Metronomic Dosing of Chemotherapy: Applications in Pediatric Oncology

Metronomic therapy in pediatric oncology: A snapshot

Metronomic chemotherapy transitioned from the bench to bedside in the early 2000s and since then has carved a niche for itself in pediatric oncology. It has been used solely or in combination with other modalities such as radiotherapy, maximum tolerated dose chemotherapy, and targeted agents in adjuvant, palliative, as well as maintenance settings. No wonder, the resulting medical literature is extremely heterogeneous. In this review, the authors review and synthesize the published literature in pediatric metronomics giving a glimpse of its history, varied applications, and evolution of this genre of chemotherapy in pediatric cancers. Limitations, future prospects, and grey areas are also highlighted.

Low-Dose Continuous 5-Fluorouracil Combined with Leucovorin, nab-Paclitaxel, Oxaliplatin, and Bevacizumab for Patients with Advanced Pancreatic Cancer: A Retrospective Analysis

BACKGROUND

Continuous-infusion 5-fluorouracil (5FU) and calcium leucovorin plus nab-paclitaxel and oxaliplatin have been shown to be active in patients with pancreatic cancer. As a protracted low-dose infusion, 5FU is antiangiogenic, and has synergy with bevacizumab. As shown in the treatment of breast cancer, bevacizumab and nab-paclitaxel are also synergetic.

OBJECTIVE

In this paper we retrospectively analyze the survival of 65 patients with advanced pancreatic cancer who were treated with low-dose continuous (metronomic) chemotherapy given in conjunction with conventional anti-VEGF therapy.

PATIENTS AND METHODS

Since July of 2008, we have treated 65 patients with 5FU (180 mg/m2/day × 14 days) via an ambulatory pump. Calcium leucovorin (20 mg/m2 IV), nab-paclitaxel (60 mg/m2) IV as a 30-min infusion, and oxaliplatin (50 mg/m2) IV as a 60-min infusion were given on days 1, 8, and 15. Bevacizumab (5 mg/kg) IV over 30 min was administered on days 1 and 15. Cycles were repeated every 28-35 days. There were 42 women and 23 men, and the median age was 59 years. Forty-six patients had stage IV disease.

RESULTS

The median survival was 19 months, with 82% of patients surviving 12 months or longer. The overall response rate was 49%. There were 28 patients who had received prior treatment, 15 of whom responded to therapy. Fifty-two patients had elevated CA 19-9 prior to treatment. Of these, 21 patients had 90% or greater reduction in CA 19-9 levels. This cohort had an objective response rate of 71% and a median survival of 27 months. Thirty patients stopped treatment due to disease progression, and an additional 22 stopped because of toxicity. One patient died while on therapy.

CONCLUSIONS

This non-gemcitabine-based regimen resulted in higher response rates and better survival than what is commonly observed with therapy given at conventional dosing schedules. Low-dose continuous (metronomic therapy) cytotoxic chemotherapy combined with antiangiogenic therapy is safe and effective.

Results of a randomized, prospective clinical trial evaluating metronomic chemotherapy in nonmetastatic patients with high-grade, operable osteosarcomas of the extremities: A report from the Latin American Group of Osteosarcoma Treatment

BACKGROUND

Metronomic chemotherapy (MC) consists of the administration of a low dose of chemotherapy on a daily or weekly basis without a long break to achieve an antitumoral effect through an antiangiogenic effect or stimulation of the immune system. The potential effect of MC with continuous oral cyclophosphamide and methotrexate in patients with high-grade operable osteosarcomas (OSTs) of the extremities was investigated.

METHODS

Patients with high-grade OSTs who were 30 years old or younger were eligible for registration at diagnosis. Eligibility for randomization included 1) nonmetastatic disease and 2) complete resection of the primary tumor. The study design included a backbone of 10 weeks of preoperative therapy with methotrexate, adriamycin, and platinum (MAP). After surgery, patients were randomized between 2 arms to complete 31 weeks of MAP or receive 73 weeks of MC after MAP. The primary endpoint was event-free survival (EFS) from randomization.

RESULTS

There were 422 nonmetastatic patients registered (May 2006 to July 2013) from 27 sites in 3 countries (Brazil, Argentina and Uruguay), and 296 were randomized to MAP plus MC (n = 139) or MAP alone (n = 157). At 5 years, the EFS cumulative proportions surviving in the MAP-MC group and the MAP-alone group were 61% (standard error [SE], 0.5%) and 64% (SE, 0.5%), respectively, and they were not statistically different (Wilcoxon [Gehan] statistic = 0.724; P =.395). The multivariate analysis showed that necrosis grades 1 and 2, tumor size, and amputation were associated with shorter EFS.

