Cyclophosphamide-based metronomic chemotherapy: After 10 years of experience, where do we stand and where are we going?

Synergistic Combination of Quercetin and Mafosfamide in Treatment of Bladder Cancer Cells

Bladder cancer, which has a rising incidence, is the 10th most common cancer. The transitional cell carcinoma histotype is aggressive and often current therapies are ineffective. We investigated the anti-proliferative effect of quercetin, a natural flavonoid, in combination with the alkylating agent mafosfamide (MFA) on two human bladder cancer cell lines, namely RT112 and J82, representing the progression from low-grade to high-grade tumors, respectively. In both cell types, the combined treatment led to a synergic reduction in cell viability confirmed by a combination index of less than one, though different biological responses were noted. In J82 cells, MFA alone and, to a lesser extent, with quercetin caused cell cycle arrest in the G2/M phase, but only the combined treatment triggered apoptotic cell death. In contrast, in RT112 cells, quercetin induced autophagy, evidenced by the autophagosome formation and the increase in LC-3 lipidation. Interestingly, the synergistic effect was observed only when cells were pre-treated with MFA for 24 h before adding quercetin, not in the reverse order. This suggests that quercetin may help overcome MFA resistance to apoptosis. Although further studies are needed, investigating the combined effects of quercetin and MFA could help elucidate the mechanisms of drug resistance in bladder cancer treatment.

Endophytic fungi: A future prospect for breast cancer therapeutics and drug development

Globally, breast cancer is a primary contributor to cancer-related fatalities and illnesses among women. Consequently, there is a pressing need for safe and effective treatments for breast cancer. Bioactive compounds from endophytic fungi that live in symbiosis with medicinal plants have garnered significant interest in pharmaceutical research due to their extensive chemical composition and prospective medicinal attributes. This review underscores the potentiality of fungal endophytes as a promising resource for the development of innovative anticancer agents specifically tailored for breast cancer therapy. The diversity of endophytic fungi residing in medicinal plants, success stories of key endophytic bioactive metabolites tested against breast cancer and the current progress with regards to in vivo studies and clinical trials on endophytic fungal metabolites in breast cancer research forms the underlying theme of this article. A thorough compilation of putative anticancer compounds sourced from endophytic fungi that have demonstrated therapeutic potential against breast cancer, spanning the period from 1990 to 2022, has been presented. This review article also outlines the latest trends in endophyte-based drug discovery, including the use of artificial intelligence, machine learning, multi-omics approaches, and high-throughput strategies. The challenges and future prospects associated with fungal endophytes as substitutive sources for developing anticancer drugs targeting breast cancer are also being highlighted.

Metronomic chemotherapy: bridging theory to clinical application in canine and feline oncology

Veterinary oncology has experienced significant evolution over the last few decades, with chemotherapy being currently applied to several neoplasms with therapeutic success. Traditionally, chemotherapy protocols are based on classic cytostatic drugs under the concept of maximum tolerated dose (MTD), which has been associated with a greater risk of toxicity and resistance. Thus, new therapeutic alternatives have emerged, such as metronomic chemotherapy (MC), introducing a new paradigm in cancer treatment. MC consists of administering low doses of chemotherapy drugs continuously over a long period of time, modulating the tumour microenvironment (TME) due to the combination of cytotoxic, antiangiogenic and immunomodulatory effects. This multi-targeted therapy has been described as a treatment option in several canine and feline cancers since 2007, with positive results already published in the literature, particularly in mammary carcinomas and soft tissue sarcomas in dogs. The aim of this review article is to describe the current knowledge about the use of MC in small animal oncology, with emphasis on its mechanisms of action, the most commonly used drugs and clinical outcome.

Metronomic chemotherapy in hematology: Lessons from preclinical and clinical studies to build a solid rationale for future schedules

Metronomic chemotherapy (mCHEMO), based on frequent, regular administration of low, but pharmacologically active drug doses, optimizes antitumor efficacy by targeting multiple targets and reducing toxicity of antineoplastic drugs. This minireview will summarize preclinical and clinical studies on cytotoxic drugs given at weekly, daily, or at continuous metronomic schedules alone or in combination with novel targeted agents for hematological malignancies, including lymphoma, multiple myeloma, and leukemia. Most of the preclinical in vitro and in vivo studies have reported a significant benefit of both mCHEMO monotherapy and combinatorial regimens compared with chemotherapy at the maximum tolerated dose. However, the combination of mCHEMO with targeted drugs is still little explored in the hematologic clinical setting. Data obtained from preclinical studies on low dose metronomic chemotherapy in hematological malignancies clearly suggested the possibility to clinically investigate more tolerable and effective strategies for the treatment of patients with advanced hematological malignancies, or at least for those frail and elderly patients, who are not eligible or resistant to standard treatments.

A Comprehensive Overview on Chemotherapy-Induced Cardiotoxicity: Insights into the Underlying Inflammatory and Oxidative Mechanisms

While oncotherapy has made rapid progress in recent years, side effects of anti-cancer drugs and treatments have also come to the fore. These side effects include cardiotoxicity, which can cause irreversible cardiac damages with long-term morbidity and mortality. Despite the continuous in-depth research on anti-cancer drugs, an improved knowledge of the underlying mechanisms of cardiotoxicity are necessary for early detection and management of cardiac risk. Although most reviews focus on the cardiotoxic effect of a specific individual chemotherapeutic agent, the aim of our review is to provide comprehensive insight into various agents that induced cardiotoxicity and their underlying mechanisms. Characterization of these mechanisms are underpinned by research on animal models and clinical studies. In order to gain insight into these complex mechanisms, we emphasize the role of inflammatory processes and oxidative stress on chemotherapy-induced cardiac changes. A better understanding and identification of the interplay between chemotherapy and inflammatory/oxidative processes hold some promise to prevent or at least mitigate cardiotoxicity-associated morbidity and mortality among cancer survivors.

Long-Term Survival of Cellulose Sulphate-Encapsulated Cells and Metronomic Ifosfamide Control Tumour Growth in Pancreatic Cancer Models-A Prelude to Treating Solid Tumours Effectively in Pets and Humans

BACKGROUND

The use of encapsulated cells for the in vivo delivery of biotherapeutics is a promising new technology to potentiate the effectiveness of cell-based therapies for veterinary and human application. One use of the technology is to locally activate chemotherapeutics to their short-lived highly active forms. We have previously shown that a stable clone of HEK293 cells overexpressing a cytochrome P450 enzyme that has been encapsulated in immunoprotective cellulose sulphate beads can be implanted near solid tumours in order to activate oxazaphosphorines such as ifosfamide and cyclophosphamide to the tumour-killing metabolite phosphoramide mustard. The efficacy of this approach has been shown in animal models as well as in human and canine clinical trials. In these previous studies, the oxazaphosphorine was only given twice. An analysis of the Kaplan-Meier plots of the results of the clinical trials suggest that repeated dosing might result in a significant clinical benefit.

AIMS

In this study, we aimed to (i) demonstrate the stable long-term expression of cytochrome P450 from a characterized, transfected cell clone, as well as (ii) demonstrate that one implanted dose of these encapsulated cytochrome P450-expressing cells is capable of activating multiple doses of ifosfamide in animal models.

METHODOLOGY

We initially used cell and molecular methods to show cell line stability over multiple passages, as well as chemical and biological function in vitro. This was followed by a demonstration that encapsulated HEK293 cells are capable of activating multiple doses of ifosfamide in a mouse model of pancreatic cancer without being killed by the chemotherapeutic.

CONCLUSION

A single injection of encapsulated HEK293 cells followed by multiple rounds of ifosfamide administration results in repeated anti-tumour activity and halts tumour growth but, in the absence of a functioning immune system, does not cause tumour regression.

