Prolonged clinical benefit with metronomic chemotherapy in patients with metastatic breast cancer

Modulating cancer mechanopathology to restore vascular function and enhance immunotherapy

Solid tumor pathology, characterized by abnormalities in the tumor microenvironment (TME), challenges therapeutic effectiveness. Mechanical factors, including increased tumor stiffness and accumulation of intratumoral forces, can determine the success of cancer treatments, defining the tumor's "mechanopathology" profile. These abnormalities cause extensive vascular compression, leading to hypoperfusion and hypoxia. Hypoperfusion hinders drug delivery, while hypoxia creates an unfavorable TME, promoting tumor progression through immunosuppression, heightened metastatic potential, drug resistance, and chaotic angiogenesis. Strategies targeting TME mechanopathology, such as vascular and stroma normalization, hold promise in enhancing cancer therapies with some already advancing to the clinic. Normalization can be achieved using anti-angiogenic agents, mechanotherapeutics, immune checkpoint inhibitors, engineered bacterial therapeutics, metronomic nanomedicine, and ultrasound sonopermeation. Here, we review the methods developed to rectify tumor mechanopathology, which have even led to cures in preclinical models, and discuss their bench-to-bedside translation, including the derivation of biomarkers from tumor mechanopathology for personalized therapy.

Combined oral low-dose cyclophosphamide endocrine therapy may improve clinical response among patients with metastatic breast cancer via Tregs in TLSs

Despite limited research on refractory and/or endocrine therapy failure in elderly metastatic breast cancer (MBC) patients, a prior study showed that low-dose oral cyclophosphamide (CY) can improve the overall survival rate of MBC patients, possibly through the immunoregulation of regulatory T cells (Tregs). We preliminarily investigated the combination of endocrine therapy (ET) with oral low-dose CY as salvage therapy in elderly patients via peripheral blood regulatory T-cell analyses. In addition, we evaluated the associations of tumor tertiary lymphoid structures (TLSs) with therapeutic outcomes. HR+/HER2- advanced breast cancer patients who received low-dose CY combined with ET or ET only from April 2015 to August 2021 were enrolled in this retrospective study. The primary outcome was the clinical control rate (CCR), and the secondary outcome was progression-free survival (PFS). Circulating T lymphocyte subpopulations represented by Tregs were monitored during treatment by flow cytometry methods. TLSs wereconfirmed by hematoxylin-eosin staining of pretreatment specimens, and CD3, CD4, and Foxp3 were detected using Opal multicolor immunofluorescence. A total of 85 patients who received CY + ET and 50 patients who received ET only were enrolled, the percentage of patients who received CCR was 73% (62/85) vs. 70% (45/50), and the objective response rate (ORR) was 28% (24/85) vs. 24% (12/50). No deaths occurred during the study period. The mean PFS time was 13 vs. 11 months (P = 0.03). In the CY + ET group, decreases in CD4+/CD25+/Foxp3+ T cells (P < 0.001) were favorable for both clinical control and prolonged PFS (P < 0.001). Compared with patients without TLSs, those with TLSs were more likely to have better clinical control and PFS (mean time = 6 months), and a greater number of Treg cells during TLS pretreatment correlated with longer PFS (P = 0.043). Oral low-dose CY combined with standard ET exerts immunological effects by decreasing Treg levels to achieve improved clinical responses. Moreover, patients with TLSs might benefit more from such therapy than those without TLSs, and a high Treg cell count in TLSs before treatment predicts better therapeutic efficacy.

A randomized phase II study of metronomic cyclophosphamide and methotrexate (CM) with or without bevacizumab in patients with advanced breast cancer

PURPOSE

Metronomic chemotherapy has the potential to offer tumor control with reduced toxicity when compared to standard dose chemotherapy in patients with metastatic breast cancer. As metronomic chemotherapy may target the tumor microvasculature, it has the potential for synergistic effects with antiangiogenic agents such as the VEGF-A inhibitor bevacizumab.

METHODS

In this randomized phase II study, patients with metastatic breast cancer were randomized to receive metronomic oral cyclophosphamide and methotrexate (CM) combined with bevacizumab (Arm A) or CM alone (Arm B). The primary endpoint was objective response rate (ORR). Secondary endpoints included progression-free survival (PFS), overall survival (OS), and safety and tolerability.

RESULTS

A total of 55 patients were enrolled, with 34 patients treated on Arm A and 21 patients treated on Arm B. The ORR was modestly higher in Arm A (26%) than in Arm B (10%); neither met the 40% cutoff for further clinical evaluation. The median time to progression (TTP) was 5.52 months (3.22-13.6) on Arm A and 1.82 months (1.54-6.70) on Arm B (log-rank p = 0.008). The median OS was 29.6 months (17.2-NA) on Arm A and 16.2 months (15.7-NA) on Arm B (log-rank p = 0.7). Common all-grade adverse events in both arms included nausea, fatigue, and elevated AST.

CONCLUSION

The combination of metronomic CM with bevacizumab significantly improved PFS over CM alone, although there was no significant difference in OS. Oral metronomic chemotherapy alone has limited activity in advanced breast cancer.

CLINICALTRIALS

gov Identifier: NCT00083031. Date of Registration: May 17, 2004.

High-Risk Peritoneal Mesothelioma: Does Metronomic Chemotherapy Have a Role?

Objective

To evaluate the feasibility, tolerance, and efficacy of OMCT (oral metronomic chemotherapy) after CRS + HIPEC for peritoneal mesothelioma in patients with poor prognostic factors: PCI > 20, incomplete CRS, poor performance status, or progression on systemic chemotherapy.

Methods

A retrospective analysis of patients undergoing CRS + HIPEC for peritoneal mesothelioma and receiving OMCT for poor risk factors.

Results

Sixteen patients underwent CRS + HIPEC between 2013 and 2017. The median PCI was 31.5. Complete cytoreduction (CC-0/1) was obtained in 8 patients (50%). All 16 received HIPEC except one patient with baseline renal dysfunction.Thirteen patients had PCI > 20 where only 5 had CC-0/1. Of 8 suboptimal cytoreduction (CC-2/3), 7 received OMCT (6 for progression on chemotherapy and one for mixed histology). Three patients had PCI < 20 and all had CC-0/1 clearance. Only one received OMCT for progression on adjuvant chemotherapy. Patients receiving OMCT for progression on adjuvant chemotherapy (ACT) were in poor PS.The median follow-up was 13.4 months. Five are alive with the disease (three are on OMCT). Six are alive without disease (2 are on OMCT). The mean OS was 24.3 months and the mean DFS was 18 months. Outcomes were similar between CC-0/1 and CC-2/3 groups, OMCT vs no OMCT groups.All patients receiving OMCT for progression on neoadjuvant chemotherapy had better survival (alive at 12, 20, 32, 36 months) compared to those receiving OMCT for progression on the ACT (p = 0.012).

