Human intratumoral therapy: Linking drug properties and tumor transport of drugs in clinical trials

Engineered bacteria breach tumor physical barriers to enhance radio-immunotherapy

Radiotherapy widely applied for local tumor therapy in clinic has been recently reinvigorated by the discovery that radiotherapy could activate systematic antitumor immune response. Nonetheless, the endogenous radio-immune effect is still incapable of radical tumor elimination due to the prevention of immune cell infiltration by the physical barrier in tumor microenvironment (TME). Herein, an engineered Salmonella secreting nattokinase (VNPNKase) is developed to synergistically modulate the physical and immune characteristics of TME to enhance radio-immunotherapy of colon tumors. The facultative anaerobic VNPNKase enriches at the tumor site after systemic administration, continuously secreting abundant NKase to degrade fibronectin, dredge the extracellular matrix (ECM), and inactivate cancer-associated fibroblasts (CAFs). The VNPNKase- dredged TME facilitates the infiltration of CD103+ dendritic cells (DCs) and thus the presentation of tumor-associated antigens (TAAs) after radiotherapy, recruiting sufficient CD8+ T lymphocytes to specifically eradicate localized tumors. Moreover, the pre-treatment of VNPNKase before radiotherapy amplifies the abscopal effect and achieves a long-term immune memory effect, preventing the metastasis and recurrence of tumors. Our research suggests that this strategy using engineered bacteria to breach tumor physical barrier for promoting immune cell infiltration possesses great promise as a translational strategy to enhance the effectiveness of radio-immunotherapy in treating solid tumors.

Targeting tumor-associated macrophages with mannosylated nanotherapeutics delivering TLR7/8 agonist enhances cancer immunotherapy

Tumor-associated macrophages (TAMs) constitute 50-80% of stromal cells in most solid tumors with high mortality and poor prognosis. Tumor-infiltrating dendritic cells (TIDCs) and TAMs are key components mediating immune responses within the tumor microenvironment (TME). Considering their refractory properties, simultaneous remodeling of TAMs and TIDCs is a potential strategy of boosting tumor immunity and restoring immunosurveillance. In this study, mannose-decorated poly(lactic-co-glycolic acid) nanoparticles loading with R848 (Man-pD-PLGA-NP@R848) were prepared to dually target TAMs and TIDCs for efficient tumor immunotherapy. The three-dimensional (3D) cell culture model can simulate tumor growth as influenced by the TME and its 3D structural arrangement. Consequently, cancer spheroids enriched with tumor-associated macrophages (TAMs) were fabricated to assess the therapeutic effectiveness of Man-pD-PLGA-NP@R848. In the TME, Man-pD-PLGA-NP@R848 targeted both TAMs and TIDCs in a mannose receptor-mediated manner. Subsequently, Man-pD-PLGA-NP@R848 released R848 to activate Toll-like receptors 7 and 8, following dual-reprograming of TIDCs and TAMs. Man-pD-PLGA-NP@R848 could uniquely reprogram TAMs into antitumoral phenotypes, decrease angiogenesis, reprogram the immunosuppressive TME from "cold tumor" into "hot tumor", with high CD4+ and CD8+ T cell infiltration, and consequently hinder tumor development in B16F10 tumor-bearing mice. Therefore, dual-reprograming of TIDCs and TAMs with the Man-pD-PLGA-NP@R848 is a promising cancer immunotherapy strategy.

An Immunomodulator-Boosted Lactococcus Lactis Platform For Enhanced In Situ Tumor Vaccine

In situ vaccination is an attractive type of cancer immunotherapy, and methods of persistently dispersing immune agonists throughout the entire tumor are crucial for maximizing their therapeutic efficacy. Based on the probiotics usually used for dietary supplements, an immunomodulator-boosted Lactococcus lactis (IBL) strategy is developed to enhance the effectiveness of in situ vaccination with the immunomodulators. The intratumoral delivery of OX40 agonist and resiquimod-modified Lactococcus lactis (OR@Lac) facilitates local retention and persistent dispersion of immunomodulators, and dramatically modulates the key components of anti-tumor immune response. This novel vaccine activated dendritic cells and cytotoxic T lymphocytes in the tumor and tumor-draining lymph nodes, and ultimately significantly inhibited tumor growth and prolonged the survival rate of tumor-bearing mice. The combination of OR@Lac and ibrutinib, a myeloid-derived suppressor cell inhibitor, significantly alleviated or even completely inhibited tumor growth in tumor-bearing mice. In conclusion, IBL is a promising in situ tumor vaccine approach for clinical application and provides an inspiration for the delivery of other drugs.

A platform technology for ultra-long acting intratumoral therapy

Intratumoral (IT) therapy is a powerful method of controlling tumor growth, but a major unsolved problem is the rapidity that injected drugs exit tumors, limiting on-target exposure and efficacy. We have developed a generic long acting IT delivery system in which a drug is covalently tethered to hydrogel microspheres (MS) by a cleavable linker; upon injection the conjugate forms a depot that slowly releases the drug and "bathes" the tumor for long periods. We established technology to measure tissue pharmacokinetics and studied MSs attached to SN-38, a topoisomerase 1 inhibitor. When MS ~ SN-38 was injected locally, tissues showed high levels of SN-38 with a long half-life of ~ 1 week. IT MS ~ SN-38 was ~ tenfold more efficacious as an anti-tumor agent than systemic SN-38. We also propose and provide an example that long-acting IT therapy might enable safe use of two drugs with overlapping toxicities. Here, long-acting IT MS ~ SN-38 is delivered with concurrent systemic PARP inhibitor. The tumor is exposed to both drugs whereas other tissues are exposed only to the systemic drug; synergistic anti-tumor activity supported the validity of this approach. We propose use of this approach to increase efficacy and reduce toxicities of combinations of immune checkpoint inhibitors such as αCTLA-4 and αPD-1.

