Phase I study of the halichondrin B analogue eribulin mesylate in combination with cisplatin in advanced solid tumors

Background:

Eribulin mesylate is a synthetic macrocyclic ketone analogue of Halichondrin B that has demonstrated high antitumor activity in preclinical and clinical settings. This phase I study aimed to determine the maximum tolerated dose (MTD), dose-limiting toxicities (DLTs), and pharmacokinetics in combination with cisplatin (CP) in patients with advanced solid tumours.

Methods:

Thirty-six patients with advanced solid tumours received eribulin mesylate 0.7–1.4 mg m⁻² and CP 60–75 mg m⁻². Eribulin mesylate was administered on days 1, 8, and 15 in combination with CP day 1 every 28-day cycle. The protocol was amended after dose level 4 (eribulin mesylate 1.4 mg m⁻², CP 60 mg m⁻²) when it was not feasible to administer eribulin mesylate on day 15 because of neutropenia; the treatment schedule was changed to eribulin mesylate on days 1 and 8 and CP on day 1 every 21 days.

Results:

On the 28-day schedule, three patients had DLT during the first cycle: grade (G) 4 febrile neutropenia (1.0 mg m⁻², 60 mg m⁻²); G 3 anorexia/fatigue/hypokalemia (1.2 mg m⁻², 60 mg m⁻²); and G 3 stomatitis/nausea/vomiting/fatigue (1.4 mg m⁻², 60 mg m⁻²). On the 21-day schedule, three patients had DLT during the first cycle: G 3 hypokalemia/hyponatremia (1.4 mg m⁻², 60 mg m⁻²); G 4 mucositis (1.4 mg m⁻², 60 mg m⁻²); and G 3 hypokalemia (1.2 mg m⁻², 75 mg m⁻²). The MTD and recommended phase II dose was determined as eribulin mesylate 1.2 mg m⁻² (days 1, 8) and CP 75 mg m⁻² (day 1), on a 21-day cycle. Two patients had unconfirmed partial responses (PR) (pancreatic and breast cancers) and two had PR (oesophageal and bladder cancers).

Conclusions:

On the 21-day cycle, eribulin mesylate 1.2 mg m⁻², administered on days 1 and 8, in combination with CP 75 mg m⁻², administered on day 1 is well tolerated and showed preliminary anticancer activity.     

An account of nursing a child with complex needs in the home

A children's nurse in the Republic of Ireland describes her experience working with children with complex needs in their homes, the preferred setting for their care. The varied duties involved in meeting essential, often complicated, requirements and gradually improving the quality of life of child and family are explored using Peplau's model of care. Career pathways for children's nurses in Ireland now include the development of community posts and planned support in the home for children with long-term illnesses and their caregivers.     

National Institute for Health and Clinical Excellence appraisal and ageism

The requirements of the UK Equality Act 2010 and some high profile criticism for using a potentially ageist methodology have prompted the National Institute for Health and Clinical Excellence (NICE) to assess the processes and methodology it uses to make appraisal decisions. This paper argues that NICE has established rigorous systems to protect against ageist decisions, has no track record of ageism and is well placed to meet the requirements of new UK equality legislation.     

Invasive mold infections in iatrogenically immunocompromised children: an eight-yr review

Abstract:  IMI are emerging as an important cause of mortality and morbidity among the growing number of immunocompromised children. A retrospective chart review was performed in all patients with a proven diagnosis of IMI over an eight-yr period (1997–2004) at The Hospital for Sick Children, Toronto, Canada to document the incidence, clinical spectrum, microbiology, treatment, and outcome of pediatric IMI. Twenty-eight patients developed IMI over the study period (10 cancer, 12 HCT, and six SOT patients). IMI occurred in 0.51%, 2.2% and 3.2% after a median time of 118, 60 and 71 days, among cancer, HCT and SOT recipients, respectively. Aspergillus spp. infection was diagnosed most commonly (23 patients) and the most common site of infection was the lung (21 patients). Patients at increased risk included those with acute myelogenous leukemia, allogeneic unrelated HCT recipients, graft-versus-host disease, and lung transplant recipients. The mortality after one yr was 60% among cancer patients, 58% among HCT patients, and 16% among SOT patients.     

