Search for anti-metastatic therapy: effects of phenytoin on B16 melanoma metastasis

Voltage-gated sodium channel as a target for metastatic risk reduction with re-purposed drugs

Objective: To determine the exact role of sodium channel proteins in migration, invasion and metastasis and understand the possible anti-invasion and anti-metastatic activity of repurposed drugs with voltage gated sodium channel blocking properties.

Material and methods: A review of the published medical literature was performed searching for pharmaceuticals used in daily practice, with inhibitory activity on voltage gated sodium channels. For every drug found, the literature was reviewed in order to define if it may act against cancer cells as an anti-invasion and anti-metastatic agent and if it was tested with this purpose in the experimental and clinical settings.

Results: The following pharmaceuticals that fulfill the above mentioned effects, were found: phenytoin, carbamazepine, valproate, lamotrigine, ranolazine, resveratrol, ropivacaine, lidocaine, mexiletine, flunarizine, and riluzole. Each of them are independently described and analyzed.

Conclusions: The above mentioned pharmaceuticals have shown anti-metastatic and anti-invasion activity and many of them deserve to be tested in well-planned clinical trials as adjunct therapies for solid tumors and as anti-metastatic agents. Antiepileptic drugs like phenytoin, carbamazepine and valproate and the vasodilator flunarizine emerged as particularly useful for anti-metastatic purposes.

Further characterization of a clinically relevant model of melanoma metastasis and an effective vaccine

A major problem in evaluating the effectiveness of tumor cell vaccination and other biological therapies is the variability of experimental models. In this study we have further developed and characterized a model for metastatic melanoma that approximates the major clinical stages of metastatic dissemination: stage I--growth of the primary (local) tumor, stage II--dissemination to regional lymph nodes, and stage III--metastasis to distant organs (lungs). C57BL/6 mice were challenged subcutaneously with B16 F10 murine melanoma cells in the midtail, and within 3 weeks 100% of the mice had local tumors growing in their tails. By 5-7 weeks after challenge, most of the mice had developed metastases to the inguinal lymph nodes and subsequently had metastatic colonies in the lungs and in the bone marrow. Preimmunization of mice with a formalinized extracellular antigen vaccine, derived from B16 F10 melanoma cells, provided partial inhibition of the growth of the primary melanoma tumors, as well as reducing the number of metastases to the regional (inguinal) lymph nodes and lungs along with concomitantly increasing survival time. This model for melanoma metastasis provides a reasonable and reproducible test system for the study of anti-melanoma immunity and the different cellular and humoral mechanisms involved.

Preimmunization of mice with formalinized extracellular antigens of melanoma in combination with IL-2 and surgical resection increased survival and tumor control in metastatic melanoma model

Recently we found that immunization with formalized extracellular antigens (FECAs) could induce the production of specific antimelanoma antibodies and increase the defense mechanisms of antimelanoma cellular and humoral immunity. In experiments we used pathogen-free female mice C57BL/6 18-20 g. We injected FECA (0.02 mg of protein/per S.C.--subcutaneous injection) for 1 month, once per week. Concurrently we injected S.C. human recombinant IL-2: 100 U/g of weight (2,000 U/per mouse). Interleukin-2 (IL-2) was injected for 1 month, 5 days/week. On days 7, 14, 21, and 28 we took retroorbital blood from mice for the study of anti-FECA and anti-IL-2 antibody production with ELISA. Control and experimental mice were then given a subcutaneous injection with 0.5 x 10(6) cells B16-F10 melanoma in 25 microliters into the middle of the tail. By 18 days 100% developed local melanoma tumors. We resected tails of all control and experimental animals 5 mm distal the base of the tail under metaphan anesthesia. The production of antibodies to FECA and IL-2 started after the 21st day and was higher in the group of mice immunized with FECA and with IL-2 than in control animals. Combining preimmunization with FECA and IL-2 and resection of local melanoma tumors decreased the mortality and the number of mice with local recurrence and metastatic melanoma tumors to the lungs.