Conclusion

OMCT is a good alternative in high-volume peritoneal mesothelioma with incomplete cytoreduction and progression on chemotherapy. OMCT may improve outcomes in these scenarios when started early.

What Is Known about Breast Cancer in Young Women?

Breast cancer (BC) is the second leading cause of cancer-related death in women under the age of 40 years worldwide. In addition, the incidence of breast cancer in young women (BCYW) has been rising. Young women are not the focus of screening programs and BC in younger women tends to be diagnosed in more advanced stages. Such patients have worse clinical outcomes and treatment complications compared to older patients. BCYW has been associated with distinct tumour biology that confers a worse prognosis, including poor tumour differentiation, increased Ki-67 expression, and more hormone-receptor negative tumours compared to women >50 years of age. Pathogenic variants in cancer predisposition genes such as BRCA1/2 are more common in early-onset BC compared to late-onset BC. Despite all these differences, BCYW remains poorly understood with a gap in research regarding the risk factors, diagnosis, prognosis, and treatment. Age-specific clinical characteristics or outcomes data for young women are lacking, and most of the standard treatments used in this subpopulation currently are derived from older patients. More age-specific clinical data and treatment options are required. In this review, we discuss the epidemiology, clinicopathologic characteristics, outcomes, treatments, and special considerations of breast cancer in young women. We also underline future directions and highlight areas that require more attention in future studies.

CHEOPS trial: a GINECO group randomized phase II assessing addition of a non-steroidal aromatase inhibitor to oral vinorelbine in pre-treated metastatic breast cancer patients

BACKGROUND

The objective of the CHEOPS trial was to assess the benefit of adding aromatase inhibitor (AI) to metronomic chemotherapy, oral vinorelbine, 50 mg, three times a week for pre-treated, HR + /HER2- metastatic breast cancer patients.

METHODS

In this multicentric phase II study, patients had to have progressed on AI and one or two lines of chemotherapy. They were randomized between oral vinorelbine (Arm A) and oral vinorelbine with non-steroidal AI (Arm B).

RESULTS

121 patients were included, 61 patients in Arm A and 60 patients in Arm B. The median age was 68 years. 109 patients had visceral metastases. They all had previously received an AI. The study had been prematurely stopped following the third death due to febrile neutropenia. Median PFS trend was found to be different with 2.3 months and 3.7 months in Arm A and Arm B, respectively (HR 0.73, 95%CI 0.50-1.06, p value = 0.0929). No statistical difference was shown in OS and better tumor response. 56 serious adverse events corresponding to 25 patients (21%) were reported (respectively, 12 (20%) versus 13 (22%) for arms A and B) (NS).

CONCLUSION

The addition of AI to oral vinorelbine over oral vinorelbine alone in aromatase inhibitor-resistant metastatic breast cancer was associated with a non-significant improvement of PFS. Several unexpected serious adverse events were reported. Metronomic oral vinorelbine schedule, at 50 mg three times a week, requires close biological monitoring. The question of hormonal treatment and chemotherapy combination remains open.

Evaluation of metronomic chemotherapy response using diffusion and dynamic contrast-enhanced MRI

PURPOSE

To investigate the feasibility of using diffusion MRI (dMRI) and dynamic contrast-enhanced (DCE) MRI to evaluate the treatment response of metronomic chemotherapy (MCT) in the 4T1 mammary tumor model of locally advanced breast cancer.

METHODS

Twelve Balb/c mice with metastatic breast cancer were divided into treated and untreated (control) groups. The treated group (n = 6) received five treatments of anti-metabolite agent 5-Fluorouracil (5FU) in the span of two weeks. dMRI and DCE-MRI were acquired for both treated and control groups before and after MCT. Immunohistochemically staining and measurements were performed after the post-MRI measurements for comparison.

RESULTS

The control mice had significantly (p<0.005) larger tumors than the MCT treated mice. The DCE-MRI analysis showed a decrease in contrast enhancement for the control group, whereas the MCT mice had a more stable enhancement between the pre-chemo and post-chemo time points. This confirms the antiangiogenic effects of 5FU treatment. Comparing amplitude of enhancement revealed a significantly (p<0.05) higher enhancement in the MCT tumors than in the controls. Moreover, the MCT uptake rate was significantly (p<0.001) slower than the controls. dMRI analysis showed the MCT ADC values were significantly larger than the control group at the post-scan time point.

CONCLUSION

dMRI and DCE-MRI can be used as potential biomarkers for assessing the treatment response of MCT. The MRI and pathology observations suggested that in addition to the cytotoxic effect of cell kills, the MCT with a cytotoxic drug, 5FU, induced changes in the tumor vasculature similar to the anti-angiogenic effect.

Metronomic chemotherapy of cyclophosphamide plus methotrexate for advanced breast cancer: Real-world data analyses and experience of one center

Background

Real‐world data of the CM regimen [cyclophosphamide (CTX) plus methotrexate (MTX)] in metronomic pattern for advanced breast cancer is limited to small‐sample or retrospective studies. This study was aimed to determine the effectiveness and safety of CM regimen in treating advanced breast cancer and to identify which patients are most likely to benefit from metronomic CM regimen.

Methods

Patients with advanced breast cancer who received the metronomic CM regimen at least once between January 2009 and February 2019 in Sun Yat‐sen University Cancer Center were included. Clinicopathological characteristics were collected. Overall survival (OS) and progression‐free survival (PFS) were assessed using Kaplan‐Meier estimates. Characteristics between patients with PFS < 6 months and ≥6 months were compared using the Chi‐square test. Univariate and multivariate Cox regression model was used to estimate the prognostic factors for PFS and OS.

Results

A total of 186 patients were included. The median age and follow‐up were 49 years and 13.3 months, respectively. Over 50% of the patients were estrogen receptor/progesterone receptor‐positive, and 60.8% had been heavily treated (≥3 lines). The objective response rate was 3.8%, the disease control rate at 12 weeks was 41.4%, and the clinical benefit rate at 24 weeks was 31.2% (58/186). The median PFS was 4.0 months [95% confidence interval (CI): 3.6‐4.7 months], the median duration of clinical benefit was 9.5 months (95% CI: 8.2‐10.8 months), and the median OS was 26.8 months (95% CI: 20.9‐37.7 months). Multivariate analysis for PFS revealed the CM regimen as maintenance therapy and no liver metastasis as favorable prognostic factors. Furthermore, patients without liver metastasis were more likely to have a PFS over 6 months than those with liver involvement (P = 0.022). Liver, lymph node, and brain metastases were unfavorable prognostic factors for OS. The CM regimen was well‐tolerated without newly reported adverse events.

Conclusions

The CM regimen was effective in selected patients. In clinical practice, it would be better used as maintenance therapy and in patients without liver metastasis. Further follow‐up investigation should be performed to examine its effect when used in combination with other treatments and determine predictive biomarkers.

