Thrombospondin 1, a mediator of the antiangiogenic effects of low-dose metronomic chemotherapy

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.

Metronomic Chemotherapy in Elderly Patients

PURPOSE OF REVIEW

This review describes the most relevant studies found in the scientific literature regarding metronomic chemotherapy (MCT) in the geriatric oncology population to support its use as a feasible treatment of care in the frail elderly patients.

RECENT FINDINGS

Recent years have seen a reevaluation of cancer chemotherapeutic drugs and MCT is an emerging schedule in phase II and III clinical trials. Ageing is one of the risk factors for the development of cancer, the incidence of whom increases dramatically in people who live longer. To date, standard oncological protocols involve chemotherapeutic drugs in short cycles of therapy at the maximum tolerated dose (MTD). Although these therapeutic regimens may be successful, they can cause important adverse drug reactions, especially in elderly or frail patients. MCT is a different modality of delivery of chemotherapeutic drugs (frequent low dose for prolonged time) and it looks at the overcoming of the limitations and disadvantages of MTD, in particular the toxicity aspect. We reviewed the experience of clinicians who have used MCT in clinical trials enrolling elderly patients with different cancer types.

Thrombospondin-1 in drug activity and tumor response to therapies

Thrombospondins (TSPs) have numerous different roles in cancer, regulating the behavior of cancer cells and non-neoplastic cells, and defining the responses of tumor cells to environmental changes, thorough their ability to orchestrate cellular and molecular interactions in the tumor microenvironment (TME). As a result of these activities, TSPs can also control drug delivery and activity, tumor response and resistance to therapies, with different outcomes depending on the nature of TSP-interacting cell types, receptors, and ligands, in a highly context-dependent manner. This review, focusing primarily on TSP-1, discusses the effects of TSPs on tumor response to chemotherapy, antiangiogenic, low-dose metronomic chemotherapy, immunotherapy, and radiotherapy, by analyzing TSP activity on different cell compartments - tumor cells, vascular endothelial cells and immune cells. We review evidence of the value of TSPs, specifically TSP-1 and TSP-2, as biomarkers of prognosis and tumor response to therapy. Finally, we examine possible approaches to develop TSP-based compounds as therapeutic tools to potentiate the efficacy of anticancer therapy.

Metronomic chemotherapy and drug repurposing: A paradigm shift in oncology

Cancer represents a significant global health and economic burden due to its high mortality rates. While effective in some instances, traditional chemotherapy often falls short of entirely eradicating various types of cancer. It can cause severe side effects due to harm to healthy cells. Two therapeutic approaches have risen to the forefront to address these limitations: metronomic chemotherapy (MCT) and drug repurposing. Metronomic chemotherapy is an innovative approach that breaks from traditional models. It involves the administration of chemotherapeutic regimens at lower doses, without long drug-free intervals that have previously been a hallmark of such treatments. This method offers a significant reduction in side effects and improved disease management. Simultaneously, drug repurposing has gained considerable attraction in cancer treatment. This approach involves utilizing existing drugs, initially developed for other therapeutic purposes, as potential cancer treatments. The application of known drugs in a new context accelerates the timeline from laboratory to patient due to pre-existing safety and dosage data. The intersection of these two strategies gives rise to a novel therapeutic approach named 'Metronomics.' This approach encapsulates the benefits of both MCT and drug repurposing, leading to reduced toxicity, potential for oral administration, improved patient quality of life, accelerated clinical implementation, and enhanced affordability. Numerous clinical studies have endorsed the efficacy of metronomic chemotherapy with tolerable side effects, underlining the potential of Metronomics in better cancer management, particularly in low- and middle-income countries. This review underscores the benefits and applications of metronomic chemotherapy and drug repurposing, specifically in the context of breast cancer, showcasing the promising results of pre-clinical and clinical studies. However, we acknowledge the necessity of additional clinical investigations to definitively establish the role of metronomic chemotherapy in conjunction with other treatments in comprehensive cancer management.

A review and metanalysis of metronomic oral single-agent cyclophosphamide for treating advanced ovarian carcinoma in the era of precision medicine

OBJECTIVE

Oral metronomic cyclophosphamide has been used as a single agent or in combination with other drugs for several solid tumors with interesting results in disease palliation and mild to moderate toxicity, notably in patients with recurrent epithelial ovarian cancer (EOC) progressing after systemic chemotherapy. In this paper, we report a review and a metanalysis of heterogeneous data published up to date.

DATA SOURCES

The literature search was restricted to single-agent MOC. The analysis was conducted through March 2023 by consulting PubMed, Embase, Google Scholar, and The Cochrane Library databases. Research string and Medical Subject Headings included "ovarian tumor," "ovarian carcinoma," or "ovarian cancer," "fallopian tube cancer," "primary peritoneal cancer," "oral chemotherapy," and "metronomic cyclophosphamide." All articles were assessed for quality by at least two investigators independently, and a < 18 patients sample size cutoff was chosen as a lower limit with a Cohen's kappa statistical coefficient for accuracy and reliability. Metanalysis of selected papers was carried out according to a fixed model.

DATA SUMMARY

The percentage of agreement between investigators on literature study selection was very high, reaching 96.9% with a Cohen's k of 0.929. MOC pooled objective response rate (ORR) and disease control rate for recurrent or platinum-refractory ovarian cancer were 18.8% (range 4-44%) and 36.2% (range 16-58.8%), respectively. The mean progressive-free survival and overall survival were 3.16 months (range 1.9 to 5.0 months) and 8.7 months (range 8 to 13 months), respectively. The fixed model metanalysis of selected studies showed a 16% median ORR (12-20% CI, p < 0.001).

CONCLUSIONS

Single-agent oral cyclophosphamide in EOC holds promise as a treatment option, even in the era of precision medicine. Genetic factors, such as DNA repair gene polymorphisms, may influence treatment response. Combining cyclophosphamide with biological agents such as PARP inhibitors or immunotherapy agents is an area of active investigation.

Homeostatic Regulation of Pro-Angiogenic and Anti-Angiogenic Proteins via Hedgehog, Notch Grid, and Ephrin Signaling in Tibial Dyschondroplasia

Precise coupling of two fundamental mechanisms, chondrogenesis and osteogenesis via angiogenesis, plays a crucial role during rapid proliferation of growth plates, and alteration in their balance might lead to pathogenic conditions. Tibial dyschondroplasia (TD) is characterized by an avascular, non-mineralized, jade-white "cartilaginous wedge" with impaired endochondral ossification and chondrocyte proliferation at the proximal end of a tibial bone in rapidly growing poultry birds. Developing vascular structures are dynamic with cartilage growth and are regulated through homeostatic balance among pro and anti-angiogenic proteins and cytokines. Pro-angiogenic factors involves a wide spectrum of multifactorial mitogens, such as vascular endothelial growth factors (VEGF), platelet-derived growth factors (PDGF), basic fibroblast growth factor (bFGF), placental growth factors, transforming growth factor-β (TGF-β), and TNF-α. Considering their regulatory role via the sonic hedgehog, notch-gridlock, and ephrin-B2/EphB4 pathways and inhibition through anti-angiogenic proteins like angiostatin, endostatin, decoy receptors, vasoinhibin, thrombospondin, PEX, and troponin, their possible role in persisting inflammatory conditions like TD was studied in the current literature review. Balanced apoptosis and angiogenesis are vital for physiological bone growth. Any homeostatic imbalance among apoptotic, angiogenetic, pro-angiogenic, or anti-angiogenic proteins ultimately leads to pathological bone conditions like TD and osteoarthritis. The current review might substantiate solid grounds for developing innovative therapeutics for diseases governed by the disproportion of angiogenesis and anti-angiogenesis proteins.

