Controlled coupling of an ultrapotent auristatin warhead to cetuximab yields a next-generation antibody-drug conjugate for EGFR-targeted therapy of KRAS mutant pancreatic cancer

Expression of fibroblast growth factor receptor 1 correlates inversely with the efficacy of single-agent fibroblast growth factor receptor-specific inhibitors in pancreatic cancer

BACKGROUND AND PURPOSE

Elevated fibroblast growth factor receptor (FGFR) activity correlates with pancreatic adenocarcinoma (PDAC) progression and poor prognosis. However, its potential as a therapeutic target remains largely unexplored.

EXPERIMENTAL APPROACH

The mechanisms of action and therapeutic effects of selective pan-FGFR inhibitors (pan-FGFRi) were explored using in vitro and in vivo PDAC models ranging from gemcitabine-sensitive to highly gemcitabine-resistant (GemR). Gain-/loss-of-function investigations were employed to define the role of individual FGFRs in cell proliferation, migration, and treatment response and resistance.

RESULTS

The pan-FGFRi NVP-BGJ398 significantly inhibited cell proliferation, migration, and invasion, and downregulated key cell survival- and invasiveness markers in multiple PDAC cell lines. Gemcitabine is a standard-of-care for PDAC, but development of resistance to gemcitabine (GemR) compromises its efficacy. Acquired GemR was modelled experimentally by developing highly GemR cells using escalating gemcitabine exposure in vitro and in vivo. FGFRi treatment inhibited GemR cell proliferation, migration, GemR marker expression, and tumour progression. FGFR2 or FGFR3 loss-of-function by shRNA knockdown failed to decrease cell growth, whereas FGFR1 knockdown was lethal. FGFR1 overexpression promoted cell migration more than proliferation, and reduced FGFRi-mediated inhibition of proliferation and migration. Single-agent FGFRi suppressed the viability and growth of multiple patient-derived xenografts inversely with respect to FGFR1 expression, underscoring the influence of FGFR1-dependent tumour responses to FGFRi. Importantly, secondary data analysis showed that PDAC tumours expressed FGFR1 at lower levels than in normal pancreas tissue.

CONCLUSIONS AND IMPLICATIONS

Single-agent FGFR inhibitors mediate selective, molecularly-targeted suppression of PDAC proliferation, and their effects are greatest in PDAC tumours expressing low-to-moderate levels of FGFR1.

Integrated PK/PD Modeling Relates Smoothened Inhibitor Biomarkers to The Heterogeneous Intratumor Disposition of Cetuximab in Pancreatic Cancer Tumor Models

Therapeutic antibodies have shown little efficacy in the treatment of pancreatic ductal adenocarcinomas (PDAC). Tumor desmoplasia, hypovascularity, and poor perfusion result in insufficient tumor cell exposure, contributing to treatment failure. Smoothened inhibitors of hedgehog signaling (sHHi) increase PDAC tumor permeability, perfusion, and drug delivery, and provide a tool to develop a quantitative, mechanistic understanding as to how the temporal dynamics of tumor priming can impact intratumor distribution of monoclonal antibodies (mAb). A linked pharmacokinetic (PK)/pharmacodynamic (PD) model was developed to integrate the plasma and tumor PK of a sHHi priming agent with its effects upon downstream stromal biomarkers Gli1, hyaluronic acid, and interstitial fluid pressure in PDAC patient-derived xenograft (PDX) tumors. In parallel, in situ tumor concentrations of cetuximab (CTX: anti-epidermal growth factor receptor; EGFR) were quantified as a marker for tumor delivery of mAb or antibody-drug conjugates. A minimal, physiologically-based pharmacokinetic (mPBPK) model was constructed to link sHHi effects upon mechanistic effectors of tumor barrier compromise with the intratumor distribution of CTX, and CTX occupancy of EGFR in tumors. Integration of the mPBPK model of mAb deposition and intratumor distribution with the PK/PD model of tumor responses to priming not only identified physiological parameters that are critical for tumor antibody distribution, but also provides insight into dosing regimens that could achieve maximal tumor disposition of therapeutic antibodies under conditions of transient PDAC tumor permeability barrier compromise that mechanistically-diverse tumor priming strategies may achieve.

