Kenneth Francis Hofland

Dexrazoxane Protects against Myelosuppression from the DNA Cleavage–Enhancing Drugs Etoposide and Daunorubicin but not Doxorubicin

Purpose: The anthracyclines daunorubicin and doxorubicin and the epipodophyllotoxin etoposide are potent DNA cleavage–enhancing drugs that are widely used in clinical oncology; however, myelosuppression and cardiac toxicity limit their use. Dexrazoxane (ICRF-187) is recommended for protection against anthracycline-induced cardiotoxicity. Experimental Design: Because of their widespread use, the hematologic toxicity following coadministration of dexrazoxane and these three structurally different DNA cleavage enhancers was investigated: Sensitivity of human and murine blood progenitor cells to etoposide, daunorubicin, and doxorubicin ± dexrazoxane was determined in granulocyte-macrophage colony forming assays. Likewise, in vivo, B6D2F1 mice were treated with etoposide, daunorubicin, and doxorubicin, with or without dexrazoxane over a wide range of doses: posttreatment, a full hematologic evaluation was done. Results: Nontoxic doses of dexrazoxane reduced myelosuppression and weight loss from daunorubicin and etoposide in mice and antagonized their antiproliferative effects in the colony assay; however, dexrazoxane neither reduced myelosuppression, weight loss, nor the in vitro cytotoxicity from doxorubicin. Conclusion: Although our findings support the observation that dexrazoxane reduces neither hematologic activity nor antitumor activity from doxorubicin clinically, the potent antagonism of daunorubicin activity raises concern; a possible interference with anticancer efficacy certainly would call for renewed attention. Our data also suggest that significant etoposide dose escalation is perhaps possible by the use of dexrazoxane. Clinical trials in patients with brain metastases combining dexrazoxane and high doses of etoposide is ongoing with the aim of improving efficacy without aggravating hematologic toxicity. If successful, this represents an exciting mechanism for pharmacologic regulation of side effects from cytotoxic chemotherapy.

The European Medicines Agency Review of Eribulin for the Treatment of Patients with Locally Advanced or Metastatic Breast Cancer: Summary of the Scientific Assessment of the Committee for Medicinal Products for Human Use

The European Commission issued on March 17, 2011, a marketing authorization valid throughout the European Union (EU) for eribulin (Halaven; Eisai Limited). The decision was based on the favorable opinion of the Committee for Medicinal Products for Human Use recommending a marketing authorization for the treatment of patients with locally advanced or metastatic breast cancer who have progressed after at least 2 chemotherapeutic regimens for advanced disease. Eribulin mesylate is a structurally simplified synthetic analogue of halichondrin B, which is a natural product isolated from the marine sponge Halichondria okadai (ATC code L01XX41). Eribulin is a nontaxane, microtubule dynamics inhibitor belonging to the halichondrin class of antineoplastic agents. Eribulin inhibits the growth phase of microtubules without affecting the shortening phase and sequesters tubulin into nonproductive aggregates leading to G2–M cell-cycle block, disruption of mitotic spindles, and, ultimately, apoptotic cell death after prolonged mitotic blockage. The recommended dose of eribulin is 1.23 mg/m2 (equivalent to 1.4 mg/m2 eribulin mesylate) to be administered intravenously over 2 to 5 min on days 1 and 8 of a 3-week cycle. In the pivotal trial, eribulin was associated with increased overall survival in patients with locally advanced or metastatic breast cancer who received at least 2 prior chemotherapy lines for advanced disease (median overall survival was 13.2 months in the eribulin arm vs. 10.6 months in the control arm; HR = 0.805; 95% confidence interval, 0.677–0.958; P = 0.014). The most common side effects are asthenia or fatigue and neutropenia. The objective of this article is to summarize the scientific review of the application leading to approval in the EU. The detailed scientific assessment report and product information, including the summary report and product information, including product characteristics, are available on the European Medicines Agency website. Clin Cancer Res; 18(17); 4491–7. ©2012 AACR.

Indication of a role of plasminogen activator inhibitor type I in protecting murine fibrosarcoma cells against apoptosis.

In a number of cancer types high tumor tissue levels of plasminogen activator inhibitor type 1 (PAI-1) protein are strongly associated with shorter cancer patient survival. This association has been intriguing since PAI-1 is known to inhibit urokinase plasminogen activator (uPA) that converts plasminogen to plasmin, which is actively involved in tumor progression and invasion. In order to further explore the biological role of PAI-1 in cancer, we have prepared fibroblasts from PAI-1 gene deficient mice and from their wild type littermates. From these fibroblasts fibrosarcoma cell lines were established and characterized. Both types of fibroblasts underwent spontaneous transformation as indicated by aneuploidy, immortalization, clonogenicity in soft agar and tumor formation in vivo. While both PAI-1 deficient and PAI-1 expressing cell lines showed similar proliferation rates in vitro, cells devoid of PAI-1 were significantly more sensitive to apoptotic stimuli. When inoculated subcutaneously into nude mice PAI-1 expressing cells rapidly established tumors, while PAI-1 deficient cells had a significantly longer lag-phase before they started to grow (p<0.0001). The present study suggests that PAI-1, besides its uPA inhibiting function, has a role in cancer progression by protecting tumor cells from undergoing apoptosis.