Intratumoral therapies in head and neck squamous cell carcinoma: A systematic review and future perspectives

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) presents an ideal scenario for intratumoral therapies (IT), due to its local recurrence pattern and frequent superficial extension. IT therapies aim to effect tumor regression by directly injecting antineoplastic agents into lesions. However, there is a lack of updated evidence regarding IT therapies in HNSCC.

PATIENTS AND METHODS

A systematic literature search (CRD42023462291) was conducted using WebOfScience, ClinicalTrials.gov, and conference abstracts from ESMO and ASCO, identifying for IT clinical trials in patients with HNSCC, from database creation to September 12th, 2023. Efficacy as well as safety (grade ≥ 3 treatment-related adverse events[trAEs]) were reported.

RESULTS

After evaluation of 1180 articles identified by the systematic search, 31 studies treating 948 patients were included. IT injectables were categorized as chemotherapies with or without electroporation (k = 4, N = 268), oncolytic viruses, plasmids, and bacteria-based (k = 16, N = 446), immunotherapies and EGFR-based therapies (k = 5, N = 160), radioenhancer particles (k = 2, N = 68), and calcium electroporation (k = 1, n = 6). EGFR-antisense plasmids, NBTXR3 radioenhancer and immune innate agonists show best overall response rates, at 83 %, 81 % and 44 % respectively. Eleven (35 %) studies added systemic therapy or radiotherapy to the IT injections. No study used predictive biomarkers to guide patient selection. 97 % studies were phase I-II. Safety-wise, electroporation and epinephrine-based injectable trials had significant local symptoms such as necrosis, fistula formation and post-injection dysphagia. Treatment-related tumor haemorrhages of various grades were described in several trials. Grade ≥ 3 trAEs attributable to the other therapies mainly comprised general symptoms such as fatigue. There were 3 injectable-related deaths across the systematic review.

CONCLUSION

This is the first review to summarize all available evidence of IT in HNSCC. As of today, IT therapies lack sufficient evidence to recommend their use in clinical practice. Continuing research on potential molecules, patient selection, safe administration of injections and controlled randomized trials are needed to assess their added benefit.

Nucleic acid-based drugs for patients with solid tumours

The treatment of patients with advanced-stage solid tumours typically involves a multimodality approach (including surgery, chemotherapy, radiotherapy, targeted therapy and/or immunotherapy), which is often ultimately ineffective. Nucleic acid-based drugs, either as monotherapies or in combination with standard-of-care therapies, are rapidly emerging as novel treatments capable of generating responses in otherwise refractory tumours. These therapies include those using viral vectors (also referred to as gene therapies), several of which have now been approved by regulatory agencies, and nanoparticles containing mRNAs and a range of other nucleotides. In this Review, we describe the development and clinical activity of viral and non-viral nucleic acid-based treatments, including their mechanisms of action, tolerability and available efficacy data from patients with solid tumours. We also describe the effects of the tumour microenvironment on drug delivery for both systemically administered and locally administered agents. Finally, we discuss important trends resulting from ongoing clinical trials and preclinical testing, and manufacturing and/or stability considerations that are expected to underpin the next generation of nucleic acid agents for patients with solid tumours.

Efficient chemo-immunotherapy leveraging minimalist electrostatic complex nanoparticle as "in situ" vaccine integrated tumor ICD and immunoagonist

INTRODUCTION

Immunotherapy has unprecedentedly opened up a series of neoteric tactics for cancer treatment. As a burgeoning approach, chemo-immunotherapy has innovatively expanded the accomplishments of conventional chemotherapeutic agents for cancer governing.

OBJECTIVES

An efficacious chemo-immunotherapy leveraging minimalist electrostatic complex nanoparticle (NP) integrated tumor immunogenic cell death (ICD) and immunoagonist was developed as a watertight "in situ" vaccine for cancer therapy through convenient intratumoral administration with minimized systemic toxicity.

METHODS

Chemical-modified pH-sensitive cis-aconityl-doxorubicin (CAD) and immunoadjuvant unmethylated cytosine-phosphate-guanine (CpG) were co-packaged by polycationic polyethylenimine (PEI) though electrostatic-interaction to construct PEI/CpG/CAD NP. By intratumoral injection, this positively charged NP could be detained at tumor site and endocytosed by tumor cells effortlessly. Then, doxorubicin was released through cis-aconityl cleavage induced by endosomal-acidity and further triggered tumor ICD, the moribund tumor cells could release damage-associated molecular patterns (DAMPs) to recruit dendritic cells (DCs). Meanwhile, the entire tumor debris derived into diversified antigens and cooperated with immunostimulatory CpG to excite DC maturation and activated comprehensive antitumor immunity.

RESULTS

Prominent tumor suppression was achieved in aggressive mouse melanoma tumor model, which verified the feasibility and effectiveness of this minimalist CAD/CpG-codelivered NP.

CONCLUSION

This study has provided a convenient and promising paradigm for potent cancer chemo-immunotherapy.

