Pharmacology and therapeutic efficacy of capecitabine: focus on breast and colorectal cancer

Capecitabine (N -pentyloxycarbonyl-5-deoxy-5-fluorocytidine), an oral prodrug of 5-fluorouracil, has provided compelling efficacy data for the treatment of metastatic breast cancer and stage III or IV colorectal cancer, both as monotherapy and in combination regimens. The preferential conversion of capecitabine to 5-fluorouracil in neoplastic tissues renders this fluoropyrimidine particularly appealing for clinical use. The enzyme thymidine phosphorylase, which mediates the final step of the capecitabine activation pathway, is expressed in higher concentration in neoplastic than in healthy tissues. This makes capecitabine more tumor specific than other chemotherapeutic agents. Accordingly, capecitabine is generally well tolerated. In particular, the incidence of myelosuppression and alopecia is low, and the most common side effects, hand-foot syndrome and diarrhea, are usually manageable. Given its good toxicity profile, capecitabine was assessed in combination with several chemotherapeutic or biologic agents. In addition, the observation that thymidine phosphorylase is upregulated after treatment with other anticancer drugs, namely taxanes, provided a rationale for the prominent antitumor activity recently observed for the combination of capecitabine with these agents. This review provides an evidence-based update of clinical trials investigating the role of capecitabine in the treatment of breast and colorectal cancer, with special emphasis on pharmacological and safety issues that form the basis of currently used schedules.

Phase III study of gemcitabine plus docetaxel compared with capecitabine plus docetaxel for anthracycline-pretreated patients with metastatic breast cancer

PURPOSE

Patients with metastatic breast cancer who are pretreated with anthracyclines frequently receive taxane-based combinations. This phase III study compared the efficacy and safety of gemcitabine-docetaxel (GD) with capecitabine-docetaxel (CD) in advanced breast cancer.

PATIENTS AND METHODS

Patients were randomly assigned to GD (G 1,000 mg/m(2) days 1 and 8; D 75 mg/m(2) day 1) or CD (C 1,250 mg/m(2) twice daily days 1 through 14; D 75 mg/m(2) day 1) every 21 days. Comparison of progression-free survival (PFS) was the primary objective.

RESULTS

Patient characteristics were balanced between arms (N = 305). Median PFS was 8.05 months (95% CI, 6.60 to 8.71) for GD and 7.98 (95% CI, 6.93 to 8.77) for CD (log-rank P = .121). Overall response rate (ORR) was 32% in both arms, and overall survival (OS) was not different between arms (P = .983). Time to treatment failure (TTF; defined as discontinuation, progressive disease, death as a result of any cause, or the start of a new anticancer therapy) was superior in the GD arm (P = .059). Hematologic toxicity was similar in both arms, except for grades 3 to 4 leukopenia (GD, 78%; CD, 66%; P = .025) and transfusions (GD, 17%; CD, 7%; P = .0051). Grades 3 to 4 diarrhea, mucositis, and hand-and-foot syndrome were significantly higher in the CD arm. Fewer patients in the GD arm discontinued because of drug-related adverse events (13% v 27% in CD; P = .002).

CONCLUSION

No difference was observed between GD and CD arms in PFS, ORR, and OS. TTF was longer in the GD arm. These findings, combined with a nonhematologic toxicity profile that favors GD over approved doses of CD, suggest that gemcitabine may be a better option than capecitabine in combination with docetaxel in this clinical setting.

Paclitaxel and docetaxel in the treatment of breast cancer

BACKGROUND

Paclitaxel and docetaxel are considered fundamental drugs in the treatment of breast cancer.

OBJECTIVES

To review the current role of taxanes in the treatment breast cancer, with emphasis on data from randomized trials comparing the two taxanes.

METHODS

We have reviewed the available evidence in the literature to gauge the results of therapy of early and advanced breast cancer with taxanes.

RESULTS

Clinically benefits were first shown in metastatic setting. More recently, benefits have also been seen in the therapy of early-stage disease. It seems reasonable to consider either drug as standard treatment for node-positive early stage or metastatic breast cancer. Future studies should explore the optimal way of combining taxanes with novel biological and cytotoxic drugs.

CONCLUSION

Based on existing evidence, clinicians should choose a taxane-based regimen for their patients, according to clinical activity, toxicity profile, pharmacokinetics, and a dosing schedule that best meets the therapeutic needs and convenience.

