CDK12 promotes tumorigenesis but induces vulnerability to therapies inhibiting folate one-carbon metabolism in breast cancer.

Cyclin-dependent kinase 12 (CDK12) overexpression is implicated in breast cancer, but whether it has a primary or only a cooperative tumorigenic role is unclear. Here, we show that transgenic CDK12 overexpression in the mouse mammary gland per se is sufficient to drive the emergence of multiple and multifocal tumors, while, in cooperation with known oncogenes, it promotes earlier tumor onset and metastasis. Integrative transcriptomic, metabolomic and functional data reveal that hyperactivation of the serine-glycine-one-carbon network is a metabolic hallmark inherent to CDK12-induced tumorigenesis. Consistently, in retrospective patient cohort studies and in patient-derived xenografts, CDK12-overexpressing breast tumors show positive response to methotrexate-based chemotherapy targeting CDK12-induced metabolic alterations, while being intrinsically refractory to other types of chemotherapy. In a retrospective analysis of hormone receptor-negative and lymph node-positive breast cancer patients randomized in an adjuvant phase III trial to 1-year low-dose metronomic methotrexate-based chemotherapy or no maintenance chemotherapy, a high CDK12 status predicts a dramatic reduction in distant metastasis rate in the chemotherapy-treated vs. not-treated arm. Thus, by coupling tumor progression with metabolic reprogramming, CDK12 creates an actionable vulnerability for breast cancer therapy and might represent a suitable companion biomarker for targeted antimetabolite therapies in human breast cancers.

Long-term results of International Breast Cancer Study Group Trial VIII: adjuvant chemotherapy plus goserelin compared with either therapy alone for premenopausal patients with node-negative breast cancer.

BACKGROUND: The International Breast Cancer Study Group Trial VIII compared long-term efficacy of endocrine therapy (goserelin), chemotherapy [cyclophosphamide, methotrexate and fluorouracil (CMF)], and chemoendocrine therapy (CMF followed by goserelin) for pre/perimenopausal women with lymph-node-negative breast cancer. PATIENTS AND METHODS: From 1990 to 1999, 1063 patients were randomized to receive (i) goserelin for 24 months (n = 346), (ii) six courses of 'classical' CMF (cyclophosphamide, methotrexate, 5-fluorouracil) chemotherapy (n = 360), or (iii) six courses of CMF plus 18 months goserelin (CMF→ goserelin; n = 357). Tumors were classified as estrogen receptor (ER) negative (19%), ER positive (80%), or ER unknown (1%); 19% of patients were younger than 40. Median follow-up was 12.1 years. RESULTS: For the ER-positive cohort, sequential therapy provided a statistically significant benefit in disease-free survival (DFS) (12-year DFS = 77%) compared with CMF alone (69%) and goserelin alone (68%) (P = 0.04 for each comparison), due largely to the effect in younger patients. Patients with ER-negative tumors whose treatment included CMF had similar DFS (12-year DFS CMF = 67%; 12-year DFS CMF→ goserelin = 69%) compared with goserelin alone (12-year DFS = 61%, P= NS). CONCLUSIONS: For pre/perimenopausal women with lymph-node-negative ER-positive breast cancer, CMF followed by goserelin improved DFS in comparison with either modality alone. The improvement was the most pronounced in those aged below 40, suggesting an endocrine effect of prolonged CMF-induced amenorrhea.

Adverse prognostic value of peritumoral vascular invasion: is it abrogated by adequate endocrine adjuvant therapy? Results from two International Breast Cancer Study Group randomized trials of chemoendocrine adjuvant therapy for early breast cancer.