CONCLUSIONS

According to the current follow-up, EFS with MAP plus MC is not statistically superior to EFS with MAP alone in patients with high-grade, resectable OSTs of the extremities. Cancer 2017;123:1003-10. © 2016 American Cancer Society.

Natural products against cancer angiogenesis

The process of angiogenesis is quite well-known nowadays. Some medicines and extracts affecting this process are already used routinely in supporting the conventional treatment of many diseases that are considered angiogenic such as cancer. However, we must be aware that the area of currently used drugs of this type is much narrower than the theoretical possibilities existing in therapeutic angiogenesis. Plant substances are a large and diverse group of compounds that are found naturally in fruits, vegetables, spices, and medicinal plants. They also have different anticancer properties. The aim of this literature review article is to present the current state of knowledge concerning the molecular targets of tumor angiogenesis and the active substances (polyphenols, alkaloids, phytohormones, carbohydrates, and terpenes) derived from natural sources, whose activity against cancer angiogenesis has been confirmed.

A case of relapsing spinal atypical teratoid/rhabdoid tumor (AT/RT) responding to vinorelbine, cyclophosphamide, and celecoxib

INTRODUCTION

Atypical teratoid/rhabdoid tumor (AT/RT) of the central nervous system is a highly aggressive neoplasm which prevalently affects children and is characterized by a severe prognosis.

CASE PRESENTATION

The authors describe an extremely rare case of a primary spinal AT/RT that occurred in a young girl. The patient underwent a wide surgical resection of a lumbar mass, followed by aggressive chemotherapy, myeloablative treatment, and local radiotherapy. After 7 months from the end of the treatment, the patient experienced local recurrence and was treated with surgery and second-line chemotherapy with antiangiogenic purposes, consisting of oral vinorelbine, cyclophosphamide, and celecoxib. Treatment was well tolerated, and patient was still alive 36 months after diagnosis.

CONCLUSION

The peculiarity of this case report is the clinical-radiological response to a metronomic therapy in a case of early-relapsing spinal AT/RT despite previous maximal surgery, chemotherapy, and radiotherapy.

Tumor dynamics in response to antiangiogenic therapy with oral metronomic topotecan and pazopanib in neuroblastoma xenografts

Metronomic chemotherapy, combined with targeted antiangiogenic drugs, has demonstrated significant anticancer efficacy in various studies. Though, tumors do acquire resistance. Here, we have investigated the effect of prolonged therapy with oral metronomic topotecan and pazopanib on tumor behavior in a neuroblastoma mouse xenograft model. SK-N-BE(2) xenograft-bearing mice were treated with either of the following regimens (daily, orally): vehicle (control), 150 mg/kg pazopanib, 1.0 mg/kg topotecan, and combination of topotecan and pazopanib. Planned durations of treatment for each regimen were 28, 56, and 80 days or until the end point, after which animals were sacrificed. We found that only combination-treated animals survived until 80 days. Combination halted tumor growth for up to 50 days, after which gradual growth was observed. Unlike single agents, all three durations of combination significantly lowered microvessel densities compared to the control. However, the tumors treated with the combination for 56 and 80 days had higher pericyte coverage compared to control and those treated for 28 days. The proliferative and mitotic indices of combination-treated tumors were higher after 28 days of treatment and comparable after 56 days and 80 days of treatment compared to control. Immunohistochemistry, Western blot, and real-time polymerase chain reaction revealed that combination treatment increased the hypoxia and angiogenic expression. Immunohistochemistry for Glut-1 and hexokinase II expression revealed a metabolic switch toward elevated glycolysis in the combination-treated tumors. We conclude that prolonged combination therapy with metronomic topotecan and pazopanib demonstrates sustained antiangiogenic activity but also incurs resistance potentially mediated by elevated glycolysis.

Management of neuroblastoma: a study of first- and second-line chemotherapy responses, a single institution experience

Neuroblastoma is a high-grade malignancy of childhood. It is chemo- and radio-sensitive but prone to relapse after initial remission.

