Therapeutic effect of cisplatin given with a lymphatic drug delivery system on false-negative metastatic lymph nodes

A combination of lymphatic drug delivery of anti-CTLA-4 antibody and local radiotherapy for solid-tumor treatment

The combination of radiotherapy and immunotherapy is a promising approach that has been shown in clinical trials to improve significantly survival and response rates compared with monotherapy against solid tumor. Since anti-CTLA-4 antibodies block immunosuppressive signals mainly in the lymph nodes (LNs), efficient drug delivery to the lymphatic system is desirable. However, the immune checkpoint inhibitors, especially anti-CTLA-4 are currently administered intravenously (i.v.), resulting in limited efficacy in controlling solid tumor and inhibiting metastases, and the method of administration has not been optimized. Here, we show that a combination of local radiotherapy and administration of anti-CTLA-4 antibodies using a lymphatic drug delivery system (LDDS) suppresses solid tumor and metastases. We compared the efficacy of LDDS-based immunotherapy or radioimmunotherapy with i.v. administration in a solid-tumor model created by subcutaneous inoculation into LN-swollen mice with osteosarcoma cells. Tumor-bearing mice were divided into various groups (no treatment, immunotherapy [i.v. or LDDS], radiotherapy, and radioimmunotherapy [i.v. or LDDS]) and were observed for 28 days. Immunotherapy was administered with a cumulative dose of 10 mg/kg of anti-CTLA-4 monoclonal antibody, and radiotherapy was administered with a cumulative 8 Gy of fractionated X-ray irradiation. For immunotherapy alone, LDDS provided slight tumor growth inhibition but did not inhibit distant metastasis. For radioimmunotherapy, however, tumor growth was delayed and distant metastasis was suppressed compared with radiotherapy alone. In particular, the LDDS group achieved a high tumor-suppressive effect with T cell-mediated immune activity, indicating the efficacy of LDDS in radioimmunotherapy.

Intralymphatic injection of chemotherapy drugs modulated with glucose improves their anticancer effect

Lymph node metastasis (LNM) has a significant impact on cancer prognosis, emphasizing the need for effective treatment strategies. This study investigated the potential use of high osmotic pressure drug solutions with low viscosity administration using a lymphatic drug delivery system (LDDS) to improve LNM treatment outcomes. The hypothesis was that injection of epirubicin or nimustine at high osmotic pressure but without altered viscosity would enhance drug retention and accumulation in LNs, thereby improving the efficacy of treatment. Biofluorescence analysis revealed enhanced drug accumulation and retention in LNs after administration using LDDS compared to intravenous (i.v) injection. Histopathological results demonstrated minimal tissue damage in the LDDS groups. Pharmacokinetic analysis revealed an improved treatment response with higher drug accumulation and retention in LNs. The LDDS approach offers the potential for greatly reduced side effects of chemotherapy drugs, lower dosage requirements and crucially increased drug retention in LNs. The results highlight the promise of high osmotic pressure drug solutions with low viscosity administrated using the LDDS for enhancing the treatment efficacy of LN metastasis. Further research and clinical trials are warranted to validate these results and optimize the clinical translation of this novel treatment technique.

Drug formulation augments the therapeutic response of carboplatin administered through a lymphatic drug delivery system

