A phase I study of vitamin E, 5-fluorouracil and leucovorin for advanced malignancies

gRASping the redox lever to modulate cancer cell fate signaling

RAS proteins are critical regulators of signaling networks controlling diverse cellular functions such as cell proliferation and survival and its mutation are among the most powerful oncogenic drivers in human cancers. Despite intense efforts, direct RAS-targeting strategies remain elusive due to its "undruggable" nature. To that end, bulk of the research efforts has been directed towards targeting upstream and/or downstream of RAS signaling. However, the therapeutic efficacies of these treatments are limited in the long run due to the acquired drug resistance in RAS-driven cancers. Interestingly, recent studies have uncovered a potential role of RAS in redox-regulation as well as the interplay between ROS and RAS-associated signaling networks during process of cancer initiation and progression. More specifically, these studies provide ample evidence to implicate RAS as a redox-rheostat, manipulating ROS levels to provide a redox-milieu conducive for carcinogenesis. Importantly, the understanding of RAS-ROS interplay could provide us with novel targetable vulnerabilities for designing therapeutic strategies. In this review, we provide a brief summary of the advances in the field to illustrate the dual role of RAS in redox-regulation and its implications in RAS signaling outcomes and also emerging redox-based strategies to target RAS-driven cancers.

Systematic review: generating evidence-based guidelines on the concurrent use of dietary antioxidants and chemotherapy or radiotherapy

The risk-benefit ratio for concurrent use of dietary antioxidants with chemotherapy or radiation therapy is a controversial topic. In this review, the medical literature on concurrent antioxidant use with chemotherapy or radiotherapy was assessed and further steps for generating evidence-based guidelines are suggested. The clinical cancer research community should cooperate and focus new studies on the use of a specific combination of antioxidant and chemotherapy or radiotherapy, and determine optimal doses for a specific cancer setting. Mechanistic studies on the interaction between antioxidants and conventional cancer therapy could lead to novel biomarkers for assessing dose adequacy.

A phase II study of high-dose calcitriol combined with mitoxantrone and prednisone for androgen-independent prostate cancer

OBJECTIVE

To evaluate the preliminary efficacy, safety, and impact on quality of life (QoL) of high-dose calcitriol (DN-101) combined with mitoxantrone and glucocorticoids in androgen-independent prostate cancer (AIPC).

PATIENTS AND METHODS

Nineteen patients with metastatic AIPC and no previous chemotherapy received DN-101 180 microg orally on day 1 and mitoxantrone 12 mg/m(2) intravenously on day 2 every 21 days with continuous daily prednisone 10 mg orally for a maximum of 12 cycles. A confirmed decline in prostate-specific antigen (PSA) levels by half was the primary endpoint. QoL was evaluated using the European Organization for Research and Treatment of Cancer QLQ-C30 questionnaire, and pain and analgesic use were evaluated.

RESULTS

Five of 19 patients (26%; 95% confidence interval, CI, 9-51) achieved a >/=50% decline in PSA level. The median (95% CI) time to PSA progression was 16 (6-26) weeks. The overall median (95% CI) survival was 16 (6-26) months; 47 (21-73)% of patients achieved an analgesic response. Toxicity was similar to that expected with mitoxantrone and prednisone alone. The QoL analysis suggested a decrease in physical functioning and increase in fatigue, insomnia, and diarrhoea.

CONCLUSIONS

DN-101 given every 3 weeks does not add significant activity to mitoxantrone and prednisone in AIPC, as measured by the PSA decline. The high rate of analgesic response is encouraging. The addition of DN-101 does not appear to increase the toxicity of mitoxantrone.

Modulation of response to cancer chemotherapeutic agents by diet constituents – Is the available evidence sufficiently robust for rational advice for patients?

BACKGROUND

Patients who are diagnosed with cancer want advice on how they may alter their diet or which diet supplements they should take to augment chemotherapy.

METHODS

We conducted a review of the literature mostly from the last 15 years on the interaction between dietary constituents and antineoplastic therapy in preclinical rodent models and in clinical trials.

RESULTS

Studies have explored the effect of predominantly antioxidant vitamins and folate on efficacy or toxicity mediated by cisplatin and anthracyclins. Cisplatin toxicity in rodents was ameliorated by vitamin E. The design of clinical studies of dietary agents in combination with cytotoxic agents has been very heterogeneous and results have been inconclusive.

CONCLUSIONS

Whilst preclinical experiments hint at a potential benefit of certain dietary agents, the evidence emanating from clinical studies does not allow firm conclusions to be made. Future studies should explore physiological doses of dietary agent and include pharmacokinetic and pharmacodynamic measurements.