The aim of the current study was to study the results of the first- and second-line chemotherapy on the short-term response and long-term survival of children, and to further describe the side effects of treatment. Ninety-five children with advanced neuroblastoma were included in the study, divided into two groups according to the treatment strategy: 65 were treated by first-line chemotherapy alone, and 30 children who were not responding or relapsed after first-line chemotherapy were treated by second-line chemotherapy. External beam radiotherapy was given to bone and brain secondary cancers when detected. Staging workup was performed before, during and after management. Response was documented after surgery for the primary tumor. Median follow up was 32 months (range 24–60 months). Chemothe rapy was continued until toxicity or disease progression occurred, indicating interruption of chemotherapy. Patients received a maximum of 8 cycles. Toxicity was mainly myelo-suppression, with grade II-III severity in 60% of the firstline and 70% of the second-line chemotherapy patients. Median total actuarial survival was nearly 51 months for the first-line chemotherapy group and 30 months for the second-line line group, with a statistically significant difference between the two groups (P<0.01).

Suppression of hepatic tumor growth and metastasis by metronomic therapy in a rat model of hepatocellular carcinoma

Although continuous low-dose (metronomic [MET]) therapy exerts anti-cancer efficacy in various cancer models, the effect of long-term MET therapy for hepatocellular carcinoma (HCC) remains unknown. This study assessed the long-term efficacy of MET on suppression of tumor growth and spontaneous metastasis in a rat model of HCC induced by administration of diethylnitrosamine for 16 wk. The rats were divided into 3 groups: MTD group received intraperitoneal (i.p.) injections of 40 mg/kg cyclophosphamide on days 1, 3, and 5 of a 21-day cycle; Control and MET groups received i.p. injections of saline and 20 mg/kg cyclophosphamide twice a week, respectively. Anti-tumor and anti-angiogenic effects and anti-metastatic mechanisms including matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) were evaluated. Twelve wk of MET therapy resulted in a significant reduction in intrahepatic tumors than control or MTD therapy. The MET group had fewer proliferating cell nuclear antigen-positive cells and decreased hypoxia-inducible factor-1α levels and microvessel density. Lung metastases were detected in 100%, 80%, and 42.9% in the control, MTD, and MET groups, respectively. MET therapy significantly decreased expression of TIMP-1, MMP-2 and -9. For mediators of pro-MMP-2 activation, MET therapy induced significant suppression in the TIMP-2 and MMP-14 level. The survival in the MET group was significantly prolonged compared to the control and MTD groups. Long-term MET scheduling suppresses tumor growth and metastasis via its potent anti-angiogenic properties and a decrease in MMPs and TIMPs activities. These results provide a rationale for long-term MET dosing in future clinical trials of HCC treatment.

Metronomic oral topotecan with pazopanib is an active antiangiogenic regimen in mouse models of aggressive pediatric solid tumor

PURPOSE

Low dose metronomic (LDM) chemotherapy, combined with VEGF signaling pathway inhibitors, is a highly effective strategy to coordinately inhibit angiogenesis and tumor growth in many adult preclinical cancer models. We have tested the efficacies of daily oral LDM topotecan alone and in combination with pazopanib, a VEGF receptor inhibitor, in three pediatric extracranial solid tumor mouse models.

EXPERIMENTAL DESIGN

In vitro dose-response study of topotecan and pazopanib was conducted on several neuroblastoma, osteosarcoma, and rhabdomyosarcoma cell lines. In vivo antitumor efficacies of the LDM topotecan and pazopanib as single agents and in combination were tested on 4 subcutaneous xenograft models and on 2 neuroblastoma metastatic models. Circulating angiogenic factors such as circulating endothelial cells (CEC), circulating endothelial pro genitor cells (CEP), and microvessel densities were used as surrogate biomarker markers of antiangiogenic activity.

RESULTS

In vitro, topotecan caused a dose-dependent decrease in viabilities of all cell lines, while pazopanib did not. In vivo, combination of topotecan + pazopanib (TP + PZ) showed significant antitumor activity and significant enhancement in survival compared with the respective single agents in all models. Reductions in viable CEP and/or CEC levels and tumor microvessel density were correlated with tumor response and therefore confirmed the antiangiogenic activity of the regimens. Pharmacokinetic studies of both drugs did not reveal any drug-drug interaction.

CONCLUSION

Metronomic administration of TP + PZ showed a statistically significant antitumor activity compared with respective single agents in pediatric tumor mouse models and represent a valid option as a maintenance therapy in aggressive pediatric solid tumors.

