Metronomic cyclophosphamide and metformin inhibited tumor growth and repopulated tumor-infiltrating lymphocytes in an experimental carcinoma model

Metformin is a widely used antidiabetic biguanide. Retrospective data demonstrated the association of metformin use with survival benefit in multiple tumor types. Interest in repurposing metformin to treat cancer has not been translated into encouraging clinical benefit. In animal models, metformin activated cytotoxic T cells and exerted an immune-mediated anticancer effect. The current research was conducted to investigate the possible therapeutic benefit of metformin in combination with metronomic cyclophosphamide in an experimental cancer model. Ehrlich ascites carcinoma was injected into the subcutaneous tissue to induce solid tumors in syngeneic mice. Exponential solid tumor growth ensued and was effectively arrested with the administration of a cytotoxic dose of parenteral cyclophosphamide. Alternatively, oral metformin and continuous, low-dose cyclophosphamide significantly inhibited tumor growth relative to untreated mice. The drug combination was well tolerated. Histopathological examination of the tumor showed an increased number of tumor-infiltrating lymphocytes and enhanced expression of granzyme B by this drug combination. The current data suggests a potential role of metformin and metronomic chemotherapy that warrants further investigation.

Challenges and Opportunities for Celecoxib Repurposing

Drug repositioning, also known as drug repurposing, reprofiling, or rediscovery, is considered to be one of the most promising strategies to accelerate the development of new original drug products. Multiple examples of successful rediscovery or therapeutic switching of old molecules that did not show clinical benefits or safety in initial trials encourage the following of the discovery of new therapeutic pathways for them. This review summarizes the efforts that have been made, mostly over the last decade, to identify new therapeutic targets for celecoxib. To achieve this goal, records gathered in MEDLINE PubMed and Scopus databases along with the registry of clinical trials by the US National Library of Medicine at the U.S. National Institutes of Health were explored. Since celecoxib is a non-steroidal anti-inflammatory drug that represents the class of selective COX-2 inhibitors (coxibs), its clinical potential in metronomic cancer therapy, the treatment of mental disorders, or infectious diseases has been discussed. In the end, the perspective of a formulator, facing various challenges related to unfavorable physicochemical properties of celecoxib upon the development of new oral dosage forms, long-acting injectables, and topical formulations, including the latest trends in the pharmaceutical technology, such as the application of mesoporous carriers, biodegradable microparticles, lipid-based nanosystems, or spanlastics, was presented.

Metronomic Therapy in Palliation of Oral Cancer Patients-A Home Based Approach at the End of Life

INTRODUCTION

Despite the development of targeted therapies for the management of oral cancer patients, the cost of treatment is a concern in middle- and low-income countries. The present study assessed the feasibility of low-cost metronomic therapy as an alternative treatment modality in patients with unresectable or inoperable oral cancers.

METHODOLOGY

The study was a prospective, single-arm study. Unresectable, inoperable, and metastatic lip and oral cavity cancers were started on metronomic therapy, a combination of oral methotrexate 15 mg/m2 once a week and oral celecoxib 200 mg twice daily, as palliative therapy. The primary endpoint was overall survival. The secondary endpoints were a response to metronomic therapy, compliance, and toxicity.

RESULTS

From June 2018 to May 2020, 25 patients were started on metronomic therapy. The median age was 60 years. The median overall survival was 8.8 months. At eight weeks of therapy, 11 patients (44%) had a partial response, ten patients had stable disease (40%), and four patients had progressive disease (16%). The compliance with the therapy was 100%, and one patient (4%) developed grade III toxicity.

CONCLUSIONS

Considering the resource constraints and cost limitations in low and middle-income countries, oral metronomic therapy in the form of methotrexate and celecoxib should be regarded as a suitable regimen in the palliative treatment of patients with unresectable, metastatic, or advanced, recurrent cancers.

