Five years of clinical experience with metronomic chemotherapy: achievements and perspectives

Case report: An exceptional responder of low-dose continuous 5-FU in a patient with de-novo stage IV triple-negative breast cancer with liver and bone marrow failure

Continuous low-dose 5-FU was popularized as a therapy for pretreated metastatic breast cancer for the past few decades, spurred by the advent of the electronic infusion pump. Capecitabine, otherwise known by its trade name Xeloda, is a prodrug of 5-fluorouracil (5-FU), which is administered orally in many chemotherapy regimens, and plays a role in metastatic breast cancer treatment refractory to traditional anthracyclines and taxane therapy. In this case presentation, we describe a unique case of refractory de-novo stage IV triple-negative breast cancer presented with right breast primary invasive ductal carcinoma, extensive lymphadenopathy, with biopsy proven bone marrow infiltration, diffuse hepatomegaly, splenomegaly, significant hyperbilirubinemia, and bone marrow failure treated with continuous 5-FU infusion and subsequently oral capecitabine after initial treatment failure with nab-paclitaxel and sacituzimab govitecan. With this case presentation, the authors aim to showcase the versatility of 5-FU and its prodrug in treatment of metastatic triple-negative breast cancer with severe bone marrow and liver involvement while highlighting key physiologic and pharmacologic mechanisms.

Metronomic capecitabine vs. best supportive care in Child-Pugh B hepatocellular carcinoma: a proof of concept

There is a relative lack of evidence about systemic treatments in patients with hepatocellular carcinoma (HCC) and moderate liver dysfunction (Child-Pugh B). In this multicenter study we retrospectively analyzed data from Child-Pugh B-HCC patients naïve to systemic therapies, treated with MC or best supportive care (BSC). To reduce the risk of selection bias, an inverse probability of treatment weighting approach was adopted. Propensity score was generated including: extrahepatic spread; macrovascular invasion; performance status, alphafetoprotein > 400 ng/ml, Child- Pugh score [B7 vs. B8-9]. We identified 35 MC-treated patients and 70 controls. Median overall survival was 7.5 [95% CI: 3.733-11.267]in MC-patients and 5.1 months [95% CI: 4.098-6.102] in the BSC group (p = 0.013). In patients treated with MC, median progression-free survival was 4.5 months (95% CI: 2.5-6.5). The univariate unweighted Cox regression showed a 42% reduction in death risk for patients on MC (95%CI: 0.370-0.906; p = 0.017). After weighting for potential confounders, death risk remained essentially unaltered. In the MC group, 12 patients (34.3%) experienced at least one adverse event, the most common of which were: fatigue (17.1%), hand-foot syndrome (8.5%), thrombocytopenia (8.5%), and neutropenia (5.7%). MC seems a safe option for Child-Pugh B-HCC patients. Its potential antitumour activity warrants prospective evaluations.

Metronomic Capecitabine Effectively Blocks Leptomeningeal Carcinomatosis From Breast Cancer: A Case Report and Literature Review

Patient: Female, 57

Final Diagnosis: Meningeal carcinomatosis from breast cancer

Symptoms: Seizures

Medication: —

Clinical Procedure: —

Specialty: Oncology

Metronomic chemotherapy and anti-angiogenesis: can upgraded pre-clinical assays improve clinical trials aimed at controlling tumor growth?

Metronomic chemotherapy, which is continuously administered systemically at close to non-toxic doses, targets the endothelial cells (ECs) that are proliferating during tumor angiogenesis. This leads to harmful effects of an even greatly increased number contiguous tumor cells. Although pre-clinical studies of angiogenesis-related EC features in vitro and of the anti-angiogenic and anti-tumor effects in vivo of metronomic chemotherapy have provided valuable insights, clinical trials with this type of therapy have been less successful in inhibiting tumor growth. One possible reason for the apparent disconnect between the pre-clinical and clinical outcomes is that most of the currently used experimental angiogenesis assays and tumor models are incapable of yielding data that can be translated readily into the clinical setting. Many of the assays used suffer from unintentional artifactual effects, e.g., oxidative stress in vitro, and inflammation in vivo, which reduces the sensitivity and discriminatory power of the assays. Co-treatment with an antioxidant or the inclusion of antioxidants in the vehicle often significantly affects the angiogenesis-modulating outcome of metronomic mono-chemotherapy in vivo. This ‘metronomic chemotherapy vehicle factor’ merits further study, as do the observations of antagonistic effects following metronomic treatment with a combination of standard chemotherapeutic drugs in vivo.