Advances in targeted therapy for pancreatic cancer

Pancreatic cancer (PC) represents a group of malignant tumours originating from pancreatic duct epithelial cells and acinar cells, and the 5-year survival rate of PC patients is only approximately 12%. Molecular targeted drugs are specific drugs designed to target and block oncogenes, and they have become promising strategies for the treatment of PC. Compared to traditional chemotherapy drugs, molecular targeted drugs have greater targeting precision, and they have significant therapeutic effects and minimal side effects. This article reviews several molecular targeted drugs that are currently in the experimental stage for the treatment of PC; these include antibody-drug conjugates (ADCs), aptamer-drug conjugates (ApDCs) and peptide-drug conjugates (PDCs). ADCs can specifically recognize cell surface antigens and reduce systemic exposure and toxicity of chemotherapy drugs. By delivering nucleic acid drugs to target cells, the targeting RNA of ApDCs can inhibit the expression or translation of mutated genes, thereby inhibiting tumour development. Moreover, PDCs can effectively penetrate tumour cells, and the peptide groups in PDCs preferentially target tumour cells with minimal side effects. In the targeted therapy of PC, molecular targeted drugs have very broad prospects, which provides new hope for the clinical treatment of PC patients and is worth further research.

Antibody drug conjugates: hitting the mark in pancreatic cancer?

Pancreatic cancer is one of the most common causes of cancer-related death, and the 5-year survival rate has only improved marginally over the last decade. Late detection of the disease means that in most cases the disease has advanced locally and/or metastasized, and curative surgery is not possible. Chemotherapy is still the first-line treatment however, this has only had a modest impact in improving survival, with associated toxicities. Therefore, there is an urgent need for targeted approaches to better treat pancreatic cancer, while minimizing treatment-induced side-effects. Antibody drug conjugates (ADCs) are one treatment option that could fill this gap. Here, a monoclonal antibody is used to deliver extremely potent drugs directly to the tumor site to improve on-target killing while reducing off-target toxicity. In this paper, we review the current literature for ADC targets that have been examined in vivo for treating pancreatic cancer, summarize current and on-going clinical trials using ADCs to treat pancreatic cancer and discuss potential strategies to improve their therapeutic window.

Advances and Prospects in the Treatment of Pancreatic Cancer

Pancreatic cancer is a highly malignant and incurable disease, characterized by its aggressive nature and high fatality rate. The most common type is pancreatic ductal adenocarcinoma (PDAC), which has poor prognosis and high mortality rate. Current treatments for pancreatic cancer mainly encompass surgery, chemotherapy, radiotherapy, targeted therapy, and combination regimens. However, despite efforts to improve prognosis, and the 5-year survival rate for pancreatic cancer remains very low. Therefore, it's urgent to explore novel therapeutic approaches. With the rapid development of therapeutic strategies in recent years, new ideas have been provided for treating pancreatic cancer. This review expositions the advancements in nano drug delivery system, molecular targeted drugs, and photo-thermal treatment combined with nanotechnology for pancreatic cancer. It comprehensively analyzes the prospects of combined drug delivery strategies for treating pancreatic cancer, aiming at a deeper understanding of the existing drugs and therapeutic approaches, promoting the development of new therapeutic drugs, and attempting to enhance the therapeutic effect for patients with this disease.

Enabling the formation of native mAb, Fab' and Fc-conjugates using a bis-disulfide bridging reagent to achieve tunable payload-to-antibody ratios (PARs)

Either as full IgGs or as fragments (Fabs, Fc, etc.), antibodies have received tremendous attention in the development of new therapeutics such as antibody-drug conjugates (ADCs). The production of ADCs involves the grafting of active payloads onto an antibody, which is generally enabled by the site-selective modification of native or engineered antibodies via chemical or enzymatic methods. Whatever method is employed, controlling the payload-antibody ratio (PAR) is a challenge in terms of multiple aspects including: (i) obtaining homogeneous protein conjugates; (ii) obtaining unusual PARs (PAR is rarely other than 2, 4 or 8); (iii) using a single method to access a range of different PARs; (iv) applicability to various antibody formats; and (v) flexibility for the production of heterofunctional antibody-conjugates (e.g. attachment of multiple types of payloads). In this article, we report a single pyridazinedione-based trifunctional dual bridging linker that enables, in a two-step procedure (re-bridging/click), the generation of either mAb-, Fab'-, or Fc-conjugates from native mAb, (Fab')2 or Fc formats, respectively. Fc and (Fab')2 formats were generated via enzymatic digestion of native mAbs. Whilst the same reduction and re-bridging protocols were applied to all three of the protein formats, the subsequent click reaction(s) employed to graft payload(s) drove the generation of a range of PARs, including heterofunctional PARs. As such, exploiting click reactivity and/or orthogonality afforded mAb-conjugates with PARs of 6, 4, 2 or 4 + 2, and Fab'- and Fc-conjugates with a PAR of 3, 2, 1 or 2 + 1 on-demand. We believe that the homogeneity, novelty and variety in accessible PARs, as well as the applicability to various antibody-conjugate formats enabled by our non-recombinant method could be a suitable tool for antibody-drug conjugates optimisation (optimal PAR value, optimal payloads combination) and boost the development of new antibody therapeutics (Fab'- and Fc-conjugates).