Breast cancer: Muscarinic receptors as new targets for tumor therapy

The development of breast cancer is a complex process that involves the participation of different factors. Several authors have demonstrated the overexpression of muscarinic acetylcholine receptors (mAChRs) in different tumor tissues and their role in the modulation of tumor biology, positioning them as therapeutic targets in cancer. The conventional treatment for breast cancer involves surgery, radiotherapy, and/or chemotherapy. The latter presents disadvantages such as limited specificity, the appearance of resistance to treatment and other side effects. To prevent these side effects, several schedules of drug administration, like metronomic therapy, have been developed. Metronomic therapy is a type of chemotherapy in which one or more drugs are administered at low concentrations repetitively. Recently, two chemotherapeutic agents usually used to treat breast cancer have been considered able to activate mAChRs. The combination of low concentrations of these chemotherapeutic agents with muscarinic agonists could be a useful option to be applied in breast cancer treatment, since this combination not only reduces tumor cell survival without affecting normal cells, but also decreases pathological neo-angiogenesis, the expression of drug extrusion proteins and the cancer stem cell fraction. In this review, we focus on the previous evidences that have positioned mAChRs as relevant therapeutic targets in breast cancer and analyze the effects of administering muscarinic agonists in combination with conventional chemotherapeutic agents in a metronomic schedule.

Necrosis in the Tumor Microenvironment and Its Role in Cancer Recurrence

Cancer recurrence is one of the most imminent problems in the current world of medicine, and it is responsible for most of the cancer-related death rates worldwide. Long-term administration of anticancer cytotoxic drugs may act as a double-edged sword, as necrosis may lead to renewed cancer progression and treatment resistance. The lack of nutrients, coupled with the induced hypoxia, triggers cell death and secretion of signals that affect the tumor niche. Many efforts have been made to better understand the contribution of hypoxia and metabolic stress to cancer progression and resistance, but mostly with respect to inflammation. Here we provide an overview of the direct anticancer effects of necrotic signals, which are not necessarily mediated by inflammation and the role of DAMPs (damage-associated molecular patterns) on the formation of a pro-cancerous environment.

Immune-triggered cancer treatment by intestinal lymphatic delivery of docetaxel-loaded nanoparticle

The maximally tolerated dose (MTD) approach in conventional chemotherapy accompanies adverse effects, primarily due to high drug concentrations in the blood after intravenous administration and non-specific damages to highly proliferating cells, including immune cells. This causes the immune system to dysfunction. To rather boost intrinsic tumor-fighting immune capacity, we demonstrate a new oral route treatment regimen of docetaxel (DTX) without apparent toxicity. The DTX-loaded cationic solid lipid nanoparticles (DSLN-CSG) were coated with an anionic polymer conjugated with glycocholic acid. The resulting nanoparticles (DSLN-CSG, ~120 nm in diameter) were actively absorbed in the distal ileum mediated by interactions with the apical sodium bile acid transporter. The plasma DTX profile was sustained up to 24 h after a single oral dose and did not impair the functions of the immune system. In mouse models, daily oral DSLN-CSG administration inhibited the growth of existing tumors and tumor formation by medication prior to cancer cell inoculation. The extent of effects depended on the cancer cell lines of melanoma, colorectal adenocarcinoma, and breast carcinoma. It was most effective for melanoma in growth inhibition and in preventing tumor formation in mice. During the medication, the cytotoxic T cell population increased while the populations of tumor-associated macrophage and regulatory T cell declined. The low dose daily oral treatment may help patients with intermittent maintenance therapy between MTD cycles and prevent tumor recurrence after completing remission for certain tumors.

Oral maintenance metronomic vinorelbine versus best supportive care in advanced non-small-cell lung cancer after platinum-based chemotherapy: The MA.NI.LA. multicenter, randomized, controlled, phase II trial

BACKGROUND

Oral vinorelbine administered at the maximum tolerated dose has already showed activity and a good safety profile in advanced non-small-cell lung cancer (NSCLC). The MA.NI.LA study was a phase II, multicenter, randomized, controlled trial that aimed to assess the effects of a 'switched maintenance' regimen with oral metronomic vinorelbine (OMV) in patients with NSCLC who had not progressed after first-line platinum-based chemotherapy.