Phase 2 study of gemcitabine and irinotecan in metastatic breast cancer with correlatives to determine topoisomerase I localization as a predictor of response

BACKGROUND

Gemcitabine incorporation into DNA enhances cleavage complexes in vitro when combined with topoisomerase I inhibitors and demonstrates synergy in cancer cells when given with irinotecan. Topoisomerase I inhibitors require that topoisomerase I interacts with DNA to exert activity.

METHODS

Patients who had received previous anthracycline therapy or were not candidates for anthracycline therapy received gemcitabine at a dose of 1000 mg/m2 intravenously over 30 minutes followed by irinotecan at a dose of 100 mg/m2 over 90 minutes on Days 1 and 8 of a 21-day cycle. The primary endpoint was improvement in response from that historically observed with gemcitabine (from 25% to 45%) as measured by Response Evaluation Criteria in Solid Tumors. Correlative studies included characterization of cellular levels and nuclear distribution of topoisomerase I and pharmacokinetic analysis of gemcitabine and irinotecan.

RESULTS

Forty-nine patients were assessed for response. The response rate was approximately 25% (all partial responses [PRs], 12 patients; 95% confidence interval [95% CI], 13-39). Six patients had stable disease (SD) for > or =6 months for a clinical benefit rate (PR + SD) of 39%. The median time to disease progression was 3.7 months (95% CI, 2.5 months-4.6 months), and median survival was 11.6 months (95% CI, 8.9 months-15 months). Toxicities included neutropenia, nausea, and vomiting. Seven of 9 tissue biopsies were assessable for topoisomerase I. Tumors with the 2 lowest nuclear to cytoplasmic ratios demonstrated no response to irinotecan.

CONCLUSIONS

Gemcitabine and irinotecan are active in metastatic breast cancer, but response did not meet predetermined response parameters, and the null hypothesis was accepted. Topoisomerase I localization can be measured in metastatic breast cancer. Further validation is needed to determine whether this assay can predict response.

First-line treatment options for patients with HER-2 negative metastatic breast cancer: the impact of modern adjuvant chemotherapy

The management of early breast cancer has evolved rapidly in recent years. Consequently, the range of first-line treatment options for metastatic breast cancer (MBC) is becoming increasingly complicated and therapy depends on a complex interaction of tumor, patient, and physician variables. Arguably one of the most important factors determining choice of first-line chemotherapy is prior adjuvant therapy. We have reviewed data from large, randomized clinical trials to identify the most effective regimens and help clinicians to select first-line treatment based on previous adjuvant therapy. In this review we provide recommendations on the most appropriate first-line therapy according to the type of previous adjuvant therapy. With such a wide array of treatment options available, none is likely to become the gold-standard first-line treatment for MBC. Furthermore, as increasing emphasis is placed on the quality as well as the duration of survival after development of MBC, treatment decisions should take into account tumor characteristics, toxicity, convenience, potential impact on quality of life, and patient preference, in addition to robust efficacy data.

Role of gemcitabine in metastatic breast cancer patients: a short review

Many active cytotoxic drugs, given according to a number of different regimens are approved for the treatment of metastatic breast cancer patients. However, these therapies have not changed the outcome of patients affected by this malignancy. As a consequence, the balance between chemotherapy-induced side effects and relief of cancer-related symptoms must be carefully considered in this setting. Gemcitabine is an antimetabolite that is incorporated as a triphosphate into DNA. As a single agent, it yields responses rates ranging from 14% to 37% in chemotherapy-naïve patients and from 12% to 30% in patients previously treated with anthracyclines and/or taxanes. In combination with paclitaxel, it produces a significantly higher response rate (41.4% vs. 26.2%), longer time to progression (6.1 vs. 4 months) and significantly higher overall survival (18.6 vs. 15.8 months) than paclitaxel alone. In addition, a phase III study revealed that gemcitabine plus docetaxel is as effective as capecitabine plus docetaxel, but causes significantly less non-haematologic toxicity. Lastly, in another phase III trial, progression free survival was significantly longer with the combination of gemcitabine plus vinorelbine than with vinorelbine alone (6 vs. 4 months), but without a significant difference in overall survival; the incidence of haematologic toxicity was higher in the group treated with combined therapy. Novel gemcitabine combinations are being investigated in phase II studies.