Effective oral combination metronomic chemotherapy with low toxicity for the management of castration-resistant prostate cancer

Prostate cancer (PC) was previously believed to be a chemoresistant disease. In recent years taxane-based chemotherapy has been shown to prolong survival in patients with castration-resistant prostate cancer (CRPC). It remains to be shown, however, which type of chemotherapy provides the most beneficial effect with the least amount of side effects. Seventeen patients with chemonaive CRPC were enrolled in a pilot study evaluating an orally administered chemo-hormonal treatment regimen using a weekly sequential combination called KEES; consisting of ketoconazole in combination with cyclophosphamide or etoposide in combination with estramustine administered on alternate weeks. Prednisone was administered throughout the treatment period. Prostate-specific antigen (PSA) response and acute and chronic toxicities were evaluated. Seventeen patients with CRPC were treated; eleven patients demonstrated a median reduction in PSA of 87% (range 26-99%). Ten (59%) patients responded with a decrease in PSA >50%. Thrombocytopenia and anaemia were the most common side effects. One study fatality was reported, however, it was unclear whether this was treatment related. In conclusion, KEES may be a promising option for patients with CRPC, resulting in a clear reduction in PSA with limited toxicity. Further clinical evaluation of this metronomic chemohormonal combination is underway.

Retrospective comparison between a regular and a split-dose protocol of 5-fluorouracil, cisplatin, and mitoxantrone for the treatment of far advanced hepatocellular carcinoma

BACKGROUND

In patients with advanced hepatocellular carcinoma (HCC), combination chemotherapy using 5- fluorouracil, cisplatin, and mitoxantrone (FMP) could achieve a response rate > 20%, but the beneficial effect was compromised by formidable adverse events. Chemotherapy given in a split-dose manner was associated with reduced toxicities. In this retrospective study, we compared the efficacies and side effects between a regular and a split-dose FMP protocol approved in our medical center.

METHODS

From 2005 to 2008, the clinical data of 84 patients with far advanced HCC, who had either main portal vein thrombosis and/or extrahepatic metastasis, were reviewed. Of them, 65 were treated by either regular (n = 27) or split-dose (n = 38) FMP and had completed at least one therapeutic course. The remaining 19 patients were untreated. Clinical parameters, therapeutic responses, survivals and adverse events were compared.

RESULTS

The median overall survival was 6.0, 5.2, and 1.5 months, respectively, in patients receiving regular FMP, split-dose FMP, and no treatment (regular versus split-dose group, P = 0.447; regular or split-dose versus untreated group; P < 0.0001). Patients receiving split-dose treatment had a significantly lower risk of grade 3/4 neutropenia (51.9 versus 10.5%, P = 0.0005). When the two treated groups were combined, the median overall survival was 10.6 and 3.8 months respectively for patients achieving disease control and progressive disease (P < 0.001). Cox proportion hazard model identified Child-Pugh stage B (hazard ratio [HR], 2.216; P = 0.006), presence of extrahepatic metastasis (HR, 0.574; P = 0.048), and achievement of disease control (HR, 0.228; P < 0.001) as independent factors associated with overall survival. Logistic regression analysis revealed that anti-hepatitis C virus antibody (odds ratio [OR], 9.219; P = 0.002) tumor size (OR, 0.816; P = 0.036), and previous anti-cancer therapy (OR, 0.195; P = 0.017) were significantly associated with successful disease control.

CONCLUSIONS

Comparable overall survival was observed between patients receiving regular and split-dose FMP therapies. Patients receiving split-dose therapy had a significantly lower risk of grade 3/4 neutropenia. Positive anti-hepatitis C virus antibody, smaller tumor size, and absence of previous anti-cancer therapy were independent predictors for successful disease control.

New anti-angiogenic strategies in pediatric solid malignancies: agents and biomarkers of a near future

IMPORTANCE OF THE FIELD

Antiangiogenic strategies are affording considerable interest and have become a major milestone in therapeutics of various adult cancers. However, progress has been slow to expand such therapies to patients with pediatric solid malignancies.

AREAS COVERED IN THIS REVIEW

This review discusses the principal pathways for angiogenesis in pediatric solid malignancies and summarizes recent preclinical and clinical data on antiangiogenesis strategies in these tumors.

