Abstract Copper overload induced by specific ionophores can trigger cuproptosis, a newly defined form of regulated cell death that offers a novel strategy to target cancer. While this mechanism has been well characterized in cultured cells, its relevance in vivo and potential for therapeutic use remain unclear. The best-characterized ionophore, elesclomol (ES), had been previously tested in clinical trials with limited success; however, these studies were conducted without knowledge or consideration of its copper-binding mechanism or its ability to induce cuproptosis. Here, we define the biological and pharmacologic determinants of ES-induced cuproptosis in vivo, guiding the design of a more effective and tolerable ES analog. We first established that pre-bound ES (ES-Cu) is more potent and pharmacologically active than ES alone, maintaining on-target cuproptosis activity in culture and showing superior efficacy in a xenograft model. Although ES-Cu treatment produced marked tumor responses, complete regression was not achieved. To uncover mechanisms limiting response, we performed a genome-scale ORF overexpression screen and identified CYP11A1 and CYP27A1, mitochondrial partners of FDX1, as resistance factors. These findings indicate that FDX1 expression alone is not sufficient for sensitivity and that effective cuproptosis requires FDX1 activity uncoupled from CYP metabolism, a relationship that may also protect FDX1-high organs such as the adrenal gland and kidney from toxicity. To further overcome ES’s poor solubility and pharmacokinetic limitations, we synthesized a new copper ES analog, which exhibits improved solubility, enhanced antitumor efficacy, and reduced systemic toxicity. Multiplexed imaging confirmed intratumoral aggregation of lipoylated proteins consistent with on-target cuproptosis induction. Together, these findings uncover a previously unrecognized role of FDX1-CYP coupling in regulating cuproptosis sensitivity and define a path toward biomarker-guided development of copper ionophore-based cancer therapies. Citation Format: Piyush Mishra, Mainak Banerjee, Jian-Ren Lin, Shannon Coy, Jeffrey Hsiao, Jonah Lee, John Clohessey, Alexandre Detappe, Todd R. Golub, Loic Charbonniere, Sandro Santagata, Peter Tsvetkov. Selective induction of cuproptosis in vivo by a soluble Elesclomol analog [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 553.

Antibody-drug conjugates (ADCs) are often described as simple carriers that shuttle cytotoxic payloads to tumors. However, many backbones, exemplified by trastuzumab, are potent biologics whose pharmacology is eroded by conjugation. In this Perspective, we introduce the concept of an antibody exposure deficit. This represents the systematic reduction in both antibody mass and systemic exposure delivered by an ADC relative to its approved unconjugated monoclonal antibody. We show how payload type, drug-to-antibody ratio (DAR), linker and payload-linker hydrophobicity, and conjugation architecture together drive this deficit. Site-specific DAR 1 formats can mitigate this deficit, unlike higher-DAR constructs such as antibody-polymer conjugates, where the monoclonal antibody serves primarily as a carrier for effective payloads. This defines a landscape of ADC design to which fragment crystallizable (Fc) activity modulation adds further complexity. Altogether, these strategies span the continuum of possible ADC constructs.

Subcutaneous (SC) delivery has evolved beyond a convenience formulation to become an operational re-architecture of cancer care, with the potential to convert infusion-centered oncology into a distributed model without compromising exposure, safety, or product quality. Monoclonal antibodies have already completed this transition, establishing that the SC route delivers clinical equivalence while improving patient experience and system efficiency. Antibody-drug conjugates (ADCs) represent the next frontier, yet they remain almost exclusively intravenous (IV). This gap reflects not an incompatibility with SC delivery but rather the specific points at which ADCs stress the delivery stack: tissue poroelasticity and backpressure, extreme concentration requirements, non-Newtonian injectability, route-dependent linker degradation, and payload-driven interfacial instability. Here we argue that these barriers are tractable design targets amenable to advanced materials and integrated engineering. In this perspective, we outline the conceptual and technical approaches required to enable subcutaneous ADC delivery. We frame the SC compartment as a biophysical reactor governed by interstitial osmotic pressure, convection-dominated transport, and immune surveillance. We then outline two enabling pillars already in motion, namely transient matrix modulation (for example, hyaluronidase-mediated hyaluronic acid depolymerisation) and high-concentration formulation science (>100 mg mL-1), and show why ADCs require a fundamentally different playbook than antibodies alone. Finally, we position injectable, biodegradable, stimulus-responsive polymers and hydrogels as the enabling layer that can co-control injectability, depot protection, linker integrity, and release kinetics under SC constraints (pH ∼6.8, volume-limited compliance). SC ADC formulations are inevitable because they align clinical need, patient preference, and healthcare capacity. However, we propose that the systems most likely to succeed will be those that co-design molecule, formulation, material, process, and device as a single integrated platform.