Low dose Gemcitabine plus cisplatin in a weekly-based regimen as salvage therapy for relapsed breast cancer after taxane-anthracycline-containing regimens

PURPOSE

Cisplatin-gemcitabine is a synergistic chemotherapy (CT) combination highly proven in a broad spectrum of epithelial neoplasms and shows a non-cross-resistance profile with the most active drugs in metastatic breast cancer (MBC). We have conducted an exploratory study to determine if treatment with low doses of a combination of fixed-rate gemcitabine infusion and cisplatin was clinically meaningful in women relapsing after a minimum of 2 prior lines of CT for advanced disease (range 2-6), which had to have necessarily included both anthracyclines and taxanes. Another goal was to find the optimal individual schedule by adjusting frequency and dosage according to patient tolerability.

PATIENTS AND METHODS

From May 2002 to November 2003, 22 patients with relapsed advanced BC and a minimum of two prior CT lines were offered treatment with gemcitabine (G) (initial dose 750 mg/m(2), or 600 mg/m(2) if the patient had received more than two previous CT lines) plus cisplatin (P) (initial dose 30 mg/m(2), or 20 mg/m(2) in case of > or =3 prior CT lines) on days 1 and 8 of a 21-day cycle. Treatment was postponed to day 15 if it could not be given on day 8, without dose reduction. If treatment could not be given on day 15, a 20% dose reduction was allowed and treatment given the next week. Further dose reductions were allowed as needed up to a maximum of three. Treatment continued until disease progression or intolerable toxicity. Median age was 54.5 years (35-75). Median Karnofsky was 90 (range 80-90). Median number of prior CT lines was 3 (2-6). 90.9% of patients had received adjuvant CT. All had prior anthracyclines and taxanes. Other agents used included 5-FU/eniluracil, MTA, RPR 109881A, trastuzumab, cisplatin, VP16, vinorelbine, capecitabine and irinotecan. 72.7% had received radiotherapy and 68.1% hormonal therapy (median 2 lines, range 1-4).

RESULTS

Partial responses (PR) were seen in 9.1% of patients and stable disease (SD) in 36.4%. Clinical Benefit Rate (PR+SD) was derived in 45.5% of patients. Median time to progression was 4 months (95% CI, 3-5) in general and 6 months (95% CI, 4-8) in patients with clinical benefit. Median survival for the entire group was 8 months (95% CI, 5-11) and 19 months when clinical benefit was obtained (95% CI, 11-25). Patients received a median of 8.5 CT administrations (range, 2-45). Forty-three percent of doses were delayed. Sixteen out of 22 patients needed a delay and/or reduction of initial dose. Cisplatin and gemcitabine doses were reduced in 75% and 62% of all cycles, respectively. Sixteen out of 22 patients needed a delay and/or reduction of initial dose. Toxicities grade >3 were neutropenia 35% and thrombocytopenia 15%. All other toxicities were grade 2 or less, including sensorial neuropathy (30%), asthenia (34%), nausea/vomiting (20%) and oral mucositis (15%). There were no treatment-related deaths. Reasons for discontinuation were progression (18 patients), death (3 patients) and patient decision (1 patient).

CONCLUSION

Weekly cisplatin-gemcitabine with flexible downwards individual tailoring is a safe and effective salvage treatment in heavily pretreated MBC patients with good PS.

Gemcitabine in the management of metastatic breast cancer: a systematic review

BACKGROUND

A systematic review of the evidence for gemcitabine chemotherapy, alone or in combination, in women with metastatic/advanced breast cancer was undertaken in order to determine gemcitabine's role in the first-line and/or second-line or greater setting.

METHODS

MEDLINE, EMBASE, the American Society of Clinical Oncologists, San Antonio Breast Cancer Symposium proceedings, and the Cochrane Library were searched through September 2006 for randomized controlled trials and non-randomized phase two trials.

RESULTS

Eighty-three trials were identified, including four randomized phase III trials. All of the phase III trials included first-line patients. Two of the phase III trails demonstrated clinical benefit with gemcitabine-based chemotherapy in terms of superior efficacy or less toxicity while two phase III trials found no clinical benefit based on less efficacy or increased toxicity. Although 78 phase II trials of gemcitabine alone or in combination with other chemotherapy agents were identified, few combinations showed results compelling enough to warrant randomized trials.