Treatment of metastatic lymph nodes (LNs) is challenging due to their unique architecture and biophysical traits. Systemic chemotherapy fails to impede tumor progression in LNs due to poor drug uptake and retention by LNs, resulting in fatal systemic metastasis. To effectively treat LN metastasis, achieving specific and prolonged retention of chemotherapy drugs in the tumor-draining LNs is essential. The lymphatic drug-delivery system (LDDS) is an ultrasound-guided drug-delivery methodology for administration of drugs to LNs that addresses these requirements. However, early-stage metastatic LNs have an additional set of drug transport barriers, such as elevated intranodal pressure and viscosity, that negatively impact drug diffusion. In the present study, using formulations of elevated osmotic pressure and viscosity relative to saline, we sought to favorably alter the LN's physical environment and study its impact on pharmacokinetics and consequently the therapeutic efficacy of carboplatin delivered using the LDDS. Our study confirmed the capability of a drug formulation with elevated osmotic pressure and viscosity to alter the architecture of LNs, as it caused notable expansion of the lymphatic sinus. Additionally, the study delineated an optimal range of osmotic pressure and viscosity, centered around 1897 kPa and 11.5 mPa·s, above and below which therapeutic efficacy was found to decline markedly. These findings suggest that formulation osmotic pressure and viscosity are parameters that require critical consideration as they can both hinder and promote tumorigenesis. The facile formulation reported here has wide-ranging applicability across cancer spectrums and is thus anticipated to be of great clinical benefit.

Intranodal delivery of modified docetaxel: Innovative therapeutic method to inhibit tumor cell growth in lymph nodes

Delivery of chemotherapeutic agents into metastatic lymph nodes (LNs) is challenging as they are unevenly distributed in the body. They are difficult to access via traditional systemic routes of drug administration, which produce significant adverse effects and result in low accumulation of drugs into the cancerous LN. To improve the survival rate of patients with LN metastasis, a lymphatic drug delivery system (LDDS) has been developed to target metastatic LN by delivering chemotherapy agents into sentinel LN (SLN) under ultrasound guidance. The LDDS is an advanced method that can be applied in the early stage of the progression of tumor cells in the SLN before tumor mass formation has occurred. Here we investigated the optimal physicochemical ranges of chemotherapeutic agents’ solvents with the aim of increasing treatment efficacy using the LDDS. We found that an appropriate osmotic pressure range for drug administration was 700–3,000 kPa, with a viscosity < 40 mPa⋅s. In these physicochemical ranges, expansion of lymphatic vessels and sinuses, drug retention, and subsequent antitumor effects could be more precisely controlled. Furthermore, the antitumor effects depended on the tumor progression stage in the SLN, the injection rate, and the volumes of administered drugs. We anticipate these optimal ranges to be a starting point for developing more effective drug regimens to treat metastatic LN with the LDDS.

Protocols for the Evaluation of a Lymphatic Drug Delivery System Combined with Bioluminescence to Treat Metastatic Lymph Nodes

Bioluminescence (BL) imaging is a powerful non-invasive imaging modality widely used in a broad range of biological disciplines for many types of measurements. The applications of BL imaging in biomedicine are diverse, including tracking bacterial progression, research on gene expression patterns, monitoring tumor cell growth/regression or treatment responses, determining the location and proliferation of stem cells, and so on. It is particularly valuable when studying tissues at depths of 1 to 2 cm in mouse models during preclinical research. Here we describe the protocols for the therapeutic evaluation of a lymphatic drug delivery system (LDDS) using an in vivo BL imaging system (IVIS) for the treatment of metastatic lymph nodes (LNs) with 5-fluorouracil (5-FU). The LDDS is a method that directly injects anticancer drugs into sentinel LNs (SLNs) and delivers them to their downstream LNs. In the protocol, we show that metastases in the proper axillary LN (PALN) are induced by the injection of luciferase-expressing tumor cells into the subiliac LN (SiLN) of MXH10/Mo-lpr/lpr (MXH10/Mo/lpr) mice. 5-FU is injected using the LDDS into the accessory axillary LN (AALN) to treat tumor cells in the PALN after the tumor cell growth is confirmed in the PALN. The tumor growth and therapeutic effects are evaluated by IVIS. This method can be used to evaluate tumor growth and efficacy of anticancer drugs/particles, radiotherapy, surgery, and/or a combination of these methods in various experimental procedures in the oncology field.