Maintenance Chemotherapy for Patients with Rhabdomyosarcoma

Maintenance chemotherapy (MC) defines the administration of prolonged relatively low-intensity chemotherapy with the aim of "maintaining" tumor complete remission. This paper aims to report an update of the RMS2005 trial, which demonstrated better survival for patients with high-risk localized rhabdomyosarcoma (RMS) when MC with vinorelbine and low-dose cyclophosphamide was added to standard chemotherapy, and to discuss the published experience on MC in RMS. In the RMS2005 study, the outcome for patients receiving MC vs. those who stopped the treatment remains superior, with a 5-year disease-free survival of 78.1% vs. 70.1% (p = 0.056) and overall survival of 85.0% vs. 72.4% (p = 0.008), respectively. We found seven papers describing MC in RMS, but only one randomized trial that did not demonstrate any advantage when MC with eight courses of trofosfamide/idarubicine alternating with trofosfamide/etoposide has been employed in high-risk RMS. The use of MC showed better results in comparison to high-dose chemotherapy in non-randomized studies, including metastatic patients, and demonstrated feasibility and tolerability in relapsed RMS. Many aspects of MC in RMS need to be investigated, including the best drug combination and the optimal duration. The ongoing EpSSG trial will try to answer some of these questions.

Long-term adjuvant metronomic chemotherapy in a dog with recurrent maxillofacial osteosarcoma

Osteosarcoma (OSA) is the most common malignant bone tumour in dogs; however, OSA of the maxilla is uncommon compared to appendicular OSA. Oral melanoma also commonly occurs in dogs with frequent distant metastasis. The role of adjuvant chemotherapy has been questioned in maxillary OSA and melanoma. A 17-year-old English Cocker Spaniel was referred with a growing mass on the right maxilla and a right lower lip mass. Osteosarcoma was diagnosed after partial maxillectomy, and the right lower lip mass was diagnosed as oral melanoma. Metronomic chemotherapy (MC) was performed, and the number of doses was tapered due to side effects at 5 weeks after initiation of MC. After 130 weeks of MC, chemotherapy was suspended due to kidney disease. After the suspension of chemotherapy, findings suggesting recurrence and metastasis were detected. The dog suddenly died 193 weeks after surgery, which was 8-14 times longer than the expected survival time. To the best of our knowledge, this is the first case report of successful long-term combination therapy, including surgery and MC, in a dog with maxillary OSA and lip melanoma. Our results show that the survival time can be greatly extended if MC is performed with proper management.

The potential role of nanomedicine in the treatment of breast cancer to overcome the obstacles of current therapies

Breast cancer (BC) is the most frequently diagnosed malignant tumor among women in the world. BC is the heterogeneous tumor with different subtypes including luminal A-like, luminal B-like (HER2-/HER2+), HER2 enriched, and triple-negative BC. The therapeutic strategies including surgery, chemotherapy, radiotherapy, targeted therapy, and endocrine therapy are well developed and commonly used in the treatment of BC. However, some adverse effects of these conventional treatments limited their wide application in clinical. Therefore, it is necessary to develop more safe and more efficient individualized treatment strategies of the BC. Nanomedicine, as the most promising strategy for controlled and targeted drug delivery, is widely used in multiple aspects of cancer therapy. Importantly, accumulative evidences show that nanomedicine has achieved good outcomes in the treatment of BC and a huge amount of BC patients benefited from the nanomedicine related treatments. In this review, we summarized and discussed the major problems occurred during the administration of conventional treatment strategies for BC and the potential roles of nanomedicine in promoting the treatment efficacy of BC by overcoming obstacles of current treatment of BC.

Pharmacokinetics of Carboplatin in Combination with Low-Dose Cyclophosphamide in Female Dogs with Mammary Carcinoma

This prospective study aimed to evaluate the effect of metronomic cyclophosphamide on carboplatin’s tolerability, efficacy, and pharmacokinetics in dogs with mammary carcinoma. Sixteen female dogs with mammary carcinoma were divided into groups: 300 mg/m2 intravenous (i.v.) carboplatin therapy (G1 = 8) or 300 mg/m2 i.v. carboplatin which was associated with 12.5 mg/m2 oral cyclophosphamide in a metronomic regimen (G2 = 8). The investigated animals underwent a clinical evaluation, a mastectomy, a carboplatin chemotherapy, and serial blood sampling for the pharmacokinetic analysis. The adverse events and survival rates were monitored. A non-compartmental analysis was applied to calculate the pharmacokinetic parameters of carboplatin in the 2nd and 4th chemotherapy cycles. Carboplatin PK showed high interindividual variability with a 10-fold variation in the area under the plasma concentration−time curve (AUC) in G1. The systemic plasma exposure to carboplatin was equivalent in both of the treatments considering the AUC and maximum plasma concentration (Cmax) values. Although the red blood cells (p < 0.0001), platelets (p = 0.0005), total leukocytes (p = 0.0002), and segmented neutrophils (p = 0.0007) were reduced in G2, the survival rate increased (p = 0.0044) when it was compared to G1. In conclusion, adding low daily doses of cyclophosphamide to a carboplatin therapy showed promising outcomes in female dogs with mammary tumors.

Long-Term Efficacy and Safety of Anlotinib as a Monotherapy and Combined Therapy for Advanced Sarcoma

Objective

To analyze the effectiveness of the long-term (> 12 months) administration of anlotinib as a monotherapy or combined therapy in patients with advanced sarcomas.

Methods

A retrospective analysis was conducted of patients with advanced sarcomas with measurable target lesions since 2018. Twenty-two of the patients had taken anlotinib regularly for > 12 months. The patients’ general information and the drug’s clinical efficacy and toxicity data were collected and statistically analyzed using RECIST 1.1 to measure the target lesions and tumor PFS time as the main endpoints. We used a swimmer plot to observe the drug’s efficacy and duration, and employed a waterfall plot to express the best treatment effect.

Results

The study included 14 male and 8 female patients, ranging in age from 14 to 75 (mean: 44.82) years. The primary diseases included alveolar soft part sarcoma, synovial sarcoma, leiomyosarcoma, and others. The metastasis sites were the lungs in fifteen cases, lymph nodes in four cases, and multiple sites in three cases. Fourteen patients had previously undergone chemotherapy. The current therapy protocol was oral anlotinib alone for nine cases, combination chemotherapy for nine cases, and combination immunotherapy (anti-PD-1) for four cases. The highest clinical efficacy was complete remission (CR) in four (18.18%) cases, partial response (PR) in five (22.73%) cases, and stable disease in 13 (59.09%) cases, with an odds ratio of response of 40.91%. The mean PFS for the CR, PR, and stable disease groups was 16.50, 14.50, and 29.31 months, respectively (p < 0.05). The main adverse effects included hand-foot syndrome, hypertension, and leukopenia.

Conclusion

Anlotinib monotherapy or combination therapy can be more effective and safer for certain advanced sarcomas, with more extended maintenance and acceptable side effects. Clinical efficacy at the CR and PR levels might predict the long-term PFS in certain advanced sarcomas.

Phthalimide Analogs Enhance Genotoxicity of Cyclophosphamide and Inhibit Its Associated Hypoxia

Cyclophosphamide (CP) is a mutagen that is used in cancer chemotherapy, due to its genotoxicity and as an immunosuppressive agent. Thalidomide (TH) is another cancer chemotherapeutic drug. In this study, the cytogenotoxicity and hypoxia modulatory activities of two phthalimide analogs of TH have been evaluated with/without CP. Both analogs have increased CP-stimulated chromosomal aberrations than those induced by TH, including gaps, breaks/fragments, deletions, multiple aberrations, and tetraploidy. The analogs have elevated the cytotoxic effect of CP by inhibiting the mitotic activity, in which analog 2 showed higher mitosis inhibition. CP has induced binucleated and polynucleated bone marrow cells (BMCs), while micronuclei (MN) are absent. TH and analogs have elevated the CP-stimulated binucleated BMCs, while only analogs have increased the CP-induced polynucleated BMCs and inhibited the mononucleated BMCs. MN-BMCs were shown together with mononucleated, binucleated, and polynucleated cells in the CP group. Both analogs have elevated mononucleated and polynucleated MN-BMCs, whereas in presence of CP, TH and analogs have enhanced mononucleated and binucleated MN-BMCs. The analogs significantly induce DNA fragmentation in a comet assay, where analog 1 is the strongest inducer. The treatment of mice with CP has resulted in a high hypoxia status as indicated by high pimonidazole adducts and high HIF-1α and HIF-2α concentrations in lymphocytes. Analogs/CP-treated mice showed low pimonidazole adducts. Both analogs have inhibited HIF-1α concentration but not HIF-2α. Taken together, the study findings suggest that both analogs have a higher potential to induce CP-genotoxicity than TH and that both analogs inhibit CP-hypoxia via the HIF-1α-dependent mechanism, in which analog 1 is a more potent anti-hypoxic agent than analog 2. Analog 1 is suggested as an adjacent CP-complementary agent to induce CP-genotoxicity and to inhibit CP-associated hypoxia.