Use of a multi-drug regimen gemcitabine, 5-fluorouracil, irinotecan, cisplatin, bevacizumab, docetaxel, and cyclophosphamide (GFIP/BDC) for heavily pretreated relapsed epithelial ovarian, fallopian tube and primary peritoneal cancer

Background

Epithelial ovarian cancer has the highest fatality rate of all gynecologic malignancies. Although the majority of patients achieve complete clinical response after initial cytoreductive surgery and platinum-based chemotherapy, most recur and almost all will eventually acquire platinum-resistance for which treatment options become limited. The objective of the study was to describe response and tolerability of metronomic chemotherapy regimen GFIP/BDC, a modification of the G-FLIP regimen, in patients with persistent or recurrent epithelial ovarian, fallopian tube, and primary peritoneal cancer.

Methods

A retrospective descriptive analysis of 20 patients from a single academic institution who received combination GFIP/BDC therapy from January 1, 2011 to August 31, 2016 for persistent or recurrent EOC/FT/PP. Treatment consisted of a 2-day combination of gemcitabine 300 mg, 5-fluorouracil 500 mg/m2, irinotecan 20-30 mg/m2, cisplatin 20 mg/m2, bevacizumab 4 mg/kg, docetaxel 20 mg/m2, and cyclophosphamide 200 mg/m2 administered every 14 days. Toxicities were retrospectively graded using CTCAE v4.0.

Results

Twenty patients were identified with a median age 57.5 years (range 32–71). A total of 85% of patients were non-Hispanic white, 90% had cancer of high-grade serous histology, and all had a GOG performance status of 0–1. Patients had received a median of 3 prior regimens and 95% were platinum-resistant. Median number of cycles of GFIP/BDC administered was 9 (range 3–48) and patients remained on treatment for a median of 5.1 months (range 1.5–24). Eleven patients (55%) experienced a partial clinical response with a median duration of 6 months (range 1.5–20). Six patients (30%) survived progression free for at least 6 months.

Ten patients (50%) experienced at least one grade 3/4 adverse event. Grade 3 adverse events were hematologic (n = 5), constitutional (n = 3), gastrointestinal (n = 3), neurologic (n = 2), and vascular (n = 1). There was only one grade 4 adverse event which was severe neutropenia. Patients discontinued treatment due to disease progression 65% (n = 13), toxicity 20% (n = 4), patient preference 10% (n = 2), and 5% (n = 1) is currently on treatment.

Conclusions

Selected patients with epithelial ovarian, fallopian tube or primary peritoneal cancer who have failed multiple lines of conventional cytotoxic treatment may benefit from GFIP/BDC. Toxicity might be a limiting factor for administration.

Metronomic Chemotherapy: A Systematic Review of the Literature and Clinical Experience

Metronomic chemotherapy, continuous and dose-dense administration of chemotherapeutic drugs with lowered doses, is being evaluated for substituting, augmenting, or appending conventional maximum tolerated dose regimens, with preclinical and clinical studies for the past few decades. To date, the principle mechanisms of its action include impeding tumoral angiogenesis and modulation of hosts' immune system, affecting directly tumor cells, their progenitors, and neighboring stromal cells. Its better toxicity profile, lower cost, and easier use are main advantages over conventional therapies. The evidence of metronomic chemotherapy for personalized medicine is growing, starting with unfit elderly patients and also for palliative treatment. The literature reviewed in this article mainly demonstrates that metronomic chemotherapy is advantageous for selected patients and for certain types of malignancies, which make it a promising therapeutic approach for filling in the gaps. More clinical studies are needed to establish a solidified role for metronomic chemotherapy with other treatment models in modern cancer management.

Activation of immune responses in patients with relapsed-metastatic head and neck cancer (CONFRONT phase I-II trial): Multimodality immunotherapy with avelumab, short-course radiotherapy, and cyclophosphamide

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Treatment of relapsed/metastatic head and neck cancer is unclear.

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Cyclophosphamide, avelumab, and radiotherapy may be effective for R/M-HNC.

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Combined treatment may improve avelumab activity without increasing its toxicity.

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Ongoing trials will clarify the potential of immunotherapy in RM-HNC patients.

Introduction and background

Second-line treatment of platinum-resistant relapsed/metastatic (R/M) head and neck cancer (HNC) is a currently unmet clinical need. Clinical trials showed improvement in overall survival and quality of life of R/M-HNC patients treated with anti-PD-1 regardless of the number of prior chemotherapy lines; however, the percentage of long-term survivors remains limited.

This study aims to test the hypothesis that attacking the tumor microenvironment at multiple levels can increase immunogenicity of R/M-HNC without worsening the safety profile of immune checkpoint inhibitors.

Methods/design

In this open label, multi-center, single-arm, Phase Ib/II, R/M-HNC patients pretreated with at least one line of therapy containing platinum, fluorouracil, and cetuximab will receive a daily metronomic dose of 50 mg cyclophosphamide without a drug-free break, 10 mg/kg avelumab on day 1 and every other week until progression, and a single fraction of 8 Gy radiotherapy on day 8.

Discussion

The treatment protocol aims to reverse immune evasion of the tumor through a radiotherapy-induced self-vaccination effect, suppression of CD4+ CD25+ FoxP3+ regulatory T-cell function by metronomic cyclophosphamide, and effector T-cell reactivation owing to the inhibition of the PD-1–PD-L1 axis by avelumab.

The immunologic interplay induced by the proposed combined treatment may theoretically improve the activity of avelumab without increasing its toxicity profile.

Finally, an ancillary translational study will be extended to all the patients’ population.

Trial registration

EudraCT n. 2017-000353-39.

Treatment of advanced breast cancer with a metronomic schedule of oral vinorelbine: what is the opinion of Italian oncologists?

BACKGROUND

The aim of this study was to record the opinions of Italian oncologists about the use of oral vinorelbine administered metronomically in patients with advanced breast cancer.

METHODS

A series of meetings were held throughout Italy, and participants were asked how much they agreed with each of the several statements.

RESULTS

The majority of oncologists agreed that the concept of the minimum biologically effective dose should be used for drugs administered metronomically. Over 50% agreed that metronomic vinorelbine is an option in first-line chemotherapy for patients with advanced breast cancer, including those with a terminal illness and the elderly, as well as in young and fit patients. Just over one-third of experts agreed that a combination of two chemotherapy agents instead of one is not desirable in metastatic breast cancer because of increased toxicity. Most experts agreed that the main aim of a first-line therapy is to control the disease over time and to preserve quality of life.

CONCLUSION

Metronomically administered oral vinorelbine, either as monotherapy or in combination with other drugs, is effective in the long-term treatment of patients with advanced breast cancer. The clinical profiles of patients should be carefully considered to determine the appropriate treatment strategy.

Explorative Analysis of Low-Dose Metronomic Chemotherapy with Cyclophosphamide and Methotrexate in a Cohort of Metastatic Breast Cancer Patients

Background

Low-dose metronomic chemotherapy (LDMC) is increasingly used in metastatic breast cancer (MBC). In this retrospective analysis, we examined the therapeutic effects and side effects of LDMC in a cohort of MBC patients.