Combining Etoposide and Dexrazoxane Synergizes with Radiotherapy and Improves Survival in Mice with Central Nervous System Tumors

Purpose: The treatment of patients with brain metastases is presently ineffective, but cerebral chemoradiotherapy using radiosensitizing agents seems promising. Etoposide targets topoisomerase II, resulting in lethal DNA breaks; such lesions may increase the effect of irradiation, which also depends on DNA damage. Coadministration of the topoisomerase II catalytic inhibitor dexrazoxane in mice allows for more than 3-fold higher dosing of etoposide. We hypothesized that dexrazoxane combined with escalated etoposide doses might improve the efficacy of cerebral radiotherapy. Experimental Design: Mice with cerebrally inoculated Ehrlich ascites tumor (EHR2) cells were treated with combinations of etoposide + dexrazoxane + cerebral radiotherapy. Similar chemotherapy and radiation combinations were investigated by clonogenic assays using EHR2 cells, and by DNA double-strand break assay through quantification of phosphorylated histone H2AX (γH2AX). Results: Escalated etoposide dosing (90 mg/kg) combined with dexrazoxane (125 mg/kg) and cerebral radiotherapy (10 Gy × 1) increased the median survival by 60% (P = 0.001) without increased toxicity, suggesting that escalated etoposide levels may indeed represent a new strategy for improving radiotherapy. Interestingly, 125 mg/kg dexrazoxane combined with normal etoposide doses (34 mg/kg) also increased survival from radiotherapy, but only by 27% (P = 0.002). This indicates a direct dexrazoxane modulation of the combined effects of etoposide and radiation in brain tumors. Further, in vitro, concurrent dexrazoxane, etoposide, and irradiation significantly increased DNA double-strand breaks. Conclusion: Combining etoposide (high or normal doses) and dexrazoxane synergizes with cerebral radiotherapy and significantly improves survival in mice with central nervous system tumors. This regimen may thus improve radiation therapy of central nervous system tumors.

A Mouse Model for Studying the Interaction of Bisdioxopiperazines with Topoisomerase IIα in Vivo

The bisdioxopiperazines such as (+)-(S)-4,4′-propylenedi-2,6-piperazinedione (dexrazoxane; ICRF-187), 1,2-bis(3,5-dioxopiperazin-1-yl)ethane (ICRF-154), and 4,4′-(1,2-dimethyl-1,2-ethanediyl)bis-2,6-piperazinedione (ICRF-193) are agents that inhibit eukaryotic topoisomerase II, whereas their ring-opened hydrolysis products are strong iron chelator. The clinically approved analog ICRF-187 is a pharmacological modulator of topoisomerase II poisons such as etoposide in preclinical animal models. ICRF-187 is also used to protect against anthracycline-induced cardiomyopathy and has recently been approved as an antidote for alleviating tissue damage and necrosis after accidental anthracycline extravasation. This dual modality of bisdioxopiperazines, including ICRF-187, raises the question of whether their pharmacological in vivo effects are mediated through interaction with topoisomerase II or via their intracellular iron chelating activity. In an attempt to distinguish between these possibilities, we here present a transgenic mouse model aimed at identifying the contribution of topoisomerase IIα to the effects of bisdioxopiperazines. A tyrosine 165 to serine mutation (Y165S) in topoisomerase IIα, demonstrated previously to render the human ortholog of this enzyme highly resistant toward bisdioxopiperazines, was introduced at the TOP2A locus in mouse embryonic stem cells by targeted homologous recombination. These cells were used for the generation of transgenic TOP2AY165S/+ mice, which were demonstrated to be resistant toward the general toxicity of both ICRF-187 and ICRF-193. Hematological measurements indicate that this is most likely caused by a decreased ability of these agents to induce myelosuppression in TOP2AY165S/+ mice, highlighting the role of topoisomerase IIα in this process. The biological and pharmacological implications of these findings are discussed, and areas for further investigations are proposed.

Neoadjuvant bevacizumab and irinotecan versus bevacizumab and temozolomide followed by concomitant chemoradiotherapy in newly diagnosed glioblastoma multiforme: A randomized phase II study