Metronomic Chemotherapy for Palliative Treatment of Malignant Oral Tumors in Dogs

The aim of this study was to evaluate the efficacy of metronomic chemotherapy in the palliative treatment of various malignant oral tumors in dogs. Our focus was to determine the effect of treatment on local disease control and to assess the tolerability and safety of the treatment in dogs with various oral malignancies. Metronomic chemotherapy with cyclophosphamide was used to treat 12 dogs and was combined with non-steroidal anti-inflammatory drugs in 6/12 (50%) of dogs. A clinical benefit was observed in 6/12 (50%) patients 1 month and in 4/12 (33%) 3 months after treatment initiation. The median survival time of the dogs was 155 days (range 21–529 days). At the end of the observation period, the disease had progressed in 10/12 (83.3%) of the patients. Sterile hemorrhagic cystitis was the most commonly reported side effect of treatment, occurring in 4/12 (33.3%) dogs. The results of our study suggest that metronomic chemotherapy with cyclophosphamide can be, in a subset of dogs, beneficial in the palliation of malignant oral tumors.

Breast Cancer Treatments: Updates and New Challenges

Breast cancer (BC) is the most frequent cancer diagnosed in women worldwide. This heterogeneous disease can be classified into four molecular subtypes (luminal A, luminal B, HER2 and triple-negative breast cancer (TNBC)) according to the expression of the estrogen receptor (ER) and the progesterone receptor (PR), and the overexpression of the human epidermal growth factor receptor 2 (HER2). Current BC treatments target these receptors (endocrine and anti-HER2 therapies) as a personalized treatment. Along with chemotherapy and radiotherapy, these therapies can have severe adverse effects and patients can develop resistance to these agents. Moreover, TNBC do not have standardized treatments. Hence, a deeper understanding of the development of new treatments that are more specific and effective in treating each BC subgroup is key. New approaches have recently emerged such as immunotherapy, conjugated antibodies, and targeting other metabolic pathways. This review summarizes current BC treatments and explores the new treatment strategies from a personalized therapy perspective and the resulting challenges.

Efficacy of the new therapeutic approach in curing malignant neoplasms on the model of human glioblastoma

OBJECTIVE

Glioma is a highly invasive tumor, frequently disposed in essential areas of the brain, which makes its surgical excision extremely difficult; meanwhile adjuvant therapy remains quite ineffective.

METHODS

In the current report, a new therapeutic approach in curing malignant neoplasms has been performed on the U87 human glioblastoma model. This approach, termed "Karanahan", is aimed at the eradication of cancer stem cells (CSCs), which were recently shown to be capable of internalizing fragments of extracellular double-stranded DNA. After being internalized, these fragments interfere in the process of repairing interstrand cross-links caused by exposure to appropriate cytostatics, and such an interference results either in elimination of CSCs or in the loss of their tumorigenic potency. Implementation of the approach requires a scheduled administration of cytostatic and complex composite double-stranded DNA preparation.

RESULTS

U87 cells treated in vitro in accordance with the Karanahan approach completely lost their tumorigenicity and produced no grafts upon intracerebral transplantation into immunodeficient mice. In SCID mice with developed subcutaneous grafts, the treatment resulted in reliable slowing down of tumor growth rate (P < 0.05). In the experiment with intracerebral transplantation of U87 cells followed by surgical excision of the developed graft and subsequent therapeutic treatment, the Karanahan approach was shown to reliably slow down the tumor growth rate and increase the median survival of the mice twofold relative to the control.

CONCLUSIONS

The effectiveness of the Karanahan approach has been demonstrated both in vitro and in vivo in treating developed subcutaneous grafts as well as orthotopic grafts after surgical excision of the tumor.

Metronomic Therapy in Oral Squamous Cell Carcinoma

Metronomic therapy is characterized by drug administration in a low-dose, repeated, and regular manner without prolonged drug-free interval. The two main anticancer mechanisms of metronomic therapy are antiangiogenesis and immunomodulation, which have been demonstrated in several delicate in vitro and in vivo experiments. In contrast to the traditional maximum tolerated dose (MTD) dosing of chemotherapy, metronomic therapy possesses comparative efficacy but greatlydecreases the incidence and severity of treatment side-effects. Clinical trials of metronomic anticancer treatment have revealed promising results in a variety cancer types and specific patient populations such as the elderly and pediatric malignancies. Oral cavity squamous cell carcinoma (OCSCC) is an important health issue in many areas around the world. Long-term survival is about 50% in locally advanced disease despite having high-intensity treatment combined surgery, radiotherapy, and chemotherapy. In this article, we review and summarize the essence of metronomic therapy and focus on its applications in OCSCC treatment.

Penis as a primary site of an extraskeletal Ewing sarcoma: A case report

RATIONALE

The Ewing sarcoma family of malignant tumors is a group of tumors characterized by morphologically similar round-cell neoplasms and by the presence of a common chromosomal translocation; Ewing sarcoma family of tumors typically occur in children and young adults between 4 to 15 years of age. The primary tumor usually originates in the bone, extraskeletal localization is rare.

PATIENT CONCERN

We present a case report concerning a 32-year-old male patient with a primary involvement of the penis.

DIAGNOSIS

The histopathology from the first penile biopsy showed a small-cell neuroendocrine carcinoma; however, that result was based on a sample obtained at a different facility than the Sarcoma Center, where the investigating pathologist did not have the adequate expertise. The patient then underwent a radical penectomy and a second reading of the histology was demanded after a radical penile amputation when Ewing sarcoma with R1 resection was confirmed.

INTERVENTIONS

The patient was referred to the national Sarcoma Center, where - using a multidisciplinary approach - the treatment was started with curative intent. However, it was preceded by a non-standard initiation of the therapy due to the poor primary diagnosis.

OUTCOMES

The non-standard therapy at the onset of the disease caused a poor prognosis of an otherwise curable diagnosis. Despite all that, the patient survived for a relatively long time.

LESSONS

The treatment of sarcomas with atypical localizations should be conducted by an experienced multidisciplinary team in a center with experience in sarcoma treatment.

Astragalus polysaccharides and astragaloside IV ameliorates cyclophosphamide-induced mouse model of overactive bladder

OBJECTIVE

Previous studies have shown that Astragalus polysaccharides (APS) and Astragaloside IV (AS-IV) protect against inflammation-related cell damage and exhibit immune enhancement. Since urothelial injury may result in an overactive bladder (OAB), the aim of this study was to investigate the efficacy of APS and AS-IV on urothelial injury in an experimental animal model.

MATERIALS AND METHODS

The effects of APS and AS-IV on the proliferation and migration of primary human urothelial cells (HUCs) or primary human fibroblast cells (HFCs) were assessed using an in vitro wounding model and colorimetric thiazolyl blue assays. Sixty virgin female mice were randomized into five groups: group 1-saline-injected plus treatment with H₂O, group 2-cyclophosphamide (CYP) plus treatment with H₂O, group 3-CYP plus treatment with solifenacin succinate (SS; 10 mg/kg), group 4-CYP plus treatment with AS-IV (100 mg/kg), and group 5-CYP plus treatment with APS (100 mg/kg). Cystometry assessment was conducted and cell junction-associated protein zonula occludens-2 (ZO-2) expression was measured. Voiding interval values (time between voids) were assessed in mice under anesthesia. Lastly, immunohistochemistry analysis was used to confirm the location and level, respectively, of ZO-2 expression.