Methods

Patients with MBC were included when LDMC with oral cyclophosphamide (CTX) and methotrexate (MTX) was administered between 2009 and 2015. The primary endpoint was disease control rate (DCR) ≥ 24 weeks after the start of LDMC. Secondary endpoints were duration of progression-free survival (PFS), rates of discontinuation due to side effects, and DCR with regard to subgroups.

Results

Retrospective data of 35 patients were available for this analysis. 31% patients achieved DCR. The median PFS was 12 weeks. 9% of patients discontinued LDMC due to adverse events. DCR was 37% in the first 2 lines and 25% in further lines of therapy. 22% of patients with multiple metastases and 35% with ≤2 different metastatic sites achieved DCR. DCR was achieved in 33% of hormone receptor(HR)-positive patients and 27% of HR-negative patients.

Conclusion

The DCR of 31% is in line with the results of previous phase II studies. LDMC was well tolerated. Subgroup analysis was not able to identify a group in which LDMC was more efficient.

Whether low-dose metronomic oral cyclophosphamide improves the response to docetaxel in first-line treatment of non-triple-negative metastatic breast cancer

Oral metronomic chemotherapy may target tumor cells indirectly via antiangiogenic activity, restoration of anticancer immune response, or induction of tumor dormancy. We initiated the single-center, randomized, open-label, phase II study to determine whether the addition of metronomic cyclophosphamide to docetaxel (T) (w/o trastuzumab) improves overall response rate (ORR) as first-line treatment among patients with non-triple-negative metastatic breast cancer (MBC). Eligible patients with previously untreated non-triple-negative MBC were randomly assigned (1:1) to receive 3-weekly cycles of Metro-TC (T 75mg/m², d1 plus oral cyclophosphamide 50 mg daily) or T alone. All patients received treatment until disease progression, unacceptable toxicity, or withdrawal of consent. The primary endpoint was ORR. Finally, 35 patients were randomized to Metro-TC group while 31 to T group. Median treatment cycles of T for both groups were 8. ORR was not improved by addition of metronomic cyclophosphamide to T (71.4% vs. 51.6%; P = 0.09). There was no statistically significant difference with regard to progression free survival (median 18.5 vs. 11.7 months; P = 0.07) or overall survival (median 33.7 vs. 33.6 months; P = 0.84) between the two group. Grade 3/4 adverse events (eg. neutropenia [100% vs. 100%], febrile neutropenia [29% vs. 29%], and neurotoxicity [6% vs. 3%]) were also comparable. There were no treatment-related deaths. We conclude that concomitant administration of metronomic cyclophosphamide and T does not appear to be a significantly active schedule for first-line treatment of non-triple-negative MBC.

Unfavorable prognostic role of tumor-infiltrating lymphocytes in hormone-receptor positive, HER2 negative metastatic breast cancer treated with metronomic chemotherapy

BACKGROUND

High levels of tumor-infiltrating lymphocytes (TILs) in primary triple negative and HER2-positive breast cancer (BC) have been associated with an improved patients' outcome. The role of TILs in Luminal (hormone receptor positive and HER2 negative) tumors remains to be elucidated. Moreover, the association between TILs and prognosis in the metastatic setting is still unknown.

PATIENTS AND METHODS

We evaluated the relationship between TILs and time to progression (TTP) in metastatic BC patients enrolled in a prospective phase II trial of metronomic chemotherapy, that used cyclophosphamide 50 mg daily, capecitabine 500 mg thrice daily and vinorelbine 40 mg orally three times a week (VEX combination).

RESULTS

Of the 108 ER + BC patients enrolled in the VEX trial, 92 (85%) had sufficient tumor tissue and were assessed for TILs in H&E stained slides. TILs were evaluated in 38 primary BC samples and 54 metastatic sites. High (≥10%) TILs levels were significantly correlated with high Ki-67 labeling index. At multivariable analysis, each 10% increase in TILs strongly predicted a worse TTP (HR: 1.27, p = 0.008). VEX trial patients, categorized by a 3 tiers system (0-4%, 5-9% and >10% TILs) showed significantly different progression free survival curves (p = 0.011).

CONCLUSIONS

High TILs levels are significantly associated with a worse TTP in Luminal metastatic BC patients treated by metronomic chemotherapy. Our data confirm the reliability of TILs as a biomarker in the BC metastatic setting. The putative unfavorable prognostic role of TILs in Luminal BC patients might have clinical utility if validated by further studies.

Knockdown of Hypoxia-Inducible Factor 1α Improved the Efficacy of Low-Dose Metronomic Chemotherapy of Paclitaxel in Human Colon Cancer Xenografts

Low-dose metronomic chemotherapy represents a new strategy for solid tumor treatments with a strong antiangiogenic activity and few side effects. However, low-dose metronomic therapy alone is not always as effective as traditional chemotherapy on eradication of tumor. On the contrary, low-dose metronomic in some cases could stimulate tumor growth due to hypoxia of tumor cells induced during therapy. Our study aimed to investigate whether knockdown of hypoxia-inducible factor-1α expression in tumor cell could facilitate low-dose metronomic therapy with paclitaxel for human colon cancer. Human colon cancer cell line (HT-29) stably transfected with specific short hairpin RNAs silencing hypoxia-inducible factor-1α exhibited marked attenuation of hypoxia-induced expression of the target genes such as vascular endothelial growth factor, glucose transporter 1, and P-glycoprotein. Compared with HT-29-c xenograft tumor model established by subcutaneous injection of HT-29 cells stably transfected with scrambled control short hairpin RNA, HT-29-ih xenograft tumor model showed more significant and long-lasting antitumor responses of empirical metronomic paclitaxel regimens, accompanied by drastic angiogenesis decrease and neglectable toxicity. All these data indicated that the combination of paclitaxel low-dose metronomic therapy with hypoxia-inducible factor-1α knockdown might provide a potent battle against colon cancer.

Targeted expression of BikDD combined with metronomic doxorubicin induces synergistic antitumor effect through Bax activation in hepatocellular carcinoma

Conventional chemotherapy is commonly used to treat advanced non-resectable hepatocellular carcinoma (HCC) but this treatment modality has not demonstrated convincing survival benefit in HCC patients. Our previous studies indicated that targeted expression of therapeutic BikDD driven by a liver cancer-specific α-fetoprotein promoter/enhancer (eAFP) in the VISA backbone (eAFP-VISA-BikDD) significantly and specifically kills HCC cells in multiple orthotopic animal models. To enhance its therapeutic efficacy, we combined eAFP-VISA-BikDD with chemotherapeutic agents and found that eAFP-VISA-BikDD plus doxorubicin (Dox) or 5-fluorouracil (5-FU) demonstrated synergistic cytotoxicity in HCC cells. Specifically, the combination of eAFP-VISA-BikDD plus Dox markedly induced apoptosis via increased Bax mitochondrial translocation and cytoplasmic cytochrome c release. Compared with either agent alone, a low dose of Dox combined with eAFP-VISA-BikDD induced better antitumor effect and prolonged longer survival of mice in two orthotopic liver cancer xenograft models. Our findings provide strong preclinical support for evaluating the combined therapy of eAFP-VISA-BikDD and Dox in a clinical setting as a treatment option for HCC.