BACKGROUND: Peritumoral vascular invasion (PVI) may assist in assigning optimal adjuvant systemic therapy for women with early breast cancer. PATIENTS AND METHODS: Patients participated in two International Breast Cancer Study Group randomized trials testing chemoendocrine adjuvant therapies in premenopausal (trial VIII) or postmenopausal (trial IX) node-negative breast cancer. PVI was assessed by institutional pathologists and/or central review on hematoxylin-eosin-stained slides in 99% of patients (analysis cohort 2754 patients, median follow-up >9 years). RESULTS: PVI, present in 23% of the tumors, was associated with higher grade tumors and larger tumor size (trial IX only). Presence of PVI increased locoregional and distant recurrence and was significantly associated with poorer disease-free survival. The adverse prognostic impact of PVI in trial VIII was limited to premenopausal patients with endocrine-responsive tumors randomized to therapies not containing goserelin, and conversely the beneficial effect of goserelin was limited to patients whose tumors showed PVI. In trial IX, all patients received tamoxifen: the adverse prognostic impact of PVI was limited to patients with receptor-negative tumors regardless of chemotherapy. CONCLUSION: Adequate endocrine adjuvant therapy appears to abrogate the adverse impact of PVI in node-negative disease, while PVI may identify patients who will benefit particularly from adjuvant therapy.

Timing of CMF chemotherapy in combination with tamoxifen in postmenopausal women with breast cancer: role of endocrine responsiveness of the tumor.

BACKGROUND: Controversy persists about whether chemotherapy benefits all breast cancer patients. PATIENTS AND METHODS: In the International Breast Cancer Study Group (IBCSG) trial VII, 1212 postmenopausal patients with node-positive disease were randomized to receive tamoxifen for 5 years or tamoxifen plus three concurrent courses of cyclophosphamide, methotrexate and 5-fluorouracil ('classical' CMF) chemotherapy, either early, delayed or both. In IBCSG trial IX, 1669 postmenopausal patients with node-negative disease were randomized to receive either tamoxifen alone or three courses of adjuvant classical CMF prior to tamoxifen. Results were assessed according to estrogen receptor (ER) content of the primary tumor. RESULTS: For patients with node-positive, ER-positive disease, adding CMF either early, delayed or both reduced the risk of relapse by 21% (P=0.06), 26% (P=0.02) and 25% (P=0.02), respectively, compared with tamoxifen alone. There was no difference in disease-free survival when CMF was given prior to tamoxifen in patients with node-negative, ER-positive tumors. CONCLUSIONS: CMF given concurrently (early, delayed or both) with tamoxifen was more effective than tamoxifen alone for patients with node-positive, endocrine-responsive breast cancer, supporting late administration of chemotherapy even after commencement of tamoxifen. In contrast, sequential CMF and tamoxifen for patients with node-negative, endocrine-responsive disease was ineffective.

Preoperative and perioperative chemotherapy with 5-fluorouracil as continuous infusion in operable breast cancer expressing a high proliferation fraction: cytotoxic treatment during the surgical phase.

BACKGROUND: Experimental data on perioperative chemotherapy (PeCT) indicate that its initiation might be most useful if administered as close as possible to the time of first 'disturbance of the tumour'. Regimens including 5-fluorouracil (5-FU) as continuous infusion are commonly used in the preoperative setting, especially for large tumours and locally advanced disease. We therefore evaluated the role of PeCT with 5-FU as continuous infusion after preoperative chemotherapy (PreCT), covering the surgical phase and acute wound healing period, in patients with breast cancer too large to attempt breast-conserving surgery upon diagnosis. PATIENTS AND METHODS: Breast cancer patients, clinical stages T2-T3, N0-N2, M0, and Ki-67 labelling index >/= 20%, were treated every 3 weeks with a maximum of six courses of vinorelbine 20 mg total dose intravenously (i.v.) on days 1 and 3, cisplatin 60 mg/ m(2) i.v. on day 1 and 5-FU 200 mg/m(2)/day as a continuous infusion (ViFuP regimen). Patients who achieved a clinical and radiological objective remission with PreCT were also treated with perioperative 5-FU that was continued until 30 min before, and restarted immediately after surgery, prolonging infusion until 15 days after surgery. RESULTS: Following preoperative treatment, 39 of 49 evaluable patients [80%; 95% confidence interval (CI) 70% to 90%] had an objective response. Pathological complete remission (pCR) was achieved in 14 (29%) patients. No relevant clinical or haematological toxicity due to PeCT was observed. In 36 patients submitted to PeCT the rate of pCR was 33% (95% CI 18% to 48%). The highest response of the primary tumour to PreCT and PeCT was observed in women with tumours not expressing estrogen and progesterone receptors (pCR 46%; 95% CI 19% to 73%). CONCLUSIONS: Preoperative therapy can be protracted into the surgical (and wound healing) period without significant additional short-term toxicity. Proper selection of patients according to biological features might improve the therapeutic yield of preoperative therapies.

