and sequencing with cytoreductive nephrectomy are the primary focus of this review. We will also discuss the role of biomarkers and novel therapeutic targets in the management of renal cell carcinoma.

RECENT FINDINGS

The management of metastatic renal cell cancer has undergone a paradigm shift with immune checkpoint inhibitors being used in the frontline setting. Over the last 4 years, programmed cell death-1 (PD-1) inhibitors as well as programmed cell death ligand-1 inhibitors have become available in various combinations with cytotoxic T lymphocyte-associated protein-4 (CTLA-4) inhibitors and tyrosine kinase inhibitors (TKIs). These drugs have improved outcomes in patients with renal cell cancer and more work is being done to refine these targets as well as discover newer ones. Despite the availability of several new treatment options, some questions that still need to be addressed in the management of kidney cancer include the sequencing of treatment options, treatment of patients who progress on immune checkpoint inhibitors, and role of biomarkers to ascertain the best treatment options to minimize costs and improve outcomes.

ADCs, as Novel Revolutionary Weapons for Providing a Step Forward in Targeted Therapy of Malignancies

:

Antibody drug conjugates (ADCs), as potent pharmaceutical trojan horses for cancer treatment, provide superior efficacy and specific targeting along with low risk of adverse reactions compared to traditional chemotherapeutics. In fact, the development of these agents combines the selective targeting capability of monoclonal antibody (mAb) with high cytotoxicity of chemotherapeutics for controlling the neoplastic mass growth. Different ADCs (more than 60 ADCs) in preclinical and clinical trials were introduced in this novel pharmaceutical field. Various design-based factors must be taken into account for improving the functionality of ADC technology, including selection of appropriate target antigen and high binding affinity of fragment (miniaturized ADCs) or full mAbs (preferentially use of humanized or fully human antibodies compared to murine and chimeric ones), use of bispecific antibodies for dual targeting effect, linker engineering and conjugation method efficacy to obtain more controlled drug to antibody ratio (DAR). Challenging issues affecting therapeutic efficacy and safety of ADCs, including bystander effect, on- and off-target toxicities, multi drug resistance (MDR) are also addressed. 4 FDA-approved ADCs in the market, including ADCETRIS ®, MYLOTARG®, BESPONSA ®, KADCYLA®. The goal of the current review is to evaluate the key parameters affecting ADCs development.

Impaired Expression of Ectonucleotidases in Ectopic and Eutopic Endometrial Tissue Is in Favor of ATP Accumulation in the Tissue Microenvironment in Endometriosis

Endometriosis is a prevalent disease defined by the presence of endometrial tissue outside the uterus. Adenosine triphosphate (ATP), as a proinflammatory molecule, promotes and helps maintain the inflammatory state of endometriosis. Moreover, ATP has a direct influence on the two main symptoms of endometriosis: infertility and pain. Purinergic signaling, the group of biological responses to extracellular nucleotides such as ATP and nucleosides such as adenosine, is involved in the biology of reproduction and is impaired in pathologies with an inflammatory component such as endometriosis. We have previously demonstrated that ectonucleotidases, the enzymes regulating extracellular ATP levels, are active in non-pathological endometria, with hormone-dependent changes in expression throughout the cycle. In the present study we have focused on the expression of ectonucleotidases by means of immunohistochemistry and in situ activity in eutopic and ectopic endometrial tissue of women with endometriosis, and we compared the results with endometria of women without the disease. We have demonstrated that the axis CD39-CD73 is altered in endometriosis, with loss of CD39 and CD73 expression in deep infiltrating endometriosis, the most severe, and most recurring, endometriosis subtype. Our results indicate that this altered expression of ectonucleotidases in endometriosis boosts ATP accumulation in the tissue microenvironment. An important finding is the identification of the nucleotide pyrophophatase/phosphodiesterase 3 (NPP3) as a new histopathological marker of the disease since we have demonstrated its expression in the stroma only in endometriosis, in both eutopic and ectopic tissue. Therefore, targeting the proteins directly involved in ATP breakdown could be an appropriate approach to consider in the treatment of endometriosis.