Tumor-infiltrating lymphocytes (TILs) are a powerful prognostic marker in patients with triple-negative breast cancer enrolled in the IBCSG phase III randomized clinical trial 22-00

The purpose of this study was to assess the prognostic and predictive value of tumor-infiltrating lymphocytes (TILs) in the triple-negative breast cancer (TNBC) cohort of the phase III IBCSG trial 22-00, comparing low-dose oral 'metronomic' cyclophosphamide-methotrexate maintenance chemotherapy (CM-maintenance) to no-CM-maintenance in early breast cancer. TILs were evaluated in full-face hematoxylin-and-eosin-stained sections of tumor samples confirmed centrally as TNBC (< 1 % of ER and PgR immunoreactivity and absence of HER2 overexpression or amplification). Mononuclear cells were evaluated in the stromal area within the borders of the invasive tumor. The primary endpoint was breast cancer-free interval (BCFI). Cox proportional hazards regression model assessed the association of BCFI and secondary endpoints with TILs score. In the 647 tumor samples, the median percentage of TILs was 18 % (IQR = 8-40 %), with 18 % having TILs ≥ 50 % (lymphocyte-predominant breast cancer, LPBC). At a median follow-up of 6.9 years, TILs were associated with better prognosis. For every 10 % increase of TILs, BCFI risk reduction was 13 % (HR 0.87, 95 % CI 0.79-0.95,P = 0.003). DFS, DRFI, and OS risk reductions were 11 % (P = 0.005), 16 % (P = 0.003), and 17 % (P < 0.001), respectively. Multivariable analysis confirmed the independent prognostic value of TILs. No significant TILs-by-treatment interaction was observed (P = 0.39) for associations of TILs with BCFI, although patients with LPBC receiving CM-maintenance had a greater breast cancer risk reduction (HR 0.64,95 % CI 0.23-1.78) than those with non-LPBC (TILs < 50 %) (HR 0.96, 95 % CI 0.67-1.40). TILs score is a potent prognostic factor in patients with TNBC. Low-dose chemotherapy confers a greater (not statistically significant) clinical benefit in patients with LPBC.

Palliative systemic therapy for young women with metastatic breast cancer

PURPOSE OF REVIEW

Breast cancer in young women age less than 40 years remains a relatively rare disease. Emerging data suggest that the biology of breast cancer in younger women may differ from that of older women. Although metastatic breast cancer remains incurable, it is definitely treatable; especially in this era of emerging novel therapeutics.

RECENT FINDINGS

Most women have hormone receptor-positive disease and strategies that interfere with proliferation and the PI3 kinase pathway are reporting exciting results. The prognosis of the metastatic HER2 subtype has been extended to a median survival of 56 months with dual HER2 targeting agents in the first-line setting. Finally, triple negative breast cancer has an enlarging range of therapeutic options including immunotherapy, antiangiogenesis therapy, and targeted therapies including agents that interfere with androgen receptor signaling.

SUMMARY

Combined palliative and holistic approaches are essential to help young women navigate the marathon of treatment for metastatic breast cancer.

Dose-Dense Chemotherapy in Metastatic Breast Cancer: Shortening the Time Interval for a Better Therapeutic Index

Despite the advancement of targeted therapies in metastatic breast cancer, chemotherapy is still of pivotal importance. The concept of dose density is known to increase the efficacy of chemotherapy. In metastatic disease, preservation of the quality of life is equally important. Because of this, weekly regimens are a cornerstone in metastatic disease. Taxanes like paclitaxel or nab-paclitaxel as well as antracyclines are often used in palliative treatment. Further advances to increase dose density have led to the concept of daily metronomic schedules with oral chemotherapeutic drugs like cyclophosphamide, capecitabine, or vinorelbine. Metronomic chemotherapy affects tumor angiogenesis and also weakens immunosuppressive regulatory T cells, promoting better control of tumor progression. Weekly or daily dose-dense regimens are a reasonable compromise between efficacy and toxicity to improve the therapeutic index. This is most important for the treatment of chronic disease where palliation and preservation of quality of life are vital.

Potent efficacy of metronomic topotecan and pazopanib combination therapy in preclinical models of primary or late stage metastatic triple-negative breast cancer

Metronomic chemotherapy has shown promising activity in numerous preclinical studies and also some phase II clinical studies involving various tumor types, and is currently undergoing phase III trial evaluation. Triple-negative breast cancer (TNBC) is an aggressive histological subtype with limited treatment options and very poor prognosis following progression after standard chemotherapeutic regimens. Herein, we evaluated the potential therapeutic impact and molecular mechanisms of topotecan administered in a continuous low-dose metronomic (LDM) manner, alone or in concurrent combination with pazopanib, an antiangiogenic tyrosine kinase inhibitor (TKI), in a triple-negative, primary and metastatic breast cancer orthotopic model; potential molecular mechanisms of efficacy were also studied, especially the impact of hypoxic conditions. The combination of metronomic topotecan and pazopanib significantly enhanced antitumor activity compared to monotherapy with either drug and prolonged survival, even in the advanced metastatic survival setting, with a marked decrease in tumor vascularity, proliferative index, and the induction of apoptosis. Significant changes in tumor angiogenesis, cancer cell proliferation, apoptosis, HIF1α levels, HIF-1 target genes and ABCG2 were found both in vitro and in tumor tissue. Notably, the pazopanib and metronomic topotecan combination treatment inhibited expression of HIF1α and ABCG2 genes in cells grown under hypoxic conditions, and this was associated with an increased intracellular concentration of the active form of topotecan. Our results suggest a potential novel therapeutic option for the treatment of metastatic triple-negative breast cancer patients.

The war on cancer: a military perspective

Actually it has not quite happened yet, but almost imperceptibly, by degrees, we are learning to live with cancer. The “War on Cancer,” although generally successful in the pediatric population, has gradually been replaced with a kinder, gentler treatment paradigm that strives to contain and maintain with stalemate over checkmate, a strategy that may literally constitute the path to least resistance. The purpose of this review is (1) to critically examine the War on Cancer as a powerfully evocative metaphor that is directly responsible for a counterproductive and even potentially dangerous war-like cell-kill treatment paradigm, (2) to suggest that a reframing of this metaphor in less retaliatory and aggressive terms along with a shift in clinical practice from a maximalist to a minimalist strategy is more appropriate to the treatment of cancer, and (3) to draw on examples from the military sector as points of reference and comparison that closely parallel the three therapeutic “control and containment” strategies discussed in this review: (1) “Optimox-like” trial designs, (2) epigenetic modulation, and (3) metronomic dosing.