CONCLUSION

Available data do not support the acceptance of gemcitabine as a standard therapeutic option in women with metastatic breast cancer in the third-line or greater setting, nor should it be considered as first-line therapy in anthracycline naïve women. Gemcitabine appears to be most effective when administered with a taxane (docetaxel/paclitaxel) in the first- or second-line setting, with gemcitabine/taxane combinations representing a viable alternative to currently accepted taxane combinations such as capecitabine/docetaxel. There is no evidence at this time to support the use of gemcitabine triplets, given the equal efficacy to anthracycline triplets and the added toxicity.

Capecitabine in Combination with Novel Targeted Agents in the Management of Metastatic Breast Cancer: Underlying Rationale and Results of Clinical Trials

At present there is no established standard of care for metastatic breast cancer and prognosis remains poor, although the use of newer chemotherapeutic regimens has led to modest improvements in survival. Capecitabine, an oral prodrug of 5-fluorouracil, is a promising addition to these approaches, having already shown single-agent activity against metastatic breast cancer. Following a pivotal trial demonstrating that capecitabine confers increased survival when used in combination with docetaxel, it is being investigated intensively in combined regimens using other standard chemotherapeutic agents, as well as with novel molecularly targeted therapies. Among the novel agents, the most intensively studied in combination with capecitabine is trastuzumab. Despite preclinical data suggesting that these two agents might not show additive effects, clinical trials have been very encouraging for both heavily pretreated patients and for patients receiving first-line therapy in the metastatic setting. This work is being further extended in an ongoing trial in the neoadjuvant setting. An initial trial in combination with bevacizumab, enrolling heavily pretreated patients, was less successful, but following the example of the E2100 trial, this combination is being re-examined in less heavily treated patients. In addition, this review discusses ongoing trials with an array of newer molecularly targeted agents. Significant improvement in time to progression has already been demonstrated in the combination of lapatinib and capecitabine compared with capecitabine monotherapy; for the most part, however, these trials are still in early stages.

Second consensus on medical treatment of metastatic breast cancer

The present consensus manuscript defines evidence-based recommendations for state-of-the-art treatment of metastatic breast cancer depending on disease-associated and biologic variables.

Phase II study of gemcitabine, doxorubicin and paclitaxel (GAT) as first-line chemotherapy for metastatic breast cancer: a translational research experience

BACKGROUND

Patients with metastatic breast cancer are frequently treated with anthracyclines and taxanes, which are among the most active agents in this disease. Gemcitabine is an interesting candidate for a three-drug combination because of its different mechanism of action and non-overlapping toxicity with respect to the other two drugs. We aimed to evaluate the activity and toxicity of the GAT (gemcitabine, doxorubicin and paclitaxel) regimen, derived from experimental preclinical studies, as first-line chemotherapy in patients with stage IIIB-IV breast cancer.

METHODS

Patients with locally advanced or metastatic breast cancer and at least one bidimensionally measurable lesion were included in the present study. Adequate bone marrow reserve, normal cardiac, hepatic and renal function, and an ECOG performance status of 0 to 2 were required. Only prior adjuvant non anthracycline-based chemotherapy was permitted. Treatment consisted of doxorubicin 50 mg/m2 on day 1, paclitaxel 160 mg/m2 on day 2 and gemcitabine 800 mg/m2 on day 6, repeated every 21-28 days.

RESULTS

Thirty-three consecutive breast cancer patients were enrolled onto the trial (7 stage IIIB and 26 stage IV). All patients were evaluable for toxicity and 29 were assessable for response. A total of 169 cycles were administered, with a median of 6 cycles per patient (range 1-8 cycles). Complete and partial responses were observed in 6.9% and 48.3% of patients, respectively, for an overall response rate of 55.2%. A response was reported in all metastatic sites, with a median duration of 16.4 months. Median time to progression and overall survival were 10.2 and 36.4 months, respectively. The most important toxicity was hematological, with grade III-IV neutropenia observed in 69% of patients, sometimes requiring the use of granulocyte colony-stimulating factor (27%). Non hematological toxicity was rare and mild. One patient died from sepsis during the first treatment cycle before the administration of gemcitabine.

CONCLUSION

The strong synergism among the three drugs found in the preclinical setting was confirmed in terms of both clinical activity and hematological toxicity. Our results seem to indicate that the GAT regimen is effective in anthracycline-naïve metastatic breast cancer and provides a feasible chemotherapeutic option in this clinical setting.