Targeted protein degraders (TPDs), including proteolysis-targeting chimeras (PROTAC) and molecular glue degraders (MGD), are among the most promising small-molecule-based drug treatments in oncology. The May 2026 U.S. Food and Drug Administration (FDA) approval of vepdegestrant provides a regulatory milestone for heterobifunctional protein degradation and for PROTAC therapeutics. First-generation TPDs were developed for oral delivery; however, the intrinsic physicochemical properties of TPDs impose constraints on their oral bioavailability, systemic exposure, target-site accumulation, and therapeutic efficacy. As the field transitions toward a second wave of TPD development, nanoparticle-based targeted protein degraders (nano-TPD) are gaining momentum for broadening the therapeutic landscape of protein degradation. In this context, drug delivery systems offer opportunities to overcome key translational barriers by improving pharmacokinetics, tissue distribution, target site localization, cellular uptake, and therapeutic index. Here, we provide an overview of TPD discovery, from early laboratory to (pre-) clinical progress, discuss translational challenges, and suggest advanced drug delivery solutions to help realize the full potential of TPD therapies.

Abstract Antibody-drug conjugates (ADCs) deliver cytotoxic payloads to tumors with antibody selectivity, yet all approved ADCs are administered by intravenous (IV) infusion despite a strong patient and clinical preference for subcutaneous (SC) delivery. SC administration would reduce treatment burden, but many ADC payloads are vesicants that cause tissue necrosis upon local release, a liability amplified, not mitigated, by the dispersion-enhancing excipients used for SC antibody formulations. We developed an injectable diacetyl-L-tartaric anhydride-functionalized chitosan hydrogel (TACT) that addresses this conflict by confining ADCs within a protective SC depot. TACT is compatible with clinically approved ADC formulations without drug-product modification and provides drug-to-antibody ratio (DAR)-dependent release kinetics that support a quantitative relationship with in vivo absorption timing. In direct comparison, recombinant human hyaluronidase (rHuPH20) co-formulated with vesicant ADCs caused severe tissue necrosis, whereas TACT prevented macroscopic injury while preserving antitumor efficacy comparable to intravenous dosing. TUNEL staining of injection sites showed that TACT attenuated peri-depot apoptotic injury 3-fold relative to T-DM1 alone and 2-fold relative to rHuPH20 co-formulation. In non-human primates, SC TACT achieved 78% relative bioavailability for total trastuzumab, reduced peak circulating T-DM1 catabolite (free DM1) exposure 7.6-fold compared to IV administration and produced only transient, self-resolving cutaneous reactions. These results identify depot-mediated confinement as a viable alternative to excipient-mediated dispersion for SC delivery of vesicant ADCs, demonstrated here for trastuzumab-based conjugates across two approved ADC drug products (T-DM1 and T-DXd, with non-cleavable MCC and cleavable peptide linkers), with supporting validation in a custom cleavable monomethyl auristatin E (MMAE) series. Additional validation with enfortumab vedotin (EV), a Nectin-4-targeting MMAE ADC, supported the applicability of this strategy beyond trastuzumab-based conjugates.

The high cost of trastuzumab (Herceptin®) limits its accessibility for patients worldwide. Biosimilars, such as Tuznue® (HD201), represent a promising alternative to improve access to this essential therapy for HER2-positive breast cancer. This study aims to assess the similarity of Tuznue® with the reference product Herceptin® through comprehensive analytical and biofunctional evaluations, ensuring similar quality, safety, and efficacy profiles. Multiple analytical methods were performed to assess key quality attributes of Tuznue® and Herceptin®. Physicochemical properties, HER2 binding, anti-proliferative activity, antibody-dependent cellular cytotoxicity, complement dependent cytotoxicity, and Fc receptor binding were evaluated through various bioassays. Statistical analyses were conducted according to a risk-based tiered approach (Tiers 1–3) to demonstrate biosimilarity. The equivalence margin for critical quality attributes (Tier 1) was set at ±1.5 standard deviations from the reference product’s mean. Tuznue® showed highly comparable results to Herceptin® across all evaluated biofunctional assays. HER2 binding affinity, inhibition of cellular proliferation, and antibody-dependent cellular cytotoxicity activity were equivalent between Tuznue® and Herceptin®, with 90