Metronomic chemotherapy, dampening of immunosuppressive cells, antigen presenting cell activation, and T cells. A quartet against refractoriness and resistance to checkpoint inhibitors

Chemotherapeutic agents have profound effects on cancer, stroma and immune cells that - in most cases - depend upon the dosage and schedule of administration. Preclinical and clinical studies summarized and discussed in the present review have demonstrated that maximum tolerable dosage (MTD) vs low-dosage, continuous (metronomic) administration of most chemotherapeutics have polarized effects on immune cells. In particular, metronomic schedules might be associated - among others effects - with activation of antigen presenting cells and generation of new T cell clones to enhance the activity of several types of immunotherapies. Ongoing and planned clinical trials in different types of cancer will confirm or dismiss this hypothesis and provide candidate biomarker data for the selection of patients who are likely to benefit from these combinatorial strategies.

Combination of levofloxacin and cisplatin enhances anticancer efficacy via co-regulation of eight cancer-associated genes

Chemosensitizer or combined chemotherapy can sensitize cancer cells to therapy and minimize drug resistance. We reveal that levofloxacin has broad-spectrum anticancer activity. Here we report that combination of levofloxacin and cisplatin further enhanced cytotoxicity in cancer cells by further promotion of apoptosis. Levofloxacin concentration-dependently promoted the inhibition of clone formation in cancer cells treated by cisplatin, and their combination further suppressed the tumor growth in mice. Levofloxacin and cisplatin co-regulated genes in directions supporting the enhancement of anticancer efficacy, of which, THBS1, TNFAIP3, LAPTM5, PI3 and IL24 were further upregulated, NCOA5, SRSF6 and SFPQ were further downregulated. Out of the 24 apoptotic pathways significantly enriched in the combination group, TNFAIP3, THBS1, SRSF6 and SFPQ overlapped in 14, 13, 3 and 1 pathway respectively. Jak-STAT/Cytokine-cytokine receptor interaction pathway network and extrinsic apoptotic signaling pathway were significantly enriched in levofloxacin group, cisplatin group and combination group. Jak-STAT/Cytokine-cytokine receptor interaction/Focal adhesion/EMC-receptor interaction pathway network was significantly enriched in the combination group, and IL24 and THBS1 were the overlapped genes. In conclusion, enhancement of anticancer efficacy in combination group was associated with the further regulation of THBS1, TNFAIP3, LAPTM5, PI3, IL24 and NCOA5, SFPQ, SRSF6. Targeting of Jak-STAT/Cytokine-cytokine receptor interaction/Focal adhesion/EMC-receptor interaction pathway network was correlated to the enhancement. With additional benefit to cancer patients for treatment or prophylaxis of an infectious syndrome, levofloxacin can benefit cancer chemotherapy no matter it is used independently or used with other chemotherapeutic drugs.

Current Research Status of Metronomic Chemotherapy in Combination Treatment of Breast Cancer

BACKGROUND

Metronomic chemotherapy (MCT), termed sustained low-dose administration with minimal toxicity, is a new modality of conventional chemotherapy, a verified therapy alternative, and has acquired significant recognition and interest in oncology. Numerous clinical trials of MCT in combination with other treatments, including targeted therapies, biologics, and endocrine therapy, are in progress to obtain better results.

SUMMARY

We comprehensively described the clinical benefits of MCT in combination with other treatments in different molecular subtypes of breast cancer and assessed the feasibility of its adoption in varying phases of treatment. Due to the promising preclinical and clinical investigations, it is expected that MCT in combination with other treatments will enhance the advantages of this strategy and apply it to clinical practice.

KEY MESSAGE

MCT, in combination with other therapeutic interventions, will fully exploit the benefits of this strategy, ushering in a new paradigm in oncology treatment and driving the transformation of cancer into a more manageable chronic disease using newly developed treatment approaches.

Effectiveness and toxicity of metronomic oral cyclophosphamide for recurrent or platinum-refractory ovarian cancer: A meta-analysis

Purpose

To systematically assess the effectiveness and toxicity of metronomic oral cyclophosphamide (MOC) on recurrent or platinum-refractory ovarian cancer.

Methods

We searched the Cochrane Library, Embase, PubMed, CNKI, Weipu, and Wanfang databases for eligible studies. A descriptive statistical method was used to analyze the pooled results. Ratios and means were merged to analyze the objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS), and the rate of serious adverse events (SAEs). Subgroup analysis, sensitivity analysis, and examination of publication bias were conducted for heterogeneity test and quality assurance of the results.

Results

The ORR and DCR by MOC were 25% (95% CI 12–41) and 61% (95% CI 43–77), respectively. The median PFS and OS were 4.29 months (95% CI 2.62–5.97) and 11.26 months (95% CI 8.13–14.39), respectively. The rate of SAEs was 41% (95% CI 30–52). The most frequent SAEs were gastrointestinal toxicity 6% (95% CI 1–12), lymphopenia 6% (95% CI 1–13), and neutropenia 5% (95% CI 2–9). In the subgroup analysis, the ORR and DCR in the subgroup of MOC combined with bevacizumab/pazopanib were 42% (95% CI 26–58) and 82% (95% CI 63–95), respectively. The median PFS and OS were 7.32 months (95% CI 5.93–8.70) and 17.35 months (95% CI 12.89–21.82), respectively.

Conclusion

MOC has a certain effect in clinical response on patients with recurrent or platinum-refractory ovarian cancers, especially when MOC combined with bevacizumab/pazopanib. However, there is a high risk of SAEs.

Development of a population pharmacokinetic/pharmacodynamic model for various oral paclitaxel formulations co-administered with ritonavir and thrombospondin-1 based on data from early phase clinical studies

Purpose

Orally administered paclitaxel offers increased patient convenience while providing a method to prolong exposure without long continuous, or repeated, intravenous infusions. The oral bioavailability of paclitaxel is improved through co-administration with ritonavir and application of a suitable pharmaceutical formulation, which addresses the dissolution-limited absorption of paclitaxel. We aimed to characterize the pharmacokinetics of different paclitaxel formulations, co-administered with ritonavir, and to investigate a pharmacodynamic relationship between low-dose metronomic (LDM) treatment with oral paclitaxel and the anti-angiogenic marker thrombospondin-1 (TSP-1).

Methods

Fifty-eight patients treated with different oral paclitaxel formulations were included for pharmacokinetic analysis. Pharmacodynamic data was available for 36 patients. All population pharmacokinetic/pharmacodynamic modelling was performed using non-linear mixed-effects modelling.

Results

A pharmacokinetic model consisting of gut, liver, central, and peripheral compartments was developed for paclitaxel. The gastrointestinal absorption rate was modelled with a Weibull function. Relative gut bioavailabilities of the tablet and capsule formulations, as fractions of the gut bioavailability of the drinking solution, were estimated to be 0.97 (95%CI: 0.67–1.33) and 0.46 (95%CI: 0.34–0.61), respectively. The pharmacokinetic/pharmacodynamic relationship between paclitaxel and TSP-1 was modelled using a turnover model with paclitaxel plasma concentrations driving an increase in TSP-1 formation rate following an E_max relationship with an EC₅₀ of 284 ng/mL (95%CI: 122–724).

Conclusion

The developed pharmacokinetic model adequately described the paclitaxel plasma concentrations for the different oral formulations co-administered with ritonavir. This model, and the established pharmacokinetic/pharmacodynamic relationship with TSP-1, may facilitate future development of oral paclitaxel.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00280-022-04445-z.

Metronomic Chemotherapy in Prostate Cancer

Despite the significant expansion of the therapeutic armamentarium associated with the introduction of novel endocrine therapies, cytotoxic agents, radiopharmaceuticals, and PARP inhibitors, progression of metastatic castration-resistant prostate cancer (mCRPC) beyond treatment options remains the leading cause of death in advanced prostate cancer patients. Metronomic chemotherapy (MC) is an old concept of wise utilization of cytotoxic agents administered continuously and at low doses. The metronomic is unique due to its multidimensional mechanisms of action involving: (i) inhibition of cancer cell proliferation, (ii) inhibition of angiogenesis, (iii) mitigation of tumor-related immunosuppression, (iv) impairment of cancer stem cell functions, and (v) modulation of tumor and host microbiome. MC has been extensively studied in advanced prostate cancer before the advent of novel therapies, and its actual activity in contemporary, heavily pretreated mCRPC patients is unknown. We have conducted a prospective analysis of consecutive cases of mCRPC patients who failed all available standard therapies to find the optimal MC regimen for phase II studies. The metronomic combination of weekly paclitaxel 60 mg/m² i.v. with capecitabine 1500 mg/d p.o. and cyclophosphamide 50 mg/d p.o. was selected as the preferred regimen for a planned phase II study in heavily pretreated mCRPC patients.

