Levofolene modulates apoptosis induced by 5-fluorouracil through autophagy inhibition: clinical and occupational implications.

5-Fluorouracil (5-FU), often used in combination with levofolene (LF), can induce, as an important side effect, the hand-foot syndrome (HFS) due to toxicity on keratinocytes. This can also damage workers involved in its handling. In the present study, we investigated the mechanisms of the toxicity induced by 5-FU alone or together with LF on human keratinocytes in culture. We found that the two drugs, as expected, had potentiating activity on keratinocyte growth inhibition and that this effect was mediated by induction of apoptosis. In our experimental model, an increased autophagic vacuole accumulation was observed in keratinocytes treated with 5-FU as a significant increase of the monodansylcadaverine (MDC) labeling (marker of late autophagy vacuoles) was recorded. However, the synergism of 5-FU with LF on apoptotic occurrence was not paralleled by a similar increase in autophagic vacuoles at 72 h suggesting an antagonistic effect of LF on autophagy elicited by 5-FU. Differential effects on reactive oxygen species (ROS) elevation in cells treated with 5-FU alone or the combination between 5-FU and LF were also observed. 5-FU induced a time-dependent increase of both O2- and lipid peroxidation while the combination of 5-FU and LF caused a stronger intracellular O2- increase only at 24 h while at 48 and 72 h its effect was lower when compared with that one of 5-FU alone. On the other hand, the addition of LF to 5-FU caused a stronger increase of lipid peroxidation at 48 and 72 h, but its effects were significantly lower at 24 h. These results suggest for the first time that LF potentiates the cytotoxicity of 5-FU on keratinocytes likely through the antagonism on autophagy escape pathway and consequent apoptosis potentiation.

Levoleucovorin as replacement for leucovorin in cancer treatment.

OBJECTIVE: To comprehensively review the literature regarding the efficacy, safety, and costs associated with the use of levoleucovorin in cancer treatment and to assess whether levoleucovorin would be a reasonable alternative to the use of racemic leucovorin. DATA SOURCES: A MEDLINE search was conducted for English-language human studies published between January 1980 and April 2012 using the terms l-LV, levoleucovorin, d,l-LV, leucovorin, folinic acid, folinate, 5-formyltetrahydrofolate, folic acid, folates, methotrexate, 5-fluorouracil, and clinical trials. STUDY SELECTION AND DATA EXTRACTION: Articles pertinent to clinical trials (Phase 1, 2, 3) related to evaluating the efficacy, interchangeability, and safety of levoleucovorin were collected and their contents reviewed. DATA SYNTHESIS: From these pharmacokinetics and clinical studies, information on the use of levoleucovorin as a modulator of fluorouracil as well as when combined with other antitumor agents were scrutinized and extracted for comparison with leucovorin whenever possible. Two randomized Phase 3 clinical studies comparing the efficacy and adverse effect profiles of leucovorin and levoleucovorin demonstrated that levoleucovorin is as effective as leucovorin in terms of response, toxicity, and survival. Six randomized Phase 3 clinical studies demonstrated the safety and efficacy of levoleucovorin as a modulator of fluorouracil in combination with/without other antitumor agents in colorectal cancer patients. Levoleucovorin has been studied in other cancers. These clinical Phase 1/2/3 studies demonstrated efficacy and safety of levoleucovorin in combination chemotherapeutic regimens comprising fluorouracil and other antitumor agents. CONCLUSIONS: The results of the clinical studies suggest that levoleucovorin is efficacious and can be used safely in combination with fluorouracil and other antitumor agents. Levoleucovorin can be used interchangeably with leucovorin for modulating fluorouracil. The current shortage of the supply of leucovorin centered in North America renders levoleucovorin a reasonable alternative in terms of efficacy and toxicity profile, but from the perspective of cost, leucovorin remains the drug of choice.