Optimizing radioenhancer design for cancer therapy has been limited by inconsistent metal comparisons and unclear nanoscale mechanisms. High-Z nanoparticles are expected to enhance radiation effects through increased photoelectric absorption and secondary electron production, with the common assumption that radioenhancement efficacy increases uniformly with atomic number. However, this linear relationship may be oversimplified. Here, we introduce a versatile, supramolecular peptide platform enabling direct and standardized comparison of gadolinium (Gd), bismuth (Bi), and hafnium (Hf) as radioenhancers within a single, biologically targeted framework. This system is based on autoassembled peptide heterodimers (E3-K3) incorporating a flexible chelator (DOTAGA) and variable heavy-chain antibody (VHH) domains, ensuring uniform cellular uptake and precise tumor targeting. Systematic in vitro and in vivo analyses across HER2+ breast cancer and disseminated multiple myeloma models demonstrate that radioenhancement efficacy correlates with atomic number but not in a simple linear fashion, with physicochemical properties of each metal determining biological outcomes such as DNA damage induction, reactive oxygen species generation, and clonogenic survival reduction. Specifically, Gd- and Bi-loaded formulations significantly enhanced tumor control under external beam radiotherapy, with Bi exhibiting superior efficacy, while Gd-based constructs facilitated MRI-guided radioligand therapy. Our study elucidates fundamental physical mechanisms governing metal-dependent radioenhancement at the nanoscale but also establishes a broadly applicable theranostic approach with significant translational implications for personalized radiation oncology.

Developing and synthesizing nano-objects capable of enabling early targeted diagnosis and ensuring effective tumor treatment represents a significant challenge in the theranostic field. Among various nanoparticles (NPs), iron oxide nanoparticles (IONPs) have made significant contributions to advancing this field. However, a key challenge lies in achieving selective recognition of specific cell types. In oncology, the primary goal is to develop innovative strategies to enhance NP uptake by tumors, primarily through active targeting. This involves adding targeting ligands (TL) to the NP surface to facilitate tumor accumulation and increase retention within the tumor microenvironment. Despite biofunctionalization strategies, overall tumor uptake remains modest at only 5-7% of the injected dose per gram. In this work, we demonstrate the effect of spacing between the NPs and the TL to improve their availability and thus the tumor uptake of the complex. This proof-of-concept study targets the epidermal growth factor receptor (EGFR) using a peptide as a targeting ligand. Specifically, we characterized the PEG-peptide coupled to dendronized IONPs, including the density of grafted TL. These nano-objects underwent in vitro evaluation to assess their ability to specifically target and be internalized by tumor cells. Therapeutically, compared to non-functionalized NPs, the presence of the TL with a PEG linker enhanced targeting efficacy and increased internalization, leading to improved photothermal efficacy.

The development of injectable hydrogels that respond to physiological stimuli represents a promising strategy for a range of biomedical applications, although the precise tuning of gelation kinetics, mechanical stability, and biocompatibility remains a significant challenge. This study presents a pH- and osmolarity-responsive injectable hydrogel, formulated from a combination of chitosan and chitosan functionalized with a macrocyclic polycarboxylate. The functionalization of chitosan significantly modifies the electrostatic charges along the polymer backbone, enabling fast gelation under physiological conditions. The gelation process is driven by pH neutralization and osmolarity increase, where electrostatic interactions between the zwitterionic chitosan and unmodified chitosan generate a dynamic, entangled network strengthened by both electrostatic crosslinking and hydrophobic interactions. Rheological and structural analyses reveal the possibility of fine-tuning the gelation kinetics and mechanical properties by altering the ratio of zwitterionic chitosan to conventional chitosan in the formulation. Here, the optimized 67:33 % ratio achieved favorable compromise between rapid gelation and stability in physiological media. Different microscopy experiments, including conventional scanning electronic microscopy and live imaging, have confirmed the porous architecture of the hydrogels. In vivo experiments confirmed the injectability, biocompatibility, and biodegradability of the hydrogels, with gradual degradation observed by magnetic resonance imaging and fluorescence imaging over time in healthy mice after subcutaneous administration. Additionally, preclinical safety assessments in rabbits demonstrated good local tolerance to both single and repeated subcutaneous injections, with no systemic toxicity observed. These findings support the potential for broad biomedical future applications, including drug delivery, wound healing, local metal uptake and tissue regeneration.