WHAT THE READER WILL GAIN

The reader will gain state-of-the-art knowledge in the current advancements of antiangiogenic therapies in pediatric clinical trials in regard to supporting preclinical data, and in the status of potential biomarkers investigated for monitoring angiogenesis inhibitors. Mechanisms of resistance to antiangiogenic therapy will also be discussed. Finally, we describe our experience in the monitoring of circulating endothelial cells and progenitors and their potential role as biomarkers of metastatic disease and resistance to antiangiogenic therapies.

TAKE HOME MESSAGE

Evaluation and development of antiangiogenesis protocols are starting and represent a crucial step in the management of pediatric solid malignancies today. Emphasis should be placed on the development of proper surrogate markers to monitor antiangiogenic activity and on the possible long-term effects of these therapies in a pediatric population.

Metronomic small molecule inhibitor of Bcl-2 (TW-37) is antiangiogenic and potentiates the antitumor effect of ionizing radiation

PURPOSE

To investigate the effect of a metronomic (low-dose, high-frequency) small-molecule inhibitor of Bcl-2 (TW-37) in combination with radiotherapy on microvascular endothelial cells in vitro and in tumor angiogenesis in vivo.

METHODS AND MATERIALS

Primary human dermal microvascular endothelial cells were exposed to ionizing radiation and/or TW-37 and colony formation, as well as capillary sprouting in three-dimensional collagen matrices, was evaluated. Xenografts vascularized with human blood vessels were engineered by cotransplantation of human squamous cell carcinoma cells (OSCC3) and human dermal microvascular endothelial cells seeded in highly porous biodegradable scaffolds into the subcutaneous space of immunodeficient mice. Mice were treated with metronomic TW-37 and/or radiation, and tumor growth was evaluated.

RESULTS

Low-dose TW-37 sensitized primary endothelial cells to radiation-induced inhibition of colony formation. Low-dose TW-37 or radiation partially inhibited endothelial cell sprout formation, and in combination, these therapies abrogated new sprouting. Combination of metronomic TW-37 and low-dose radiation inhibited tumor growth and resulted in significant increase in time to failure compared with controls, whereas single agents did not. Notably, histopathologic analysis revealed that tumors treated with TW-37 (with or without radiation) are more differentiated and showed more cohesive invasive fronts, which is consistent with less aggressive phenotype.

CONCLUSIONS

These results demonstrate that metronomic TW-37 potentiates the antitumor effects of radiotherapy and suggest that patients with head and neck cancer might benefit from the combination of small molecule inhibitor of Bcl-2 and radiation therapy.

Enhancement of ATRA-induced differentiation of neuroblastoma cells with LOX/COX inhibitors: an expression profiling study

BACKGROUND

We performed expression profiling of two neuroblastoma cell lines, SK-N-BE(2) and SH-SY5Y, after combined treatment with all-trans retinoic acid (ATRA) and inhibitors of lipoxygenases (LOX) and cyclooxygenases (COX). This study is a continuation of our previous work confirming the possibility of enhancing ATRA-induced cell differentiation in these cell lines by the application of LOX/COX inhibitors and brings more detailed information concerning the mechanisms of the enhancement of ATRA-induced differentiation of neuroblastoma cells.

METHODS

Caffeic acid, as an inhibitor of 5-lipoxygenase, and celecoxib, as an inhibitor on cyclooxygenase-2, were used in this study. Expression profiling was performed using Human Cancer Oligo GEArray membranes that cover 440 cancer-related genes.

RESULTS

Cluster analyses of the changes in gene expression showed the concentration-dependent increase in genes known to be involved in the process of retinoid-induced neuronal differentiation, especially in cytoskeleton remodeling. These changes were detected in both cell lines, and they were independent of the type of specific inhibitors, suggesting a common mechanism of ATRA-induced differentiation enhancement. Furthermore, we also found overexpression of some genes in the same cell line (SK-N-BE(2) or SH-SY5Y) after combined treatment with both ATRA and CA, or ATRA and CX. Finally, we also detected that gene expression was changed after treatment with the same inhibitor (CA or CX) in combination with ATRA in both cell lines.

CONCLUSIONS

Obtained results confirmed our initial hypothesis of the common mechanism of enhancement in ATRA-induced cell differentiation via inhibition of arachidonic acid metabolic pathway.

Beneficial effect of metronomic chemotherapy on tumor suppression and survival in a rat model of hepatocellular carcinoma with liver cirrhosis

PURPOSE

Recent studies have demonstrated that frequent, low-dose metronomic (MET) dosing of cytotoxic agents may not only be as efficient as conventional maximum tolerated dose (MTD) chemotherapy but also less toxic. In this study, we investigated the therapeutic effect and safety of MET chemotherapy using cyclophosphamide (CTX) in rats with chemically induced hepatocellular carcinoma (HCC).