Metronomic chemotherapy in combination with antiangiogenic treatment induces mosaic vascular reduction and tumor growth inhibition in hepatocellular carcinoma xenografts

BACKGROUND

In addition to sprouting angiogenesis, other mechanisms, such as mosaic tumor vessel formation, have been recognized to contribute to tumor vascularization. We sought to examine vascular alteration as well as tumor growth inhibition after treatment with antiangiogenic therapy, chemotherapy alone or in combination.

METHODS

Hepatocellular carcinoma cells (Hep3B) expressed green fluorescent protein were utilized to establish orthotopic xenograft model in nude mice. The formation and distribution of mosaic vessels was analyzed quantitatively by immunolabeling. Next, changes in tumor microcirculation and therapeutic effects on tumor growth were evaluated in several different treatment groups: control, conventional doxorubicin, metronomic doxorubicin, bevacizumab, bevacizumab plus conventional doxorubicin, and bevacizumab plus metronomic doxorubicin. In addition, we examined the effects of combined regimens on lung metastasis using a highly metastatic human hepatocellular carcinoma (HCCLM3) mouse model.

RESULTS

Approximately 62 % of the vessels were present in the central part or near the midsection of the tumor and were mosaic. Only the combined antiangiogenic treatment and chemotherapy (metronomic schedule, P = 0.00; conventional schedule, P = 0.02) had a significant effect on the degree of mosaic vasculature. Metronomic doxorubicin in combination with bevacizumab had an even more profound effect than bevacizumab plus conventional doxorubicin (P < 0.05) on tumor growth inhibition and survival. However, bevacizumab plus metronomic doxorubicin failed to inhibit lung metastasis compared with antiangiogenic monotherapy.

CONCLUSIONS

Metronomic chemotherapy in combination with antiangiogenic treatment results in the reduction of mosaic tumor vasculature, inhibition of tumor growth, and enhanced survival of mice. Further investigation of drug scheduling is required to optimize antitumor activity.

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.

Metronomic gemcitabine in combination with sunitinib inhibits multisite metastasis and increases survival in an orthotopic model of pancreatic cancer

Metronomic chemotherapy suppresses growth of primary tumors and established metastases. However, its effect on metastatic progression is essentially unknown. We report the treatment of a metastatically competent model of pancreatic cancer with metronomic gemcitabine and sunitinib. Mice with orthotopic, red fluorescent protein-expressing, pancreatic cancer tumorgrafts were treated with gemcitabine on a metronomic (1 mg/kg daily, METG) or maximum tolerated dose (150 mg/kg twice weekly, MTDG) schedule with or without sunitinib (SU). Rates of primary tumor growth, metastasis, ascites, and survival were calculated. Gemcitabine at a daily dose of 2 mg or greater led to toxicity within 1 month in mice without tumors but METG at 1 mg/kg/d was well tolerated. Mice with pancreatic cancer tumorgrafts died with metastatic disease at a median of 25 days. METG/SU significantly prolonged median overall survival (44 days) compared with control or either regimen alone (P < 0.05). Primary tumor growth was inhibited by METG/SU (P = 0.03) but neither METG nor sunitinib alone. In contrast, treatment with METG suppressed metastasis at multiple sites, an effect enhanced by sunitinib. MTDG with or without sunitinib had the most favorable effect on primary tumor growth and survival, but its antimetastatic efficacy was similar to that of METG/SU. von Willebrand factor expression was inhibited by METG. Antimetastatic activity approaching that of MTDG is achieved with a total dose reduced 42 times using METG and is further enhanced by sunitinib. Our results suggest the potential of this therapeutic paradigm against pancreatic cancer in the adjuvant and maintenance settings.