Cyclic Metronomic Chemotherapy for Pediatric Tumors: Six Case Reports and a Review of the Literature

We report a retrospective case series of six Hispanic children with tumors treated with metronomic chemotherapy. The six cases comprised one rhabdoid tumor of the kidney, one ependymoma, two medulloblastomas, one neuroblastoma, and a type II neurocytoma of the spine. Treatment included oral cyclophosphamide daily for 21 days alternating with oral etoposide daily for 21 days in a backbone of daily valproic acid and celecoxib. In one case, celecoxib was substituted with sulindac. Of the six patients, three showed complete responses, and all patients showed some response to metronomic therapy with only minor hematologic toxicity. One patient had hemorrhagic gastritis likely associated with NSAIDs while off prophylactic antacids. These data add to a growing body of evidence suggesting that continuous doses of valproic acid and celecoxib coupled with alternating metronomic chemotherapy of agents such as etoposide and cyclophosphamide can produce responses in pediatric tumors relapsing to conventional dose chemotherapy.

Levofloxacin exerts broad-spectrum anticancer activity via regulation of THBS1, LAPTM5, SRD5A3, MFAP5 and P4HA1

One cost-effective way for identifying novel cancer therapeutics is in the repositioning of available drugs for which current therapies are inadequate. Levofloxacin prevents DNA duplication in bacteria by inhibiting the activity of DNA helicase. As eukaryotic cells have similar intracellular biologic characteristics as prokaryotic cells, we speculate that antibiotics inhibiting DNA duplication in bacteria may also affect the survival of cancer cells. Here we report that levofloxacin significantly inhibited the proliferation and clone formation of cancer cells and xenograft tumor growth through cell cycle arrest at G2/M and by enhancing apoptosis. Levofloxacin significantly altered gene expression in a direction favoring anticancer activity. THBS1 and LAPTM5 were dose-dependently upregulated whereas SRD5A3, MFAP5 and P4HA1 were downregulated. Pathway analysis revealed that levofloxacin significantly regulated canonical oncogenic pathways. Specific network enrichment included a MAPK/apoptosis/cytokine-cytokine receptor interaction pathway network that associates with cell growth, differentiation, cell death, angiogenesis and development and repair processes and a bladder cancer/P53 signaling pathway network mediating the inhibition of angiogenesis and metastasis. THBS1 overlapped in 16 of the 22 enriched apoptotic pathways and the 2 pathways in the bladder cancer/P53 signaling pathway network. P4HA1 enriched in 7 of the top 10 molecular functions regulated by differential downregulated genes. Our results indicate that levofloxacin has broad-spectrum anticancer activity with the potential to benefit cancer patients already treated or requiring prophylaxis for an infectious syndrome. The efficacy we find with levofloxacin may provide insight into the discovery and the design of novel less toxic anticancer drugs.

Metronomic chemotherapy regimens and targeted therapies in non-Hodgkin lymphoma: The best of two worlds

Novel drugs are rapidly moving forward the treatment-paradigm of non-Hodgkin-lymphomas (NHLs). Notwithstanding, especially in aggressive subtypes, chemotherapy remains the pillar of treatment. Indeed, the combination of highly effective Maximum-Tolerated-Dose Chemotherapy (MTD-CHEMO) + "novel drugs", has so far, fallen short from expectations, often because it caused excessive toxicity. Metronomic chemotherapy (mCHEMO), which is the frequent, long-term administration of low dose cytotoxic drugs, may allow more effective and tolerable combinations. mCHEMO pharmacodynamics, has been described as pleiotropic. In fact, it may have different cellular and molecular targets, when drugs or their schedules are modified. Although mCHEMO has been little explored in NHLs, pre-clinical studies - in lymphoma models - which addressed the activity of mCHEMO in combination with novel drugs, have shown very promising results. These included inhibitors of histone deacetylase, mTOR and PI3K/mTOR, as well as the immune checkpoint inhibitor anti-PD-L1. Moreover, a few impressive reports have recently shown all-oral mCHEMO schedules, with or without rituximab, can effectively shrink both B and T-cell aggressive NHLs. Indeed, these regimens allowed elderly-frail patients to achieve sustained remission, while toxicity proved manageable. In our opinion, all-oral mCHEMO, is an active, easy-to start, well-tolerated, and inexpensive therapeutic approach, which deserves further investigation. Most importantly, mCHEMO, holds promise to empower the activity of novel targeted therapies, without causing excessive toxicity.

Thrombospondin-1 induced programmed death-ligand 1-mediated immunosuppression by activating the STAT3 pathway in osteosarcoma

Thrombospondin‐1 (TSP1) is generally assumed to suppress the growth of osteosarcoma through inhibiting angiogenesis; however, it is unclear whether TSP1 could affect the antitumor immunity against osteosarcoma. We aimed to explore the immune‐related tumor‐promoting effects of TSP1 and decipher its underlying mechanism. First, we identified that TSP1 regulated programmed death‐ligand 1 (PD‐L1) expression, which was related to the CD8⁺ T cells anergy in osteosarcoma cells. The exact role of PD‐L1 in the immunosuppressive effect of TSP1 was then further confirmed by the addition of the PD‐L1 neutralizing Ab. With the addition of PD‐L1 neutralizing Abs during cocultivation, the inhibition of CD8⁺ T cells was abolished to a certain extent. Further mechanistic investigations showed that TSP1‐induced PD‐L1 upregulation was achieved by activation of the signal transducer and activator of transcription 3 (STAT3) pathway. In vivo experiments also indicated that TSP1 overexpression could promote the growth of primary lesions, whereas TSP1 knockdown effectively inhibits the growth of the primary lesion as well as lung metastasis by restoring the antitumor immunity. Thrombospondin‐1 knockdown combined with PD‐L1 neutralizing Ab achieved a more pronounced antitumor effect. Taken together, our study showed that TSP1 upregulates PD‐L1 by activating the STAT3 pathway and, therefore, impairs the antitumor immunity against osteosarcoma.

BRAF mutation status and its prognostic significance in 79 canine urothelial carcinomas: A retrospective study (2006-2019)

Urothelial carcinoma (UC) is the most common tumour of the canine urinary bladder. Recently, BRAF mutation testing emerged as a diagnostic option, but its prognostic significance is unknown. This study investigates the relationship between BRAF (variant V595E) mutation status and overall survival in UC-bearing dogs. Seventy-nine patients histologically diagnosed with UC of the bladder and/or urethra between 2006 and 2019 were included in this retrospective single-centre-study. Treatment consisted of meloxicam (n = 39, group 1 'Melox'), mitoxantrone and meloxicam (+/- followed by metronomic chlorambucil; n = 23, group 2 'Chemo') or partial cystectomy followed by meloxicam +/- mitoxantrone (n = 17, group 3 'Sx'). Survival was significantly influenced by treatment (p = .0002) and tumour location (p < .001) in both uni- and multivariable analyses. BRAF mutation was identified in 51 tumours (=64.6%) and had no statistically significant influence on overall survival: MST for BRAF-negative patients 359 versus 214 days for BRAF-positive dogs (p = .055). However, in BRAF-positive dogs, survival depended significantly on type of treatment in univariable analysis: MSTs for groups 1-3 were 151, 244 and 853 days, respectively (p = .006); In BRAF-positive group 2 ('Chemo')-patients, adjuvant metronomic chlorambucil after mitoxantrone more than doubled MST compared to patients receiving mitoxantrone alone (588 vs. 216 days; p = .030). In contrast, MSTs were not significantly different in BRAF-negative patients among the three treatment groups (p = .069). Multivariate analysis of these data was not possible due to group size limitations. This study identified tumour location and treatment type, but not BRAF mutation status, as independent prognostic factors for overall survival.