Metronomic therapy and breast cancer: a systematic review

Metronomic therapy (MT) refers to repetitive, low doses of chemotherapy drugs. MT exerts an effect not only on tumour cells, but also on their microenvironment. In particular, the low-dose schedule compromises the repairing process of endothelial cells, leading to an anti-angiogenic effect. In addition to the anti-angiogenic effect, MT could have an immunological action through the restoration of the anticancer effect of the immune system and induction of tumour dormancy. Consequently the association of targeted therapy with anti-angiogenic properties or specific immunologic drugs could enhance the efficacy of MT. During the past 15 years, several studies have been published evaluating the metronomic strategy in breast cancer. We conducted a systematic review of the results of phase I, II and III studies testing MT in breast cancer patients. The analyses included the efficacy and toxicity data of MT, and the future development of this strategy in breast cancer are also discussed. The systematic review presented here suggests that MT is a treatment option for breast cancer patients, has a low toxicity profile, efficacy in most patients and has potentially significant cost-effective advantages for public health.

Personalized adjuvant therapies: lessons from the past: the opening address by the St. Gallen 2013 award recipient

For several decades, personalized adjuvant therapies have been prescribed based on features that predict response to specific types of treatment. In this summary four specific issues regarding adjuvant therapies are described. Each one developed using information from past experience and is ready to be challenged by future findings from clinical trials and maturation of follow-up data. 1) Accuracy of determination of steroid hormone receptors and of HER2-status was the key feature in International Breast Cancer Study Group (IBCSG) and Breast International Group (BIG) trials. 2) Investigations on ovarian function suppression in IBCSG clinical trials led to the design of two trials (SOFT and TEXT), which are likely to lead to improved adjuvant therapy for premenopausal women with breast cancer. 3) Data from the BIG 1-98 trial of letrozole vs tamoxifen for postmenopausal patients with endocrine-responsive breast cancer provided information on which patients might obtain increased benefit from aromatase inhibitors and which might achieve similar treatment outcome with tamoxifen alone. 4) Finally, low-dose, frequently administered cytotoxics (metronomic chemotherapy) were tested in advanced disease with surprisingly favorable disease control and very low incidence of side effects. Personalized treatments are likely to improve substantially with increasingly accurate determination of their targets and by using risk- and toxicity-modulated therapies.

Metronomic cyclophosphamide: an alternative treatment for hepatic epithelioid hemangioendothelioma

Hepatic epithelioid hemangioendothelioma is a rare liver mesenchymatous tumor with an epithelial aspect developed from endothelial cells with a lack of validated therapeutic options at metastatic stage. Metronomic chemotherapy has been described as an anti-angiogenic therapy leading to the depletion of circulating endothelial progenitors. We report the results of two patients treated for metastatic hemangioendothelioma with metronomic cyclophosphamide chemotherapy. Following initiation of metronomic cyclophosphamide chemotherapy (50mg once a day continuously), the two patients exhibited significant clinical improvement and decrease in metastasis size without any clinically relevant side-effect. Metronomic cyclophosphamide could be proposed as a new therapeutic option to treat metastatic hepatic epithelioid hemangioendothelioma.

Combination antiangiogenic therapy in advanced breast cancer: a phase 1 trial of vandetanib, a VEGFR inhibitor, and metronomic chemotherapy, with correlative platelet proteomics

This phase 1 study evaluated the safety and tolerability of antiangiogenic therapy using vandetanib and metronomic cyclophosphamide and methotrexate in metastatic breast cancer. Eligible patients had metastatic breast cancer with 0-4 prior chemotherapy regimens. All received cyclophosphamide 50 mg daily, methotrexate 2.5 mg days 1-2 weekly, and vandetanib daily in 3 dose-escalation cohorts: 100 mg (C1), 200 mg (C2), and 300 mg (C3). The primary endpoint was safety and tolerability; secondary endpoints included response rate and evaluation of platelet-associated proteins. Twenty three patients were treated and evaluable for toxicity. Common mild toxicities included nausea, vomiting, LFTs abnormalities, fatigue, and rash. Three episodes of dose-limiting toxicity occurred in C3. In all cohorts, 1/3 of patients required vandetanib dose reduction, and 22 % ended therapy for toxicity. Of the 20 response-evaluable patients, 10 % demonstrated partial response and 15 % stable disease ≥24 weeks. Proteomic analyses demonstrated changes in platelet content of angiogenesis regulators, including vascular endothelial growth factor and platelet factor 4, with exposure to therapy. This regimen was tolerable at a maximum vandetanib dose of 200 mg; modest clinical activity was observed in this heavily pretreated population. Changes in the platelet proteome may serve as pharmacodynamic markers of angiogenesis inhibition. Metronomic chemotherapy is an attractive partner with biologics and deserves further study in metastatic breast cancer.

Chlorophyll derivative mediated PDT versus methotrexate: an in vitro study using MCF-7 cells

BACKGROUND

Breast cancer is the most common cause of cancer deaths among women worldwide. Although chemotherapy is a standard method for the treatment of breast cancer, the photodynamic therapy (PDT) is a recent promising modality for cancer diagnosis and treatment. Its major advantages over chemotherapy are better selectivity of tumour tissue destruction and lack of severe local and systemic complications. This work is directed towards evaluation of the efficacy of Photodynamic therapy using chlorophyll derivative (CHL) as a photosensitizer in treatment of breast cancer. It also aims at investigation of the genetic safety of chlorophyll mediated PDT in comparison to the conventional chemotherapy.

METHODS

Both methotrexate (MTX) and light activated chlorophyll derivative were used to target MCF-7 breast cancer cell line. Standard karyotyping and alkaline single cell microgel electrophoresis assay (Comet assay) were applied on normal human peripheral blood lymphocytes (HPL) in order to investigate the respective possible mutagenic and genotoxic side effects that might result from application of each therapeutic modality.

RESULTS

Results obtained from this study showed that 50% of MCF-7 tumour cell death (LC(50)) was reached by using a concentration of chlorophyll derivative that is 138 times lower than MTX. Moreover, chlorophyll derivative exerted no genetic side effects as compared to MTX that resulted into several types of chromosomal breakages.

CONCLUSIONS

Compared to MTX, light activated chlorophyll derivative proved to be a better candidate for breast cancer cell toxicity, referring to its higher efficacy at tumour cells killing, safety to normal cells and simple method of extraction.

Fine-tuning anti-tumor immunotherapies via stochastic simulations

BACKGROUND

Anti-tumor therapies aim at reducing to zero the number of tumor cells in a host within their end or, at least, aim at leaving the patient with a sufficiently small number of tumor cells so that the residual tumor can be eradicated by the immune system. Besides severe side-effects, a key problem of such therapies is finding a suitable scheduling of their administration to the patients. In this paper we study the effect of varying therapy-related parameters on the final outcome of the interplay between a tumor and the immune system.