Potential relevance of bell-shaped and u-shaped dose-responses for the therapeutic targeting of angiogenesis in cancer

Tumor angiogenesis, the growth of new blood vessels into tumors, facilitates tumor growth and thus represents an attractive therapeutic target. Numerous experimental angiogenesis inhibitors have been characterised and subsequently trialled in patients. Some of these agents have failed to show any substantial activity in patients. In contrast, others have been more successful, but even these provide only a few months extra patient survival. Recent work has focused on understanding the effects of anti-angiogenic agents on tumor biology and has revealed a number of new findings that may help to explain the limited efficacy of angiogenesis inhibitors. Herein, I review the evidence that hormetic dose-responses (i.e. bell-shaped and U-shaped dose-response curves) are often observed with anti-angiogenic agents. Agents reported to exhibit these types of dose-response include: 5-fluorouracil, ATN-161, bortezomib, cisplatin, endostatin, enterostatin, integrin inhibitors, interferon-α, plasminogen activator-1 (PAI-1), rapamycin, rosiglitazone, statins, thrombospondin-1, TGF-α1 and TGF-α3. Hormesis may also be relevant for drugs that target the vascular endothelial growth factor (VEGF) signalling pathway and for metronomic chemotherapy. Here I argue that hormetic dose-responses present a challenge for the clinical translation of several anti-angiogenic agents and discuss how these problems might be circumvented.

Combination of antiangiogenesis with chemotherapy for more effective cancer treatment

Angiogenesis is a hallmark of tumor development and metastasis and is now a validated target for cancer treatment. However, the survival benefits of antiangiogenic drugs have thus far been rather modest, stimulating interest in developing more effective ways to combine antiangiogenic drugs with established chemotherapies. This review discusses recent progress and emerging challenges in this field; interactions between antiangiogenic drugs and conventional chemotherapeutic agents are examined, and strategies for the optimization of combination therapies are discussed. Antiangiogenic drugs such as the anti-vascular endothelial growth factor antibody bevacizumab can induce a functional normalization of the tumor vasculature that is transient and can potentiate the activity of coadministered chemoradiotherapies. However, chronic angiogenesis inhibition typically reduces tumor uptake of coadministered chemotherapeutics, indicating a need to explore new approaches, including intermittent treatment schedules and provascular strategies to increase chemotherapeutic drug exposure. In cases where antiangiogenesis-induced tumor cell starvation augments the intrinsic cytotoxic effects of a conventional chemotherapeutic drug, combination therapy may increase antitumor activity despite a decrease in cytotoxic drug exposure. As new angiogenesis inhibitors enter the clinic, reliable surrogate markers are needed to monitor the progress of antiangiogenic therapies and to identify responsive patients. New targets for antiangiogenesis continue to be discovered, increasing the opportunities to interdict tumor angiogenesis and circumvent resistance mechanisms that may emerge with chronic use of these drugs.

Bevacizumab in the treatment of HER2-negative breast cancer

Angiogenesis has a clear and definite role in the breast cancer progression process, making antivascular endothelial growth factor (VEGF) therapies an attractive option for the treatment of metastatic breast cancer (MBC). Bevacizumab is a potent humanized monoclonal antibody to VEGF, which has shown regression of breast cancer in preclinical and clinical setting, either alone or in combination with cytotoxic treatment. Additionally, bevacizumab potentially increases the effectiveness of other anticancer therapies through the normalization of tumor vasculature, reduction of intratumoral pressure and improved tumor oxygenation. Phase 1/2 trials showed significant antitumor effects of bevacizumab in MBC, in particular in tumors not expressing HER2 receptor. A first phase 3 trial in pre-treated MBC patients showed better response rates but no survival benefit from the addition of bevacizumab to capecitabine. However, in two phase 2 trial in first-line setting in patients with MBC, bevacizumab improved progression-free survival in combination with weekly paclitaxel in comparison to paclitaxel alone or in combination with 3-weekly docetaxel in comparison with docetaxel alone, respectively. Bevacizumab in combination with taxanes seems to be a highly effective first-line treatment for MBC patients. Future research will investigate bevacizumab in the neoadjuvant or adjuvant setting, where even more potential may exist for these patients.