Metronomic Chemotherapy for Metastatic Breast Cancer

BACKGROUND

As disease control and quality of life play a leading role in metastatic breast cancer (MBC), metronomic chemotherapy (MCT) is gaining popularity alongside conventional chemotherapy (CCT) and targeted therapies.

SUMMARY

MCT, defined as continuous administration of low-dose chemotherapeutic agents, is accepted as a therapy that exerts its effects via immunomodulation, anti-angiogenesis and direct cytotoxic effects. Oral administration of MCT is safe, easy to handle, and allows for flexible drug dosing. Dose accumulations associated with non-tolerable side effects are rare, so the medication can be administered for longer periods of time. Patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative metastatic disease resistant to endocrine-based therapy and not requiring rapid tumor response are generally suitable for MCT. However, MCT may also be promising in patients with triple-negative and HER2-positive tumors without aggressive disease who prefer a lower toxicity profile compared to CCT. The most commonly used agents are cyclophosphamide (CTX), methotrexate (MTX), capecitabine (CAPE), and vinorelbine (VRL), whereby a combination of agents is frequently applied. Key Messages: Based on the growing body of evidence, MCT can be considered as a suitable treatment option in selected MBC patients. Nevertheless, there is an urgent need for randomized controlled trials comparing MCT with CCT, but also with best supportive care. Due to the multimodal mechanisms of action, the combination with targeted and immunological therapies may represent a new promising approach for the treatment of MBC.

REDD1 is a determinant of low-dose metronomic doxorubicin-elicited endothelial cell dysfunction through downregulation of VEGFR-2/3 expression

Low-dose metronomic chemotherapy (LDMC) inhibits tumor angiogenesis and growth by targeting tumor-associated endothelial cells, but the molecular mechanism has not been fully elucidated. Here, we examined the functional role of regulated in development and DNA damage responses 1 (REDD1), an inhibitor of mammalian target of rapamycin complex 1 (mTORC1), in LDMC-mediated endothelial cell dysfunction. Low-dose doxorubicin (DOX) treatment induced REDD1 expression in cultured vascular and lymphatic endothelial cells and subsequently repressed the mRNA expression of mTORC1-dependent translation of vascular endothelial growth factor receptor (Vegfr)-2/3, resulting in the inhibition of VEGF-mediated angiogenesis and lymphangiogenesis. These regulatory effects of DOX-induced REDD1 expression were additionally confirmed by loss- and gain-of-function studies. Furthermore, LDMC with DOX significantly suppressed tumor angiogenesis, lymphangiogenesis, vascular permeability, growth, and metastasis in B16 melanoma-bearing wild-type but not Redd1-deficient mice. Altogether, our findings indicate that REDD1 is a crucial determinant of LDMC-mediated functional dysregulation of tumor vascular and lymphatic endothelial cells by translational repression of Vegfr-2/3 transcripts, supporting the potential therapeutic properties of REDD1 in highly progressive or metastatic tumors.

Clinical Value of Serum Thrombospondin-2 Combined with CA19-9 in Early Diagnosis of Gastric Cancer

Gastric cancer (GC) is a kind of common cancer worldwide. Too late in diagnosis results in poor prognosis of patients with GC. Thrombospondin-2 (THBS2) is a type of secreted protein that has been found to be a diagnostic biomarker in a variety of cancers. Our study aimed to uncover the clinical value of THBS2 in early detection for patients with gastric cancer. THBS2 was upregulated in gastric cancer tissue compared with normal tissue via analyzing data obtained from The Cancer Genome Atlas (TCGA) database. Additionally, the enzyme-linked immunosorbent assay revealed that the level of serum THBS2 and carcinoembryonic antigen, CA19-9, was higher dramatically in patients with early gastric cancer (EGC) than that in healthy control (HC) in addition to patients with benign gastric tumor (BGT), which suggested that THBS2 indeed associated with GC. Receiver operator characteristic (ROC) curve assay was conducted to demonstrate that serum THBS2 was similar to CA19-9 to distinguish patients with early gastric cancer from healthy control and patients with benign gastric tumor and that THBS2 combined with CA19-9 improved the detective performance of THBS2 for early gastric cancer. Furthermore, we applied the gene set enrichment analysis assay to analyze signaling pathways related to THBS2. We found that THBS2 positively controlled MAPK and WNT signaling pathways, which indicated that THBS2 might exert its functions via the pathway mentioned above. Thus, our study expounded that serum THBS2 could serve as a vital early diagnostic marker for patients with gastric cancer.

Low-dose metronomic doxorubicin inhibits mobilization and differentiation of endothelial progenitor cells through REDD1-mediated VEGFR-2 downregulation

Low-dose metronomic chemotherapy has been introduced as a less toxic and effective strategy to inhibit tumor angiogenesis, but its anti-angiogenic mechanism on endothelial progenitor cells (EPCs) has not been fully elucidated. Here, we investigated the functional role of regulated in development and DNA damage response 1 (REDD1), an endogenous inhibitor of mTORC1, in low-dose doxorubicin (DOX)-mediated dysregulation of EPC functions. DOX treatment induced REDD1 expression in bone marrow mononuclear cells (BMMNCs) and subsequently reduced mTORC1-dependent translation of endothelial growth factor (VEGF) receptor (Vegfr)-2 mRNA, but not that of the mRNA transcripts for Vegfr-1, epidermal growth factor receptor, and insulin-like growth factor-1 receptor. This selective event was a risk factor for the inhibition of BMMNC differentiation into EPCs and their angiogenic responses to VEGF-A, but was not observed in Redd1-deficient BMMNCs. Low-dose metronomic DOX treatment reduced the mobilization of circulating EPCs in B16 melanoma-bearing wild-type but not Redd1-deficient mice. However, REDD1 overexpression inhibited the differentiation and mobilization of EPCs in both wild-type and Redd1-deficient mice. These data suggest that REDD1 is crucial for metronomic DOX-mediated EPC dysfunction through the translational repression of Vegfr-2 transcript, providing REDD1 as a potential therapeutic target for the inhibition of tumor angiogenesis and tumor progression.

Metronomic chemotherapy (mCHT) in metastatic triple-negative breast cancer (TNBC) patients: results of the VICTOR-6 study

Purpose

Triple-negative breast cancer (TNBC) represents a subtype of breast cancer which lacks the expression of oestrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor-2 (HER2): TNBC accounts for approximately 20% of newly diagnosed breast cancers and is associated with younger age at diagnosis, greater recurrence risk and shorter survival time. Therapeutic options are very scarce. Aim of the present analysis is to provide further insights into the clinical activity of metronomic chemotherapy (mCHT), in a real-life setting.

Methods

We used data included in the VICTOR-6 study for the present analysis. VICTOR-6 is an Italian multicentre retrospective cohort study, which collected data of metastatic breast cancer (MBC) patients who have received mCHT between 2011 and 2016. Amongst the 584 patients included in the study, 97 were triple negative. In 40.2% of the TNBC patients, mCHT was the first chemotherapy treatment, whereas 32.9% had received 2 or more lines of treatment for the metastatic disease. 45.4% out of 97 TNBC patients received a vinorelbine (VRL)-based regimen, which resulted in the most used type of mCHT, followed by cyclophosphamide (CTX)-based regimens (30.9%) and capecitabine (CAPE)-based combinations (22.7%).

Results

Overall response rate (ORR) and disease control rate (DCR) were 17.5% and 64.9%, respectively. Median progression free survival (PFS) and overall survival (OS) were 6.0 months (95% CI: 4.9–7.2) and 12.1 months (95% CI: 9.6–16.7). Median PFS was 6.9 months for CAPE-based regimens (95% CI: 5.0–18.4), 6.1 months (95% CI: 4.0–8.9) for CTX-based and 5.3 months (95% CI: 4.1–9.5) for VRL-based ones. Median OS was 18.2 months (95% CI: 9.1-NE) for CAPE-based regimens and 11.8 months for VRL- (95% CI: 9.3–16.7 and CTX-based ones (95%CI: 8.7–52.8). Tumour response, PFS and OS decreased proportionally in later lines.

