Dosimetry study of a phase II multiple-dose intracavitary administration of 131I-TM601 in adult patients with recurrent high-grade glioma

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Background: Postoperative radiotherapy for glioma has been shown to improve survival with increased radiation doses. Dose escalation of external beam radiotherapy or brachytherapy is limited by normal brain radionecrosis. Radiolabeled targeting molecules can deliver localized radiation to tumor and reduce normal brain radionecrosis. TM601, or synthetic Chlorotoxin, is a peptide derived from scorpion venom that specifically binds to tumor cells. Here we report dosimetry results of an imaging sub-study of a phase II trial, in which weekly doses of 131I-TM601 were infused into surgically created tumor resection cavities for 3 or 6 weeks. Methods: Five out of 76 patients treated in a phase II trial were imaged after receiving 1, 3, or 6 doses of 40 mCi/0.8 mg 131I-TM601 intracavitarily. For each imaging study, 5 sequential SPECT images (1–168 hour) were registered with MRI to determine the 131I-TM601 radiation dose to the 2-cm tumor cavity margin. Five sequential body scans were also acquired to determine 131I-TM601 radiation dose to extra-cranial organs. Results: 131I-TM601 is a rapidly penetrating and clearing radiolabeled peptide. The median residual activity in the cavity at 7 days post injection was 8.4%. Median radiation dose to the cavity margin was 121 cGy/mCi and ranged 52- 338 cGy/mCi in 5 subjects. The median coefficient of variation (intra-patient inter-fraction) for the 2-cm margin dose was 14.7% and ranged 7.1–18.9%. Median tumor cavity volume was 11.4 mL, and ranged 5.2 - 35.5 mL. There was no observed correlation between the 2-cm margin dose and the cavity volume. Median radiation dose to thyroid, kidneys, red marrow, and body was 8.3, 1.3, 0.4, and 0.6 cGy/mCi, respectively. Conclusions: Radiation dose ratio for 2-cm cavity margin-to-normal tissues was quite high. While intra-patient reproducibility was relatively good, cumulative effect of the residual activity was only meaningful within a week. These results support the multi-dose fractionation scheme for 131I-TM601 to minimize normal tissue toxicity, including radiation necrosis, and extend continuous irradiation to clinical or sub-clinical residual tumor cells after surgery.

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A phase I evaluation of intravenous (IV) 131I-chlorotoxin delivery to solid peripheral and intracranial tumors

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Background: Pre-clinical studies demonstrate TM601 binding to glioblastoma, melanoma, and other tumor types in vitro and in vivo (human xenograft tumors in mice). Here we report imaging and safety data from a Phase I clinical trial in patients with recurrent metastatic somatic and/or cerebral solid tumors that received IV 131I-TM601. Methods: Patients received an IV imaging test dose of 10 mCi/0.2mg 131I-TM601. Subjects not showing tumor localization, received a second imaging test dose of 20 mC/0.4mg 131I-TM601. Subjects without localization at either dose were dropped from study; patients showing tumor localization without toxicity then received a 30 mCi/0.6mg 131I-TM601 IV injection. The primary objectives were to: 1) determine whole body localization and dosimetry, 2) estimate the maximum tolerated dose based on normal tissue dosimetry and 3) determine the acute toxicity of IV 131I-TM601. Results: A total of 44 evaluable patients received IV doses of 131I-TM601 without dose-limiting toxicity. 31/44 (70%) showed tumor specific uptake on follow-up gamma camera or SPECT imaging. Tumor-specific uptake was observed in patients with malignant glioma (7/8), metastatic melanoma (7/7), non-small cell lung cancer (3/4), colon cancer (6/7), pancreatic cancer (2/3), prostate cancer (2/2), breast cancer (1/4) and in one evaluable patient each with transitional cell carcinoma, pleomorphic xanthoastrocytoma and metastatic paraganglioma. Notably, all patients with metastatic cerebral disease showed tumor-specific uptake of systemically injected 131I-TM601. No uptake was seen in CNS lymphoma (n=1), ovarian (n=2), small cell lung (n=2), or medulllary thyroid cancers (n=1). Conclusions: Tumor-specific uptake of IV 131I-TM601 in primary and metastatic (including brain) solid tumors suggests that further dose escalation is warranted. Notably, IV injected 131I-TM601 crossed the blood brain barrier. Based on normal tissue dosimetry from this study, future clinical trials will evaluate safety and therapeutic efficacy in patients with recurrent glioma and metastatic melanoma at doses up to 100 mCi 131I-TM601 (maximum single dose).