Duration of adjuvant chemotherapy for breast cancer: a joint analysis of two randomised trials investigating three versus six courses of CMF.

Cyclophosphamide, methotrexate and fluorouracil adjuvant combination chemotherapy for breast cancer is currently used for the duration of six monthly courses. We performed a joint analysis of two studies on the duration of adjuvant cyclophosphamide, methotrexate and fluorouracil in patients with node-positive breast cancer to investigate whether three courses of cyclophosphamide, methotrexate and fluorouracil might suffice. The International Breast Cancer Study Group Trial VI randomly assigned 735 pre- and perimenopausal patients to receive 'classical' cyclophosphamide, methotrexate and fluorouracil for three consecutive cycles, or the same chemotherapy for six consecutive cycles. The German Breast Cancer Study Group randomised 289 patients to receive either three or six cycles of i.v. cyclophosphamide, methotrexate and fluorouracil day 1, 8. Treatment effects were estimated using Cox regression analysis stratified by clinical trial without further adjustment for covariates. The 5-year disease-free survival per cents (+/-s.e.) were 54+/-2% for three cycles and 55+/-2% for six cycles (n=1024; risk ratio (risk ratio: CMFx3/CMFx6), 1.00; 95% confidence interval, 0.85 to 1.18; P=0.99). Use of three rather than six cycles was demonstrated to be adequate in both studies for patients at least 40-years-old with oestrogen-receptor-positive tumours (n=594; risk ratio, 0.86; 95% confidence interval, 0.68 to 1.08; P=0.19). In fact, results slightly favoured three cycles over six for this subgroup, and the 95% confidence interval excluded an adverse effect of more than 2% with respect to absolute 5-year survival. In contrast, three cycles appeared to be possibly inferior to six cycles for women less than 40-years-old (n=190; risk ratio, 1.25; 95% confidence interval, 0.87 to 1.80; P=0.22) and for women with oestrogen-receptor-negative tumours (n=302; risk ratio, 1.15; 95% confidence interval, 0.85 to 1.57; P=0.37). Thus, three initial cycles of adjuvant cyclophosphamide, methotrexate and fluorouracil chemotherapy were as effective as six cycles for older patients (40-years-old) with oestrogen-receptor-positive tumours, while six cycles of adjuvant cyclophosphamide, methotrexate and fluorouracil might still be required for other cohorts. Because endocrine therapy with tamoxifen and GnRH analogues is now available for younger women with oestrogen-receptor-positive tumours, the need for six cycles of cyclophosphamide, methotrexate and fluorouracil is unclear and requires further investigation.

Influence of endocrine-related factors on response to perioperative chemotherapy for patients with node-negative breast cancer.