Conclusion

This analysis represents the largest series of TNBC patients treated with mCHT in a real-life setting and provides further insights into the advantages of using this strategy even in this poor prognosis subpopulation.

Normalizing Tumor Vasculature to Reduce Hypoxia, Enhance Perfusion, and Optimize Therapy Uptake

Simple Summary

In order for solid tumors to grow, they need to develop new blood vessels in order to support their increasing metabolic requirements. To facilitate the novel vessel formation, the tumor initiates an aggressive pro-angiogenic program. As a result of the aggressive angiogenesis, blood vessels form very rapidly and are often malformed and dysfunctional. There is a reduction in perfusion to the tumor, and often the tumors exhibit significant areas of tumor hypoxia. This review paper discusses the pro-tumorigenic environment induced by tumor hypoxia and how this can be targeted through normalization of the tumor vasculature. Here, we review tumor angiogenesis, the development of a hypoxic phenotype, and how this contributes to sustained tumorigenesis and resistance to therapy. We further discuss the potential of vascular normalization to reduce tumor hypoxia and facilitate uptake and efficacy of a variety of therapies.

Abstract

A basic requirement of tumorigenesis is the development of a vascular network to support the metabolic requirements of tumor growth and metastasis. Tumor vascular formation is regulated by a balance between promoters and inhibitors of angiogenesis. Typically, the pro-angiogenic environment created by the tumor is extremely aggressive, resulting in the rapid vessel formation with abnormal, dysfunctional morphology. The altered morphology and function of tumor blood and lymphatic vessels has numerous implications including poor perfusion, tissue hypoxia, and reduced therapy uptake. Targeting tumor angiogenesis as a therapeutic approach has been pursued in a host of different cancers. Although some preclinical success was seen, there has been a general lack of clinical success with traditional anti-angiogenic therapeutics as single agents. Typically, following anti-angiogenic therapy, there is remodeling of the tumor microenvironment and widespread tumor hypoxia, which is associated with development of therapy resistance. A more comprehensive understanding of the biology of tumor angiogenesis and insights into new clinical approaches, including combinations with immunotherapy, are needed to advance vascular targeting as a therapeutic area.

Low-dose metronomic doxorubicin inhibits mobilization and differentiation of endothelial progenitor cells through REDD1-mediated VEGFR-2 downregulation

Low-dose metronomic chemotherapy has been introduced as a less toxic and effective strategy to inhibit tumor angiogenesis, but its anti-angiogenic mechanism on endothelial progenitor cells (EPCs) has not been fully elucidated. Here, we investigated the functional role of regulated in development and DNA damage response 1 (REDD1), an endogenous inhibitor of mTORC1, in low-dose doxorubicin (DOX)-mediated dysregulation of EPC functions. DOX treatment induced REDD1 expression in bone marrow mononuclear cells (BMMNCs) and subsequently reduced mTORC1-dependent translation of endothelial growth factor (VEGF) receptor (Vegfr)-2 mRNA, but not that of the mRNA transcripts for Vegfr-1, epidermal growth factor receptor, and insulin-like growth factor-1 receptor. This selective event was a risk factor for the inhibition of BMMNC differentiation into EPCs and their angiogenic responses to VEGF-A, but was not observed in Redd1-deficient BMMNCs. Low-dose metronomic DOX treatment reduced the mobilization of circulating EPCs in B16 melanoma-bearing wild-type but not Redd1-deficient mice. However, REDD1 overexpression inhibited the differentiation and mobilization of EPCs in both wild-type and Redd1-deficient mice. These data suggest that REDD1 is crucial for metronomic DOX-mediated EPC dysfunction through the translational repression of Vegfr-2 transcript, providing REDD1 as a potential therapeutic target for the inhibition of tumor angiogenesis and tumor progression. [BMB Reports 2021; 54(9): 470-475].

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.

Comparative efficacy and safety of metronomic chemotherapy in breast cancer: A protocol for network meta-analysis protocol

BACKGROUND

Metronomic chemotherapy (MC) strategy has been used in breast cancer for more than a decade since it was first proposed. The purpose of this study is to systematically evaluate its efficacy and safety for breast cancer patients at various stages, as well as to clarify the most effective medication strategy when applying MC and discover its most sensitive subpopulation in breast cancer patients.

METHOD

We will systematically retrieve random controlled trials evaluating the efficacy and safety of MC in breast cancer on PubMed, Cochrane Library, Embase, and web of science to perform this network meta-analysis. Markov chain Monte Carlo method based on Bayesian Theory will be used to conduct network meta-analysis and the efficacy and safety will be ranked by combining direct and indirect evidence in mixed treatment comparisons. We will assess the quality of literatures with the Cochrane Risk Bias Assessment Tool and assess the strength of the evidence using the GRADE methodology. Data analysis will be completed with the WinBUGS, R, Stata and RevMan softwares.

RESULTS AND CONCLUSION

Through the analysis, we can obtain the ranking of efficacy and safety in different MC strategy, and reveal the specific breast cancer groups that are more sensitive to MC. We access the effectiveness by disease free survival, progress free survival, time to progress, objective response rate, and overall survival, and measure the toxicity by dose-limiting toxicity. The result of our study could provide evidence for clinicians to make a better choice when they consider MC.

INPLASY REGISTRATION NUMBER

INPLASY202140142.

Metronomic Chemotherapy

Simple Summary

The present article reviews the state of the art of metronomic chemotherapy use to treat the principal types of cancers, namely breast, non-small cell lung cancer and colorectal ones, and of the most recent progresses in understanding the underlying mechanisms of action. Areas of novelty, in terms of new regimens, new types of cancer suitable for Metronomic chemotherapy (mCHT) and the overview of current ongoing trials, along with a critical review of them, are also provided.

Abstract

Metronomic chemotherapy treatment (mCHT) refers to the chronic administration of low doses chemotherapy that can sustain prolonged, and active plasma levels of drugs, producing favorable tolerability and it is a new promising therapeutic approach in solid and in hematologic tumors. mCHT has not only a direct effect on tumor cells, but also an action on cell microenvironment, by inhibiting tumor angiogenesis, or promoting immune response and for these reasons can be considered a multi-target therapy itself. Here we review the state of the art of mCHT use in some classical tumour types, such as breast and no small cell lung cancer (NSCLC), see what is new regarding most recent data in different cancer types, such as glioblastoma (GBL) and acute myeloid leukemia (AML), and new drugs with potential metronomic administration. Finally, a look at the strategic use of mCHT in the context of health emergencies, or in low –and middle-income countries (LMICs), where access to adequate healthcare is often not easy, is mandatory, as we always need to bear in in mind that equity in care must be a compulsory part of our medical work and research.

Alternative Vascularization Mechanisms in Tumor Resistance to Therapy

Simple Summary

Tumors rely on blood vessels to grow and metastasize. Malignant tumors can employ different strategies to create a functional vascular network. Tumor cells can use normal processes of vessel formation but can also employ cancer-specific mechanisms, by co-opting normal vessels present in tissues or by turning themselves into vascular cells. These different types of tumor vessels have specific molecular and functional characteristics that profoundly affect tumor behavior and response to therapies, including drugs targeting the tumor vasculature (antiangiogenic therapies). In this review, we discuss how vessels formed by different mechanisms affect the intrinsic sensitivity of tumors to therapy and, on the other hand, how therapies can affect tumor vessel formation, leading to resistance to drugs, cancer recurrence, and treatment failure. Potential strategies to avoid vessel-mediated resistance to antineoplastic therapies will be discussed.

