Metronomic chemotherapy from rationale to clinical studies: a dream or reality?

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

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

Primary atypical teratoid/rhabdoid tumor of the spine in an adult patient

BACKGROUND

Atypical teratoid/rhabdoid tumor (AT/RT) is an aggressive neoplasm of the central nervous system that generally arises intracranially in patients under 2 years of age. Primary spinal AT/RT in an adult is rare.

CASE DESCRIPTION

A 23-year-old female presented with left lower extremity sciatica attributed to a magnetic resonance imaging (MRI)-documented intradural mass between L2 and L4. The lesion was biopsied (was unresectable) and treated with high-dose chemotherapy (methotrexate, vincristine, cyclophosphamide, etoposide, and cisplatin) with autologous hematopoietic stem cells rescue, followed by 2 months of radiation therapy (36 Gy to craniospinal axis, 20 Gy to lumbar region) with concurrent temozolomide; the latter was discontinued after 3 weeks due to myelosuppression. Tumor relapsed 1 year later at C7-T1 level. She was started on oral metronomic therapy, and bevacizumab was added 2 months later. Three months later, a cervical MRI showed progression of the tumor, along with new lesions in the thoracic/lumbar spine plus intracranial punctate nodular tumors. Following resection of the C7/T1 lesion, she was started on palliative alisertib; a month later, a cranial computed tomography showed progression of her disease with hydrocephalus. Treatment was discontinued, and she expired 12 months after initial diagnosis.

CONCLUSION

Primary spinal AT/RT in the adult patient is rare. The pathology is associated with early recurrence and a poor prognosis. Although potential benefits of metronomic chemotherapy and alisertib have been reported, the patient in this study did not favorably respond to these modalities.

Antiangiogenesis and vascular disrupting agents in cancer: circumventing resistance and augmenting their therapeutic utility

Angiogenesis is a process essential for tumor growth and metastasis. Inhibition of angiogenesis as an anticancer strategy has shown only moderately improved results and is beset with practical limitations, despite theoretical therapeutic advantages. Inevitably resistance develops, through redundancy of signaling pathways and selection for subclonal populations adapted for hypoxic conditions, with more invasive phenotypes. Antiangiogenic-targeted therapies may find improved efficacy in combination therapies; with others in this class, that directly or indirectly target separate pathways or different components of the same pathway, or with a separate class of tumor vasculature-disrupting agents. This review discusses the challenges and strategies for optimization of combination therapies including metronomic administration of drugs and the need for suitable prognostic and surrogate response biomarkers.

Combinatorial immunotherapy strategies for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common liver malignancy. The prognosis for HCC patients greatly varies according to the stage at diagnosis. Overall it is poor, with a 5-year survival rate of approximately 5-6%. Immunotherapeutic interventions represent a novel and effective therapeutic tool. However, only few immunotherapy trials for HCC have been conducted so far with contrasting results, suggesting that significant improvements are needed. Indeed, the liver is characterized by a strong intrinsic immune suppressive microenvironment which needs to be counterbalanced with immune stimulatory approaches. Therefore, the implementation of combinatorial protocols combining immune stimulatory strategies with specific immunotherapy approaches could result in a dramatic improvement of efficacy and clinical outcome in HCC patients. The present review aims at describing the state of the art in immunotherapy strategies for HCC and future perspectives.

Third-Line Chemotherapy for Metastatic Urothelial Cancer: A Retrospective Observational Study