High-dose calcitriol and carboplatin in metastatic androgen-independent prostate cancer

Calcitriol acts synergistically with carboplatin in preclinical models of adenocarcinoma of the prostate. The authors sought to test high-dose oral calcitriol in combination with carboplatin in patients with metastatic androgen-independent prostate cancer. Seventeen patients received oral calcitriol (0.5 microg/kg) on day 1 and intravenous carboplatin (AUC 7 or AUC 6 in patients with prior radiation) on day 2, repeated every 4 weeks. PSA response was the primary end point and was defined as a 50% reduction confirmed 4 weeks later. Palliative response (2-point reduction or normalization of pain on the present pain intensity [PPI] scale without increased analgesic consumption) was also examined. One of 17 patients (6%, 95% CI, 0-28) achieved a confirmed PSA response. Four patients (24%, 95% CI, 7-49) had PSA reductions ranging from 24 to 38%. Of the 15 patients with a PPI > or = 1 point on entry, 3 (18%, 95% CI, 4-48) met criteria for palliative response. Treatment-related toxicity was mild and generally similar to that expected with single-agent carboplatin. Despite encouraging preclinical evidence, the addition of oral calcitriol to carboplatin in this study was not associated with an increase in the response rate when compared with the reported activity of carboplatin alone.

Antioxidants and cancer therapy: a systematic review

PURPOSE

Many patients with cancer take antioxidant nutritional supplements during cancer treatment to alleviate treatment toxicities and to improve long-term outcomes, but little is known about the efficacy and safety of antioxidant use during cancer treatment. We reviewed English-language manuscripts published in the biomedical literature, reporting the results of observational studies of antioxidant status and cancer outcomes and of intervention trials of antioxidants among patients receiving chemotherapy with or without radiation for various malignancies.

METHODS

We searched the Medline database and the bibliographies of the retrieved manuscripts, reviews, and books on antioxidants and cancer. The retrieved studies are grouped by study design, malignancy, and end points.

RESULTS

More than 100 citations were retrieved; 52 met our criteria, 31 were observational studies, and 21 were intervention trials. The studies varied in study design, timing of observation/intervention, intervention protocol, malignancy, and anticancer regimen.

CONCLUSION

These inconsistencies preclude a definitive conclusion as to the effect of chemotherapy on antioxidant status in patients undergoing anticancer therapy. However, our review suggests that total antioxidant status (measured by total radical antioxidant parameter) declines during cancer treatment. Adequately powered trials or observational studies among patients with a specific cancer diagnosis receiving a specific treatment regimen are needed to address patients' and physicians' concerns regarding these associations.

Weekly high-dose calcitriol and docetaxel in metastatic androgen-independent prostate cancer

PURPOSE

To determine the safety and efficacy of weekly high-dose oral calcitriol (Rocaltrol, Roche Pharmaceuticals, Basel, Switzerland) and docetaxel (Taxotere, Aventis Pharmaceuticals, Bridgewater, NJ) in patients with metastatic androgen-independent prostate cancer (AIPC).

PATIENTS AND METHODS

Thirty-seven patients were treated with oral calcitriol (0.5 micro g/kg) on day 1 followed by docetaxel (36 mg/m(2)) on day 2, repeated weekly for 6 weeks of an 8-week cycle. Patients maintained a reduced calcium diet and increased oral hydration. Prostate-specific antigen (PSA) response was the primary end point, which was defined as a 50% reduction in PSA level confirmed 4 weeks later.

RESULTS

Thirty of 37 patients (81%; 95% confidence interval [CI], 68% to 94%) achieved a PSA response. Twenty-two patients (59%; 95% CI, 43% to 75%) had a confirmed > 75% reduction in PSA. Eight of the 15 patients with measurable disease (53%; 95% CI, 27% to 79%) had a confirmed partial response. Median time to progression was 11.4 months (95% CI, 8.7 to 14 months), and median survival was 19.5 months (95% CI, 15.3 months to incalculable). Overall survival at 1 year was 89% (95% CI, 74% to 95%). Treatment-related toxicity was generally similar to that expected with single-agent docetaxel. Pharmacokinetics of either calcitriol or docetaxel were not affected by the presence of its companion drug in an exploratory substudy.

CONCLUSION

The combination of weekly oral high-dose calcitriol and weekly docetaxel is a well-tolerated regimen for AIPC. PSA and measurable disease response rates as well as time to progression and survival are promising when compared with contemporary phase II studies of single-agent docetaxel in AIPC. Further study of this regimen is warranted.