Abstract

Blood vessels in tumors are formed through a variety of different mechanisms, each generating vessels with peculiar structural, molecular, and functional properties. This heterogeneity has a major impact on tumor response or resistance to antineoplastic therapies and is now emerging as a promising target for strategies to prevent drug resistance and improve the distribution and efficacy of antineoplastic treatments. This review presents evidence of how different mechanisms of tumor vessel formation (vasculogenesis, glomeruloid proliferation, intussusceptive angiogenesis, vasculogenic mimicry, and vessel co-option) affect tumor responses to antiangiogenic and antineoplastic therapies, but also how therapies can promote alternative mechanisms of vessel formation, contributing to tumor recurrence, malignant progression, and acquired drug resistance. We discuss the possibility of tailoring treatment strategies to overcome vasculature-mediated drug resistance or to improve drug distribution and efficacy.

Taxanes in cancer treatment: Activity, chemoresistance and its overcoming

Since 1984, when paclitaxel was approved by the FDA for the treatment of advanced ovarian carcinoma, taxanes have been widely used as microtubule-targeting antitumor agents. However, their historic classification as antimitotics does not describe all their functions. Indeed, taxanes act in a complex manner, altering multiple cellular oncogenic processes including mitosis, angiogenesis, apoptosis, inflammatory response, and ROS production. On the one hand, identification of the diverse effects of taxanes on oncogenic signaling pathways provides opportunities to apply these cytotoxic drugs in a more rational manner. On the other hand, this may facilitate the development of novel treatment modalities to surmount anticancer drug resistance. In the latter respect, chemoresistance remains a major impediment which limits the efficacy of antitumor chemotherapy. Taxanes have shown impact on key molecular mechanisms including disruption of mitotic spindle, mitosis slippage and inhibition of angiogenesis. Furthermore, there is an emerging contribution of cellular processes including autophagy, oxidative stress, epigenetic alterations and microRNAs deregulation to the acquisition of taxane resistance. Hence, these two lines of findings are currently promoting a more rational and efficacious taxane application as well as development of novel molecular strategies to enhance the efficacy of taxane-based cancer treatment while overcoming drug resistance. This review provides a general and comprehensive picture on the use of taxanes in cancer treatment. In particular, we describe the history of application of taxanes in anticancer therapeutics, the synthesis of the different drugs belonging to this class of cytotoxic compounds, their features and the differences between them. We further dissect the molecular mechanisms of action of taxanes and the molecular basis underlying the onset of taxane resistance. We further delineate the possible modalities to overcome chemoresistance to taxanes, such as increasing drug solubility, delivery and pharmacokinetics, overcoming microtubule alterations or mitotic slippage, inhibiting drug efflux pumps or drug metabolism, targeting redox metabolism, immune response, and other cellular functions.

A Dose-finding Study of Metronomic Oral Vinorelbine in Combination With Oral Cyclophosphamide and Bevacizumab in Patients With Advanced Breast Cancer

BACKGROUND

Metronomic chemotherapy can induce disease control in patients with metastatic breast cancer (MBC) and has better safety profiles than conventional chemotherapy. Evidence suggests that cytotoxics can be anti-angiogenic in pre-clinical models and may have synergistic effects when combined with anti-vascular endothelial growth factor therapies.

PATIENTS AND METHODS

Patients pretreated with ≥ 1 prior line of therapy for MBC received oral cyclophosphamide 50 mg daily in combination with oral vinorelbine at escalating doses of 20 mg (V20), 30 mg (V30), and 40 mg (V40) 3 times per week, and intravenous bevacizumab 15 mg/kg every 3 weeks. Patients with human epidermal growth factor receptor 2-positive disease were given the same regimen plus standard trastuzumab. Doses were escalated when 3 patients completed 3 treatment cycles of V20 and V30, without experiencing dose-limiting toxicities. The recommended dose was then tested in a further 6 patients. Circulating tumour cells and circulating endothelial cells (CEC) were measured in 30 mL of whole blood samples at baseline, after cycle 1, and at the disease progression.

RESULTS

Fifteen patients were recruited from June 2013 to October 2015. The median age was 61 years (range, 29-72 years); 80% had estrogen receptor-positive and 33% had human epidermal growth factor receptor 2-positive disease. At least 67% had visceral metastases, and 80% had received ≥ 2 lines of prior treatment. No dose-limiting toxicities were observed at the 3 dose-levels, making V40 the recommended dose. Overall 8 (53%) patients developed grade 2 adverse events (arthralgia, n = 3 [20%]; asthenia, n = 2 [13%]; diarrhea, n = 2 [13%]; leukopenia, n = 2 [13%]). Bevacizumab was associated with grade 3 hypertension (n = 3 [20%]). Stable disease as best response was observed in 11 (73.3%) patients. The clinical benefit rate was 66.6% (10/15 patients). The median time to progression was 6.9 months. At baseline, CECs were more commonly detectable than circulating tumor cells; however, no statistical correlation was found between CEC kinetics and response.

CONCLUSION

A metronomic vinorelbine dose of 40 mg combined with cyclophosphamide and bevacizumab is a promising treatment regimen in pretreated patients with MBC.

Pharmacodynamic biomarkers in metronomic chemotherapy: multiplex cytokine measurements in gastrointestinal cancer patients

Metronomic chemotherapy has shown promising antitumor activity in a number of malignancies. We previously reported a phase II clinical trial of metronomic UFT (a 5-fluorouracil prodrug; 100 mg/twice per day p.o.) and cyclophosphamide (CTX; 500 mg/m² i.v. bolus on day 1 and then 50 mg/day p.o.) plus celecoxib (200 mg/twice a day p.o.) in 38 patients with advanced refractory gastrointestinal tumors. The mechanisms of action of metronomic chemotherapy include inhibition of angiogenesis, direct cytotoxic effects on cancer cells, and, at least for drugs such as CTX, activation of the immune system. To further evaluate the latter, we carried out an immune system multiplex 14-cytokine profiling of plasma samples that were available (for day 0, day 28, and day 56) from 31 of the 38 patients in the above-noted clinical trial. Our results show that pre-treatment plasma-level cutoffs of interferon gamma (> 12.84 pg/ml), sCD40L (< 2168 pg/ml), interferon alpha 2 (> 55.11 pg/ml), and IL-17a (< 15.1 pg/ml) were predictive markers for those patients with better progression-free survival (p < .05 for each cytokine). After 28 days of metronomic therapy, the plasma levels of sCD40L, IL-17a, and IL-6 (< 130 pg/ml) could serve as predictors of improved progression-free survival, as could levels interferon gamma and sCD40L after 56 days of therapy. We observed minimal changes in cytokine profiles, from baseline, as a consequence of the metronomic therapy, with the exception of an elevation of IL-6 and IL-8 levels 28 days (and 56 days) after treatment started (p < 0.05). Our results indicate that a selective cytokine elevation involves IL-6 and IL-8, following metronomic chemotherapy administration. In addition, interferon gamma and sCD40L may be potential biomarkers for gastrointestinal cancer patients that are likely to benefit from metronomic chemotherapy. Our study contributes to our understanding of the mechanisms of action of metronomic chemotherapy, and the cytokine profiling we describe may guide future selection of gastrointestinal cancer patients for UFT/CTX/celecoxib combination metronomic chemotherapy.

Thrombospondins in bone remodeling and metastatic bone disease

Thrombospondins (TSPs) are a family of five multimeric matricellular proteins. Through a wide range of interactions, TSPs play pleiotropic roles in embryogenesis and in tissue remodeling in adult physiology as well as in pathological conditions, including cancer development and metastasis. TSPs are active in bone remodeling, the process of bone resorption (osteolysis) and deposition (osteogenesis) that maintains bone homeostasis. TSPs are particularly involved in aberrant bone remodeling, including osteolytic and osteoblastic skeletal cancer metastasis, frequent in advanced cancers such as breast and prostate carcinoma. TSPs are major players in the bone metastasis microenvironment, where they finely tune the cross talk between tumor cells and bone resident cells in the metastatic niche. Each TSP family member has different effects on the differentiation and activity of bone cells-including the bone-degrading osteoclasts and the bone-forming osteoblasts-with different outcomes on the development and growth of osteolytic and osteoblastic metastases. Here, we overview the involvement of TSP family members in the bone tissue microenvironment, focusing on their activity on osteoclasts and osteoblasts in bone remodeling, and present the evidence to date of their roles in bone metastasis establishment and growth.

