Implantable chemotherapy-loaded silk protein materials for neuroblastoma treatment

Abstract

Neuroblastoma is the most common extracranial childhood solid tumor. Treatment of high risk tumors require intense multicycle chemotherapies, resulting in short-and long-term toxicities. Here, we present treatment of an orthotopic neuroblastoma mouse model, with silk fibroin materials loaded with vincristine, doxorubicin or the combination as a intratumoral, sustained release system. The materials, loaded with vincristine with or without doxorubicin, significantly decreased neuroblastoma tumor growth compared to materials loaded without drug or doxorubicin only as well as intravenous (IV) drug treatment. The intratumoral drug concentration was significantly higher with intratumoral delivery versus IV. Furthermore, intratumor delivery decreased the maximum plasma concentration compared to IV delivery, reducing systemic exposure and possibly reduing long-term side effects of chemotherapy exposure. Histopathologically, tumors with remission periods >25 days before recurrence transformed from a "small-round-blue cell" (SBRC) to predominantly "large cell" neuroblastoma (LCN) histopathology, a more aggressive tumor subtype with unfavorable clinical outcomes. These results show that intratumoral chemotherapy delivery may be a treatment strategy for pediatric neuroblastoma, potentially translatable to other focal tumors types. Furthermore, this treatment modality allows for a clinically relevant mouse model of tumor transformation that may be used for studying the phenotypical tumor recurrence and developing more effective treatment strategies for recurrent tumors.Neuroblastoma represents the most common extracranial solid tumor in the pediatric population and accounts for 15% of pediatric oncologic deaths.1 This tumor is derived from neural crest cells, and the location of the tumor can vary, including the adrenal medulla, sympathetic chain and thoracic cavity.

In vitro and in vivo evaluation of etoposide - silk wafers for neuroblastoma treatment

“…Controlled release doxorubicin–silk films were implanted over the neuroblastoma tumor resection beds and local doxorubicin treatment was effective in control of tumor growth [23]. Combinations of doxorubicin and vincristine were formulated in silk sponges and these controlled release drug-loaded silk sponges were implanted into murine orthotopic neuroblastoma tumors [24]. Compared to delivering the same amount of chemotherapeutic drugs intravenously, implanting the drug-loaded silk sponges into the center of the tumor significantly decreased tumor growth, with higher intra-tumoral drug concentration and lower drug concentration in plasma.…”

“…The establishment of orthotopic neuroblastoma xenograft in a seven-week old female NCr nude mouse (Harlan, Indianapolis, IN, USA) was previously described [27]. Briefly, the mouse was anesthetized with inhalational isoflurane.…”

“…This procedure was previously described [27]. Briefly, once the tumor volume reached >100 mm 3 as determined via high frequency ultrasound imaging, animals underwent treatment.…”

“…Hydrophobic molecules have high affinity to silk fibroin, which makes this protein a suitable candidate for controlled delivery of chemotherapeutic drugs. Doxorubicin and vincristine have been loaded onto silk sponges and gels individually or in combination and demonstrated decreased tumor growth after intra-tumoral implantation into an orthotopic neuroblastoma tumor [20, 23, 24]. …”

Manipulation of variables in local controlled release vincristine treatment in neuroblastoma

“…As novel drug reservoir systems become available, the adoption of improved drug delivery methods that can maximize tumor kill and minimize systemic side effects is a top-priority, especially for the pediatric population [3–5]. Previously, we have utilized sustained release silk platforms to treat orthotopic neuroblastoma mouse xenografts by implanting the platform into the center of the tumor [6]. This treatment strategy has resulted in significant decrease in tumor growth and reduction in systemic toxicity compared to delivering the same drug dose intravenously.…”