Characterizing perfusion defects in metastatic lymph nodes at an early stage using high-frequency ultrasound and micro-CT imaging

A perfusion defect in a metastatic lymph node (LN) can be visualized as a localized area of low contrast on contrast-enhanced CT, MRI or ultrasound images. Hypotheses for perfusion defects include abnormal hemodynamics in neovascular vessels or a decrease in blood flow in pre-existing blood vessels in the parenchyma due to compression by LN tumor growth. However, the mechanisms underlying perfusion defects in LNs during the early stage of LN metastasis have not been investigated. We show that tumor mass formation with very few microvessels was associated with a perfusion defect in a non-enlarged LN at the early stage of LN metastasis in a LN adenopathy mouse (LN size circa 10 mm). We found in a mouse model of LN metastasis, induced using non-keratinizing tumor cells, that during the formation of the perfusion defect in a non-enlarged LN, the number of blood vessels ≤ 50 μm in diameter decreased, while those of > 50 μm in diameter increased. The methods used were contrast-enhanced high-frequency ultrasound and contrast-enhanced micro-CT imaging systems, with a maximum spatial resolution of > 30 μm. Furthermore, we found no tumor angiogenesis or oxygen partial pressure (pO₂) changes in the metastatic LN. Our results demonstrate that the perfusion defect appears to be a specific form of tumorigenesis in the LN, which is a vascular-rich organ. We anticipate that a perfusion defect on ultrasound, CT or MRI images will be used as an indicator of a non-enlarged metastatic LN at an early stage.

Study of the physicochemical properties of drugs suitable for administration using a lymphatic drug delivery system

Lymph node (LN) metastasis is thought to account for 20‐30% of deaths from head and neck cancer. The lymphatic drug delivery system (LDDS) is a new technology that enables the injection of drugs into a sentinel LN (SLN) during the early stage of tumor metastasis to treat the SLN and secondary metastatic LNs. However, the optimal physicochemical properties of the solvent used to carry the drug have not been determined. Here, we show that the osmotic pressure and viscosity of the solvent influenced the antitumor effect of cisplatin (CDDP) in a mouse model of LN metastasis. Tumor cells were inoculated into the proper axillary LN (PALN), and the LDDS was used to inject CDDP solution into the subiliac LN (SiLN) to treat the tumor cells in the downstream PALN. CDDP dissolved in saline had no therapeutic effects in the PALN after it was injected into the SiLN using the LDDS or into the tail vein (as a control). However, CDDP solution with an osmotic pressure of ~ 1,900 kPa and a viscosity of ~ 12 mPa⋅s suppressed tumor growth in the PALN after it was injected into the SiLN using the LDDS. The high osmotic pressure dilated the lymphatic vessels and sinuses to enhance drug flow in the PALN, and the high viscosity increased the retention of CDDP in the PALN. Our results demonstrate that optimizing the osmotic pressure and viscosity of the solvent can enhance the effects of CDDP, and possibly other anticancer drugs, after administration using the LDDS.

Optimization of the delivery of molecules into lymph nodes using a lymphatic drug delivery system with ultrasound

Conventional treatment for lymph node (LN) metastasis such as systemic chemotherapy have notable disadvantages that lead to the development of unwanted effects. Previously, we have reported the lymphatic administration of drugs into metastatic LNs using a lymphatic drug delivery system (LDDS). However, prior studies of the LDDS have not attempted to optimize the conditions for efficient drug delivery. Here, we investigated the influence of several factors on the efficiency of drug delivery by a LDDS in conjunction with ultrasound (US). First, the effect of the injection rate on delivery efficiency was evaluated. Fluorescent molecules injected into an upstream LN were delivered more effectively into a downstream LN when a lower injection rate was used. Second, the influence of molecular weight on drug delivery efficiency was determined. We found that molecules with a molecular weight >10,000 were poorly delivered into the LN. Finally, we assessed whether the administration route affected the delivery efficiency. We found that the delivery efficiency was higher when molecules were administered into an upstream LN that was close to the target LN. These findings revealed the importance of a drug's physical properties if it is to be administered by LDDS to treat LN metastasis.