RESULTS

APS and AS-IV did not influence the cell viability but increased migration in HFCs compared with the controls. The OAB mice showed significantly lower voiding interval values. Voiding interval values were significantly higher in the CYP plus treatment with APS (100 mg/kg) and AS-IV (100 mg/kg) groups than in the CYP-induced OAB group. Additionally, the expression of ZO-2, a tight junction protein, was increased in the CYP plus treatment APS (100 mg/kg) and AS-IV (100 mg/kg) groups compared with the CYP-induced OAB group.

CONCLUSION

These findings suggest that APS and AS-IV modulate urothelial wound healing, which ameliorates urinary frequency of mice treated with CYP. APS or AS-IV may have the potential benefit of acting as urothelial wound healing modulators.

Ziyuglycoside II alleviates cyclophosphamide-induced leukopenia in mice via regulation of HSPC proliferation and differentiation

Ziyuglycoside II (ZGS II) is a major bioactive ingredient of Sanguisorbae officinalis L., which has been widely used for managing myelosuppression or leukopenia induced by chemotherapy or radiotherapy. In the current study, we investigated the pro-hematopoietic effects and underlying mechanisms of ZGS II in cyclophosphamide-induced leukopenia in mice. The results showed that ZGS II significantly increased the number of total white blood cells and neutrophils in the peripheral blood. Flow cytometry analysis also showed a significant increase in the number of nucleated cells and hematopoietic stem and progenitor cells (HSPCs) including ST-HSCs, MPPs, and GMPs, and enhanced HSPC proliferation in ZGS II treated mice. The RNA-sequencing analysis demonstrated that ZGS II effectively regulated cell differentiation, immune system processes, and hematopoietic system-related pathways related to extracellular matrix (ECM)-receptor interaction, focal adhesion, hematopoietic cell lineage, cytokine-cytokine receptor interaction, the NOD-like receptor signaling pathway, and the osteoclast differentiation pathway. Moreover, ZGS II treatment altered the differentially expressed genes (DEGs) with known functions in HSPC differentiation and mobilization (Cxcl12, Col1a2, and Sparc) and the surface markers of neutrophilic precursors or neutrophils (Ngp and CD177). Collectively, these data suggest that ZGS II protected against chemotherapy-induced leukopenia by regulating HSPC proliferation and differentiation.

Maintenance therapy and drug holiday in sarcoma patients: systematic review

Purpose: Overall prognosis of advanced sarcoma remains poor, optimization of systemic treatment is urgently needed in this setting.Materials and methods: We systematically reviewed fully published English-speaking literature about maintenance therapy and drug holiday in sarcoma patients management.Results: We found that switch maintenance therapy with cyclophosphamide/vinorelbine improves the outcome of localized high-risk rhabdomyosarcoma. There is no other maintenance therapy recommended in sarcoma patients. After classical chemotherapy, maintenance therapy with immune-stimulating agents for localized osteosarcoma, bevacizumab for advanced angiosarcoma or pediatric advanced sarcoma, or mTOR inhibitors for metastatic sarcoma does not improve the outcome. Drug holiday has been assessed for metastatic gastrointestinal stromal tumor treated with imatinib as the first-line therapy or for metastatic soft-tissue sarcoma treated with trabectedin. Drug holiday has been found to lead to rapid disease progression and should be avoided.Conclusions: Data about both maintenance and drug holiday are spare in sarcoma management.

Toxicity of a methotrexate metronomic schedule in Wistar rats

Metronomic chemotherapy is a relevant strategy that uses low doses of antineoplastic drugs for sustained periods to control tumor growth, an alternative frequently utilized in veterinary patients. This work aimed to evaluate the toxic effects of a metronomic oral dose of methotrexate (MTX) for 45 days in tumor-free Wistar rats when compared with control animals. Clinical alterations, body weight, food, and water intake were monitored daily, and bone marrow suppression, hematological, biochemical, and histopathological analyses were performed at three points (days 30, 45, and 60). MTX-treated animals did not demonstrate severe systemic involvement. At 30 days, compared with control animals, MTX-treated animals showed significant leukocytosis (11.9 ± 2.3 vs. 7.8 ± 0.2 10⁶/μL; P < .05) and augmentation of immature myeloid populations from bone marrow (9.0 ± 0.8 vs. 6.5 ± 1.5%; P < .05), and at 60 days, treated animals showed significant neutrophilia (35.0 ± 11.0 vs. 23.00 ± 3.0%; P < .05), depletion of bone marrow lymphocytes (8.2 ± 0.7 vs. 11.5 ± 1.9%; P < .05), and immature myeloid populations (7.2 ± 0.7 vs. 8.3 ± 0.6%; P < .05). At a histopathological level, splenic hypoplasia and respiratory inflammatory lesions were significant when compared with control animals, presenting mild to moderate myelotoxicity, immune suppression, and associated clinical compromise that persisted beyond treatment withdrawal. This suggested that MTX metronomic toxicity should not be neglected owing to the observed residual side-effects and special care should be taken regarding myelosuppression.

Delicate Balances in Cancer Chemotherapy: Modeling Immune Recruitment and Emergence of Systemic Drug Resistance

Metronomic chemotherapy can drastically enhance immunogenic tumor cell death. However, the mechanisms responsible are still incompletely understood. Here, we develop a mathematical model to elucidate the underlying complex interactions between tumor growth, immune system activation, and therapy-mediated immunogenic cell death. Our model is conceptually simple, yet it provides a surprisingly excellent fit to empirical data obtained from a GL261 SCID mouse glioma model treated with cyclophosphamide on a metronomic schedule. The model includes terms representing immune recruitment as well as the emergence of drug resistance during prolonged metronomic treatments. Strikingly, a single fixed set of parameters, adjusted neither for individuals nor for drug schedule, recapitulates experimental data across various drug regimens remarkably well, including treatments administered at intervals ranging from 6 to 12 days. Additionally, the model predicts peak immune activation times, rediscovering experimental data that had not been used in parameter fitting or in model construction. Notably, the validated model suggests that immunostimulatory and immunosuppressive intermediates are responsible for the observed phenomena of resistance and immune cell recruitment, and thus for variation of responses with respect to different schedules of drug administration.

Oral metronomic chemotherapy for recurrent & refractory epithelial ovarian cancer: A retrospective analysis

Background & objectives:

Advanced epithelial ovarian cancer (EOC) is associated with dismal outcome and progression-free survival (PFS) shortens with each subsequent relapse. For patients with recurrent and platinum refractory disease, therapeutic options are limited. Oral metronomic therapy (OMT) is associated with symptomatic relief and stable response in a significant proportion of patients. We retrospectively evaluated the outcome of patients with EOC treated with OMT at a tertiary care hospital in north India.

Methods:

Between January 2011 to December 2017, 36 EOC patients received OMT. Patients’ median age was 50 yr (range, 38-81 yr) and they had received a median of two lines of prior chemotherapy. OMT regimen included a combination of cyclophosphamide, etoposide (VP-16) and celecoxib with or without pazopanib along with supportive care. Response rates and outcomes were ascertained using the Gynecological Cancer Intergroup Guidelines. The toxicity was graded according to the Common Terminology Criteria for Adverse Events v.4.03.

Results:

The median CA-125 before initiating OMT was 160 U/ml (range, 42.23-5330 U/ml). The median interval between last chemotherapy and starting OMT regimen was 159 days (range, 1-1211 days). The overall response rate was 50 per cent. The median progression-free survival (PFS) was 8.2 months [95% confidence interval (CI): 5.03-10.33], and the median overall survival was 38 months (95% CI: 25.6-NR). Patients who received two lines of chemotherapy before OMT (P=0.052) and those who received pazopanib-based OMT (P=0.0513) had better PFS.

Interpretation & conclusions:

For patients with relapse and refractory EOC, OMT could be a reasonable option. A combination of oral etoposide (VP-16) and pazopanib needs further evaluation in a large number of patients in a randomized trial.