The "Utility" of Highly Toxic Marine-Sourced Compounds

Currently a few compounds isolated from marine sources have become drugs, mainly directed towards cancer and pain. Compounds from marine sources have exquisite potencies against eukaryotic cells, as they act as protective agents against attack by predators in the marine environment. Their toxicities act as a “double-edged sword” as they are often too toxic for direct use in humans and thus have to be chemically modified. By linking suitably modified compounds to monoclonal antibodies directed against specific epitopes in mammalian cancer cells, they can be delivered to a specific cell type in humans. This review updates and extends an article published in early 2017, demonstrating how by careful chemical modifications, highly toxic compounds, frequently peptidic in nature, can be utilized as antitumor drug candidates. The antibody-drug- conjugates (ADCs) discussed are those that are currently in clinical trials listed in the NIH Clinical Trials Registry as, “currently active, recruiting or in some cases, recently completed”. There are also some ADCs discussed that are at the advanced preclinical stage, that in some cases, are repurposing current drug entities, and the review finishes with a short discussion of the aplyronines as potential candidate warheads as a result of scalable synthetic processes.

Pharmacologic Considerations in the Disposition of Antibodies and Antibody-Drug Conjugates in Preclinical Models and in Patients

The rapid advancement in the development of therapeutic proteins, including monoclonal antibodies (mAbs) and antibody-drug conjugates (ADCs), has created a novel mechanism to selectively deliver highly potent cytotoxic agents in the treatment of cancer. These agents provide numerous benefits compared to traditional small molecule drugs, though their clinical use still requires optimization. The pharmacology of mAbs/ADCs is complex and because ADCs are comprised of multiple components, individual agent characteristics and patient variables can affect their disposition. To further improve the clinical use and rational development of these agents, it is imperative to comprehend the complex mechanisms employed by antibody-based agents in traversing numerous biological barriers and how agent/patient factors affect tumor delivery, toxicities, efficacy, and ultimately, biodistribution. This review provides an updated summary of factors known to affect the disposition of mAbs/ADCs in development and in clinical use, as well as how these factors should be considered in the selection and design of preclinical studies of ADC agents in development.

Effects of antibody, drug and linker on the preclinical and clinical toxicities of antibody-drug conjugates

Antibody-drug conjugates (ADCs) represent a new class of cancer therapeutics. Their design involves a tumor-specific antibody, a linker and a cytotoxic payload. They were designed to allow specific targeting of highly potent cytotoxic agents to tumor cells whilst sparing normal cells. Frequent toxicities that may be driven by any of the components of an ADC have been reported. There are currently more than 50 ADCs in active clinical development, and a further ∼20 that have been discontinued. For this review, the reported toxicities of ADCs were analysed, and the mechanisms for their effects are explored in detail. Methods to reduce toxicities, including dosing strategies and drug design, are discussed. The toxicities reported for active and discontinued drugs are important to drive the rational design and improve the therapeutic index of ADCs of the future.

Ocular Adverse Events Associated with Antibody-Drug Conjugates in Human Clinical Trials

This article reviews ocular adverse events (AEs) reported in association with administration of antibody-drug conjugates (ADCs) in human clinical trials. References reporting ocular toxicity or AEs associated with ADCs were collected using online publication searches. Articles, abstracts, or citations were included if they cited ocular toxicities or vision-impairing AEs with a confirmed or suspected association with ADC administration. Twenty-two references were found citing ocular or vision-impairing AEs in association with ADC administration. All references reported use of ADCs in human clinical trials for treatment of various malignancies. The molecular target and cytotoxic agent varied depending on the ADC used. Ocular AEs affected a diversity of ocular tissues. The most commonly reported AEs involved the ocular surface and included blurred vision, dry eye, and corneal abnormalities (including microcystic corneal disease). Most ocular AEs were not severe (≤ grade 2) or dose limiting. Clinical outcomes were not consistently reported, but when specified, most AEs improved or resolved with cessation of treatment or with ameliorative therapy. A diverse range of ocular AEs are reported in association with administration of ADCs for the treatment of cancer. The toxicologic mechanism(s) and pathogenesis of such events are not well understood, but most are mild in severity and reversible. Drug development and medical professionals should be aware of the clinical features of these events to facilitate early recognition and intervention in the assessment of preclinical development programs and in human clinical trials.