Lymphatic immunomodulation using engineered drug delivery systems for cancer immunotherapy

Though immunotherapy has revolutionized the treatment of cancer to improve disease outcomes, an array of challenges remain that limit wider clinical success, including low rate of response and immune-related adverse events. Targeting immunomodulatory drugs to therapeutically relevant tissues offers a way to overcome these challenges by potentially enabling enhanced therapeutic efficacy and decreased incidence of side effects. Research highlighting the importance of lymphatic tissues in the response to immunotherapy has increased interest in the application of engineered drug delivery systems (DDSs) to enable specific targeting of immunomodulators to lymphatic tissues and cells that they house. To this end, a variety of DDS platforms have been developed that enable more efficient uptake into lymphatic vessels and lymph nodes to provide targeted modulation of the immune response to cancer. This can occur either by delivery of immunotherapeutics to lymphatics tissues or by direct modulation of the lymphatic vasculature itself due to their direct involvement in tumor immune processes. This review will highlight DDS platforms that, by enabling the activities of cancer vaccines, chemotherapeutics, immune checkpoint blockade (ICB) antibodies, and anti- or pro-lymphangiogenic factors to lymphatic tissues through directed delivery and controlled release, augment cancer immunotherapy.

Intranodal pressure of a metastatic lymph node reflects the response to lymphatic drug delivery system

Cancer metastasis to lymph nodes (LNs) almost certainly contributes to distant metastasis. Elevation of LN internal pressure (intranodal pressure, INP) during tumor proliferation is associated with a poor prognosis for patients. We have previously reported that a lymphatic drug delivery system (LDDS) allows the direct delivery of anticancer drugs into the lymphatic system and is a promising treatment strategy for early‐stage LN metastasis. However, methods for evaluating the treatment effects have not been established. Here, we used a mouse model of MXH10/Mo‐lpr/lpr, which develops a systemic swelling of LNs, and murine malignant fibrous histiocytoma‐like (KM‐Luc/GFP) cells or murine breast cancer (FM3A‐Luc) cells inoculated into the subiliac LN of mice to produce a tumor‐bearing LN model. The changes in INP during intranodal tumor progression and after treatment with cis‐dichlorodiammineplatinum(II) (CDDP) using an LDDS were measured. We found that tumor progression was associated with an increase in INP that occurred independently of LN volume changes. The elevation in INP was suppressed by CDDP treatment with the LDDS when intranodal tumor progression was significantly inhibited. These findings indicate that INP is a useful parameter for monitoring the therapeutic effect in patients with LN metastasis who have been given drugs using an LDDS, which will serve to manage cancer metastasis treatment and contribute to an improved quality of life for cancer patients.

Use of a Lymphatic Drug Delivery System and Sonoporation to Target Malignant Metastatic Breast Cancer Cells Proliferating in the Marginal Sinuses

Lymph node (LN) metastasis through the lymphatic network is a major route for cancer dissemination. Tumor cells reach the marginal sinuses of LNs via afferent lymphatic vessels (LVs) and form metastatic lesions that lead to distant metastasis. Thus, targeting of metastatic cells in the marginal sinuses could improve cancer treatment outcomes. Here, we investigated whether lymphatic administration of a drug combined with sonoporation could be used to treat a LN containing proliferating murine FM3A breast cancer cells, which are highly invasive, in its marginal sinus. First, we used contrast-enhanced high-frequency ultrasound and histopathology to analyze the structure of LVs in MXH10/Mo-lpr/lpr mice, which exhibit systemic lymphadenopathy. We found that contrast agent injected into the subiliac LN flowed into the marginal sinus of the proper axillary LN (PALN) and reached the cortex. Next, we examined the anti-tumor effects of our proposed technique. We found that a strong anti-tumor effect was achieved by lymphatic administration of doxorubicin and sonoporation. Furthermore, our proposed method prevented tumor cells in the marginal sinus from invading the parenchyma of the PALN and resulted in tumor necrosis. We conclude that lymphatic administration of a drug combined with sonoporation could exert a curative effect in LNs containing metastatic cells in their marginal sinuses.