PATIENTS AND METHODS

Patients were randomly assigned in a 1:1 ratio to either OMV (50 mg three-times weekly) as maintenance treatment or best supportive care (BSC). The primary endpoint was progression-free survival (PFS). Secondary endpoints included overall survival (OS), objective disease control rate (DCR, CR + PR + SD), safety and quality of life.

RESULTS

In total, 61 and 59 patients were assigned to OMV and BSC, respectively. At a median follow-up of 23.9 (IQR 10.2-38.2) months, patients treated with OMV reported a significantly lower progression rate compared to patient in the BSC arm (89% [54/61] vs 96% [56/58]; HR 0.73; 90% CI 0.53-0.999, p = 0.049). Median PFS for patients treated with vinorelbine was 4.3 months (95% CI 2.8-5.6) vs 2.8 months (95% CI 1.9-4.5) for patients receiving BSC. This benefit was specifically evident in patients aged ≥70 years, in current smokers, and in those who reported disease stabilization as best response to induction chemotherapy. OS and response rate and quality of life were similar in the two arms. Drop-out rate for major toxicity with OMV was unexpectedly high (25%, 14/61) mainly due to grade 3-4 neutropenia (11%, 7/61). Conclusions In patients with unselected NSCLC achieving disease control after platinum-based chemotherapy switch maintenance therapy with OMV prolonged PFS compared to BSC; however, the optimal dose of OMV requires further investigation.

The possible role of maintenance treatment for primary central nervous system lymphoma

Primary central nervous system lymphoma (PCNSL) is a rare and aggressive brain tumor. The prognosis is poor, with high rates of relapse and disease progression after treatment. In addition, PCNSL affects a largely older population, so that a significant proportion of patients are ineligible for intensive therapies and high-dose chemotherapy. The elderly patients are also susceptible to the accelerated and detrimental cognitive side effects of whole-brain irradiation which is an alternative consolidation to high-dose chemotherapy. Maintenance therapy has been shown to be a promising strategy to prolong remission time in other hematopoietic malignancies. Herein, we discuss the place of maintenance treatment in PCNSL in view of perspective obtained from hematological malignancies and non-Hodgkin's lymphoma.

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.

Pazopanib (GW786034) and cyclophosphamide in patients with platinum-resistant, recurrent, pre-treated ovarian cancer - Results of the PACOVAR-trial

PURPOSE

The prognosis is poor for patients with recurrent, platinum-resistant epithelial ovarian cancer (EOC). Evidence suggests that antiangiogenic treatment modalities could play a major role in EOC. A combined therapy consisting of the investigational oral antiangiogenic agent pazopanib and metronomic oral cyclophosphamide may offer a well-tolerable treatment option to patients with recurrent, previously treated EOC.

PATIENTS AND METHODS

This study was designed as a multicenter phase I trial evaluating the optimal dose as well as activity and tolerability of pazopanib with metronomic cyclophosphamide in the treatment of patients with recurrent, platinum-resistant, previously treated ovarian, peritoneal, or fallopian tube cancer. Here, 50mg cyclophosphamide were combined with 400 to 800mg pazopanib daily.

RESULTS

Sixteen patients were treated; mean age was 66years. At dose levels (DL) I and II, one instance of dose-limiting toxicity (DLT) was seen in one of 6 patients. At DL III, two of four patients showed a DLT, leading to a maximum tolerated dose (MTD) of 600mg pazopanib daily. Median number of administered cycles was 6 (2-13), with three patients being treated for at least 13months. Median progression-free survival (PFS) and overall survival (OS) were 8.35months and 24.95months, respectively. 155 adverse events (AE) occurred, most frequently elevation of liver enzymes, leukopenia, diarrhea and fatigue. Altogether, five serious adverse events (SAE) developed in four patients.

CONCLUSION

Pazopanib 600mg daily p.o. and metronomic cyclophosphamide 50mg daily p.o. is a feasible regimen for patients with recurrent platinum-resistant EOC and showed promising activity in this previously treated patient population.