Suppressive impact of metronomic chemotherapy using UFT and/or cyclophosphamide on mediators of breast cancer dissemination and invasion

Metronomic chemotherapy using the 5-FU prodrug uracil-tegafur (UFT) and cyclophosphamide (CTX) was previously shown to only modestly delay primary tumor growth, but nevertheless markedly suppressed the development of micro-metastasis in an orthotopic breast cancer xenograft model, using the metastatic variant of the MDA-MB-231 cell line, 231/LM2-4. Furthermore, a remarkable prolongation of survival, with no toxicity, was observed in a model of postsurgical advanced metastatic disease. A question that has remained unanswered is the seemingly selective anti-metastatic mechanisms of action responsible for this treatment. We assessed the in vivo effect of metronomic UFT, CTX or their combination, on vascular density, collagen deposition and c-Met (cell mediators or modulators of tumor cell invasion or dissemination) via histochemistry/immunohistochemistry of primary tumor sections. We also assessed the effect of continuous exposure to low and non-toxic doses of active drug metabolites 5-fluorouracil (5-FU), 4-hydroperoxycyclophosphamide (4-HC) or their combination, on 231/LM2-4 cell invasiveness in vitro. In the in vivo studies, a significant reduction in vascular density and p-Met[Y1003] levels was associated with UFT+CTX treatment. All treatments reduced intratumoral collagen deposition. In the in vitro studies, a significant reduction of collagen IV invasion by all treatments was observed. The 3D structures formed by 231/LM2-4 on Matrigel showed a predominantly Mass phenotype under treated conditions and Stellate phenotype in untreated cultures. Taken together, the results suggest the low-dose metronomic chemotherapy regimens tested can suppress several mediators of tumor invasiveness highlighting a new perspective for the anti-metastatic efficacy of metronomic chemotherapy.

Immune microenvironment modulation unmasks therapeutic benefit of radiotherapy and checkpoint inhibition

BACKGROUND

Immune checkpoint inhibitors (ICIs) for solid tumors, including those targeting programmed cell death 1 (PD-1) and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), have shown impressive clinical efficacy, however, most patients do not achieve durable responses. One major therapeutic obstacle is the immunosuppressive tumor immune microenvironment (TIME). Thus, we hypothesized that a strategy combining tumor-directed radiation with TIME immunomodulation could improve ICI response rates in established solid tumors.

METHODS

Using a syngeneic mouse model of human papillomavirus (HPV)-associated head and neck cancer, mEER, we developed a maximally effective regimen combining PD-1 and CTLA-4 inhibition, tumor-directed radiation, and two existing immunomodulatory drugs: cyclophosphamide (CTX) and a small-molecule inducible nitric oxide synthase (iNOS) inhibitor, L-n6-(1-iminoethyl)-lysine (L-NIL). We compared the effects of the various combinations of this regimen on tumor growth, overall survival, establishment of immunologic memory, and immunologic changes with flow cytometry and quantitative multiplex immunofluorescence.

RESULTS

We found PD-1 and CTLA-4 blockade, and radiotherapy alone or in combination, incapable of clearing established tumors or reversing the unfavorable balance of effector to suppressor cells in the TIME. However, modulation of the TIME with cyclophosphamide (CTX) and L-NIL in combination with dual checkpoint inhibition and radiation led to rejection of over 70% of established mEER tumors and doubled median survival in the B16 melanoma model. Anti-tumor activity was CD8+ T cell-dependent and led to development of immunologic memory against tumor-associated HPV antigens. Immune profiling revealed that CTX/L-NIL induced remodeling of myeloid cell populations in the TIME and tumor-draining lymph node and drove subsequent activation and intratumoral infiltration of CD8+ effector T cells.

CONCLUSIONS

Overall, this study demonstrates that modulation of the immunosuppressive TIME is required to unlock the benefits of ICIs and radiotherapy to induce immunologic rejection of treatment-refractory established solid tumors.

Can Immunogenic Chemotherapies Relieve Cancer Cell Resistance to Immune Checkpoint Inhibitors?

The unprecedented clinical activity of checkpoint blockade in several types of cancers has formally demonstrated that anti-tumor immune responses are crucial in cancer therapy. Durable responses seen in patients treated with immune checkpoint inhibitors (ICI) show that they can trigger the establishment of long-lasting immunologic memory. This beneficial outcome is however achieved for a limited number of patients. In addition, late relapses are emerging suggesting the development of acquired resistances that compromise the anticancer efficacy of ICI. How can this be prevented through combination therapies? We here review the functions of immune checkpoints, the successes of ICI in treating cancer and their therapeutic limits. We discuss how conventional cancer therapies can be properly selected to set up combinatorial approaches with ICI leading to treatment improvement. We finally summarize clinical data showing the ongoing progress in cancer treatment involving ICI and chemotherapy combination strategies.

PRIMMO study protocol: a phase II study combining PD-1 blockade, radiation and immunomodulation to tackle cervical and uterine cancer

BACKGROUND

Immunotherapeutic approaches have revolutionized oncological practice but are less evaluated in gynecological malignancies. PD-1/PD-L1 blockade in gynecological cancers showed objective responses in 13-17% of patients. This could be due to immunosuppressive effects exerted by gynecological tumors on the microenvironment and an altered tumor vasculature. In other malignancies, combining checkpoint blockade with radiation delivers benefit that is believed to be due to the abscopal effect. Addition of immune modulation agents has also shown to enhance immune checkpoint blockade efficacy. Therefore we designed a regimen consisting of PD-1 blockade combined with radiation, and different immune/environmental-targeting compounds: repurposed drugs, metronomic chemotherapy and a food supplement. We hypothesize that these will synergistically modulate the tumor microenvironment and induce and sustain an anti-tumor immune response, resulting in tumor regression.

METHODS

PRIMMO is a multi-center, open-label, non-randomized, 3-cohort phase 2 study with safety run-in in patients with recurrent/refractory cervical carcinoma, endometrial carcinoma or uterine sarcoma. Treatment consists of daily intake of vitamin D, lansoprazole, aspirin, cyclophosphamide and curcumin, starting 2 weeks before the first pembrolizumab dose. Pembrolizumab is administered 3-weekly for a total of 6 cycles. Radiation (3 × 8 Gy) is given on days 1, 3 and 5 of the first pembrolizumab dose. The safety run-in consists of 6 patients. In total, 18 and 25 evaluable patients for cervical and endometrial carcinoma respectively are foreseen to enroll. No sample size is determined for uterine sarcoma due to its rarity. The primary objective is objective response rate at week 26 according to immune-related response criteria. Secondary objectives include safety, objective response rate at week 26 according to RECIST v1.1, best overall response, progression-free survival, overall survival and quality of life. Exploratory, translational research aims to evaluate immune biomarkers, extracellular vesicles, cell death biomarkers and the gut microbiome.

DISCUSSION

In this study, a combination of PD-1 blockade, radiation and immune/environmental-targeting compounds is tested, aiming to tackle the tumor microenvironment and induce anti-tumor immunity. Translational research is performed to discover biomarkers related to the mode of action of the combination.

TRIAL REGISTRATION

EU Clinical Trials Register: EudraCT 2016-001569-97 , registered on 19-6-2017. Clinicaltrials.gov: NCT03192059 , registered on 19-6-2017.

Kinetics of Cyclophosphamide Metabolism in Humans, Dogs, Cats, and Mice and Relationship to Cytotoxic Activity and Pharmacokinetics

Cyclophosphamide (CP), a prodrug that is enzymatically converted to the cytotoxic 4-hydroxycyclophosphamide (4OHCP) by hepatic enzymes, is commonly used in both human and veterinary medicine to treat cancers and modulate the immune system. We investigated the metabolism of CP in humans, dogs, cats, and mice using liver microsomes; apparent K M, V max, and intrinsic clearance (V max/K M) parameters were estimated. The interspecies and intraspecies variations in kinetics were vast. Dog microsomes were, on average, 55-fold more efficient than human microsomes, 2.8-fold more efficient than cat microsomes, and 1.2-fold more efficient than mouse microsomes at catalyzing CP bioactivation. These differences translated to cell-based systems. Breast cancer cells exposed to 4OHCP via CP bioactivation by microsomes resulted in a stratification of cytotoxicity that was dependent on the species of microsomes measured by IC50: dog (31.65 μM), mouse (44.95 μM), cat (272.6 μM), and human (1857 μM). The contributions of cytochrome P450s, specifically, CYP2B, CYP2C, and CYP3A, to CP bioactivation were examined: CYP3A inhibition resulted in no change in 4OHCP formation; CYP2B inhibition slightly reduced 4OHCP in humans, cats, and mice; and CYP2C inhibition drastically reduced 4OHCP formation in each species. Semiphysiologic modeling of CP metabolism using scaled metabolic parameters resulted in simulated data that closely matched published pharmacokinetic profiles, determined by noncompartmental analysis. The results highlight differential CP metabolism delineated by species and demonstrate the importance of metabolism on CP clearance.