A Tumor-on-a-Chip System with Bioprinted Blood and Lymphatic Vessel Pair

Current in vitro anti-tumor drug screening strategies are insufficiently portrayed lacking true perfusion and draining microcirculation systems, which may post significant limitation in reproducing the transport kinetics of cancer therapeutics explicitly. Herein, we report the fabrication of an improved tumor model consisting of bioprinted hollow blood vessel and lymphatic vessel pair, hosted in a three-dimensional (3D) tumor microenvironment-mimetic hydrogel matrix, termed as the tumor-on-a-chip with bioprinted blood and lymphatic vessel pair (TOC-BBL). The bioprinted blood vessel was perfusable channel with opening on both ends while the bioprinted lymphatic vessel was blinded on one end, both of which were embedded in a hydrogel tumor mass, with vessel permeability individually tunable through optimization of the composition of the bioinks. We demonstrated that systems with different combinations of these bioprinted blood/lymphatic vessels exhibited varying levels of diffusion profiles for biomolecules and anti-cancer drugs. Our TOC-BBL platform mimicking the natural pathway of drug-tumor interactions would have the drug introduced through the perfusable blood vessel, cross the vascular wall into the tumor tissue via diffusion, and eventually drained into the lymphatic vessel along with the carrier flow. Our results suggested that this unique in vitro tumor model containing the bioprinted blood/lymphatic vessel pair may have the capacity of simulating the complex transport mechanisms of certain pharmaceutical compounds inside the tumor microenvironment, potentially providing improved accuracy in future cancer drug screening.

A model system for studying superselective radiotherapy of lymph node metastasis in mice with swollen lymph nodes

•

It is difficult to irradiate individual mouse lymph nodes (LNs) 1–2 mm in diameter.

•

A maximum single dose is <8 Gy for whole-body irradiation of wild-type mice.

•

We succeeded in applying radiation (8 Gy) to a single LN in mice with swollen LNs.

•

Radiation-induced abscopal effects were observed in mice with swollen LNs.

Utilizing mice with swollen lymph nodes, we succeeded in irradiating individual metastatic lymph nodes through a hole in a lead shield. This system enabled us to increase the radiation dose to >8 Gy (the lethal dose for total-body irradiation) and evaluate both direct and abscopal antitumor effects.

Treatment of false-negative metastatic lymph nodes by a lymphatic drug delivery system with 5-fluorouracil

Metastatic lymph nodes (LNs) may be the origin of systemic metastases. It will be important to develop a strategy that prevents systemic metastasis by treating these LNs at an early stage. False‐negative metastatic LNs, which are found during the early stage of metastasis development, are those that contain tumor cells but have a size and shape similar to LNs that do not host tumor cells. Here, we show that 5‐fluorouracil (5‐FU), delivered by means of a novel lymphatic drug delivery system (LDDS), can treat LNs with false‐negative metastases in a mouse model. The effects of 5‐FU on four cell lines were investigated using in vitro cytotoxicity and cell survival assays. The therapeutic effects of LDDS‐administered 5‐FU on false‐negative metastatic LNs were evaluated using bioluminescence imaging, high‐frequency ultrasound (US), and histology in MHX10/Mo‐lpr/lpr mice. These experimental animals develop LNs that are similar in size to human LNs. We found that all cell lines showed sensitivity to 5‐FU in the in vitro assays. Furthermore, a concentration‐dependent effect of 5‐FU to inhibit tumor growth was observed in tumor cells with low invasive growth characteristics, although a significant reduction in metastatic LN volume was not detected in MHX10/Mo‐lpr/lpr mice. Adverse effects of 5‐FU were not detected. 5‐Fluorouracil administration with a LDDS is an effective treatment method for false‐negative metastatic LNs. We anticipate that the delivery of anticancer drugs by a LDDS will be of great benefit in the prevention and treatment of cancer metastasis via LNs.