RESULTS

This work generalizes our previous study on hybrid models of such an interplay where interleukins are modeled as a continuous variable, and the tumor and the immune system as a discrete-state continuous-time stochastic process. The hybrid model we use is obtained by modifying the corresponding deterministic model, originally proposed by Kirschner and Panetta. We consider Adoptive Cellular Immunotherapies and Interleukin-based therapies, as well as their combination. By asymptotic and transitory analyses of the corresponding deterministic model we find conditions guaranteeing tumor eradication, and we tune the parameters of the hybrid model accordingly. We then perform stochastic simulations of the hybrid model under various therapeutic settings: constant, piece-wise constant or impulsive infusion and daily or weekly delivery schedules.

CONCLUSIONS

Results suggest that, in some cases, the delivery schedule may deeply impact on the therapy-induced tumor eradication time. Indeed, our model suggests that Interleukin-based therapies may not be effective for every patient, and that the piece-wise constant is the most effective delivery to stimulate the immune-response. For Adoptive Cellular Immunotherapies a metronomic delivery seems more effective, as it happens for other anti-angiogenesis therapies and chemotherapies, and the impulsive delivery seems more effective than the piece-wise constant. The expected synergistic effects have been observed when the therapies are combined.

Low-dose docetaxel combined with (-)-epigallocatechin-3-gallate inhibits angiogenesis and tumor growth in nude mice with gastric cancer xenografts

Low-dose metronomic (LDM) chemotherapy represents a new strategy to treat solid tumors by stronger antiangiogenic activity and less side-effects, especially in combination with other antiangiogenic agents. The aim of the study is to investigate the antiangiogenic effect of docetaxel alone and combined with (-)-epigallocatechin-3-gallate (EGCG) in preclinical settings of gastric cancer. BGC-823 human gastric cancer xenograft model was used, and tumor growth, side-effects of mice were closely monitored. Expression of vascular endothelial growth factor and CD31 were observed by immunohistochemistry, and microvessel density of the tumor tissues was assessed by CD31 immunohistochemical analysis. Our results indicated that LDM docetaxel inhibited angiogenesis and growth of gastric cancer with less toxicity, and the effects were further enhanced by the concurrent administration of EGCG. Our study, for the first time, rationally demonstrated that LDM docetaxel treatment used alone or combined with EGCG is effective and safe in preclinical settings of gastric cancer. Our data suggest that LDM docetaxel used alone or combined with EGCG may be an innovative and promising therapeutic strategy in the experimental treatment of human gastric cancer.

Metronomic chemotherapy in metastatic breast cancer: impact on VEGF

BACKGROUND

Anticancer chemotherapy is thought to be effective by means of direct cytotoxicity on tumor cells. Alternative mechanisms of efficacy have been ascribed to several common anticancer agents; including cyclophosphamide (CTX) and capecitabine (Cap) when given at lower doses for prolonged period (metronomic chemotherapy) postulating an antiangiogenic activity as well.

AIM OF WORK

To evaluate the action and tolerability of metronomic chemotherapy (MC) and its impact on serum vascular endothelial growth factor (VEGF) levels in metastatic breast cancer (MBC) patients.

PATIENTS AND METHODS

In this study we evaluated the clinical efficacy and tolerability of low dose, capecitabine (500mg twice daily) together with oral cyclophosphamide (CTX) (a dose of 50mg once daily) in patients with metastatic breast cancer. Vascular endothelial growth factor (VEGF), an angiogenic marker, was measured in the serum samples; at base line, and after 2 and 6months of therapy.

RESULTS

Sixty patients were evaluable. One achieved complete response (CR), 12 partial responses (PR), and 21 stable diseases (SD), while 26 were with progressive disease (PD). The overall response rate was 21.7% with overall disease control (CR, PR, and SD) 56.7%. The median time to progression was 7±2.59months and overall survival 16±8.02months. Toxicity was mild, Palmar-plantar erythrodythesia was the most common side effect and was observed in 22 patients (37%), leucopenia (G1+2) was the most common hematological toxicity, and it was reported in 27% of the cases. The median VEGF level was significantly declined after 2 and 6months of therapy compared to the base line among the patients with disease control (CR, PR, and SD). In multivariate logistic regression analysis, patients with post-menopausal, positive hormonal receptors, negative HER-2/Neu, and one metastatic site, were statistically significant and have a better disease control rate.

CONCLUSIONS

MC induced drop in VEGF, and was effective, minimally toxic regimen for the treatment of metastatic breast cancer patients.

Capecitabine combined with (-)-epigallocatechin-3-gallate inhibits angiogenesis and tumor growth in nude mice with gastric cancer xenografts

Low-dose metronomic chemotherapy represents a new strategy to treat solid tumors by exhibiting stronger anti-angiogenic activity and less side effects, especially in combination with other anti-angiogenic agents. Capecitabine is a novel fluoropyrimidine carbamate, which has a broader spectrum of antitumor activity than other fluoropyrimidines, such as 5-FU, DFUR or UFT; it has proved effective over a wide dose range. The aim of this study was to investigate the anti-angiogenic effect of capecitabine alone and combined with the angiogenic inhibitor (-)-epigallocatechin-3-gallate (EGCG) on gastric cancer. A BGC-823 human gastric cancer xenograft model was used, and tumor growth, side effects and the number of days of survival of mice were closely monitored and recorded. Quantitative real-time PCR was used to determine vascular endothelial growth factor (VEGF) mRNA levels. The expression of VEGF and CD31 was determined by immunohistochemistry. Our results indicated that metronomic capecitabine inhibited angiogenesis, growth of gastric cancer and improved survival with less toxicity, and the effects were further enhanced by the concurrent administration of EGCG. Clinical trials and further pre-clinical studies, will hopefully provide answers to the use of continuous low-dose anti-angiogenic therapies for the treatment of human gastric cancer.

Detection of metastatic bone lesions in breast cancer patients: fused (18)F-Fluoride-PET/MDCT has higher accuracy than MDCT. Preliminary experience

PURPOSE

So far, no studies comparing (18)F-Fluoride-PET/CT and MDCT for the detection of bone metastases are available. We compared the accuracy of (18)F-Fluoride-PET/CT (MDCT: 3.75 mm thickness-image-reconstruction), whole-body Multi-Detector-CT (MDCT: 1.25 mm thickness-image-reconstruction) and (18)F-Fluoride-PET/MDCT (MDCT: 1.25 mm thickness-image-reconstruction) in identifying bone metastases in breast cancer patients.

METHODS

We studied 39 breast cancer patients for bone metastases. Imaging was performed on an integrated PET/MDCT-system; CT images were reconstructed at 3.75 mm and 1.25 mm thickness. Two nuclear medicine physicians and one radiologist interpreted blindly (18)F-Fluoride-PET/CT, (18)F-Fluoride-PET/MDCT and MDCT. MDCT at 12 months served as the standard of reference.