PURPOSE: We investigated tumor- and patient-related features that might influence the response to perioperative chemotherapy (PeCT) compared with no adjuvant therapy for patients with node-negative breast cancer. PATIENTS AND METHODS: A total of 1,275 patients were randomized to either no adjuvant treatment (427 patients) or PeCT (848 patients). The following variables thought to have prognostic significance were evaluated: grade, tumor size, estrogen (ER) and progesterone receptor (PgR) content (absent; low, 1 to 9 fmol/mg cytosol protein; or positive, > or = 10 fmol/mg cytosol protein), c-erbB-2 overexpression, menopausal status, and age. Cox proportional hazards regression models were used to assess the relative influence of these factors to predict the effect of PeCT on disease-free survival (DFS). Median follow-up was 13.5 years. RESULTS: The 10-year DFS percentage for 692 premenopausal patients did not significantly differ between the PeCT and no-adjuvant-treatment groups: 61% and 59%, respectively (relative risk [RR], 0.95; 95% confidence interval [CI], 0.75 to 1.20; P = .70). No predictive factors were identified. For 583 postmenopausal patients, 10-year DFS percentages for the groups were 63% and 58%, respectively (RR, 0.75; 95% CI, 0.58 to 0.93; P = .03). The absence of expression of ER, PgR, or both ER and PgR was the most important factor predicting improved outcome with PeCT among postmenopausal patients. The 10-year DFS percentages were 85% and 53% for the steroid hormone receptor-absent cohort of treated and untreated patients, respectively (RR, 0.18; 95% CI, 0.06 to 0.49; P = .0009). CONCLUSION: The role of PeCT should be explored for patients whose primary tumors do not express steroid hormone receptors, because it is likely that early initiation of treatment is exclusively relevant for such patients.

Depression and degree of acceptance of adjuvant cytotoxic drugs.

An interaction between psychological attitude and outcome in early-stage breast cancer has been postulated, with a possible explanation related to the presumed tendency of depressed patients to be less proactive in obtaining health care. We report on the degree of acceptance of adjuvant chemotherapy in patients with breast cancer who have concomitant depression. Only 20 (51.3%) of the study group accepted and received the proposed chemotherapy compared with 75 (92.2%) of the control group (p<0.0001). Treatment of depression might be essential for tailoring adjuvant treatments with chemotherapy.

Early start of adjuvant chemotherapy may improve treatment outcome for premenopausal breast cancer patients with tumors not expressing estrogen receptors. The International Breast Cancer Study Group.

PURPOSE: The proper time to commence adjuvant chemotherapy after primary surgery for breast cancer is unknown. An analysis of the International (Ludwig) Breast Cancer Study Group (IBCSG) Trial V at a median follow-up of 11 years suggested that early initiation of adjuvant chemotherapy might improve outcome for premenopausal, node-positive patients whose tumors did not express any estrogen receptor (ER). PATIENTS AND METHODS: We investigated the relationship between early initiation of adjuvant chemotherapy, ER status, and prognosis in 1,788 premenopausal, node-positive patients treated on IBCSG trials I, II, and VI. The disease-free survival for 599 patients (84 with ER-absent tumors) who commenced adjuvant chemotherapy within 20 days (early initiation) was compared with the disease-free survival for 1,189 patients (142 with ER-absent tumors) who started chemotherapy 21 to 86 days after surgery (conventional initiation). The median follow-up was 7.7 years. RESULTS: Among patients with ER-absent tumors, the 10-year disease-free survival was 60% for the early initiation group compared with 34% for the conventional initiation group (226 patients; hazard ratio [HR], 0. 49; 95% confidence interval [CI], 0.33 to 0.72; P =.0003). This difference remained statistically significant in a Cox multiple regression analysis controlling for study group, number of positive nodes, tumor size, age, vessel invasion, and institution (HR, 0.60; 95% CI, 0.39 to 0.92; P =.019). Conversely, early initiation of chemotherapy did not significantly improve disease-free survival for patients with tumors expressing ER (1,562 patients; multiple regression HR, 0.93; 95% CI, 0.79 to 1.10; P =.40). CONCLUSION: In premenopausal patients with ER-absent tumors, early initiation of systemic chemotherapy after primary surgery might improve outcome. Further confirmatory studies are required before any widespread modification of current clinical practice. In premenopausal patients with tumors expressing some ER, gains from early initiation are unlikely to be clinically significant.

Primary chemotherapy in operable breast cancer with favorable prognostic factors: a pilot study evaluating the efficacy of a regimen with a low subjective toxic burden containing vinorelbine, 5-fluorouracil and folinic acid (FLN).