TRIAL REGISTRATION

Clin.trial.gov registry no.: NCT01238770.

Metronomic and metronomic-like therapies in neuroendocrine tumors - Rationale and clinical perspectives

Metronomic therapy is characterized by the administration of regular low doses of certain drugs with very low toxicity. There have been numerous debates over the empirical approach of this regimen, but fewest side effects are always something to consider in order to improve patients' quality of life. Neuroendocrine tumors (NETs) are rare malignancies relatively slow-growing; therefore their treatment is often chronic, involving several different therapies for tumor growth control. Knowing that these tumors are highly vascularized, the anti-angiogenic aspect is highly regarded as something to be targeted in all patients harboring NETs. Additionally the metronomic schedule has proved to be effective on an immunological level, rendering this approach as a multi-targeted therapy. Rationalizing that advanced NETs are in many cases a chronic disease, with which patients can live for as long as possible, a systemic therapy with regular low doses and a very low toxicity is in many cases a judicious manner of pursuing stabilization. Metronomic schedule is usually correlated with chemotherapy in oncology, but other therapies, such as radiotherapy and biotherapy can be delivered in a metronomic like manner. This review describes clinical trials and case series involving metronomic therapies alone or in combination in patients with advanced NETs. Nowadays level of evidence about metronomic therapy in NETs is quite low, therefore future prospective clinical studies are needed to validate the metronomic approach in specific clinical settings.

Pharmacokinetic strategies to improve drug penetration and entrapment within solid tumors

Despite the discovery of a large number of anticancer agents, cancer still remains among the leading causes of death since the middle of the twentieth century. Solid tumors possess a high degree of genetic instability and emergence of treatment resistance. Tumor resistance has emerged for almost all approved anticancer drugs and will most probably emerge for newly discovered anticancer agents as well. The use of pharmacokinetic approaches to increase anticancer drug concentrations within the solid tumor compartment and prolong its entrapment might diminish the possibility of resistance emergence at the molecular pharmacodynamic level and might even reverse tumor resistance. Several novel treatment modalities such as metronomic therapy, angiogenesis inhibitors, vascular disrupting agents and tumor priming have been introduced to improve solid tumor treatment outcomes. In the current review we will discuss the pharmacokinetic aspect of these treatment modalities in addition to other older treatment modalities, such as extracellular matrix dissolving agents, extracellular matrix synthesis inhibitors, chemoembolization and cellular efflux pump inhibition. Many of these strategies showed variable degrees of success/failure; however, reallocating these modalities based on their influence on the intratumoral pharmacokinetics might improve their understanding and treatment outcomes.

Phase II Study With Epirubicin, Cisplatin, and Infusional Fluorouracil Followed by Weekly Paclitaxel With Metronomic Cyclophosphamide as a Preoperative Treatment of Triple-Negative Breast Cancer. Clin Breast Cancer. 2015;15:259-265. [PMID: 25933934 DOI: 10.1016/j.clbc.2015.03.002]

BACKGROUND

The aggressive biological behavior and the lack of target therapy prompts the search for new therapeutic approaches for triple-negative breast cancers.

PATIENTS AND METHODS

We evaluated the efficacy in terms of Ki-67 variation and clinical response but also the toxicity of a neoadjuvant regimen based on metronomic principles including ECF (epidoxorubicin with cisplatin on day 1 with low-dose 5-fluorouracil in continuous infusion every 21 days for 4 courses) followed by paclitaxel (90 mg/m(2)) on day 1, 8, and 15 every 28 days for 3 courses in combination with metronomic oral cyclophosphamide 50 mg/d for 12 weeks in patients with HER2-negative breast cancer (T2-T4a-d, N0-3, M0) with estrogen receptor and progesterone receptor < 10%.

