Yumei Xie

Effects of nanomaterial physicochemical properties on in vivo toxicity

It is well recognized that physical and chemical properties of materials can alter dramatically at nanoscopic scale, and the growing use of nanotechnologies requires careful assessment of unexpected toxicities and biological interactions. However, most in vivo toxicity concerns focus primarily on pulmonary, oral, and dermal exposures to ultrafine particles. As nanomaterials expand as therapeutics and as diagnostic tools, parenteral administration of engineered nanomaterials should also be recognized as a critical aspect for toxicity consideration. Due to the complex nature of nanomaterials, conflicting studies have led to different views of their safety. Here, the physicochemical properties of four representative nanomaterials (dendrimers, carbon nanotubes, quantum dots, and gold nanoparticles) as it relates to their toxicity after systemic exposure is discussed.

Intralymphatic chemotherapy using a hyaluronan-cisplatin conjugate.

BACKGROUND Breast cancers typically spread to regional lymph nodes once they disseminate from the primary tumor, thus adequate evaluation and treatment of the axillary lymph nodes is paramount in early stage disease. One significant problem with current therapy is the side effects chemotherapy agents create systemically, either alone or in combination. The purpose of this study is to determine whether lymphatically targeted cisplatin carriers will increase the localized dose in lymphatic metastases without systemic toxicities. METHODS Hyaluronan (HA) is a highly biocompatible polymer that follows lymphatic drainage from the interstitial spaces. We formed complexes of HA and cisplatin by non-covalent conjugation. Complexes were injected subcutaneously into the upper mammary fat pad of female rats, and the tissue distribution determined. RESULTS Cisplatin-HA contained up to 0.25 w/w of Pt and released drug with a half-life of 10 h in saline. Cisplatin-HA conjugates had high anti-tumor activity in vitro similar to the free drug: cisplatin-HA IC50 7 microg/mL in MCF7 and MDA-MB-231 human breast cancer cells (free cisplatin IC50 7 microg/mL). Cisplatin-HA conjugates were well tolerated in rodents with no signs of injection site morbidity or major organ toxicity after 96 h. The area-under-the-curve of cisplatin in the axially lymph nodes after injection with cisplatin-HA increased 74% compared with normal cisplatin. CONCLUSIONS This study demonstrates a novel intralymphatic drug delivery method in breast cancer to preferentially treat at-risk regional lymph nodes and avoid systemic toxicities. Further in vivo testing related to efficacy of this approach with regard to survival, toxicity, and pharmacokinetics is warranted to support its use in human trials.

Drug delivery to the lymphatic system: importance in future cancer diagnosis and therapies

Cancer is the second leading cause of death in the US. Currently, protocols for cancer treatment include surgery to remove diseased and suspect tissues, focused radiation, systemic chemotherapy, immunotherapy and their combinations. With conventional chemotherapy, it is almost impossible to deliver anticancer drugs specifically to the tumor cells without damaging healthy organs or tissues. Over the past several decades, efforts have been made to improve drug delivery technologies that target anticancer drugs specifically to tumor cells. It has been known for over four decades that the lymphatics are the first site of metastasis for most solid cancers; however, few efforts have been made to localize chemotherapies to lymphatic tissues. Trials of several systemic targeted drug delivery systems based on nanoparticles containing chemotherapeutic agents (e.g., liposomal doxorubicin) have shown similar antitumor activity but better patient tolerance compared with conventional formulations. Animal studies have demonstrated that nanoparticles made of natural or synthetic polymers and liposomal carriers have higher accumulation in the lymph nodes and surrounding lymphatics compared to conventional intravenous therapies. This combination has the potential to both reduce nonspecific organ toxicities and increase the chemotherapeutic dose to the most likely sites of locoregional cancer metastasis.