BACKGROUND: Biological considerations support the use of primary chemotherapy in operable breast cancer; and despite wide variations of used regimens, clinical studies consistently show a significant tumor response allowing breast conservation in many patients otherwise candidates for mastectomy. We investigated the efficacy and the acceptance of a combination chemotherapy with vinorelbine, 5-fluorouracil and high-dose folinic acid in operable breast cancer with favorable prognostic factors and tested the relationship of hormone receptor status, Ki67,p53, c-erbB2 and bcl-2 with treatment response. PATIENTS AND METHODS: Thirty-nine patients (median age 51 years, range 36-71 years), eight with T1, twenty-eight with T2 and two with T3 lesions, were treated with 5-fluorouracil (350 mg/m2, i.v. on day 1 to 3) preceded by folinic acid (100 mg/m2 i.v. on day 1 to 3) and vinorelbine, given on days 1 and 3 at the dose of 20 mg/m2 (FLN regimen). Therapy was administered on an outpatient basis every three weeks. Non responders had surgery after three courses, while complete or partial responders underwent surgery after six courses. All but one were evaluable for response and toxicity. RESULTS: Objective responses were observed in 23 of the 38 evaluable patients (61%; 95% CI: 46%-76%): three complete responses (8%) and 20 partial responses (53%). Fifteen patients (39%) had stable disease, of whom nine (23%) had minor response. None of the patients had disease progression during treatment. Objective responses were significantly associated with no expression of estrogen and/or progesterone receptors and > 50% decrease in Ki67 after induction chemotherapy. Tolerance was excellent and none of the patients experienced grade 2 alopecia. CONCLUSIONS: The 'moderate' efficacy of this regimen might be partially due to the selection of patients with high expression of steroid hormone receptors and low proliferation rate, which have an unfavorable impact on response to this chemotherapy.

Mortality during adjuvant treatment of early breast cancer with cyclophosphamide, methotrexate, and fluorouracil. International Breast Cancer Study Group.

Combined chemotherapy for early breast cancer with cyclophosphamide, methotrexate, and fluorouracil has low associated mortality, but related deaths were seen among women aged 65 years or older in International Breast Cancer Study Group trials.

Adding adjuvant CMF chemotherapy to either radiotherapy or tamoxifen: are all CMFs alike? The International Breast Cancer Study Group (IBCSG).

The first reported effective adjuvant combination regimen for patients with operable breast cancer comprised oral cyclophosphamide (C) days 1-14 with intravenous methotrexate (M) and fluorouracil (F) on days 1 and 8, repeated every 28 days ('classical' CMF). These drugs have since been extensively used with or without endocrine therapies and/or other cytotoxics, as well as with radiation therapy to the chest wall yielding conflicting results. Although doses and schedules have varied widely, the combination of these three drugs has been generically referred to as CMF. Evidence exists that reducing the dose and/or altering the schedule of CMF ('modified' CMF) have compromised its efficacy in metastatic breast cancer. Reduction below standard dose of a similar regimen also gave inferior results in the adjuvant setting. In fact, the recently reported improved outcome of adding radiation therapy to CMF was only demonstrated in comparisons with a 'modified' CMF. Furthermore, trials in women with estrogen receptor-positive breast cancer, which did not demonstrate any significant benefit for the addition of adjuvant CMF to tamoxifen compared with tamoxifen alone, also used 'modified' CMF. Therefore, adherence to the 'classical' dose and schedule is recommended when CMF is used in adjuvant therapy.

Adjuvant chemoendocrine therapy in postmenopausal breast cancer: cyclophosphamide, methotrexate, and fluorouracil dose and schedule may make a difference. International Breast Cancer Study Group.