Immunogenic chemotherapy: Dose and schedule dependence and combination with immunotherapy

Conventional cytotoxic cancer chemotherapy is often immunosuppressive and associated with drug resistance and tumor regrowth after a short period of tumor shrinkage or growth stasis. However, certain cytotoxic cancer chemotherapeutic drugs, including doxorubicin, mitoxantrone, and cyclophosphamide, can kill tumor cells by an immunogenic cell death pathway, which activates robust innate and adaptive anti-tumor immune responses and has the potential to greatly increase the efficacy of chemotherapy. Here, we review studies on chemotherapeutic drug-induced immunogenic cell death, focusing on how the choice of a conventional cytotoxic agent and its dose and schedule impact anti-tumor immune responses. We propose a strategy for effective immunogenic chemotherapy that employs a modified metronomic schedule for drug delivery, which we term medium-dose intermittent chemotherapy (MEDIC). Striking responses have been seen in preclinical cancer models using MEDIC, where an immunogenic cancer chemotherapeutic agent is administered intermittently and at an intermediate dose, designed to impart strong and repeated cytotoxic damage to tumors, and on a schedule compatible with activation of a sustained anti-tumor immune response, thereby maximizing anti-cancer activity. We also discuss strategies for combination chemo-immunotherapy, and we outline approaches to identify new immunogenic chemotherapeutic agents for drug development.

Once weekly paclitaxel associated with a fixed dose of oral metronomic cyclophosphamide: a dose-finding phase 1 trial

BACKGROUND

The primary aim of this trial was to determine the recommended phase II dose (RP2D) of weekly paclitaxel (wP) administered in combination with oral metronomic cyclophosphamide (OMC).

METHODS

Patients ≥ 18 years of age with refractory metastatic cancers were eligible if no standard curative measures existed. Paclitaxel was administered IV weekly (D1, D8, D15; D1 = D28) in combination with a fixed dose of OMC (50 mg twice a day). A 3 + 3 design was used for dose escalation of wP (40 to 75 mg/m²) followed by an expansion cohort at RP2D. Dose-limiting toxicity (DLT) was defined over the first 28-day cycle as grade ≥ 3 non-hematological or grade 4 hematological toxicity (NCI-CTCAE v4.0) or any toxicity leading to a dose reduction.

RESULTS

In total, 28 pts. (18 in dose-escalation phase and 10 in expansion cohort) were included, and 16/18 pts. enrolled in the dose-escalation phase were evaluable for DLT. DLT occurred in 0/3, 1/6 (neuropathy), 0/3 and 2/4 pts. (hematological toxicity) at doses of 40, 60, 70 and 75 mg/m² of wP, respectively. The RP2D of wP was 70 mg/m²; 1/10 patients in the expansion phase had a hematological DLT. At RP2D (n = 14), the maximal grade of drug-related adverse event was Gr1 in three patients, Gr2 in six patients, Gr3 in one patient and Gr4 in one patient (no AE in three patients). At RP2D, a partial response was observed in one patient with lung adenocarcinoma.

CONCLUSION

The combination of OMC and wP resulted in an acceptable safety profile, warranting further clinical evaluation.

TRIAL REGISTRATION

TRN: NCT01374620 ; date of registration: 16 June 2011.

Low-dose metronomic delivery of cyclophosphamide is less detrimental to granulosa cell viability, ovarian function, and fertility than maximum tolerated dose delivery in the mouse

Chemotherapy can cause early menopause or infertility in women and have a profound negative impact on the quality of life of young female cancer survivors. Various factors are known to influence the risk of chemotherapy-induced ovarian failure, including the drug dose and treatment duration; however, the scheduling of dose administration has not yet been evaluated as an independent risk factor. We hypothesized that low-dose metronomic (LDM) chemotherapy scheduling would be less detrimental to ovarian function than the traditional maximum tolerated dose (MTD) strategy. In vitro, MTD cyclophosphamide exposure resulted in decreased proliferation and increased granulosa cell apoptosis, while cells treated with LDM cyclophosphamide were not different from untreated controls. Treatments of MTD cyclophosphamide induced high levels of follicle atresia and enhanced follicle recruitment in mice. In contrast, LDM delivery of an equivalent dose of cyclophosphamide reduced growing follicle numbers, but was not associated with higher levels of follicle atresia or recruitment. MTD cyclophosphamide induced significant vascular disruption and DNA damage in vivo, while LDM chemotherapy with equal cumulative amounts of cyclophosphamide was not different from controls. MTD chemotherapy also had a negative effect on mouse-fertility outcomes. Our findings suggest that LDM scheduling could potentially minimize the long-term effects of cyclophosphamide on female fertility by preventing follicle depletion from enhanced activation.

Downregulation of tight junction protein zonula occludens-2 and urothelium damage in a cyclophosphamide-induced mouse model of cystitis

OBJECTIVES

The cyclophosphamide (CYP)-induced model of cystitis in mice closely fits the symptoms of chronic bladder inflammation. Cystitis was recently found to be due to an altered gap junction protein in a rat model. Thus, this study was conducted to evaluate changes in protein expression and composition in the bladder of CYP-treated mice.

MATERIALS AND METHODS

Administration of CYP induced cystitis-related symptoms in mice. Cystometry was assessed and cell junction-associated protein zonula occludens-2 (ZO-2) expression was measured. Voiding interval values (time between voids) were assessed in mice under anesthesia. The bladders were removed for proteomic analysis using label-free quantitative proteomics and liquid chromatography-mass spectrometry. Additionally, immunochemistry (IHC) and Western blot were used to confirm the location and level, respectively, of ZO-2 expression.

RESULTS

Compared to the control group, the voiding interval values and urothelial thickness in the bladder in the CYP-treated group were significantly decreased. Additionally, we identified 105 differentially expressed proteins in the bladder of CYP-treated mice with proteomic analysis. These proteins were involved in cell-cell tight junctions, exocytosis, muscle development, contraction, and regulation, immune responses, proteolysis, and cell adhesion. IHC and Western blot confirmed the downregulation of the tight junction protein ZO-2 in the urothelium of bladder.

CONCLUSIONS

Our results suggest that downregulation in tight junction protein ZO-2 and urothelium damage may have a role in cystitis-related OAB. These changes could be related to the molecular mechanism of cystitis-related OAB.

Does metronomic chemotherapy induce tumor angiogenic dormancy? A review of available preclinical and clinical data

Tumor dormancy is the ability of cancer cells to survive in a non-proliferating state. This condition can depend on three main mechanisms: cell cycle arrest (quiescence or cell dormancy), immunosurveillance (immunologic dormancy), or lack of functional blood vessels (angiogenic dormancy). In particular, under angiogenic dormancy, cancer cell proliferation is counterbalanced by apoptosis owing to poor vascularization, impeding tumor mass expansion beyond a microscopic size, with an asymptomatic and non-metastatic state. Tumor vasculogenic or non-angiogenic switch is essential to promote escape from tumor dormancy, leading to tumor mass proliferation and metastasis. In avascular lesions angiogenesis process results blocked from the equilibrium between pro- and anti-angiogenic factors, such as vascular endothelial growth factor (VEGF) and thrombospondin-1 (TSP-1), respectively. The angiogenic switch mainly depends on the disruption of this balance, in favor of pro-angiogenic factors, and on the recruitment of circulating endothelial progenitors (CEPs) that promote the formation of new blood vessels. Metronomic chemotherapy, the regular intake of doses able to sustain low but active concentrations of chemotherapeutic drugs during protracted time periods, is an encouraging therapeutic approach that has shown to upregulate anti-angiogenic factors such as TSP-1 and decline pro-angiogenic factors such as VEGF, suppressing the proangiogenic cells such as CEPs. In this perspective, metronomic chemotherapy may be one of the available therapeutic approaches capable to modulate favorably the angiogenic tumor dormancy, but further research is essential to better define this particular characteristic.