RESULTS

We enrolled 34 patients from June 2009 to May 2013. All were considered evaluable on an intention-to treat basis. The mean difference between the percentage of Ki-67 positive cells evaluated in surgical resection specimens and in pretreatment tumor core biopsy was 41% (95% confidence interval [CI], 30-51; P < .0001) for the entire population, and 22% (95% CI, 7-38; P = .0097) in patients who did not achieve pathological complete response (pCR). Responses to the treatment were obtained in 31 patients [91%] of the patients, and 19 patients (56%; 95% CI, 35-70) had a pCR. Stable disease was observed in 3 patients and none had progressive disease. Grade ≥ 3 hematologic adverse events included leukopenia in 9% (3 of 34), neutropenia in 38% (13 of 34), and anemia in 3% (1 of 34) of patients. Nonhematologic Grade ≥ 3 toxicities included only stomatitis in 1 patient.

CONCLUSION

A neoadjuvant program with an ECF regimen followed by weekly paclitaxel with metronomic cyclophosphamide proved to be very effective, with high pCR rates, reduction of Ki-67, and it was associated with a low toxicity profile.

The toxicity of anti-VEGF agents when coupled with standard chemotherapeutics

Bevacizumab (Avastin®, Genentech, CA) was granted accelerated approval by the FDA for metastatic breast cancer in 2008. This occurred after the initial clinical trial, E2100, demonstrated an improvement in progression-free survival (PFS) and overall survival (OS) with the addition of bevacizumab to a standard chemotherapy. Unfortunately, the approval was rescinded in 2011 when two subsequent trials, AVADO and RIBBON-1, failed to show survival benefit. We compare and analyze the landmark trials E2100, AVADO and RIBBON-1, and suggest that the present-day clinical trial model may not be suited for the investigation of targeted therapies such as bevacizumab. The existing clinical trial model does not allow for modification of chemotherapeutic doses in a manner that maximizes the effect of biologic response modifiers and does not account for its "chemosensitizing" effect. The E2100, AVADO, and RIBBON-1 trials differed in the type and dose of chemotherapy, the dose and frequency of bevacizumab, and in the trial design, making it difficult to effectively compare and evaluate the results. The efficacy of combining bevacizumab with a maximum tolerated dose (MTD) of chemotherapy is also discussed in view of the observation that increased tumor response did not translate to an increase in survival. We suggest that even though angiogenesis inhibitors are non-toxic as monotherapies, they increase the toxicity of standard chemotherapy, and consequently a re-design of the now classic clinical trial model should be considered. Modifying the existing clinical trial model will lead to a more accurate evaluation of the safety and efficacy of bevacizumab and other biological agents in treating metastatic cancer.

Continuous low-dose oral chemotherapy in recurrent and persistent carcinoma of cervix following chemoradiation: a comparative study between prolonged oral cyclophosphamide and oral Etoposide

Aim:

To compare the efficacy and toxicities of low-dose oral cyclophosphamide and oral etoposide in patients with persistent and recurrent cervical cancer with gross pelvic disease following full course of chemoradiation therapy.

Materials and Methods:

30 patients with recurrent and persistent cervical cancer with gross pelvic disease were enrolled in this trial. The patients were randomly divided into two groups of 15 patients each with one group receiving low dose oral cyclophosphamide (100 mg/day) and the other group receiving low-dose oral etoposide (50 mg/day). Results were statistically analysed by IBM SPSS Statistics 19.

Results:

Oral etoposide was not well tolerated with grade 2 neutropenia occurring in 33.3% and grade 3 neutropenia in 6.6% and thrombocytopenia occurring in 13.3%. Oral cyclophosphamide group on the other hand was better tolerated with none of the patients having thrombocytopenia and 6.6% patients having grade 2 neutropenia. There were two complete response (15.38%) and one partial response at the end of study (7.6%) in the cyclophosphamide group whereas there was no complete response and two partial response (16.6%) in the oral etoposide group.

Conclusion:

Long-term, low-dose oral etoposide was found to be less tolerated without any significant effect with patients with persistent and recurrent cervical cancer with gross pelvic disease following full course of chemoradiation therapy in contrast to oral cyclophosphamide which was found to be effective and well-tolerated by the patients.