The prognosis of locally advanced (T3/T4 or N1) and metastatic disease urothelial carcinoma is poor. In this retrospective study, we reviewed data about patients receiving third-line chemotherapy for metastatic disease, in view of the lack of data in this setting.We retrospectively analyzed medical records of patients with a pathologic diagnosis of urothelial carcinoma treated with systemic chemotherapy for metastatic disease at 4 participating Institutions between January, 2010, and January, 2015. Cox proportional hazards regression was used to evaluate the association of the chemotherapy agent used versus others with overall survival, adjusted for 5 externally validated prognostic factors in advanced urothelial carcinoma.Of 182 patients that received first-line chemotherapy/adjuvant chemotherapy as defined above, 116 patients (63.73%) received second-line salvage treatment. Fifty-two patients were finally included in this analysis, whereas 9 were excluded due to missing data. Third-line chemotherapy was based on cyclophosphamide, platinum, vinflunine, taxanes, and gemcitabine in 16, 12, 11, 10, and 3 patients, respectively. Median PFS (progression-free survival) and OS (overall survival) of the population were 13 (10-17) and 31 (28-36) weeks. Single-agent cyclophosphamide was associated with a PFS of 18 (13-22) and an OS of 38 (33-41) weeks, whereas platinum-based combinations were associated with a PFS of 5 weeks and an OS of 8 weeks. Multivariate analysis showed improved survival in patients treated with cyclophosphamide (hazard ratio (HR) = 0.42; 95% CI: 0.20-0.89; P = 0.025) and a worse survival in those treated with platinum-based regimens (HR: 4.37; 95% CI = 1.95-9.77; P < 0.01).We observed a significantly longer overall survival in patients receiving single-agent cyclophosphamide, with few grade 3 to 4 toxicities. Further studies should assess the efficacy of metronomic single-agent cyclophosphamide in advanced lines of treatment, as it may yield a survival benefit with low costs and no detrimental effects on quality of life.

Metronomic oral vinorelbine in advanced breast cancer and non-small-cell lung cancer: current status and future development

Metronomic chemotherapy (mCT), a frequent administration of low-dose chemotherapy, allows prolonged treatment duration and minimizes the toxicity of standard-dose chemotherapy. mCT has multiple actions against cancer cells including inhibition of angiogenesis and modulation of the immune system. A number of studies lend support to the clinical efficacy of mCT in advanced breast cancer and non-small-cell lung cancer. However, further evidence is necessary to describe the optimal use of mCT and to identify suitable patients. Oral vinorelbine has emerged as a promising metronomic treatment in patients with metastatic breast cancer and non-small-cell lung cancer and is the only orally available microtubule-targeting agent. This paper reviews current evidence on metronomic oral vinorelbine, discusses its management and defines a suitable patient profile on the basis of a workshop of Italian experts.

Application of Evolutionary Principles to Cancer Therapy

The dynamic cancer ecosystem, with its rich temporal and spatial diversity in environmental conditions and heritable cell phenotypes, is remarkably robust to therapeutic perturbations. Even when response to therapy is clinically complete, adaptive tumor strategies almost inevitably emerge and the tumor returns. Although evolution of resistance remains the proximate cause of death in most cancer patients, a recent analysis found that evolutionary terms were included in less than 1% of articles on the cancer treatment outcomes, and this has not changed in 30 years. Here, we review treatment methods that attempt to understand and exploit intratumoral evolution to prolong response to therapy. In general, we find that treating metastatic (i.e., noncurable) cancers using the traditional strategy aimed at killing the maximum number of tumor cells is evolutionarily unsound because, by eliminating all treatment-sensitive cells, it enables rapid proliferation of resistant populations-a well-known evolutionary phenomenon termed "competitive release." Alternative strategies, such as adaptive therapy, "ersatzdroges," and double-bind treatments, shift focus from eliminating tumor cells to evolution-based methods that suppress growth of resistant populations to maintain long-term control.

The Promise of Preventive Cancer Vaccines

Years of unsuccessful attempts at fighting established tumors with vaccines have taught us all that they are only able to truly impact patient survival when used in a preventive setting, as would normally be the case for traditional vaccines against infectious diseases. While true primary cancer prevention is still but a long-term goal, secondary and tertiary prevention are already in the clinic and providing encouraging results. A combination of immunopreventive cancer strategies and recently approved checkpoint inhibitors is a further promise of forthcoming successful cancer disease control, but prevention will require a considerable reduction of currently reported toxicities. These considerations summed with the increased understanding of tumor antigens allow space for an optimistic view of the future.