RESULTS

Overall, 662 bone lesions were detected in our analysis. Of these, 542 were malignant and 120 were benign according to the standard of reference. (18)F-Fluoride-PET/CT detected 491 bone metastases, 114 (23%) of which displayed no clear morphological changes on MDCT, whereas MDCT detected 416 bone metastases, 39 (9.3%) of which showed no (18)F-Fluoride-PET uptake. Overall sensitivity and specificity were: 91% and 91%, respectively, for (18)F-Fluoride-PET/CT, and 77% and 93% for MDCT. The integrated assessment of (18)F-Fluoride-PET/MDCT yielded sensitivity and specificity values of 98% and 93%, respectively.

CONCLUSIONS

(18)F-Fluoride-PET/MDCT has higher diagnostic accuracy than (18)F-Fluoride-PET/CT and MDCT for the evaluation of bone metastases in breast cancer.

[Metronomic chemotherapy in 2011: update and perspectives]

Angiogenesis is crucial for the growth and metastasis of many cancers. A series of new inhibitors of angiogenesis are now in intensive development. Recent preclinical studies suggest that frequent administration of certain conventional cytotoxic agents at low doses increases their putative antiangiogenic activity. Moreover, many clinical trials confirm efficacy of this metronomic chemotherapy in terms of clinical benefice and survival prolongation. Combining metronomic chemotherapy with hormonotherapy, angiogenesis inhibitors and radiotherapy increases efficacy. Many biomarkers are used to predict optimal drugs and appropriate use of them. This review describes experimental and clinical studies published and discuss its potential uses and limits.

Low-dosage metronomic chemotherapy and angiogenesis: topoisomerase inhibitors irinotecan and mitoxantrone stimulate VEGF-A-mediated angiogenesis

Albertsson P, Lennernäs B, Norrby K. Low-dosage metronomic chemotherapy and angiogenesis: topoisomerase inhibitors irinotecan and mitoxantrone stimulate VEGF-A-mediated angiogenesis. APMIS 2011.

Metronomic chemotherapy with cytotoxic agents has been shown to inhibit angiogenesis and, consequently, tumor growth by targeting vascular endothelial cells (ECs). In these regimens, anti-tumor activities additional to anti-angiogenesis may operate. Moreover, chemotherapy typically generates reactive oxygen species in targeted ECs, which can affect angiogenesis. The aim of the present study was to assess the systemic effect of low-dosage metronomic treatment with either irinotecan or mitoxantrone on angiogenesis induced by VEGF-A. Angiogenesis was induced in normal adult rat mesentery by intraperitoneal injection of a low dosage of VEGF-A. Thereafter, irinotecan and mitoxantrone were infused separately continuously at minimally toxic dosages for 14 consecutive days via a subcutaneous osmotic minipump. Angiogenesis was assessed in terms of objective and quantitative variables using morphologic and computerized image analyses. Irinotecan or mitoxantrone significantly stimulated angiogenesis, with ironotecan increasing angiogenesis by 104%, when compared with the vehicle-treated animals. Low-dosage metronomic chemotherapy with irinotecan or mitoxantrone stimulates angiogenesis in the normal mesentery of rats, probably by inducing low-level oxidative stress in the targeted ECs. Whether or not this pertains to tumor angiogenesis may be difficult to confirm, as several anti-tumor modes may operate during low-dosage metronomic chemotherapy.

Metronomic Cyclophosphamide and Methotrexate Chemotherapy Combined with 1E10 Anti-Idiotype Vaccine in Metastatic Breast Cancer

The use of low doses of cytotoxic agents continuously for prolonged periods is an alternative for the treatment of patients with metastatic breast cancer who have developed resistance to conventional chemotherapy. The combination of metronomic chemotherapy with therapeutic vaccines might increase the efficacy of the treatment. Twenty one patients with metastatic breast cancer in progression and a Karnosky index ≥60%, were treated with metronomic chemotherapy (50 mg of cyclophospamide orally daily and 2.5 mg of methotrexate orally bi-daily), in combination with five bi-weekly subcutaneous injections of 1 mg of aluminum hydroxide-precipitated 1E10 anti-idiotype MAb (1E10-Alum), followed by reimmunizations every 28 days. Five patients achieved objective response, eight showed stable disease and eight had disease progression. Median time to progression was 9,8 months, while median overall survival time was 12,93 months. The median duration of the response (CR+PR+SD) was 18,43 months (12,20–24,10 months), being higher than 12 months in 76,9% of the patients. Overall toxicity was generally mild. Metronomic chemotherapy combined with 1E10-Alum vaccine immunotherapy might be a useful therapeutic option for the treatment of metastatic breast cancer due to its potential impact on survival and patient quality of live, low toxicity and advantages of the administration.

Metronomic chemotherapy: changing the paradigm that more is better

The introduction of the "maximum tolerated dose" in usual treatment protocols (and its concomitant overt toxicity) made necessary the imposition of rest periods between cycles of therapy-a practice that not only involves re-growth of tumour cells, but also growth of selected clones resistant to the therapy. To avoid the problems caused by traditional chemotherapeutic regimens, a new modality of drug administration called "metronomic chemotherapy" has been proposed. This name makes reference to the chronic, equally spaced administration of (generally) low doses of various chemotherapeutic drugs without extended rest periods. The novelty of this treatment modality lies not only in its antitumour efficacy with very low toxicity, but also in a cell target switch, now aiming at tumour endothelial cells. The knowledge acquired in the experimental field of metronomic chemotherapy, plus the increasing experience that is being obtained in the clinical setting, will help to lead a change in the design of therapeutic protocols against cancer.

Tumors that acquire resistance to low-dose metronomic cyclophosphamide retain sensitivity to maximum tolerated dose cyclophosphamide

Low-dose metronomic (LDM) chemotherapy is emerging as an alternative or supplemental dosing strategy to conventional maximum tolerated dose (MTD) chemotherapy. It is characterized primarily, but not exclusively, by antiangiogenic mechanisms of action and the absence of high-grade adverse effects commonly seen with MTD chemotherapy. However, similar to other anticancer therapies, inherent resistance to LDM chemotherapy is common. Moreover, even tumors that initially respond to metronomic regimens eventually develop resistance through mechanisms that are as yet unknown. Thus, we have developed in vivo models of PC-3 human prostate cancer cells resistant to extended LDM cyclophosphamide therapy. Such PC-3 variants show stable resistance to LDM cyclophosphamide in vivo yet retain in vitro sensitivity to 4-hydroperoxy-cyclophosphamide (precursor of the active cyclophosphamide metabolite 4-hydroxy-cyclophosphamide) and other chemotherapeutic agents, namely, docetaxel and doxorubicin. Moreover, LDM cyclophosphamide-resistant PC-3 variants remain sensitive to MTD cyclophosphamide therapy in vivo. Conversely, PC-3 variants made resistant in vivo to MTD cyclophosphamide show varying levels of resistance to metronomic cyclophosphamide when grown in mice. These results and additional studies of variants of the breast cancer cell line MDA-MB-231 suggest that resistance to LDM cyclophosphamide is a distinct phenomenon from resistance to MTD cyclophosphamide and that LDM cyclophosphamide administration does not select for MTD chemotherapy resistance. As such, our findings have various implications for the clinical use of metronomic chemotherapy.