Inhibiting HER3 Hyperphosphorylation in HER2-Overexpressing Breast Cancer through Multimodal Therapy with Branched Gold Nanoshells

Treatment failure in breast cancers overexpressing human epidermal growth factor receptor 2 (HER2) is associated mainly to the upregulation of human epidermal growth factor receptor 3 (HER3) oncoprotein linked to chemoresitence. Therefore, to increase patient survival, here a multimodal theranostic nanoplatform targeting both HER2 and HER3 is developed. This consists of doxorubicin-loaded branched gold nanoshells functionalized with the near-infrared (NIR) fluorescent dye indocyanine green, a small interfering RNA (siRNA) against HER3, and the HER2-specific antibody Transtuzumab, able to provide a combined therapeutic outcome (chemo- and photothermal activities, RNA silencing, and immune response). In vitro assays in HER2+ /HER3+ SKBR-3 breast cancer cells have shown an effective silencing of HER3 by the released siRNA and an inhibition of HER2 oncoproteins provided by Trastuzumab, along with a decrease of the serine/threonine protein kinase Akt (p-AKT) typically associated with cell survival and proliferation, which helps to overcome doxorubicin chemoresistance. Conversely, adding the NIR light therapy, an increment in p-AKT concentration is observed, although HER2/HER3 inhibitions are maintained for 72 h. Finally, in vivo studies in a tumor-bearing mice model display a significant progressively decrease of the tumor volume after nanoparticle administration and subsequent NIR light irradiation, confirming the potential efficacy of the hybrid nanocarrier.

Balancing safety and efficacy: tuning the biodistribution and pharmacokinetics of cytokine immunotherapies

Modulating the immune system shows promise in treating various conditions such as autoimmune, malignant, inflammatory, and infectious diseases. While immunotherapies can provide significant clinical benefits, they can also trigger debilitating immune-related toxicities. Achieving a balance between safety and efficacy of immunotherapy remains a significant engineering challenge. A complex immune response can be simplified into a sequence of coordinated signals with precise spatial and temporal arrangements. Mimicking or inhibiting these signals with protein immunotherapies relies on engineering them with specific biodistribution and pharmacokinetic properties. This review summarizes principles governing the movement of therapeutic proteins (i.e. biologics), focusing on cytokine immunotherapies injected intravenously or locally, and highlights approaches and considerations to balance their efficacy and safety.

Revitalizing Cytokine-Based Cancer Immunotherapy through Advanced Delivery Systems

Cytokines can coordinate robust immune responses, holding great promise as therapeutics against infections, autoimmune diseases, and cancers. In cancer treatment, numerous pro-inflammatory cytokines have displayed promising efficacy in preclinical studies. However, their clinical application is hindered by poor pharmacokinetics, significant toxicity and unsatisfactory anticancer efficacy. Thus, while IFN-α and IL-2 are approved for specific cancer treatments, other cytokines still remain subject of intense investigation. To accelerate the application of cytokines as cancer immunotherapeutics, strategies need to be directed to improve their safety and anticancer performance. In this regard, delivery systems could be used to generate innovative therapies by targeting the cytokines or nucleic acids, such as DNA and mRNA, encoding the cytokines to tumor tissues. This review centers on these innovative delivery strategies for cytokines, summarizing key approaches, such as gene delivery and protein delivery, and critically examining their potential and challenges for clinical translation.

An engineered immunocytokine with collagen affinity improves the tumor bioavailability, tolerability, and therapeutic efficacy of IL-2

The clinical utility of human interleukin-2 (hIL-2) is limited by its short serum half-life, preferential activation of regulatory T (TReg) over immune effector cells, and dose-limiting toxicities. We previously engineered F10 immunocytokine (IC), an intramolecularly assembled cytokine/antibody fusion protein that linked hIL-2 to an anti-IL-2 antibody (denoted F10) that extended IL-2 half-life and augmented the immune effector to TReg ratio. Here, we leveraged molecular engineering to improve the anti-tumor therapeutic efficacy and tolerability of F10 IC by developing an iteration, denoted F10 IC-CBD (collagen binding domain), designed for intratumoral administration and in situ retention based on collagen affinity. F10 IC-CBD retained IL-2 bioactivity exclusively in the tumor and eliminated IL-2-associated toxicities. Furthermore, F10 IC exhibited potent single-agent therapeutic efficacy and synergy with systemic immune checkpoint blockade and elicited an abscopal response in mouse tumors models. This engineered fusion protein presents a prototype for the design of intratumoral therapies.

Tumor Regression upon Intratumoral and Subcutaneous Dosing of the STING Agonist ALG-031048 in Mouse Efficacy Models

Stimulator of interferon genes (STING) agonists have shown potent anti-tumor efficacy in various mouse tumor models and have the potential to overcome resistance to immune checkpoint inhibitors (ICI) by linking the innate and acquired immune systems. First-generation STING agonists are administered intratumorally; however, a systemic delivery route would greatly expand the clinical use of STING agonists. Biochemical and cell-based experiments, as well as syngeneic mouse efficacy models, were used to demonstrate the anti-tumoral activity of ALG-031048, a novel STING agonist. In vitro, ALG-031048 is highly stable in plasma and liver microsomes and is resistant to degradation via phosphodiesterases. The high stability in biological matrices translated to good cellular potency in a HEK 293 STING R232 reporter assay, efficient activation and maturation of primary human dendritic cells and monocytes, as well as long-lasting, antigen-specific anti-tumor activity in up to 90% of animals in the CT26 mouse colon carcinoma model. Significant reductions in tumor growth were observed in two syngeneic mouse tumor models following subcutaneous administration. Combinations of ALG-031048 and ICIs further enhanced the in vivo anti-tumor activity. This initial demonstration of anti-tumor activity after systemic administration of ALG-031048 warrants further investigation, while the combination of systemically administered ALG-031048 with ICIs offers an attractive approach to overcome key limitations of ICIs in the clinic.