Pharmacokinetic analysis of metronomic capecitabine in refractory metastatic colorectal cancer patients

The aim of the present study was to assess the pharmacokinetics (PK) of metronomic capecitabine and its metabolites in a population of refractory metastatic colorectal cancer (mCRC) patients. Thirty-four patients (M/F, 22/12) with a diagnosis of mCRC received capecitabine 800 mg p.o. twice a day and cyclophosphamide 50 mg/day p.o. Blood samples were collected at baseline, 15 min, 30 min, 1 h, 1.5 h, 2 h, 3 h and 5 h at day 1 after capecitabine administration. Plasma concentrations of capecitabine and its metabolites were measured by high performance liquid chromatography and the main PK parameters were calculated. Maximum plasma concentrations (C_max) of capecitabine (11.51 ± 9.73 μg/ml) occurred at 0.5 h, whereas the C_max of 5'-deoxy-5-fluorocytidine (5'-DFCR; 2.45 ± 2.93 μg/ml), 5'-deoxy-5-fluorouridine (5'-DFUR; 6.43 ± 8.2 μg/ml), and 5-fluorouracil (5-FU; 0.24 ± 0.16 μg/ml) were found at 1 h, 1.5 h and 1 h, respectively. Capecitabine, 5'-DFCR, 5'-DFUR and 5-FU AUCs at day 1 were 21.30 ± 10.78, 5.2 ± 4.6, 19.59 ± 3.83 and 0.66 ± 0.77 hxμg/ml, respectively. In conclusion, low doses of capecitabine were rapidly absorbed and extensively metabolized, achieving measurable plasma concentrations in a heavily pretreated population of patients.

Metronomic cyclophosphamide-induced long-term remission after recurrent high-grade serous ovarian cancer: A case study

Metronomic oral cyclophosphamide has gained increasing interest in recent years as a promising maintenance therapy in advanced, platinum-sensitive, high-grade serous ovarian cancer (HGSOC). Metronomic treatment with cyclophosphamide refers to the frequent, usually daily, administration of a low (oral) dose of cyclophosphamide with no prolonged drug-free breaks. Main advantages of this treatment are the effective reduction of tumour activity, oral administration in an outpatient setting, low cost and the low toxicity profile. Metronomic oral cyclophosphamide can benefit patients suffering from types of cancer known to be sensitive to alkylating agents, such as platinum-sensitive HGSOC. In recent years, several publications have underlined the advantage of this regimen and possible explanations were explored. We here present a patient with multiple recurrences of metastasized HGSOC, platinum-sensitive, with an on-going complete response to monotherapy with oral cyclophosphamide. This observation supports that patients with relapsing HGSOC who responded to platinum-based chemotherapy and cannot continue platinum-based chemotherapy because of toxicity, can be offered a course of metronomic cyclophosphamide. This case may serve as a reminder that old drugs can be used successfully even in the age of new upcoming therapy such as anti-angiogenic agents (VEGF inhibitors) and poly-ADP-ribose polymerase (PARP) inhibitors.

Combination of metronomic cyclophosphamide and dietary intervention inhibits neuroblastoma growth in a CD1-nu mouse model

BACKGROUND

MYCN-amplification in high-grade Neuroblastoma (NB) tumors correlates with increased vascularization and therapy resistance. This study combines an anti-angiogenic approach with targeting NB metabolism for treatment.

METHODS AND RESULTS

Metronomic cyclophosphamide (MCP) monotherapy significantly inhibited NB growth and prolonged host survival. Growth inhibition was more pronounced in MYCN-amplified xenografts. Immunohistochemical evaluation of this subtype showed significant decrease in blood vessel density and intratumoral hemorrhage accompanied by blood vessel maturation and perivascular fibrosis. Up-regulation of VEGFA was not sufficient to compensate for the effects of the MCP regimen. Reduced Bcl-2 expression and increased caspase-3 cleavage were evident. In contrast non MYCN-amplified tumors developed resistance, which was accompanied by Bcl-2-up-regulation. Combining MCP with a ketogenic diet and/or calorie-restriction significantly enhanced the anti-tumor effect. Calorie-restricted ketogenic diet in combination with MCP resulted in tumor regression in all cases.

CONCLUSIONS

Our data show efficacy of combining an anti-angiogenic cyclophosphamide dosing regimen with dietary intervention in a preclinical NB model. These findings might open a new front in NB treatment.

Anti-angiogenic therapies for the treatment of angiosarcoma: a clinical update

Angiosarcomas are rare aggressive endothelial tumours, and are associated with a poor prognosis. Due to their vascular nature, there is great interest in their response to anti-angiogenic agents. A number of small prospective studies have reported angiosarcoma response to vascular-targeted agents, including agents that target vascular endothelial growth factor. To date, the response to these agents has been disappointing, and similar to the response observed in other soft tissue sarcoma subtypes. This short review will summarise the recent data in this field.

Metronomic treatment in immunocompetent preclinical GL261 glioblastoma: effects of cyclophosphamide and temozolomide

Glioblastoma (GBM) causes poor survival in patients even when applying aggressive treatment. Temozolomide (TMZ) is the standard chemotherapeutic choice for GBM treatment, but resistance always ensues. In previous years, efforts have focused on new therapeutic regimens with conventional drugs to activate immune responses that may enhance tumor regression and prevent regrowth, for example the "metronomic" approaches. In metronomic scheduling studies, cyclophosphamide (CPA) in GL261 GBM growing subcutaneously in C57BL/6 mice was shown not only to activate antitumor CD8⁺ T-cell response, but also to induce long-term specific T-cell tumor memory. Accordingly, we have evaluated whether metronomic CPA or TMZ administration could increase survival in orthotopic GL261 in C57BL/6 mice, an immunocompetent model. Longitudinal in vivo studies with CPA (140 mg/kg) or TMZ (range 140-240 mg/kg) metronomic administration (every 6 days) were performed in tumor-bearing mice. Tumor evolution was monitored at 7 T with MRI (T₂ -weighted, diffusion-weighted imaging) and MRSI-based nosological images of response to therapy. Obtained results demonstrated that both treatments resulted in increased survival (38.6 ± 21.0 days, n = 30) compared with control (19.4 ± 2.4 days, n = 18). Best results were obtained with 140 mg/kg TMZ (treated, 44.9 ± 29.0 days, n = 12, versus control, 19.3 ± 2.3 days, n = 12), achieving a longer survival rate than previous group work using three cycles of TMZ therapy at 60 mg/kg (33.9 ± 11.7 days, n = 38). Additional interesting findings were, first, clear edema appearance during chemotherapeutic treatment, second, the ability to apply the semi-supervised source analysis previously developed in our group for non-invasive TMZ therapy response monitoring to detect CPA-induced response, and third, the necropsy findings in mice cured from GBM after high TMZ cumulative dosage (980-1400 mg/kg), which demonstrated lymphoma incidence. In summary, every 6 day administration schedule of TMZ or CPA improves survival in orthotopic GL261 GBM with respect to controls or non-metronomic therapy, in partial agreement with previous work on subcutaneous GL261.

The use of low-dose metronomic chemotherapy in dogs-insight into a modern cancer field

The era of chemotherapy, which started in the middle of the last century, has been ruled by the routine use of dose-intense protocols, based on the "maximum-tolerated dose" concept. By promoting a balance between patient's quality of life and the goal of rapidly killing as many tumour cells as possible, these protocols still play a prominent role in veterinary oncology. However, with the opening of a new millennium, metronomic chemotherapy (MC) started to be considered a possible alternative to traditional dose-intense chemotherapy. Characterized by a long-term daily administration of lower doses of cytotoxic drugs, this new modality stands out for its unique combination of effects, namely on neovascularization, immune response and tumour dormancy. This article reviews the rationale for treatment with MC, its mechanism of action and the main studies conducted in veterinary medicine, and discusses the key challenges yet to be solved.