METHODS

Rats received weekly intraperitoneal (i.p.) injections of diethylnitrosamine during 16 weeks for induction of HCC. The rats were divided into three groups: MTD group received 40 mg/kg CTX i.p. injection on days 1, 3, and 5 of a 21-day cycle; Control and MET groups received saline and 20 mg/kg CTX i.p. injection twice a week, respectively. The growth-modulating effects and overall survival were compared between the groups. Anti-angiogenic effects were evaluated by a measurement of endothelial cell and VEGFR-2 expression.

RESULTS

At 6 weeks of therapy, MTD and MET chemotherapy resulted in a significant reduction in tumor number and size compared with Control group. MET chemotherapy showed more prolonged survival than MTD chemotherapy and Control groups (P < 0.05). MET chemotherapy resulted in a significant decrease in both the micro-vessel density and endothelial proliferation index (P < 0.01). Furthermore, MET chemotherapy led to a greater decrease in VEGFR-2 expression at the mRNA and protein levels (P < 0.01).

CONCLUSIONS

MET scheduling not only exhibits anti-tumor and anti-angiogenic effects, but also prolongs survival without major toxicities in a rat model of HCC. Our results suggest that MET chemotherapy has a high therapeutic value and should be considered for future clinical trials.

Dose effects of continuous vinblastine chemotherapy on mammalian angiogenesis mediated by VEGF-A

Low-dose continuous or metronomic chemotherapy with several agents can exert significant antiangiogenic effects, as shown in preclinical studies. Therapy of this kind is generally well tolerated compared with conventional chemotherapy with high, temporally spaced out bolus doses. A critical point emerges when the effects on angiogenesis of low-toxic metronomic doses of chemotherapeutics in preclinical studies are to be transferred to clinical protocols, as there is a risk that a virtually non-toxic dose might also be ineffective; clearly, dose-effect data are important. We therefore sought to investigate whether a dose-dependent response exists in metronomic vinblastine chemotherapy. The surrogate tumor-free rat mesentery model, allowing the study of antiangiogenic effects per se, was used. Following systemically administered metronomic chemotherapy, it closely reflects the indirectly assessed antiangiogenic and growth-retarding effects in a syngenic cancer model. VEGF-A, which is a central proangiogenic factor in most tumors, was administered i.p. to induce angiogenesis in the mesenteric test tissue and, using morphometry, the angiogenesis-modulating effects of vinblastine were assessed in terms of objective quantitative variables. We report that continuous vinblastine treatment with an apparently non-toxic dose (1.0 mg/kg/week or 0.143 mg/kg/day) for 10 days, and a dose that substantially inhibited the physiologic body-weight gain (2.0 mg/kg/week or 0.286 mg/kg/day) for 6 days, demonstrates a dose-response relationship; the high dose significantly suppresses angiogenesis. To our knowledge, no previous study has reported on a dose-dependent antiangiogenic effect by continuous or metronomic vinblastine treatment in a mammalian in vivo model.

Use of alternating administration of carboplatin and doxorubicin in dogs with microscopic metastases after amputation for appendicular osteosarcoma: 50 cases (1999-2006)

OBJECTIVE

To evaluate the efficacy and toxicity of an alternating carboplatin and doxorubicin chemotherapy protocol in dogs with putative microscopic metastases after amputation for appendicular osteosarcoma and assess patient-, tumor-, and treatment-related factors for associations with prognosis.

DESIGN

Retrospective case series.

ANIMALS

50 client-owned dogs.

PROCEDURES

Records of dogs that underwent amputation for appendicular osteosarcoma and received an alternating carboplatin and doxorubicin chemotherapy protocol were reviewed. Dogs had full staging and were free of detectable metastases prior to chemotherapy. Data on disease-free interval (DFI), survival time, and toxicoses were retrieved from medical records and owner or referring veterinarian communications.