Photodynamic therapy (PDT) is a promising strategy for head and neck squamous cell carcinoma (HNSCC), but the immune consequences of tumor cell death remain incompletely understood. We compared two ruthenium(II) polypyridine photosensitizers (PSs) in HNSCC models and found that both were potently phototoxic (nanomolar IC50s), triggered diverse cell death pathways (including autophagy and ferroptosis), and promoted hallmark danger signals of immunogenic cell death (ICD). Strikingly, only one PS induced apoptosis and strong endoplasmic reticulum (ER) stress, yet paradoxically led to immune tolerance in vivo. Conversely, the PS that did not induce apoptotic cell death with milder stress responses resulted in a better antitumor immunity in vivo. These unexpected findings challenge the prevailing view that PDT-triggered apoptosis and ER stress are essential for ICD. Our study underscores the complexity of PDT-induced cell death balance and immunogenic signals and highlights the need to redefine ICD-inducing criteria for the rational design of next-generation PSs.

In oncology, the advent of monoclonal antibody (mAb) therapeutics represents a breakthrough in various cancer diseases. However, these therapies often necessitate iterative hospital visits for intravenous infusion that alter patient quality of life and contribute to the chronic saturation of hospitals. Subcutaneous formulations of mAbs offer a promising alternative facilitating faster administration compared with traditional intravenous methods, while still maintaining the same dosing schedule and providing time-saving advantages. Here, an injectable mAb delivery platform using α-cyclodextrin (αCD)-reinforced polymer-nanoparticle hydrogels to perform subcutaneous mAb depots and delay their release is developed. By leveraging mAb-polymer electrostatic complexation, hyaluronic acid- and alginate-based injectable drug depots are formulated by simply mixing components that are generally regarded as safe. Trastuzumab is included as a clinically relevant therapeutic antibody. These formulations delayed mAb release both in vitro and in vivo mice models, with a similar pharmacokinetic performance to the clinically approved Herceptin SC (Roche) formulation composed of trastuzumab with recombinant human hyaluronidase (rHuPH20).

Targeting the immune system with nanoparticles (NPs) to deliver immunomodulatory molecules emerged as a solution to address intra-tumoral immunosuppression and enhance therapeutic response. While the potential of nanoimmunotherapies in reactivating immune cells has been evaluated in several preclinical studies, the impact of drug-free nanomaterials on the immune system remains unknown. Here, the molecular and functional response of human NK cells and pan T cells to a selection of five NPs that are commonly used in biomedical applications are characterized. After a pre-screen to evaluate the toxicity of these nanomaterials on immune cells, ultrasmall silica-based gadolinium (Si-Gd) NPs and poly(lactic-co-glycolic acid) (PLGA) NPs are selected for further investigation. Bulk RNA-sequencing and flow cytometry analysis showcase that PLGA NPs trigger a transcriptional priming toward activation in NK and pan T cells. While PLGA NPs improved NK cells anti-tumoral functions in a cytokines-deprived environment, Si-Gd NPs significantly impaired T cells activation as well as functional responses to a polyclonal antigenic stimulation. Altogether, PLGA NPs are identified as an attractive strategy for reactivating the immune system of cancer patients.

Dynamic precision medicine enables preemptive cancer therapy switching in response to emerging resistance. Owing to their modular architecture and tumour-targeting capabilities, nanomedicines are theoretically well-suited to support such adaptive strategies. However, the questions remain whether modular design can consistently yield durable therapeutic responses, and whether the temporal constraints imposed by tumour evolution allow the practical implementation of dynamic nanomedicine.