Targeting cancer with mRNA-lipid nanoparticles: key considerations and future prospects

Harnessing mRNA-lipid nanoparticles (LNPs) to treat patients with cancer has been an ongoing research area that started before these versatile nanoparticles were successfully used as COVID-19 vaccines. Currently, efforts are underway to harness this platform for oncology therapeutics, mainly focusing on cancer vaccines targeting multiple neoantigens or direct intratumoural injections of mRNA-LNPs encoding pro-inflammatory cytokines. In this Review, we describe the opportunities of using mRNA-LNPs in oncology applications and discuss the challenges for successfully translating the findings of preclinical studies of these nanoparticles into the clinic. We critically appraise the potential of various mRNA-LNP targeting and delivery strategies, considering physiological, technological and manufacturing challenges. We explore these approaches in the context of the potential clinical applications best suited to each approach and highlight the obstacles that currently need to be addressed to achieve these applications. Finally, we provide insights from preclinical and clinical studies that are leading to this powerful platform being considered the next frontier in oncology treatment.

Therapeutic potential and limitations of curcumin as antimetastatic agent

Treatment of metastatic cancer is one of the biggest challenges in anticancer therapy. Curcumin is interesting nature polyphenolic compound with unique biological and medicinal effects, including repression of metastases. High impact studies imply that curcumin can modulate the immune system, independently target various metastatic signalling pathways, and repress migration and invasiveness of cancer cells. This review discusses the potential of curcumin as an antimetastatic agent and describes potential mechanisms of its antimetastatic activity. In addition, possible strategies (curcumin formulation, optimization of the method of administration and modification of its structure motif) to overcome its limitation such as low solubility and bioactivity are also presented. These strategies are discussed in the context of clinical trials and relevant biological studies.

High-throughput screens identify a lipid nanoparticle that preferentially delivers mRNA to human tumors in vivo

Lipid nanoparticles (LNPs) are a clinically relevant way to deliver therapeutic mRNA to hepatocytes in patients. However, LNP-mRNA delivery to end-stage solid tumors such as head and neck squamous cell carcinoma (HNSCC) remains more challenging. While scientists have used in vitro assays to evaluate potential nanoparticles for HNSCC delivery, high-throughput delivery assays performed directly in vivo have not been reported. Here we use a high-throughput LNP assay to evaluate how 94 chemically distinct nanoparticles delivered nucleic acids to HNSCC solid tumors in vivo. DNA barcodes were used to identify LNPHNSCC, a novel LNP for systemic delivery to HNSCC solid tumors. Importantly, LNPHNSCC retains tropism to HNSCC solid tumors while minimizing off-target delivery to the liver.

Design of a Tumor Binding GMCSF as Intratumoral Immunotherapy of Solid Tumors

Next-generation cancer immunotherapies may utilize immunostimulants to selectively activate the host immune system against tumor cells. Checkpoint inhibitors (CPIs) like anti-PD1/PDL-1 that inhibit immunosuppression have shown unprecedented success but are only effective in the 20-30% of patients that possess an already "hot" (immunogenic) tumor. In this regard, intratumoral (IT) injection of immunostimulants is a promising approach since they can work synergistically with CPIs to overcome the resistance to immunotherapies by inducing immune stimulation in the tumor. One such immunostimulant is granulocyte macrophage-colony-stimulating factor (GMCSF) that functions by recruiting and activating antigen-presenting cells (dendritic cells) in the tumor, thereby initiating anti-tumor immune responses. However, key problems with GMCSF are lack of efficacy and the risk of systemic toxicity caused by the leakage of GMCSF from the tumor tissue. We have designed tumor-retentive versions of GMCSF that are safe yet potent immunostimulants for the local treatment of solid tumors. The engineered GMCSFs (eGMCSF) were synthesized by recombinantly fusing tumor-ECM (extracellular matrix) binding peptides to GMCSF. The eGMCSFs exhibited enhanced tumor binding and potent immunological activity in vitro and in vivo. Upon IT administration, the tumor-retentive eGMCSFs persisted in the tumor, thereby alleviating systemic toxicity, and elicited localized immune activation to effectively turn an unresponsive immunologically "cold" tumor "hot".

Overcoming biophysical barriers with innovative therapeutic delivery approaches

Cancer is often conceptualized as principally a cellular process, one initiated by genetic mutations in a progenitor cell that result in dysregulated cell proliferation. Accordingly, investigations into mechanisms of treatment resistance to cancer therapies often revolve around the biologic barriers to the therapies. However, there is a growing appreciation for the unique biomechanical properties for tumors and the role they play in treatment resistance for conventional, molecularly targeted, and immune-mediated cancer therapies. This understanding has inspired the development of pharmacologic and interventional approaches to overcome these barriers. Of particular promise are perfusion-enhanced drug delivery (PEDD) approaches that potentially allow for comprehensive tumor coverage with increased delivery pressure and prevention of reflux to drive therapeutics into the tumor parenchyma. In this review, we summarize the key features of the tumor microenvironment that drive tumor progression and impose barriers to anti-cancer therapies. We highlight the rationale and application of pharmacologic approaches and interventional drug delivery devices designed to overcome these impediments. We additionally contextualize these concepts by illustrating their application to the treatment of uveal melanoma liver metastases.