Long-circulating magnetoliposomes as surrogates for assessing pancreatic tumour permeability and nanoparticle deposition

Nanocarriers are candidates for cancer chemotherapy delivery, with growing numbers of clinically-approved nano-liposomal formulations such as Doxil® and Onivyde® (liposomal doxorubicin and irinotecan) providing proof-of-concept. However, their complex biodistribution and the varying susceptibility of individual patient tumours to nanoparticle deposition remains a clinical challenge. Here we describe the preparation, characterisation, and biological evaluation of phospholipidic structures containing solid magnetic cores (SMLs) as an MRI-trackable surrogate that could aid in the clinical development and deployment of nano-liposomal formulations. Through the sequential assembly of size-defined iron oxide nanoparticle clusters with a stabilizing anionic phospholipid inner monolayer and an outer monolayer of independently-selectable composition, SMLs can mimic physiologically a wide range of nano-liposomal carrier compositions. In patient-derived xenograft models of pancreatic adenocarcinoma, similar tumour deposition of SML and their nano-liposomal counterparts of identical bilayer composition was observed in vivo, both at the tissue level (fluorescence intensities of 1.5 × 108 ± 1.8 × 107 and 1.2 × 108 ± 6.3 × 107, respectively; ns, 99% confidence interval) and non-invasively using MR imaging. We observed superior capabilities of SML as a surrogate for nano-liposomal formulations as compared to other clinically-approved iron oxide nano-formulations (ferumoxytol). In combination with diagnostic and therapeutic imaging tools, SMLs have high clinical translational potential to predict nano-liposomal drug carrier deposition and could assist in stratifying patients into treatment regimens that promote optimal tumour deposition of nanoparticulate chemotherapy carriers. STATEMENT OF SIGNIFICANCE: Solid magnetoliposomes (SMLs) with compositions resembling that of FDA-approved agents such as Doxil® and Onivyde® offer potential application as non-invasive MRI stratification agents to assess extent of tumour deposition of nano-liposomal therapeutics prior to administration. In animals with pancreatic adenocarcinoma (PDAC), SML-PEG exhibited (i) tumour deposition comparable to liposomes of the same composition; (ii) extended circulation times, with continued tumour deposition up to 24 hours post-injection; and (iii) MRI capabilities to determine tumour deposition up to 1 week post-injection, and confirmation of patient-to-patient variation in nanoparticulate deposition in tumours. Hence SMLs with controlled formulation are a step towards non-invasive MRI stratification approaches for patients, enabled by evaluation of the extent of deposition in tumours prior to administration of nano-liposomal therapeutics.

Targeting the 'Undruggable' Driver Protein, KRAS, in Epithelial Cancers: Current Perspective

This review summarizes recent development in synthetic drugs and biologics targeting intracellular driver genes in epithelial cancers, focusing on KRAS, and provides a current perspective and potential leads for the field. Compared to biologics, small molecule inhibitors (SMIs) readily penetrate cells, thus being able to target intracellular proteins. However, SMIs frequently suffer from pleiotropic effects, off-target cytotoxicity and invariably elicit resistance. In contrast, biologics are much larger molecules limited by cellular entry, but if this is surmounted, they may have more specific effects and less therapy-induced resistance. Exciting breakthroughs in the past two years include engineering of non-covalent KRAS G12D-specific inhibitor, probody bispecific antibodies, drug-peptide conjugate as MHC-restricted neoantigen to prompt immune response by T-cells, and success in the adoptive cell therapy front in both breast and pancreatic cancers.