Nanoparticle (NP) surface functionalization with proteins, including monoclonal antibodies (mAbs), mAb fragments, and various peptides, has emerged as a promising strategy to enhance tumor targeting specificity and immune cell interaction. However, these methods often rely on complex chemistry and suffer from batch-dependent outcomes, primarily due to limited control over the protein orientation and quantity on NP surfaces. To address these challenges, a novel approach based on the supramolecular assembly of two peptides is presented to create a heterotetramer displaying VHHs on NP surfaces. This approach effectively targets both tumor-associated antigens (TAAs) and immune cell-associated antigens. In vitro experiments showcase its versatility, as various NP types are biofunctionalized, including liposomes, PLGA NPs, and ultrasmall silica-based NPs, and the VHHs targeting of known TAAs (HER2 for breast cancer, CD38 for multiple myeloma), and an immune cell antigen (NKG2D for natural killer (NK) cells) is evaluated. In in vivo studies using a HER2+ breast cancer mouse model, the approach demonstrates enhanced tumor uptake, retention, and penetration compared to the behavior of nontargeted analogs, affirming its potential for diverse applications.

Bispecific antibodies (bsAbs) have recently emerged as a promising platform for the treatment of several conditions, most importantly cancer. Based on the combination of two different antigen-binding motifs in a single macromolecule; bsAbs can either display the combined characteristics of their parent antibodies, or new therapeutic features, inaccessible by the sole combination of two distinct antibodies. While bsAbs are traditionally produced by molecular biology techniques, the chemical development of bsAbs holds great promises and strategies have just begun to surface. In this context, we took advantage of a chemical strategy based on the use of the Ugi reaction for the site-selective conjugation of whole antibodies and coupled the resulting conjugates in a bioorthogonal manner with Fab fragments, derived from various antibodies. We thus managed to produce five different bsAbs with 2 : 1 valency, with yields ranging from 20 % to 48 %, and showed that the affinity of the parent antibody was preserved in all bsAbs. We further demonstrated the interest of our strategy by producing two other bsAbs behaving as cytotoxic T cell engagers with IC50 values in the picomolar range in vitro. This work reports the chemical synthesis of bispecific antibodies using two site-selective conjugation reactions. Seven constructs with 2 : 1 valency were produced, including two cytotoxic T-cell engagers with IC50 values in the picomolar range in vitro. image

Antibody-drug conjugates (ADCs) are a well-established class of therapeutics primarily used in oncology to selectively deliver highly cytotoxic agents into cancer cells. While ADCs should theoretically spare healthy tissues and diminish side effects in patients, off-target toxicity is still observed, all the more serious, as the drugs are extremely potent. In the quest toward safer payloads, we used the conventional chemotherapeutic drug vincristine to develop antibody-vincristine conjugates. Vincristine was N-alkylated with a cleavable linker and the resulting linker-payload conjugated to free cysteines of antibodies. We show that trastuzumab-vincristine conjugates display subnanomolar potency in vitro on HER2-positive cells, 2 orders of magnitude lower than free vincristine and comparable with marketed ADC. In vivo, trastuzumab-vincristine conjugates led to remarkable efficacy when compared to two standards of care, with complete tumor regression just 9 days after single administration. This highlights the untapped potential of the chemotherapeutic arsenal toward the development of novel ADC.

The chemical bioconjugation of proteins has seen tremendous applications in the past decades, with the booming of antibody-drug conjugates and their use in oncology. While genetic engineering has permitted to produce bespoke proteins featuring key (un-)natural amino acid residues poised for site-selective modifications, the conjugation of native proteins is riddled with selectivity issues. Chemoselective strategies are plentiful and enable the precise modification of virtually any residue with a reactive side-chain; site-selective methods are less common and usually most effective on small and medium-sized proteins. In this context, we studied the application of the Ugi multicomponent reaction for the site-selective conjugation of amine and carboxylate groups on proteins, and antibodies in particular. Through an in-depth mechanistic methodology work supported by peptide mapping studies, we managed to develop a set of conditions allowing the highly selective modification of antibodies bearing N-terminal glutamate and aspartate residues. We demonstrated that this strategy did not alter their affinity toward their target antigen and produced an antibody-drug conjugate with subnanomolar potency. Excitingly, we showed that the high site selectivity of our strategy was maintained on other protein formats, especially on anticalins, for which directed mutagenesis helped to highlight the key importance of a single lysine residue. A thorough methodology work on the Ugi multicomponent reaction applied to the conjugation of native proteins highlighted key reaction conditions and reagents for the development of a highly site-selective procedure.image