Advances of engineered extracellular vesicles-based therapeutics strategy

Extracellular vesicles (EVs) are a heterogeneous population of lipid bilayer membrane-bound vesicles which encapsulate bioactive molecules, such as nucleic acids, proteins, and lipids. They mediate intercellular communication through transporting internally packaged molecules, making them attractive therapeutics carriers. Over the last decades, a significant amount of research has implied the potential of EVs servings as drug delivery vehicles for nuclear acids, proteins, and small molecular drugs. However, several challenges remain unresolved before the clinical application of EV-based therapeutics, including lack of specificity, stability, biodistribution, storage, large-scale manufacturing, and the comprehensive analysis of EV composition. Technical development is essential to overcome these issues and enhance the pre-clinical therapeutic effects. In this review, we summarize the current advancements in EV engineering which demonstrate their therapeutic potential.

Image-guided intratumoral immunotherapy: Developing a clinically practical technology

Immunotherapy has revolutionized the contemporary oncology landscape, with durable responses possible across a range of cancer types. However, the majority of cancer patients do not respond to immunotherapy due to numerous immunosuppressive barriers. Efforts to overcome these barriers and increase systemic immunotherapy efficacy have sparked interest in the local intratumoral delivery of immune stimulants to activate the local immune response and subsequently drive systemic tumor immunity. While clinical evaluation of many therapeutic candidates is ongoing, development is hindered by a lack of imaging confirmation of local delivery, insufficient intratumoral drug distribution, and a need for repeated injections. The use of polymeric drug delivery systems, which have been widely used as platforms for both image guidance and controlled drug release, holds promise for delivery of intratumoral immunoadjuvants and the development of an in situ cancer vaccine for patients with metastatic cancer. In this review, we explore the current state of the field for intratumoral delivery and methods for optimizing controlled drug release, as well as practical considerations for drug delivery design to be optimized for clinical image guided delivery particularly by CT and ultrasound.

A cell-laden hydrogel as prophylactic vaccine and anti-PD-L1 amplifier against autologous tumors

Immune checkpoint blockade (ICB) can elicit anti-cancer response against tumors growing at normal organs while sparing adjacent tissues. However, many orthotopic tumors respond poorly to ICB therapy due to the lack of pre-existing immune effector cells. Here, we describe a vaccine strategy that induces protective immunity and benefits ICB therapy. An injectable hydrogel platform that forms scaffold subcutaneously was applied to deliver autologous cancer cells undergoing oncolysis (ACCO) as immunogenic antigen source and toll-like receptor 9 agonists (CpG) as additional adjuvant. When administered as a prophylactic, the hydrogel-based vaccine, denoted as (ACCO+CpG)@Gel, successfully built a durable and tumor antigen-specific immune memory against subsequent challenges with orthotopic engraftment of autologous tumors including melanoma, colon carcinoma, and lung carcinoma. Although the vaccination did not completely prevent tumor occurrence, tumors orthotopically established in vaccinated mice acquired significant enhancement in tumor-infiltrating CD8+ T cells and intratumoral PD-L1 expression, which ameliorated the immune status and rendered the originally irresponsive tumors responsible to anti-PD-L1 therapy. Further treatment with PD-L1 blockade therapy efficiently delayed the tumor growth and prolonged the survival of these orthotopic cancer models. Thus, without the need for precisely delivering immunoactivatory agents to tumor or locally remodeling tumor microenvironment, "priming" intractable or inaccessible tumors for subsequent ICB therapy could be achieved by prophylactic vaccination with (ACCO+CpG)@Gel. These findings highlighted (ACCO+CpG)@Gel as a generalized framework of protective vaccine strategy that could be broadly applicable to potentiate ICB therapy against multiple types of orthotopic tumors growing in different regions.

Proactive Immunotherapeutic Approaches against Inflammatory Breast Cancer May Improve Patient Outcomes

Inflammatory breast cancer (IBC) is highly metastatic at the onset of the disease with no IBC-specific treatments, resulting in dismal patient survival. IBC treatment is a clear unmet clinical need. This commentary highlights findings from a recent seminal approach in which pembrolizumab, a checkpoint inhibitor against programmed cell death protein 1 (PD-1), was provided to a triple-negative IBC patient as a neoadjuvant immune therapy combined with anthracycline–taxane-based chemotherapy. We highlight the findings of the case report and offer a perspective on taking a proactive approach to deploy approved immune checkpoint inhibitors. On the basis of our recently published research study, we propose in situ vaccination with direct injection of immunostimulatory agents into the tumor as an option to improve outcomes safely, effectively, and economically for IBC patients.