The use of bromopyridazinedione derivatives in chemical biology

Tools that facilitate the chemical modification of peptides and proteins are gaining an increasing amount of interest across many avenues of chemical biology as they enable a plethora of therapeutic, imaging and diagnostic applications. Cysteine residues and disulfide bonds have been highlighted as appealing targets for modification due to the highly homogenous nature of the products that can be formed through their site-selective modification. Amongst the reagents available for the site-selective modification of cysteine(s)/disulfide(s), pyridazinediones (PDs) have played a particularly important and enabling role. In this review, we outline the unique chemical features that make PDs especially well-suited to cysteine/disulfide modification on a wide variety of proteins and peptides, as well as provide context as to the problems solved (and applications enabled) by this technology.

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.

CD147 Monoclonal Antibody Targeted Reduction-Responsive Camptothecin Polyphosphoester Nanomedicine for Drug Delivery in Hepatocellular Carcinoma Cells

In the treatment of tumor-targeted small-molecule anti-cancer drugs, antibody-mediated therapies, especially for antibody-drug conjugates (ADCs), have revealed great latent force. However, the therapeutic drugs provided by ADCs possess limitation. Considering that the combination of antibodies and nano-drugs can broaden their applicability in the field of tumor treatment, herein, we developed an antibody conjugated polymeric prodrug nanoparticles SAE-PEG-b-PBYP-ss-CPT for targeted camptothecin (CPT) delivery to liver tumor cells. The diblock copolymer was composed of PEG and biodegradable polyphosphoester (PBYP) containing alkynyl groups in the side chain. A derivative of CPT (CPT-ss-N₃) was bonded to the PBYP via "click" reaction. The diethyl squarate (SAE) in the terminal of PEG chain was used as a functional group to bond with CD147 monoclonal antibody (CD147 mAb). The particle size and size distribution of the both nanoparticles, with antibody binding (namely CD147-CPT NPs) and without antibody (abbreviated as CPT-loaded NPs), were measured by dynamic light scattering (DLS). The morphologies of both two kinds of nanoparticles were observed by transmission electron microscope (TEM). The results of X-ray photoelectron spectroscopy (XPS) showed that CD147 mAb had been coupled to the surface of CPT-loaded NPs. Endocytosis test indicated that CD147-CPT NPs had higher uptake rate and accumulation in HepG2 cells than those of CPT-loaded NPs without antibodies, due to CD147 mAb can specifically bind to CD147 protein overexpressed in HepG2 cells. We establish a method to bond monoclonal antibodies to anti-cancer polymeric prodrugs, and endow biodegradable polymeric prodrugs with precise targeting functions to liver cancer cells.

Anti-tumour drugs of marine origin currently at various stages of clinical trials (review)

Oncological diseases for a long time have remained one of the most significant health problems of modern society, which causes great losses in its labour and vital potential. Contemporary oncology still faces unsolved issues as insufficient efficacy of treatment of progressing and metastatic cancer, chemoresistance, and side-effects of the traditional therapy which lead to disabilities among or death of a high number of patients. Development of new anti-tumour preparations with a broad range of pharmaceutical properties and low toxicity is becoming increasingly relevant every year. The objective of the study was to provide a review of the recent data about anti-tumour preparations of marine origin currently being at various phases of clinical trials in order to present the biological value of marine organisms – producers of cytotoxic compounds, and the perspectives of their use in modern biomedical technologies. Unlike the synthetic oncological preparations, natural compounds are safer, have broader range of cytotoxic activity, can inhibit the processes of tumour development and metastasis, and at the same time have effects on several etiopathogenic links of carcinogenesis. Currently, practical oncology uses 12 anti-tumour preparations of marine origin (Fludarabine, Cytarabine, Midostaurin, Nelarabine, Eribulin mesylate, Brentuximab vedotin, Trabectedin, Plitidepsin, Enfortumab vedotin, Polatuzumab vedotin, Belantamab mafodotin, Lurbinectedin), 27 substances are at different stages of clinical trials. Contemporary approaches to the treatment of oncological diseases are based on targeted methods such as immune and genetic therapies, antibody-drug conjugates, nanoparticles of biopolymers, and metals. All those methods employ bioactive compounds of marine origin. Numerous literature data from recent years indicate heightened attention to the marine pharmacology and the high potential of marine organisms for the biomedicinal and pharmaceutic industries.