Abstract Background. Surgery followed by radiotherapy and concomitant and adjuvant temozolomide is standard therapy in newly diagnosed glioblastoma multiforme (GBM). Bevacizumab combined with irinotecan produces impressive response rates in recurrent GBM. In a randomized phase II study, we investigated the efficacy of neoadjuvant bevacizumab combined with irinotecan (Bev-Iri) versus bevacizumab combined with temozolomide (Bev-Tem) before, during and after radiotherapy in newly diagnosed GBM. Material and methods. After surgery, patients were randomized to Bev-Iri or Bev-Tem for eight weeks, followed by standard radiotherapy (60 Gy/30 fractions) and concomitant Bev-Iri or Bev-Tem followed by adjuvant Bev-Iri or Bev-Tem for another eight weeks. Bev-Iri: Bevacizumab and irinotecan were given every 14 days before, during and after radiotherapy. Bev-Tem: Bevacizumab was given as in Bev-Iri and temozolomide was given for five days every four weeks before and after radiotherapy and once daily during radiotherapy. The primary endpoint was response after neoadjuvant chemotherapy and a pre-specified response rate of 30% or more was considered of interest for future studies. Secondary endpoints were progression-free survival (PFS) and toxicity. Results. The response rate was 32% (95% CI 17–51%) for Bev-Tem (n = 32) and 23% (95% CI 9–44%) for Bev-Iri (n = 31) (p = 0.56). Median PFS was 7.7 and 7.3 months for Bev-Tem and Bev-Iri, respectively. Hematological toxicity was more frequent with Bev-Tem including one death from febrile neutropenia whereas non-hematological toxicity was manageable. Conclusions. Only the Bev-Tem arm met the pre-specified level of activity of interest. Our results did not indicate any benefit from Bev-Iri in first-line therapy as opposed to Bev-Tem in terms of response and PFS.

The European Medicines Agency Approval of Axitinib (Inlyta) for the Treatment of Advanced Renal Cell Carcinoma After Failure of Prior Treatment With Sunitinib or a Cytokine: Summary of the Scientific Assessment of the Committee for Medicinal Products for Human Use

Axitinib is a tyrosine kinase inhibitor of vascular endothelial growth factor receptor 1 (VEGFR-1), VEGFR-2, and VEGFR-3. Based on the positive opinion from the European Medicines Agency (EMA), a marketing authorization valid throughout the European Union (EU) was issued for the treatment of advanced renal cell carcinoma (RCC) after failure of prior treatment with sunitinib or a cytokine. The demonstration of clinical benefit for axitinib was based on a phase III, randomized, open-label, multicenter study of axitinib compared with sorafenib in patients with advanced RCC after failure of a prior systemic first-line regimen containing one or more of the following agents: sunitinib, bevacizumab plus interferon-α, temsirolimus, or cytokines. In the primary analysis, a 2-month increase in median progression-free survival (PFS) was observed for axitinib compared with sorafenib (hazard ratio [HR]: 0.665; 95% confidence interval [CI]: 0.544-0.812; p < .0001). In the subgroup of patients with a prior cytokine-containing regimen, the increase in median PFS associated with axitinib was 5.4 months (updated analysis, HR: 0.519; 95% CI: 0.375-0.720; p < .0001). In the subgroup of patients with prior sunitinib treatment, the increase in median PFS was 1.4 months (updated analysis, HR: 0.736; 95% CI: 0.578-0.937; p = .0063). The analysis of overall survival showed no statistically significant survival benefit of axitinib over sorafenib in patients previously treated with cytokine-containing regimens (HR: 0.813; 95% CI: 0.556-1.191) or sunitinib (HR: 0.997; 95% CI: 0.782-1.270). The most common treatment-related adverse events associated with axitinib included diarrhea, hypertension, fatigue, nausea, decreased appetite, dysphonia, and palmar-plantar erythrodysesthesia. Most of these events were mild or moderate in severity. This paper summarizes the scientific review of the application leading to approval in the EU. The detailed scientific assessment report and product information, including the summary of product characteristics, are available on the EMA website (http://www.ema.europa.eu).

Effect of bevacizumab on intracranial meningiomas in patients with neurofibromatosis type 2 – a retrospective case series

Purpose: The hallmark of neurofibromatosis type 2 (NF2) is bilateral vestibular schwannomas (VS). Approximately 80% of NF2 patients also have intracranial meningiomas. Vascular endothelial growth factor (VEGF) is expressed in both NF2-related and sporadic occurring meningiomas and anti-VEGF therapy (bevacizumab) may, therefore, be beneficial in NF2-related meningiomas. The purpose of the study was to report the effect of bevacizumab on meningiomas in NF2 patients. Materials and methods: We retrospectively reviewed the effect of bevacizumab on the cross-sectional area (CSA) of 14 intracranial meningiomas in 7 NF2 patients. Bevacizumab 10 mg/kg was administered intravenously every two weeks for six months and 15 mg/kg every three weeks thereafter. Patients were evaluated according to the modified Macdonald criteria with repeated magnetic resonance (MR) scans. Results: The median duration of therapy was 27 months (range 16–34) and 42 MR scans (median 8, range 4–11) were reviewed. The median annual change in meningioma CSA prior to bevacizumab was 2% (range –4%–+76%). During treatment, a decrease in meningioma CSA was observed in 5 of 14 meningiomas (36%) in 5 of 7 patients (71%). The median decrease in CSA was –10% (range –3%––25%). One meningioma (7%) progressed and the remaining (93%) had stable disease. Conclusions: Bevacizumab may slow or reverse the growth of some NF-related meningiomas. However, we have previously reported a fatal case of intracerebral hemorrhage following bevacizumab in NF2 patients, wherefore, this effect needs to be balanced carefully against the risk of side effects.