Mitochondria-Targeted Delivery of Camptothecin Based on HPMA Copolymer for Metastasis Suppression

Poor anti-metastasis effects and side-effects remain a challenge for the clinical application of camptothecin (CPT). Mitochondria can be a promising target for the treatment of metastatic tumors due to their vital roles in providing energy supply, upregulating pro-metastatic factors, and controlling cell-death signaling. Thus, selectively delivering CPT to mitochondria appears to be a feasible way of improving the anti-metastasis effect and reducing adverse effects. Here, we established a 2-(dimethylamino) ethyl methacrylate (DEA)-modified N-(2-hydroxypropyl) methacrylamide (HPMA) copolymer–CPT conjugate (P-DEA-CPT) to mediate the mitochondrial accumulation of CPT. The mitochondria-targeted P-DEA-CPT could overcome multiple barriers by quickly internalizing into 4T1 cells, then escaping from lysosome, and sufficiently accumulating in mitochondria. Subsequently, P-DEA-CPT greatly damaged mitochondrial function, leading to the reactive oxide species (ROS) elevation, energy depletion, apoptosis amplification, and tumor metastasis suppression. Consequently, P-DEA-CPT successfully inhibited both primary tumor growth and distant metastasis in vivo. Furthermore, our studies revealed that the mechanism underlying the anti-metastasis capacity of P-DEA-CPT was partially via downregulation of various pro-metastatic proteins, such as hypoxia induction factor-1α (HIF-1α), matrix metalloproteinases-2 (MMP-2), and vascular endothelial growth factor (VEGF). This study provided the proof of concept that escorting CPT to mitochondria via a mitochondrial targeting strategy could be a promising approach for anti-metastasis treatment.

Targeted delivery of lipid nanoparticle to lymphatic endothelial cells via anti-podoplanin antibody

Lymphatic endothelial cells (LECs) that form lymphatic vessels play a pivotal role in immune regulation. It was recently reported that LECs suppress the antigen-dependent anti-tumor immunity in cancer tissues. Thus, regulating the function of LECs is a promising strategy for cancer therapy. The objective of this study was to develop a method for the selective delivery of small interfering RNA (siRNA) to LECs. For this purpose, the siRNA was formulated into nanoparticles (LNPs) to prevent them from being degraded in body fluids and to facilitate their penetration of the cell membrane. A breakthrough technology for achieving this is ONPATTRO®, a world's first siRNA drug. Since LNPs are taken up by hepatocytes relatively well via low-density lipoprotein receptors, most of the LNP systems that have been developed so far target hepatocytes. In this study, we report on the development of a new method for the rapid and convenient method for modifying LNPs with antibodies using the CLick reaction on the Interface of the nanoParticle (CLIP). The CLIP approach was faster and more versatile than the conventional method using amide coupling. As a demonstration, we report on the LEC-targeted siRNA delivery by using antibody-modified LNPs both in vitro and in vivo. The method used for the modification of LNPs is highly promising and has the potential for expanding the LNP-based delivery of nucleic acids in the future.

Intratumorally anchored cytokine therapy

INTRODUCTION

On-target, off-tumor toxicity severely limits systemic dosing of cytokines and agonist antibodies for cancer. Intratumoral administration is increasingly being explored to mitigate this problem. Full exploitation of this mode of administration must include a mechanism for sustained retention of the drug; otherwise, rapid diffusion out of the tumor eliminates any advantage.

AREAS COVERED

We focus here on strategies for anchoring immune agonists in accessible formats. Such anchoring may utilize extracellular matrix components, cell surface receptor targets, or exogenously administered particulate materials. Promising alternative strategies not reviewed here include slow release from the interior of a material depot, expression following local transfection, and conditional proteolytic activation of masked molecules.

EXPERT OPINION

An effective mechanism for tissue retention is a critical component of intratumorally anchored cytokine therapy, as leakage leads to decreased tumor drug exposure and increased systemic toxicity. Matching variable drug release kinetics with receptor-mediated cellular uptake is an intrinsic requirement for the alternative strategies mentioned above. Bioavailability of an anchored form of the administered drug is key to obviating this balancing act.

IL15 and Anti-PD-1 Augment the Efficacy of Agonistic Intratumoral Anti-CD40 in a Mouse Model with Multiple TRAMP-C2 Tumors

PURPOSE

IL15 promotes activation and maintenance of natural killer (NK) and CD8+ T effector memory cells making it a potential immunotherapeutic agent for the treatment of cancer. However, monotherapy with IL15 was ineffective in patients with cancer, indicating that it would have to be used in combination with other anticancer agents. The administration of high doses of common gamma chain cytokines, such as IL15, is associated with the generation of "helpless" antigen-nonspecific CD8 T cells. The generation of the tumor-specific cytotoxic T cells can be mediated by CD40 signaling via agonistic anti-CD40 antibodies. Nevertheless, parenteral administration of anti-CD40 antibodies is associated with unacceptable side effects, such as thrombocytopenia and hepatic toxicity, which can be avoided by intratumoral administration.

EXPERIMENTAL DESIGN

We investigated the combination of IL15 with an intratumoral anti-CD40 monoclonal antibody (mAb) in a dual tumor TRAMP-C2 murine prostate cancer model and expanded the regimen to include an anti-PD-1 mAb.

RESULTS

Here we demonstrated that anti-CD40 given intratumorally not only showed significant antitumor activity in treated tumors, but also noninjected contralateral tumors, indicative of abscopal efficacy. The combination of IL15 with intratumoral anti-CD40 showed an additive immune response with an increase in the number of tumor-specific tetramer-positive CD8 T cells. Furthermore, the addition of anti-PD-1 further improved efficacy mediated by the anti-CD40/IL15 combination.

CONCLUSIONS

These studies support the initiation of a clinical trial in patients with cancer using IL15 in association with the checkpoint inhibitor, anti-PD-1, and intratumoral optimized anti-CD40.