Pulmonary delivery of cisplatin–hyaluronan conjugates via endotracheal instillation for the treatment of lung cancer

Cisplatin (CDDP) intravenous treatments suffer several dose-limiting toxicity issues. Hyaluronan (HA), a naturally occurring biopolymer in the interstitium, is primarily cleared by the lymphatic system. An alteration in input rate and administration route through pulmonary delivery of hyaluronan-cisplatin (HA-Pt) conjugate may increase local lung CDDP concentrations and decrease systemic toxicity. Sprague-Dawley rats were split into four groups: i.v. CDDP (3.5 mg/kg), i.v. HA-Pt conjugate (3.5 mg/kg equivalent CDDP), lung instillation CDDP and lung instillation HA-Pt conjugate. Total platinum level in the lungs of the HA-Pt lung instillation group was 5.7-fold and 1.2-fold higher than the CDDP intravenous group at 24 and 96 h, respectively. A 1.1-fold increase of Pt accumulation in lung draining nodes for the HA-Pt lung instillation group was achieved at 24h relative to the CDDP i.v. group. In the brain and kidneys, the CDDP i.v. group had higher tissue/plasma ratios compared to the HA-Pt lung instillation group. Augmented tissue distribution from CDDP i.v. could translate into enhanced tissue toxicity compared to the altered input rate and distribution of the intrapulmonary nanoformulation. In conclusion, a local pulmonary CDDP delivery system was developed with increased platinum concentration in the lungs and draining nodes compared to i.v. therapy.

A novel intralymphatic nanocarrier delivery system for cisplatin therapy in breast cancer with improved tumor efficacy and lower systemic toxicity in vivo

BACKGROUND A lymphatically delivered nanoconjugate of cisplatin was evaluated in an orthotopic mouse model of locoregionally metastatic breast cancer (LABC) to determine if it can overcome some of the limitations of standard cisplatin therapy such as high systemic toxicity. METHODS Human breast cancer cells (10(7) MDA-MB-468LN) were injected into the mammary fat pad of female nu/nu mice. Once tumor volume reached 50 mm(3), intravenous cisplatin or subcutaneous hyaluronan-cisplatin (HA-cisplatin) nanoconjugate was given 1/week x 3 weeks at 3.3 mg/kg (platinum basis). RESULTS Nanoconjugates colocalized with the tumors after subcutaneous peritumoral injection and showed improved efficacy to intravenous cisplatin. After 1 month, renal tubular hemorrhage and edema were more prevalent in the intravenous formulation compared with subcutaneous HA-cisplatin nanoconjugates. CONCLUSIONS This nanocarrier delivery platform focuses on delivering drugs to the areas in which tumor burden is greatest, potentially reducing systemic toxicity, and has future applicability as a neoadjuvant or adjuvant therapy for LABC.

Pharmacokinetics and disposition of a localized lymphatic polymeric hyaluronan conjugate of cisplatin in rodents

Cisplatin (CDDP) is an effective anticancer agent for many solid tumors but has significant systemic toxicity limiting its use in many patients. We have designed a loco-regional delivery system to increase platinum levels in the lymphatics, where early metastasis is most likely to occur, while reducing systemic toxicities. CDDP was conjugated to a biocompatible polymer hyaluronan (HA), with a conjugation degree of approximately 20% (w/w). Conjugates were delivered via subcutaneous injection into the mammary fat pad of rats. Intravenous hyaluronan-cisplatin (HA-Pt) exhibited an increased plasma area under the curve (AUC) 2.7-fold compared to conventional CDDP but with a reduced peak plasma level (C(max)), and HA-Pt increased the ipsilateral lymph node AUC by 3.8-fold compared to CDDP. Urine creatinine was unchanged over 30 days following dosing of HA-Pt. This study demonstrates that intralymphatic drug delivery with polymer-conjugated platinum may provide greater tissue and systemic plasma concentrations of platinum than intravenous CDDP. In addition, localized particle delivery augmented distribution in the loco-regional tissue basin where tumor burden predominates, while renal toxicity compared to standard intravenous CDDP was significantly reduced.

Carrier-based intralymphatic cisplatin chemotherapy for the treatment of metastatic squamous cell carcinoma of the head & neck

BACKGROUND Since head and neck squamous cell carcinoma (HNSCC) preferentially metastasizes to the locoregional lymphatics, treatment of the tumor-draining cervical lymph nodes is paramount. RESULTS We developed a hyaluronan-cisplatin (HA-Pt) nanoconjugate with prolonged lymphatic retention and greatly improved tumor tissue deposition for the treatment of metastatic HNSCC. We also developed an orthotopic metastatic xenograft model of HNSCC to examine the efficacy of the nanoconjugate. HNSCC (1/week x 3 weeks) were completely cured for 57% of the female mice in the HA-Pt treatment group, which demonstrated greatly hindered HNSCC progression compared with the standard cisplatin therapy (p < 0.05). CONCLUSION With this insight, we will be able to optimize the carriers for better uptake, penetration and retention within cancer cells.