Oral metronomic cyclophosphamide in advanced ovarian cancer: long-lasting clinical response in an elderly frailty patient

Elderly patients with ovarian cancer are an increasing population and many of them are frailty with an increased risk of postoperative complications, chemotherapy intolerance and mortality. Metronomic chemotherapy is the chronic administration of low, equally spaced, doses of antineoplastic drugs with therapeutic efficacy and low toxicity. Oral metronomic cyclophosphamide has gained increasing interest in recent years in the treatment of patients with recurrent ovarian cancer. We report the case of a 87-year-old and -frailty woman with advanced ovarian cancer, not eligible for surgery or standard first-line intravenous chemotherapy. The patient has received oral metronomic cyclophosphamide with a long-lasting clinical response and improved performance status. Oral metronomic cyclophosphamide is a promising treatment for elderly and frailty advanced ovarian cancer patients and should be further investigated.

Normalizing Function of Tumor Vessels: Progress, Opportunities, and Challenges

Abnormal blood and lymphatic vessels create a hostile tumor microenvironment characterized by hypoxia, low pH, and elevated interstitial fluid pressure. These abnormalities fuel tumor progression, immunosuppression, and treatment resistance. In 2001, we proposed a novel hypothesis that the judicious use of antiangiogenesis agents-originally developed to starve tumors-could transiently normalize tumor vessels and improve the outcome of anticancer drugs administered during the window of normalization. In addition to providing preclinical and clinical evidence in support of this hypothesis, we also revealed the underlying molecular mechanisms. In parallel, we demonstrated that desmoplasia could also impair vascular function by compressing vessels, and that normalizing the extracellular matrix could improve vascular function and treatment outcome in both preclinical and clinical settings. Here, we summarize the progress made in understanding and applying the normalization concept to cancer and outline opportunities and challenges ahead to improve patient outcomes using various normalizing strategies.

Metronomic chemotherapy combined with endocrine therapy: are we challenging some dogmas?

INTRODUCTION

Metronomic chemotherapy exerts its effects via inhibition of angiogenesis, immune modulation of the tumoral stroma, induction of senescence and apoptosis of tumor cells. Due to its favorable toxicity profile and its oral administration, metronomic chemotherapy arises as a promising alternative to be combined with endocrine therapy for the treatment of patients with luminal breast cancer.

AREAS COVERED

The present manuscript reviews the rationale supporting the combination of metronomic chemotherapy and endocrine therapy, discussing the studies that evaluated this regimen in the treatment of early-stage and metastatic breast cancer patients. Finally, we conclude by providing an expert opinion on the current role and perspectives for the combination of metronomic chemotherapy and endocrine therapy in the management of patients with luminal breast cancer.

EXPERT OPINION

Retrospective series and early-phase clinical trials have shown promising signs of activity and a favorable toxicity profile with this regimen, which warrants further investigation as a treatment option for luminal breast cancer patients.

Metronomic chemotherapy for patients with metastatic breast cancer: Review of effectiveness and potential use during pandemics

Metronomic chemotherapy (M-CT) is defined as dose dense administration of chemotherapy at lower doses than maximum tolerated dose but at shorter free intervals, to obtain a near continuous exposure of cancer cells to those potentially effective drugs. M-CT is a useful strategy to obtain response, overcome resistance and reduce side effects, with low costs. This review will focus on the use of M-CT in advanced breast cancer (ABC). Cytostatic and cytotoxic effect on cancer cells, the anti-angiogenic and the immunomodulatory effects are its main mechanisms of actions. Many clinical trials proved the efficacy and tolerability of different monotherapies and combinations of chemotherapeutic agents administered in metronomic doses and frequencies in ABC. M-CT is a reasonable option for second and later lines of chemotherapy in metastatic breast cancer including those with prior anthracycline or taxane exposure, older patients and patients with comorbidities, and even as first-line in certain groups of patients. The acceptable efficacy and low toxicity of oral metronomic chemotherapy makes it a reasonable option during COVID-19 pandemic as well as in the post-COVID era which is projected to last for some time.

TSP-1 as a novel biological marker of tumor vasculature normalization in colon carcinoma induced by Endostar

Blood vessels in tumors often exhibit abnormal morphology and function, which promotes the growth, metastasis and resistance of tumors to conventional therapies. Therefore, vascular normalization is an emerging strategy to enhance the effectiveness of radiotherapy and chemotherapy when used in combination; however, there is a lack of evidence regarding the optimal schedule for the co-administration of anti-angiogenic and chemotherapeutic drugs. Scheduling treatment is important as the period for normalization is transient, also known as the ‘time window’; however, no biomarker has been identified to detect this window. In the present study, recombinant human endostatin (rhES) was employed as an anti-angiogenic agent in xenograft tumor tissue in mice. Following rhES or control (saline) treatment, the density and integrity of tumor vessels were detected by immunofluorescence staining for cluster of differentiation 31 and α-smooth muscle actin; the level of hypoxia in tumor tissue was examined by immunohistochemistry with pimonidazole; the necrotic area was evaluated by hematoxylin and eosin staining; and the level of thrombospondin-1 (TSP-1) in plasma was tested by ELISA. The Cell Counting Kit-8 assay was also used to evaluate the effect of rhES on the proliferation of colon carcinoma SW620 cells. A ‘time window’ normalized vasculature was determined between day 4 and 6 following rhES treatment, and accompanied by a decrease in hypoxia in tumor tissue. Decreasing plasma TSP-1 levels were consistent with changes in vascular morphology and hypoxia, which exhibited features of normalization. In addition, rhES had no effect on the proliferation of SW620 cells, suggesting that the reduction in TSP-1 was associated with increased oxygen content during vascular normalization, rather than inhibited cell proliferation. In conclusion, TSP-1 may be a potential biomarker for predicting the normalization window of colon cancer vessels.

Metronomic paclitaxel improves the efficacy of PD-1 monoclonal antibodies in breast cancer by transforming the tumor immune microenvironment

The clinical efficacy of PD-1/PD-L1 monoclonal antibodies (mAbs) in triple-negative breast cancer (TNBC) is unsatisfactory. Immunotherapy combined with chemotherapy shows good therapeutic potential. Preclinical and clinical studies have shown that metronomic chemotherapy may stimulate anticancer immune responses. We aimed to verify whether metronomic paclitaxel (PTX, TAX) treatment can improve the efficacy of a PD-1 mAb in a TNBC mouse model and to explore the potential mechanism. After constructing the TNBC mouse model and treating with PD-1 mAb, metronomic PTX chemotherapy or combined therapy, the differences in the efficacy of each treatment group were compared and analyzed. Our findings suggested that the combination of metronomic PTX chemotherapy and PD-1 mAb produces a potent antitumor effect. Further experiments demonstrated that metronomic PTX chemotherapy changed the immune cell population in tumor tissues. These data suggest that metronomic PTX improves the efficacy of the PD-1 mAb in TNBC by transforming the tumor immune microenvironment, and these results provide strong evidence for the use of this treatment in TNBC patients in the future.

Chemotherapy-Induced Metastasis: Molecular Mechanisms, Clinical Manifestations, Therapeutic Interventions

Chemotherapy offers long-term clinical benefits to many patients with advanced cancer. However, recent evidence has linked the cytotoxic effects of chemotherapy with the de novo elicitation of a prometastatic tumor microenvironment. This "modified" tumor microenvironment is triggered by a chemotherapy-driven cytokine storm or through direct effects of certain chemotherapeutics on stromal and/or immune cells, the most critical being tumor-associated macrophages. These chemotherapy-educated cells act as facilitators in tumor-host cell interactions promoting the establishment of distant metastasis. Certain clinical studies now offer substantial evidence that prometastatic changes are indeed identified in the tumor microenvironment of certain patient subpopulations, especially those that do not present with any pathologic response after neoadjuvant chemotherapy. Deciphering the exact contextual prerequisites for chemotherapy-driven metastasis will be paramount for designing novel mechanism-based treatments for circumventing chemotherapy-induced metastasis.