Photothermal combined with intratumoral injection of annonaceous acetogenin nanoparticles for breast cancer therapy

ACGs (annonaceous acetogenins) possess excellent antitumor activity, but their serious accompanying toxicity has prevented their application in the clinic. To address this problem, we therefore constructed an intratumoral drug delivery system integrating chemotherapy and photothermal therapy. The PEGylation of polydopamine nanoparticles (PDA-PEG NPs) possessed an excellent biocompatibility with size of 70.96 ± 2.55 nm, thus can be used as good photothermal materials in the body. Moreover, PDA-PEG NPs can kill half of cancer cells under NIR (near-infrared) laser irradiation, and the survival rate of 4T1 cells is only 1% when ACG NPs and PDA-PEG NPs are combined. In vivo distribution studies showed that the 0.1 mg/kg ACGs NPs + PDA-PEG NPs + NIR group had the highest tumor inhibition rate, which was significantly superior to that of the 0.1 mg/kg ACGs NPs intratumoral injection group (82.65% vs. 59.08%). Altogether, the combination of PDA-PEG NPs + NIR with chemotherapy drugs may provide a feasible and effective strategy for the treatment of superficial tumors.

Advantageous Reactivity of Unstable Metal Complexes: Potential Applications of Metal-Based Anticancer Drugs for Intratumoral Injections

Injections of highly cytotoxic or immunomodulating drugs directly into the inoperable tumor is a procedure that is increasingly applied in the clinic and uses established Pt-based drugs. It is advantageous for less stable anticancer metal complexes that fail administration by the standard intravenous route. Such hydrophobic metal-containing complexes are rapidly taken up into cancer cells and cause cell death, while the release of their relatively non-toxic decomposition products into the blood has low systemic toxicity and, in some cases, may even be beneficial. This concept was recently proposed for V(V) complexes with hydrophobic organic ligands, but it can potentially be applied to other metal complexes, such as Ti(IV), Ga(III) and Ru(III) complexes, some of which were previously unsuccessful in human clinical trials when administered via intravenous injections. The potential beneficial effects include antidiabetic, neuroprotective and tissue-regenerating activities for V(V/IV); antimicrobial activities for Ga(III); and antimetastatic and potentially immunogenic activities for Ru(III). Utilizing organic ligands with limited stability under biological conditions, such as Schiff bases, further enhances the tuning of the reactivities of the metal complexes under the conditions of intratumoral injections. However, nanocarrier formulations are likely to be required for the delivery of unstable metal complexes into the tumor.

Maximizing response to intratumoral immunotherapy in mice by tuning local retention

Direct injection of therapies into tumors has emerged as an administration route capable of achieving high local drug exposure and strong anti-tumor response. A diverse array of immune agonists ranging in size and target are under development as local immunotherapies. However, due to the relatively recent adoption of intratumoral administration, the pharmacokinetics of locally-injected biologics remains poorly defined, limiting rational design of tumor-localized immunotherapies. Here we define a pharmacokinetic framework for biologics injected intratumorally that can predict tumor exposure and effectiveness. We find empirically and computationally that extending the tumor exposure of locally-injected interleukin-2 by increasing molecular size and/or improving matrix-targeting affinity improves therapeutic efficacy in mice. By tracking the distribution of intratumorally-injected proteins using positron emission tomography, we observe size-dependent enhancement in tumor exposure occurs by slowing the rate of diffusive escape from the tumor and by increasing partitioning to an apparent viscous region of the tumor. In elucidating how molecular weight and matrix binding interplay to determine tumor exposure, our model can aid in the design of intratumoral therapies to exert maximal therapeutic effect.

An in situ spontaneously-forming micelle-hydrogel system with programable release for sequential therapy of anaplastic thyroid cancer

Anaplastic thyroid carcinoma (ATC) is a lethal malignancy with 1-year-survival less than 20%. Combination chemotherapy of cisplatin and paclitaxel is recommended as a critical therapy approach for ATC. However, intolerant...

Spatiotemporally Controllable Distribution of Combination Therapeutics in Solid Tumors by Dually Modified Bacteria

Methods capable of distributing antitumor therapeutics uniformly and durably throughout an entire tumor would be of great significance in maximizing their treatment efficacy, but they have proven to be extremely challenging. Here, bacteria-mediated spatiotemporally controllable distribution of combination therapeutics in solid tumors is reported to reprogram the immune microenvironment for optimizing antitumor efficacy. By combining synthetic biology and interfacial chemistry, bacteria are inside and outside concurrently modified to express photothermal melanin and to attach immune checkpoint inhibitors on their surface. Due to the nature of bacteria to colonize the hypoxia intratumoral environment, both therapeutic agents can be distributed homogenously and lastingly in tumors during ex vivo human and in vivo mouse studies. Spatiotemporally controllable localization of melanin can repeatedly generate a moderate yet uniform heating of the tumor upon light exposure in a broad treatment window. Combination with similarly localized inhibitors elicits a dual photothermally stimulated and checkpoint-blockade-mediated immune activation effect, synergistically reprogramming the immunosuppressive tumor microenvironment. Therapeutic values are demonstrated by significantly inhibited tumor growth and prolonged survival of mice in both subcutaneous and orthotopic murine models. Colonization of dually modified bacteria paves an avenue for spatiotemporally controllable distribution of therapeutic drugs in solid tumors.