PURPOSE: Adjuvant cytotoxics prolong disease-free survival (DFS) and overall survival (OS) in patients with operable breast cancer. The first reported effective adjuvant combination regimen consisted of oral cyclophosphamide on days 1 to 14 with intravenous methotrexate and fluorouracil on days 1 and 8, repeated every 28 days (classical CMF). These drugs have since been extensively used with or without endocrine therapies and/or other cytotoxic agents. Although doses and schedules have varied widely, the combination of these three drugs is generically referred to as CMF. RESULTS: Reducing the dose and/or altering the schedule of CMF have compromised its efficacy in metastatic breast cancer. Reduction below standard dose of a similar regimen also gave inferior results in the adjuvant setting. CONCLUSION: Details of dose and schedule may therefore explain part of the heterogeneity of results observed with CMF. Particular controversy surrounds the contribution of CMF in postmenopausal women who are also receiving tamoxifen (TAM). However, the trials that demonstrated a significant benefit for the addition of CMF to TAM, even in postmenopausal women with estrogen receptor-positive tumors, used classical CMF. Therefore, adherence to the classical dose and schedule is recommended when CMF is used in adjuvant therapy.

Activity and tolerability of courses of intra-arterial chemotherapy followed by chemoembolization in unresectable hepatocellular carcinoma.

AIMS AND BACKGROUND: We previously reported encouraging response rates and survival with combined intra-arterial (i.a.) chemotherapy and chemoembolization in unresectable hepatocellular carcinoma. We therefore evaluated a new program combining three courses of i.a. chemotherapy with chemoembolization administered every 28 days. PATIENTS AND METHODS: The treatment regimen consisted of L-leucovorin (100 mg/m2 i.v.), fluorouracil (800 mg/m2 i.a.), and carboplatin (250 mg/m2 i.a.). Chemoembolization with mitoxantrone (10 mg/m2) plus ethiodized oil and gelatin sponge was performed immediately after. The same treatment was given every 28 days for 3 times. RESULTS: Twenty-eight patients entered the study and were assessable for response and side effects. There were 24 males and 4 females (median age, 68 yrs; range, 42-75). TNM stage was II-III in 20 and IVA in 8; 17 were Child's A and 11 Child's B. Baseline alpha-fetoprotein was elevated in 15, and there was cirrhosis in 23. Twelve patients had a partial response (43%; 95% confidence interval, 24-63%), 13 had stabilization, and 3 progressive disease. Median survival was 16.6 months (range, 2-24). Sixteen patients had grade I-II pain and 14 grade I-II fever. CONCLUSIONS: Our results indicate that the regimen is safe and well tolerated. Despite 43% objective remissions, our results do not seem better than those obtained with less intensive regimens.

Dose-response effect of adjuvant cyclophosphamide, methotrexate, 5-fluorouracil (CMF) in node-positive breast cancer. International Breast Cancer Study Group.

There is evidence in the literature of a relationship between dose and response to adjuvant chemotherapy for breast cancer, although published results are conflicting. We therefore retrospectively analysed the role of dose response in patients included in four adjuvant trials of the International Breast Cancer Study Group (IBCSG, formerly the Ludwig Breast Cancer Study Group (trials I, II, III and V), all using 'classical' cyclophosphamide, methotrexate, and 5-fluorouracil (CMF). A total of 1385 node-positive patients were treated with oral cyclophosphamide, and intravenous methotrexate plus 5-fluorouracil (CMF) for at least six 4 week courses. 1350 of these were included in 6 month landmark treatment outcome analyses. A total of 1029 patients were premenopausal, 321 were postmenopausal; 800 had one to three and 550 more than three involved axillary nodes at surgery. The median follow-up ranged from 12 years for trial V to 15 years for trials I-III. Patients were grouped according to three prospectively defined dose levels based on the percentage of the protocol prescribed dose that was actually administered (level I > or = 85%, level II 65-84%, level III < 65%). Patients who received dose level II had a higher disease-free (P = 0.07) and overall survival (P = 0.03) than those who received a higher (level I) or lower (level III) percentage. The 10 year overall survival was 60% for dose level II, 56% for dose level I, 51% for dose level III. The results were generally consistent within trial, menopausal status, and oestrogen receptor status groups. The results within nodal groups showed a large difference among the dose levels for the group with one to three positive nodes (P = 0.02), but no difference for the group with four or more positive nodes. Our results indicate that the dose-response effect remains a crucial factor in adjuvant chemotherapy of breast cancer. Reductions larger than 35% in the dose administered of oral CMF adversely influenced the outcome of breast cancer patients and should be avoided. The better outcome of the intermediate dose group indicates the need to investigate other aspects involved in the cytotoxicity of adjuvant CMF chemotherapy.

