Regression of Recurrent Spinal Cord High-Grade Glioma After Convection-Enhanced Delivery of Nimustine Hydrochloride: Case Reports and Literature Review

BACKGROUND

Spinal cord high-grade glioma has poor prognosis. Especially, no treatment protocols have been established for recurrent cases.

OBJECTIVE

To apply a novel treatment method, convection-enhanced delivery (CED), for recurrent high-grade glioma. CED can deliver chemotherapeutic agents directly into the intramedullary lesion and possibly lead to remarkable regression of enlarging tumors that are, otherwise, difficult to control.

METHODS

Two patients developed high-grade glioma in the thoracic spinal cord. Partial resection and chemotherapy and radiotherapy induced remission of the disease. However, following the initial treatment, recurrence was noted in the spinal cord at 6 and 12 mo, respectively. No effective treatment was available for these recurrent lesions. Therefore, the authors decided to use CED to infuse nimustine hydrochloride (ACNU) directly into the spinal cord. During the procedure, the infusion cannula was inserted into the spinal cord lesion under intraoperative computed tomography scan.

RESULTS

After ACNU CED, successive magnetic resonance imaging confirmed remarkable shrinkages of the tumors in both cases. However, the patient's preinfusion symptoms, including bilateral lower extremity weakness, did not change after the treatment. Importantly, overall survivals of the 2 patients were as long as 67 and 33 mo.

CONCLUSION

The authors report the first 2 cases of recurrent spinal cord high-grade glioma. ACNU CED dramatically regressed enhanced mass lesions and provided local tumor controls in the spinal cord.

Convection-enhanced delivery of a hydrophilic nitrosourea ameliorates deficits and suppresses tumor growth in experimental spinal cord glioma models

BACKGROUND

Convection-enhanced delivery (CED) is a technique allowing local infusion of therapeutic agents into the central nervous system, circumventing the blood-brain or spinal cord barrier.

OBJECTIVE

To evaluate the utility of nimustine hydrochloride (ACNU) CED in controlling tumor progression in an experimental spinal cord glioma model.

METHODS

Toxicity studies were performed in 42 rats following the administration of 4 μl of ACNU CED into the mid-thoracic spinal cord at concentrations ranging from 0.1 to 10 mg/ml. Behavioral analyses and histological evaluations were performed to assess ACNU toxicity in the spinal cord. A survival study was performed in 32 rats following the implantation of 9 L cells into the T8 spinal cord. Seven days after the implantation, rats were assigned to four groups: ACNU CED (0.25 mg/ml; n = 8); ACNU intravenous (i.v.) (0.4 mg; n = 8); saline CED (n = 8); saline i.v. (n = 8). Hind limb movements were evaluated daily in all rats for 21 days. Tumor sizes were measured histologically.

RESULTS

The maximum tolerated ACNU concentration was 0.25 mg/ml. Preservation of hind limb motor function and tumor growth suppression was observed in the ACNU CED (0.25 mg/ml) and ACNU i.v. groups. Antitumor effects were more prominent in the ACNU CED group especially in behavioral analyses (P < 0.05; log-rank test).

CONCLUSIONS

ACNU CED had efficacy in controlling tumor growth and preserving neurological function in an experimental spinal cord tumor model. ACNU CED can be a viable treatment option for spinal cord high-grade glioma.

Properties of convective delivery in spinal cord gray matter: laboratory investigation and computational simulations

OBJECT Convection-enhanced delivery (CED) is a method for distributing small and large molecules locally into the interstitial space of the spinal cord. Delivering these molecules to the spinal cord is otherwise difficult due to the blood-spinal cord barrier. Previous research has proven the efficacy of CED for delivering molecules over long distances along the white matter tracts in the spinal cord. Conversely, the characteristics of CED for delivering molecules to the gray matter of the spinal cord remain unknown. The purpose of this study was to reveal regional distribution of macromolecules in the gray and white matter of the spinal cord with special attention to the differences between the gray and white matter. METHODS Sixteen rats (F344) underwent Evans blue dye CED to either the white matter (dorsal column, 8 rats) or the gray matter (ventral horn, 8 rats) of the spinal cord. The rates and total volumes of infusion were 0.2 μl/min and 2.0 μl, respectively. The infused volume of distribution was visualized and quantified histologically. Computational models of the rat spinal cord were also obtained to perform CED simulations in the white and gray matter. RESULTS The ratio of the volume of distribution to the volume of infusion in the gray matter of the spinal cord was 3.60 ± 0.69, which was comparable to that of the white matter (3.05 ± 0.88). When molecules were injected into the white matter, drugs remained in the white matter tract and rarely infused into the adjacent gray matter. Conversely, when drugs were injected into the gray matter, they infiltrated laterally into the white matter tract and traveled longitudinally and preferably along the white matter. In the infusion center, the areas were larger in the gray matter CED than in the white matter (Mann-Whitney U-test, p < 0.01). In computational simulations, the aforementioned characteristics of CED to the gray and white matter were reaffirmed. CONCLUSIONS In the spinal cord, the gray and white matter have distinct characteristics of drug distribution by CED. These differences between the gray and white matter should be taken into account when considering drug delivery to the spinal cord. Computational simulation is a useful tool for predicting drug distributions in the normal spinal cord.