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Blockade of SDF-1/CXCR4 signalling inhibits pancreatic cancer progression in vitro via inactivation of canonical Wnt pathway

Extra-pancreatic metastasis is a difficult problem for surgical intervention in pancreatic cancer. CXC chemokine receptor 4 (CXCR4) was considered to have an important role in this process. We hypothesized it may contribute to the pancreatic cancer progression through influencing canonical Wnt pathway. The purpose of this study was to examine the functional role of CXCR4 in the progression of pancreatic cancers and explore the possible mechanism. To this end, the relation between CXCR4 and clinical characteristics was analysed. shRNA against CXCR4 was applied to disrupt the SDF-1/CXCR4 signal transduction pathways in pancreatic cancer cell lines. Our results showed that overall survival in the case of patients positive for CXCR4 expression was significantly lower than that in the case of patients negative for CXCR4 expression. Notably, in vitro studies we observed that the abrogation of CXCR4 could obviously influence the pancreatic cancer cell phenotype including cell proliferation, colony formation, cell invasion and also inhibit the TOPflash activity. In addition, Wnt target genes and mesenchymal markers such as Vimentin and Slug were also inhibited in CXCR4 knockdown cells. Collectively, these data reported here demonstrate CXCR4 could modulate the canonical Wnt pathway and perhaps be a promising therapeutic target for pancreatic cancer progression.

Decreased nerve distribution in mixed venous-lymphatic malformation

In order to investigate the nerve distribution in mixed venous-lymphatic malformations (MVLMs), 57 postoperative patients diagnosed with MVLMs of the tongue were selected. Immunohistochemistry staining for neurofilament (NF) was used to detect sensory nerve fibers. Distribution of NF in samples from MVLMs was compared with distribution of NF in normal tongue tissue, venous malformations, lymphatic malformations and venular malformations. Results showed that the number of NF-positive nerve fibers in MVLMs was comparable to that in venous malformations and lymphatic malformations. The number of nerve fibers in MVLMs was significantly lower than in normal tissues. NF distribution in MVLMs was not affected by the patient's age or the coexistence of infection. These data suggest that the decreased distribution of sensory nerve fibers in MVLMs may be involved in the pathogenesis of MVLM of the tongue.

A large prospective study assessing injection site reactions, quality of life and preference in patients using the Biojector vs standard needles for enfuvirtide administration

OBJECTIVES

To determine the severity of injection site reactions (ISRs), patient quality of life (QoL) and preference when enfuvirtide is administered by the Biojector (Bioject, Medical Technologies, Inc., Tualatin, OR, USA) relative to standard needles.

METHODS

A total of 201 HIV-positive patients on stable enfuvirtide-based therapy (n=184) or initiating such therapy (n=17) were evaluated prospectively after switching from standard needles to the Biojector system. Patients used needles for a minimum of 2 weeks prior to switching to the Biojector. Questionnaires to assess the incidence and severity of ISRs (31-item score) and QoL [Medical Outcomes Study HIV Health Survey (MOS-HIV)] were administered at baseline and following a minimum of 14 days of Biojector use.

RESULTS

The median changes in ISR score and number of ISRs following a median of 1.0 month [interquartile range (IQR) 0.9, 1.3] of Biojector use were -3 (IQR -7, 1) and -1 (IQR -3, 1), respectively. The severity of pain (P<0.0001), induration (P<0.0001), pruritus (P<0.0001), nodules (P<0.0001) and erythema (P<0.0001) all decreased with the Biojector. Administration of enfuvirtide with the Biojector was associated with an improved patient QoL (P<0.0001), and was preferred by 72% of patients.

CONCLUSIONS

Compared with needles, the Biojector was associated with a decreased severity of ISRs and improved QoL in patients taking enfuvirtide.