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.

The effect of cyclophosphamide on the immune system: implications for clinical cancer therapy

Cyclophosphamide is an alkylating agent belonging to the group of oxazaphosporines. As cyclophosphamide is in clinical use for more than 40 years, there is a lot of experience using this drug for the treatment of cancer and as an immunosuppressive agent for the treatment of autoimmune and immune-mediated diseases. Besides antimitotic and antireplicative effects, cyclophosphamide has immunosuppressive as well as immunomodulatory properties. Cyclophosphamide shows selectivity for T cells and is therefore now frequently used in tumour vaccination protocols and to control post-transplant allo-reactivity in haplo-identical unmanipulated bone marrow after transplantation. The schedule of administration is of special importance for the immunological effect: while cyclophosphamide can be used in high-dose therapy for the complete eradication of haematopoietic cells, lower doses of cyclophosphamide are relatively selective for T cells. Of special interest is the fact that a single administration of low-dose cyclophosphamide is able to selectively suppress regulatory T cells (Tregs). This effect can be used to counteract immunosuppression in cancer. However, cyclophosphamide can also increase the number of myeloid-derived suppressor cells. Combination of cyclophosphamide with other immunomodulatory agents could be a promising approach to treat different forms of advanced cancer.

Highlights from the 1st Latin American meeting on metronomic chemotherapy and drug repositioning in oncology, 27-28 May, 2016, Rosario, Argentina

Following previous metronomic meetings in Marseille (2011), Milano (2014), and Mumbai (2016), the first Latin American metronomic meeting was held in the School of Medical Sciences, National University of Rosario, Rosario, Argentina on 27 and 28 of May, 2016. For the first time, clinicians and researchers with experience in the field of metronomics, coming from different countries in Latin America, had the opportunity of presenting and discussing their work. The talks were organised in three main sessions related to experience in the pre-clinical, and clinical (paediatric and adult) areas. The different presentations demonstrated that the fields of metronomic chemotherapy and repurposing drugs in oncology, known as metronomics, constitute a branch of cancer therapy in permanent evolution, which have strong groups working in Latin

America, both in the preclinical and the clinical settings including large, adequately designed randomised studies. It was shown that metronomics offers treatments, which, whether they are combined or not with the standard therapeutic approaches, are not only effective but also minimally toxic, with the consequent improvement of the patient’s quality of life, and inexpensive, a feature very important in low resource clinical settings. The potential use of metronomic chemotherapy was proposed as a cost/effective treatment in low-/middle-income countries, for adjuvant therapy in selected tumours. The fundamental role of the governmental agencies and non-governmental alliances, as the Metronomic Global Health Initiative, in supporting this research with public interest was underlined.

Schedule-Dependent Antiangiogenic and Cytotoxic Effects of Chemotherapy on Vascular Endothelial and Retinoblastoma Cells

Current treatment of retinoblastoma involves using the maximum dose of chemotherapy that induces tumor control and is tolerated by patients. The impact of dose and schedule on the cytotoxicity of chemotherapy has not been studied. Our aim was to gain insight into the cytotoxic and antiangiogenic effect of the treatment scheme of chemotherapy used in retinoblastoma by means of different in vitro models and to evaluate potential effects on multi-drug resistance proteins. Two commercial and two patient-derived retinoblastoma cell types and two human vascular endothelial cell types were exposed to increasing concentrations of melphalan or topotecan in a conventional (single exposure) or metronomic (7-day continuous exposure) treatment scheme. The concentration of chemotherapy causing a 50% decrease in cell proliferation (IC50) was determined by MTT and induction of apoptosis was evaluated by flow cytometry. Expression of ABCB1, ABCG2 and ABCC1 after conventional or metronomic treatments was assessed by RT-qPCR. We also evaluated the in vivo response to conventional (0.6 mg/kg once a week for 2 weeks) and metronomic (5 days a week for 2 weeks) topotecan in a retinoblastoma xenograft model. Melphalan and topotecan were cytotoxic to both retinoblastoma and endothelial cells after conventional and metronomic treatments. A significant decrease in the IC50 (median, 13-fold; range: 3–23) was observed following metronomic chemotherapy treatment in retinoblastoma and endothelial cell types compared to conventional treatment (p<0.05). Metronomic topotecan or melphalan significantly inhibited in vitro tube formation in HUVEC and EPC compared to vehicle-treated cells (p<0.05). Both treatment schemes induced apoptosis and/or necrosis in all cell models. No significant difference was observed in the expression of ABCB1, ABCC1 or ABCG2 when comparing cells treated with melphalan or topotecan between treatment schedules at the IC50 or with control cells (p>0.05). In mice, continuous topotecan lead to significantly lower tumor volumes compared to conventional treatment after 14 days of treatment (p<0.05). Continuous exposure to melphalan or topotecan increased the chemosensitivity of retinoblastoma and endothelial cells to both chemotherapy agents with lower IC50 values compared to short-term treatment. These findings were validated in an in vivo model. None of the dosing modalities induced multidrug resistance mechanisms while apoptosis was the mechanism of cell death after both treatment schedules. Metronomic chemotherapy may be a valid option for retinoblastoma treatment allowing reductions of the daily dose.

Targeted antiangiogenic agents in combination with cytotoxic chemotherapy in preclinical and clinical studies in sarcoma

Sarcomas are a heterogeneous group of mesenchymal malignancies. In recent years, studies have demonstrated that inhibition of angiogenic pathways or disruption of established vasculature can attenuate the growth of sarcomas. However, when used as monotherapy in the clinical setting, these targeted antiangiogenic agents have only provided modest survival benefits in some sarcoma subtypes, and have not been efficacious in others. Preclinical and early clinical data suggest that the addition of conventional chemotherapy to antiangiogenic agents may lead to more effective therapies for patients with these tumors. In the current review, the authors summarize the available evidence and possible mechanisms supporting this approach.

An uncommon response to metronomic therapy in a heavily pretreated patient with metastatic carcinosarcoma: a case report

Background

Uterine carcinosarcoma is well known for its aggressive behavior. There is little evidence regarding the gold standard combination chemotherapy in metastatic or locally advanced carcinosarcoma, due to poor survival outcomes obtained with conventional scheduled chemotherapy. This case report represents the first-ever reported objective response to a metronomic chemotherapy regimen and adds to the current literature.

Case presentation

We describe a case of a Caucasian woman diagnosed with metastatic carcinosarcoma that had already been treated with multiple lines of conventional chemotherapy, with progressive disease. This patient had a surprising clinical and imaging response when treated with oral metronomic cyclophosphamide.

Conclusions

We reviewed the mechanism of action implicated in metronomic chemotherapy, and correlated it with the biology of disease in carcinosarcoma. This information may add to the current literature, providing important insights to future clinical trials in this patient population.

Complete Response and Fatigue Improvement With the Combined Use of Cyclophosphamide and Quercetin in a Patient With Metastatic Bladder Cancer: A Case Report

Bladder cancer is a major cause of cancer-related mortality, with an estimated 74,000 new cases and 16,000 deaths in the United States in 2015. In patients with metastatic disease, vinflunine and taxanes are the most widely used chemotherapy agents in the second-line setting after failure of platinum-based treatment. Cyclophosphamide has been used in combination with paclitaxel in urothelial carcinoma of the bladder, but there are no data about the effectiveness of cyclophosphamide administered as a single agent.We here describe the first case of an advanced bladder cancer patient suffering from grade 2 fatigue.He benefited from administration of third-line single-agent metronomic oral cyclophosphamide plus oral doses of quercetin. A complete, prolonged radiologic response according to the RECIST criteria 1.1 was achieved with minimal toxicity and an improvement in fatigue.Further studies are required to assess the potential benefits associated with the combined use of cyclophosphamide plus quercetin in advanced bladder cancer patients.