RESULTS

Median DFI was 202 days. Median survival time was 258 days. Twenty-nine (58%) dogs completed the protocol as planned, and the rest were withdrawn typically because of metastases or toxicoses. Grade 3 or 4 myelosuppression was reported in 9 of 50 (18%) dogs and grade 3 or 4 gastrointestinal toxicosis in 6 of 50 (12%) dogs. There were no chemotherapy-related fatalities. Univariate factors associated with significant improvement in DFI included tumor location (radius), receiving doxorubicin as the first drug, starting chemotherapy more than 14 days after amputation, and no rib lesions on preamputation bone scans. Multivariate factors associated with a significant improvement in survival time were tumor location (radius) and completing chemotherapy.

CONCLUSIONS AND CLINICAL RELEVANCE

Alternating administration of carboplatin and doxorubicin resulted in DFI and survival time similar to those reported for single-agent protocols. Clients should be counseled regarding the likelihood of toxicoses. Relevance of sequence and timing of starting chemotherapy should be further evaluated.

Effect of maximum-tolerated doses and low-dose metronomic chemotherapy on serum vascular endothelial growth factor and thrombospondin-1 levels in patients with advanced nonsmall cell lung cancer

BACKGROUND

Angiogenesis is regulated by a balance of both angiogenic inducers and inhibitors. This study was designed to evaluate the effect of both maximum-tolerated doses (MTD) and low-dose metronomic chemotherapy (LDM) on serum vascular endothelial growth factor (VEGF), thrombospondin-1 (TSP1) and VEGFR1 concentrations in patients with advanced nonsmall cell lung cancer.

PATIENTS AND METHODS

Forty consecutive patients with advanced stage nonsmall cell lung cancer were included in this prospective study. Twenty patients received MTD chemotherapy including 75 mg/m2 of cisplatin and 75 mg/m2 of docetaxel on day 1. The LDM treatment consisted of cisplatin 25 mg/m2 and docetaxel 25 mg/m2 were given to other 20 patients on weeks 1, 2 and 3. Serum levels were prospectively measured in serum by ELISA at four times; before chemotherapy and at 1, 2 and 3 weeks following initiation of chemotherapy.

RESULTS

The major finding in this study that MTD chemotherapy but not LDM chemotherapy resulted in significant changes in VEGFR1 and TSP1 serum levels. Due to the effect of LDM chemotherapy, we showed no statistically significant change in patients for all serum VEGF, TSP1 and VEGFR1 levels. Similarly, serum VEGF levels did not also change under MTD chemotherapy. The MTD chemotherapy induced significant and long-lasting increase of TSP1 levels and decrease of VEGFR1 levels that persisted for at least 3 weeks after the chemotherapy initiation. No significant correlations were found between serum VEGF and TSP1 levels in cancer patients treated with both LDM and MTD chemotherapy. The circulating angiogenic balance (TSP1/VEGF) is decreased in cancer patients (P=0.039).

CONCLUSIONS

The continuous/metronomic chemotherapy may not achieve a more pronounced antiangiogenic effect than MTD-scheduling chemotherapy. Future studies involving a larger number of patients are needed to confirm the present findings.

A pilot pharmacokinetic and antiangiogenic biomarker study of celecoxib and low-dose metronomic vinblastine or cyclophosphamide in pediatric recurrent solid tumors

Tumor vasculature is a reasonable target for cancer therapy and lower more frequent doses of traditional chemotherapeutics [low-dose metronomic (LDM) chemotherapy] has been shown to have antiangiogenic efficacy. This study evaluated the safety and pharmacokinetics of celecoxib and LDM vinblastine or cyclophosphamide in children with recurrent, refractory solid tumors. We also investigated whether a subset of circulating plasma proteins are surrogate markers of angiogenic activity. Thirty-three children were enrolled in this pilot study and received celecoxib (250 mg/m(2) PO b.i.d.) and either vinblastine (1 mg/m(2) IV 3 x /wk) or cyclophosphamide (30 mg/m(2) PO daily) continually. Celecoxib alone and with LDM chemotherapy was well tolerated and plasma concentrations were consistent with those shown to have antiangiogenic activity. Four patients (13%) had durable stable disease (28 to 78 wk) although no complete or partial responses were observed. The surrogate markers measured (vascular endothelial growth factor, basic fibroblast growth factor, soluble vascular cell adhesion molecule, soluble intercellular cell adhesion molecule, endostatin, and thrombospondin-1) were highly variable and no statistically significant relationship between them and disease progression or maintenance of stable disease was observed. We concluded that this regimen is well tolerated hence supporting the use of this form of therapy in pediatric patients. However, future studies should include more homogenous patient populations and focus on validating surrogate markers to monitor treatment activity.