Anti-Angiogenic Effect of Orally Available Pemetrexed for Metronomic Chemotherapy

Metronomic chemotherapy (MCT) is defined as the frequent administration of low-dose chemotherapeutics, without long drug-free periods, with the exertion of antitumor activity exclusively through anti-angiogenic mechanisms. In this study, we have developed an orally available formulation of pemetrexed (PMX) for MCT. PMX was first complexed ionically with N^α-deoxycholyl-l-lysyl-methylester (DCK) as the permeation enhancer. This was followed by dispersion with poloxamer 188 and Labrasol to form the solid oral formulation of PMX (PMX/DCK-OP). PMX/DCK-OP exhibited a 10.6-fold increase in permeability across a Caco-2 cell monolayer compared to PMX alone. This resulted in a 70-fold increase in the oral bioavailability of PMX/DCK-OP in mice over oral PMX alone. In the A549 xenograft model, tumor volume was reduced by 51.1% in the PMX/DCK-OP treated group compared to only 32.8% in the maximum tolerated dose (MTD)-treated group. Furthermore, PMX/DCK-OP exhibited a significant anti-angiogenic effect on the A549 xenograft mice when compared to the MTD-treated group, as indicated by microvessel density quantification for CD-31. In addition, PMX/DCK-OP enhanced the release of an endogenous angiogenesis inhibitor, thrombospondin-1 (TSP-1), into both the blood circulation and the tumor microenvironment. Therefore, due to its oral route of administration, PMX/DCK-OP appears to be a better alternative to the conventional treatment of PMX.

Next Viable Routes to Targeting Pancreatic Cancer Stemness: Learning from Clinical Setbacks

Pancreatic ductal adenocarcinoma (PDAC) is a devastating and highly aggressive malignancy. Existing therapeutic strategies only provide a small survival benefit in patients with PDAC. Laboratory and clinical research have identified various populations of stem-cell-like cancer cells or cancer stem cells (CSCs) as the driving force of PDAC progression, treatment-resistance, and metastasis. Whilst a number of therapeutics aiming at inhibiting or killing CSCs have been developed over the past decade, a series of notable clinical trial setbacks have led to their deprioritization from the pipelines, triggering efforts to refine the current CSC model and exploit alternative therapeutic strategies. This review describes the current and the evolving models of pancreatic CSCs (panCSCs) and the potential factors that hamper the clinical development of panCSC-targeted therapies, emphasizing the heterogeneity, the plasticity, and the non-binary pattern of cancer stemness, as well as the desmoplastic stroma impeding drug penetration. We summarized novel and promising therapeutic strategies implicated by the works of our groups and others' that may overcome these hurdles and have shown efficacies in preclinical models of PDAC, emphasizing the unique advantages of targeting the stroma-engendered panCSC-niches and metronomic chemotherapy. Finally, we proposed feasible clinical trial strategies and biomarkers that can guide the next-generation clinical trials.

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

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

Bioprinting of 3D breast epithelial spheroids for human cancer models

3D human cancer models provide a better platform for drug efficacy studies than conventional 2D culture, since they recapitulate important aspects of the in vivo microenvironment. While biofabrication has advanced model creation, bioprinting generally involves extruding individual cells in a bioink and then waiting for these cells to self-assemble into a hierarchical 3D tissue. This self-assembly is time consuming and requires complex cellular interactions with other cell types, extracellular matrix components, and growth factors. We therefore investigated if we could directly bioprint pre-formed 3D spheroids in alginate-based bioinks to create a model tissue that could be used almost immediately. Human breast epithelial cell lines were bioprinted as individual cells or as pre-formed spheroids, either in monoculture or co-culture with vascular endothelial cells. While individual breast cells only spontaneously formed spheroids in Matrigel-based bioink, pre-formed breast spheroids maintained their viability, architecture, and function after bioprinting. Bioprinted breast spheroids were more resistant to paclitaxel than individually printed breast cells; however, this effect was abrogated by endothelial cell co-culture. This study shows that 3D cellular structure bioprinting has potential to create tissue models that quickly replicate the tumor microenvironment.

Tumor endothelial cells as a potential target of metronomic chemotherapy

Drug resistance and toxic side effects are major therapeutic hurdles affecting cancer patients receiving conventional chemotherapy based on the maximum tolerated dose. Metronomic chemotherapy (MCT), a new therapeutic approach developed to avoid these problems generally, consists of the continuous administration of low-dose cytotoxic agents without extended intervals. This therapy targets the tumor microenvironment, rather than exerting a direct effect on tumor cells. As a result, the MCT regimen functionally impairs tumor endothelial cells and circulating endothelial progenitor cells, leading to tumor dormancy via anti-angiogenesis. Over the past 10 years, several studies have highlighted the impact of MCT on the tumor microenvironment and angiogenesis and demonstrated its potential as a switch from the pro-angiogenic to the anti-angiogenic state. However, the mechanisms of action are still obscure. Here, we systematically review the evidence regarding the anti-angiogenic potential of MCT as a crucial determinant of tumor dormancy and cancer treatment.

Attempts to strengthen and simplify the tumor vascular normalization strategy using tumor vessel normalization promoting nanomedicines

Tumor vascular normalization theory opened the door for the rational use of antiangiogenic agents and chemotherapeutics.

In vitro effect of chlorambucil on human glioma cell lines (SF767 and U87-MG), and human microvascular endothelial cell (HMVEC) and endothelial progenitor cells (ECFCs), in the context of plasma chlorambucil concentrations in tumor-bearing dogs

The objective of this study was to investigate a possible mechanism of action of metronomic chlorambucil on glioma by studying the in vitro cytotoxicity and anti-angiogenic effects on glioma and endothelial cells, respectively. The in vitro LD50 and IC50 of chlorambucil were determined using human SF767 and U87-MG glioma cell lines, human microvascular endothelial cells (HMVECs) and human endothelial colony forming cells (ECFCs). Results were analyzed in the context of chlorambucil concentrations measured in the plasma of tumor-bearing dogs receiving 4 mg m-2 metronomic chlorambucil. The LD50 and IC50 of chlorambucil were 270 μM and 114 μM for SF767, and 390 μM and 96 μM for U87-MG, respectively. The IC50 of chlorambucil was 0.53 μM and 145 μM for the HMVECs and ECFCs, respectively. In pharmacokinetic studies, the mean plasma Cmax of chlorambucil was 0.06 μM. Results suggest that metronomic chlorambucil in dogs does not achieve plasma concentrations high enough to cause direct cytotoxic or growth inhibitory effects on either glioma or endothelial cells.

Rationale for the use of metronomic chemotherapy in gastrointestinal cancer

INTRODUCTION

Metronomic chemotherapy (mCT) is endowed with various properties, ranging from antiangiogenic to immunomodulation, and may revert tumor resistance to conventional drug administration. A variety of antineoplastic agents displayed activity when administered with metronomic schedules in preclinical models of gastrointestinal cancers. However, most of the field is still unexplored.

AREAS COVERED

Herein, the authors review the existing literature from PubMed, concerning the use of mCT in gastrointestinal oncology.

EXPERT OPINION

A mounting body of evidence is emerging in support of mCT as a treatment option for gastrointestinal tumors, but the frequent signs of clinical activity inconsistently translate into a benefit for survival. Research in this field should focus on providing high-quality evidence on the safety and efficacy of mCT, with more prospective, comparative trials; identifying the subgroups of patients for whom mCT would be the best approach; establishing standardized protocols based on mCT pharmacokinetics and pharmacodynamics; developing drug activity biomarkers. mCT is also potentially suitable for combinations with targeted antiangiogenic drugs and may be incorporated with conventional administration into dual regimens.