Lymph node resection induces the activation of tumor cells in the lungs

Lymph node (LN) dissection is a crucial procedure for cancer staging, diagnosis and treatment, and for predicting patient survival. Activation of lung metastatic lesions after LN dissection has been described for head and neck cancer and breast cancer. Preclinical studies have reported that dissection of a tumor‐bearing LN is involved in the activation and rapid growth of latent tumor metastases in distant organs, but it is also important to understand how normal (non‐tumor‐bearing) LN resection influences secondary cancer formation. Here, we describe how the resection of tumor‐bearing and non‐tumor‐bearing LN affects distant metastases in MXH10/Mo‐lpr/lpr mice. Tumor cells were administered intravenously and/or intranodally into the right subiliac lymph node (SiLN) to create a mouse model of lung metastasis. Luciferase imaging revealed that tumor cells in the lung were activated after resection of the SiLN, irrespective of whether it contained tumor cells. No luciferase activity was detected in the lungs of mice that did not undergo LN resection (excluding the intravenous inoculation group). Our results indicate that resection of an LN can activate distant metastases regardless of whether the LN contains tumor cells. Hence, lung metastatic lesions are suppressed while metastatic LN are present but activated after LN resection. If this phenomenon occurs in patients with cancer, it is likely that lung metastatic lesions may be activated by elective LN dissection in clinical N0 cases. The development of minimally invasive cancer therapy without surgery would help to minimize the risk of activation of distant metastatic lesions by LN resection.

Optimal range of injection rates for a lymphatic drug delivery system

The lymphatic drug delivery system (LDDS) is a new technique that permits the injection of drugs into a sentinel lymph node (SLN) at an early stage of tumor metastasis, thereby treating metastasis in the SLN and its secondary lymph nodes (LNs). The quantity of drug required for a LDDS is much smaller than that needed for systemic chemotherapy. However, the relationship between the rate of drug injection into a SLN and the amount of drug reaching the secondary LNs has not been investigated. In this study, we used an MXH10/Mo-lpr/lpr mouse model to show that the optimal rate for the injection of a fluorescent dye by a LDDS was 10 to 80 μL/min. An injection rate of 10 to 80 μL/min was able to fill the downstream LN. However, an injection rate of 100 μL/min drove the fluorescent dye into the efferent lymphatic vessels and thoracoepigastric vein, decreasing the amount of dye retained in the downstream LN. Bolus injection (defined as an injection rate of 2400 μL/min) was unable to deliver fluorescent dye into the downstream LN. These results agree with the impulse values calculated from the injection pressures in the upstream LN. We anticipate that our findings will facilitate the development of a LDDS for use in the clinic.

Therapeutic effect of cisplatin given with a lymphatic drug delivery system on false-negative metastatic lymph nodes

Systemic administration of drugs into the blood circulation is standard treatment for prevention of metastasis. However, systemic delivery cannot maintain sufficiently high concentrations of anticancer drugs in lymph nodes (LN). Here, we show that giving cisplatin (CDDP) using a lymphatic drug delivery system (LDDS) has the potential to treat false-negative metastatic LN. We found that in MXH10/Mo-lpr/lpr mice, which develop systemic swelling of LN up to 10 mm in diameter, accumulation of indocyanine green (ICG), which has a similar molecular weight to CDDP, in a target LN was greater for lymphatic delivery of ICG than for systemic (i.v.) administration. Furthermore, CDDP administration with a LDDS inhibited tumor growth in false-negative metastatic LN and produced fewer adverse effects than systemically given CDDP. We anticipate that drug delivery using a LDDS will, in time, replace systemic chemotherapy for the treatment of false-negative metastatic LN.