Combined chemotherapy for triple negative breast cancer treatment by paclitaxel and niclosamide nanocrystals loaded thermosensitive hydrogel

Triple negative breast cancer (TNBC) is the most dangerous subtype of breast cancer accompanying by unfavorable prognosis due to lack of specific therapeutic targets. Paclitaxel (PTX) is the first-line chemotherapeutic drug for TNBC and niclosamide (NLM) was identified as an inhibitor for TNBC and breast cancer stem cells (BCSCs). Intratumoral drug delivery system was a hopeful alternative for chemotherapeutic drug administration due to its targeting efficiency with lower systemic toxicity. Herein, an injectable PTX nanocrystals (PTX-NCs) and NLM nanocrystals (NLM-NCs) co-loaded PLGA-PEG-PLGA thermosensitive hydrogel (PNNCs-Ts Gel) was designed for TNBC intratumoral treatment. The final formulation realized high drug loading and appropriate particle size. PNNCs-Ts Gel displayed sustained drug release for up to 8 days in vitro. In vitro antitumor tests observed synergetic effects of combined therapy in terms of inhibiting cell proliferation and migration, inducing apoptosis. In vivo combined therapy presented a tumor growth inhibition rate about 68.8% and desired safety. Moreover, tumors after PNNCs-Ts Gel intratumoral injection possessed the lowest ratio of BCSCs, exhibiting this formulation had good ability in suppressing BCSCs and therefore could possibly prevent TNBC recurrence and metastasis. These results suggested that PNNCs-Ts Gel could be a promising strategy for TNBC treatment.

Submicron particle docetaxel intratumoral injection in combination with anti-mCTLA-4 into 4T1-Luc orthotopic implants reduces primary tumor and metastatic pulmonary lesions

We describe here characterization of the response of local and metastatic disease and immunomodulation following intratumoral (IT) injection of submicron particle docetaxel (SPD) administered alone or in combination with systemic antibody anti-mCTLA-4 (anti-mCTLA-4) in the metastatic 4T1-Luc2-1A4 (4T1) murine breast cancer model. In-life assessments of treatment tolerance, tumor volume (TV), and metastasis were performed (n = 10 animals/group). At study end, immune cell populations in tumor-site tissues and peripheral blood were analyzed using flow cytometry. Signs of distress typical of this aggressive tumor model occurred across all animals except for the combination treated which were asymptomatic and gained weight. TV at study end was significantly reduced in the combination group versus untreated [43% reduced (p < 0.05)] and vehicle controls [54% reduced (p < 0.0001)]. No evidence of thoracic metastasis was found in 40% of combination group animals and thoracic bioluminescence imaging (BLI) was reduced vs. untreated controls (p < 0.01). Significant elevations (p < 0.05) in CD4 + T, CD4 + helper T, Treg, and NKT cells were found in tumor and blood in SPD or combination treatment compared to controls or anti-mCTLA-4. Combination treatment increased tumor-associated CD8 + T cells (p < 0.01), peripheral B cells (p < 0.01), and tumor associated and circulating dendritic cells (DC) (p < 0.05). Tumor-associated NK cells were significantly increased in SPD ± anti-mCTLA-4 treatments (p < 0.01). Myeloid-derived suppressor cells (MDSC) were reduced in bloods in SPD ± anti-mCTLA-4 groups (p < 0.05). These data demonstrate that both SPD and anti-mCTLA-4 produce local anti-tumor effects as well as reductions in metastasis which are significantly enhanced when administered in combination.

The right Timing, right combination, right sequence, and right delivery for Cancer immunotherapy

Cancer immunotherapy (CI) represented by immune checkpoint inhibitors (ICIs) presents a new paradigm for cancer treatment. However, the types of cancer that attain a therapeutic benefit from ICIs are limited, and the efficacy of these treatments does not meet expectations. To date, research on ICIs has mainly focused on identifying biomarkers and patient characteristics that can enhance the therapeutic effect on tumors. However, studies on combinational strategies for CI are being actively conducted to overcome the resistance to ICI treatment. Moreover, it has been confirmed that dramatic anticancer effects are achieved through "neoadjuvant" immunotherapy with ICIs in treatment-naïve cancer patients; consequently, it has become necessary to consider how to best apply cancer immunotherapies for patients, even with respect to their tumor stages. In this review, we sought to discuss the right timing of ICI treatment in consideration of the progression of cancer with a changing tumor-immune microenvironment. Furthermore, we investigated which types of combinational treatments and their corresponding sequences of administration could optimize the therapeutic effect of ICIs to expand the applicable target of ICIs and increase their therapeutic efficacy. Finally, we discussed several delivery pathways and methods that can maximize the effect of ICIs.

Constructing a Biomaterial to Simulate Extracellular Drug Transport in Solid Tumors

Designing an in vitro model of the tumor extracellular microenvironment to screen intratumoral drugs is an active challenge. As recent clinical successes of human intratumoral therapies stimulate research on intratumoral delivery, a need for a 3D tumor model to screen intratumoral therapies arises. When injecting the drug formulation directly into the tumor, the biophysics affecting intratumoral retention must be considered; especially for biologic therapies, which may be dominated by extracellular transport mechanisms. Fibrotic regions in solid tumors are typically rich in collagen I fibers. Using shear rheology, head and neck tumors with higher collagen density show a higher stiffness. Similarly, the stiffness of the hyaluronic acid (HA) hydrogel models is increased by adding collagen fibers to model the bulk biomechanical properties of solid tumors. HA hydrogels are then used as intratumoral injection site simulators to model in vitro the retention of glatiramer acetate (GA) and polyethylene glycol (PEG) administered intratumorally. Both compounds are also injected in murine tumors and retention is studied ex vivo for comparison. Retention of GA in the hydrogels is significantly longer than PEG, analogous to the solid tumors, suggesting the utility of HA hydrogels with collagen I fibers for screening extracellular drug transport after intratumoral administration.