Mitoxantrone, fluorouracil plus L-leucovorin, and vinorelbine in pretreated advanced breast cancer.

The combination chemotherapy including mitoxantrone, fluorouracil and leucovorin has proven to be effective and well-tolerated in advanced breast cancer (ABC). No data are available on the association with navelbine, a new vinka alkaloid, which has demonstrated high activity in ABC. The trial was designed to evaluate feasibility and efficacy of the association of vinorelbine to mitoxantrone, fluorouracil and L-leucovorin in patients who failed a previous regimen for ABC or who relapsed within 6 months of adjuvant chemotherapy. The schedule was as follows: mitoxantrone 6 mg/m2 days 1 and 8; L-leucovorin 250 mg/m2 days 1 and 8, fluorouracil 600 mg/m2 days 1 and 8, vinorelbine 25 mg/m2 days 1 and 8, cycles being repeated every 21 days. Twenty-five patients were enrolled and are evaluable for response and side effects. One hundred cycles of therapy have been delivered (median/patient, 4 cycles). In 41 cycles a delay was required and in 38 cycles it was necessary to administer granulocyte colony-stimulating factor for neutropenia. Seven partial remissions (28%; 95% confidence interval, 12-49%), 10 stabilizations of disease and 8 progressions were observed. Although grade 4 neutropenia was observed in 44% of the patients, no grade 3-4 infections were observed. Nonhematologic toxicities were mild or moderate and included alopecia, mucositis and phlebitis. In conclusion, the schedule employed, although correlated with a moderate activity, does not seem to be superior to other regimens with mitoxantrone, fluorouracil, and leucovorin.

Reversal of resistance to doxifluridine and fluorouracil in metastatic colorectal cancer: the role of high-dose folinic acid.

The benefits from medical treatment in colorectal cancer are limited. Fluorouracil remains the only recognized drug, and how to treat unresponsive patients is still debated. To evaluate the role of folinic acid (FA) in circumvence resistance in colorectal cancer, 28 patients pretreated with fluoropyrimidine were candidated to receive one of the following schedules: fluorouracil (600 mg/m2) associated with FA (500 mg/m2) weekly for 6 weeks (Regimen A: 21 cases), or fluorouracil (370 mg/m2) plus FA (200 mg/m2) daily for 5 days every 4 weeks (Regimen B: 7 cases). Fourteen patients were pretreated with doxifluridine, a new fluoropyrimidine derivative with a peculiar mechanism of action, and the remaining 14 patients with fluorouracil. All but 2 patients were unresponsive to first-line treatments. When the treatment began, the median age of the patients was 60 years (range, 30-68). The performance status (ECOG) was 0/1 in 25 of them, and the primary tumor was in the colon and rectum in 19 and 9 patients, respectively. Sites of disease were liver (64%), lung (35%), local recurrence (10%) and peritoneum (10%). A median of 3 cycles (range, 1-7) was delivered, and no objective response was observed in the group of patients pretreated with doxifluridine or in the group pretreated with fluorouracil. In 5 cases a significant decrease in baseline CEA values was observed. Therapy was well tolerated, and no grade 4 toxicity was encountered. Severe toxicity was limited and included diarrhea (7 patients), stomatitis (1 patient) and nausea/vomiting (1 patient). High-dose FA has no role in reversing resistance to fluoropyrimidine, and other mechanisms of refractoriness are surely involved. FA should be associated with fluoropyrimidine as first-line therapy together with other biochemical modulators. Further rescue therapies need to be developed.