Pneumoproteins as markers of paraquat lung injury: a clinical case

OBJECTIVE: To describe the changes in lung-specific secretory proteins in biological fluids in a fatal case of paraquat ingestion and to present immunostaining data obtained on postmortem lung tissue specimens. METHODS: A 20-year-old man committed suicide by ingesting 100ml of a 20% paraquat solution. Surfactant associated proteins A (SP-A), B (SP-B) and Clara cell 16kDa protein (CC16) were determined in the serum and on broncho-alveloar lavage performed 18h after admission. Renal failure progressed rapidly and the patient died from refractory hypoxia. Immunostaining studies using antibodies directed against CC16, SP-A and SP-B were performed on postmortem lung tissue specimens. RESULTS: Serum CC16 seemed to increase gradually with the progression of renal impairment. Serum SP-A and SP-B levels increased before any significant changes in pulmonary gas exchanges. The immunostaining study showed that the labeling for SP-A and SP-B was reduced or absent following paraquat toxicity, while Clara cells were relatively preserved. CONCLUSIONS: The elevation of serum CC16 with paraquat toxicity is probably mainly related to a reduced renal clearance. The increase of serum SP-A and SP-B could reflect an increased lung to blood leakage, independently of the alteration of the renal function.     

A Nonazole CYP51 Inhibitor Cures Chagas’ Disease in a Mouse Model of Acute Infection

Chagas’ disease, the leading cause of heart failure in Latin America, is caused by the kinetoplastid protozoan Trypanosoma cruzi. The sterols of T. cruzi resemble those of fungi, both in composition and in biosynthesis. Azole inhibitors of sterol 14α-demethylase (CYP51) successfully treat fungal infections in humans, and efforts to adapt the success of antifungal azoles posaconazole and ravuconazole as second-use agents for Chagas’ disease are under way. However, to address concerns about the use of azoles for Chagas’ disease, including drug resistance and cost, the rational design of nonazole CYP51 inhibitors can provide promising alternative drug chemotypes. We report the curative effect of the nonazole CYP51 inhibitor LP10 in an acute mouse model of T. cruzi infection. Mice treated with an oral dose of 40 mg LP10/kg of body weight twice a day (BID) for 30 days, initiated 24 h postinfection, showed no signs of acute disease and had histologically normal tissues after 6 months. A very stringent test of cure showed that 4/5 mice had negative PCR results for T. cruzi, and parasites were amplified by hemoculture in only two treated mice. These results compare favorably with those reported for posaconazole. Electron microscopy and gas chromatography-mass spectrometry (GC-MS) analysis of sterol composition confirmed that treatment with LP10 blocked the 14α-demethylation step and induced breakdown of parasite cell membranes, culminating in severe ultrastructural and morphological alterations and death of the clinically relevant amastigote stage of the parasite.Chagas’ disease, caused by the kinetoplastid protozoan Trypanosoma cruzi, is the leading cause of heart failure in Latin America. The disease is transmitted naturally by hematophagous reduviid insects (6), but human infection may also occur via other routes, including blood transfusion, congenital infection, breast-feeding, organ transplant from chagasic donors, laboratory accidents, and ingestion of contaminated foods and beverages. The acute phase of infection usually occurs in children, and 5 to 10% of symptomatic patients may die. Following a subclinical “indeterminate” phase, a chronic phase involving heart failure and gastrointestinal tract lesions often ensues (37, 42). The only clinically available drugs for Chagas’ disease are nifurtimox and benznidazole, both of which have been in use for 4 decades. While they have significant efficacy in the acute phase, both drugs suffer from the twin liabilities of serious side effects and low efficacy in the chronic phase. New drugs with improved efficacy and less toxicity are needed (14, 29).The biosynthesis of membrane sterols is one of the metabolic pathways successfully targeted in the treatment of diseases caused by pathogenic fungi (48). Clinically employed antifungal azoles target sterol 14α-demethylase (CYP51), a cytochrome P450 enzyme that catalyzes oxidative removal of the 14α-methyl group of a sterol precursor to result in Δ^14,15-desaturated intermediates in ergosterol biosynthesis (19, 20). Close similarities to fungi in sterol composition and biosynthesis, plus an absolute requirement for specific 24-methyl sterols for cell viability and proliferation, provide a basis for development of chemotherapy targeting the sterol biosynthetic pathway in T. cruzi. The successful application of antifungal drugs to anti-chagasic therapy exploits these similarities (38). In addition to compounds optimized for antifungal therapy, other CYP51 inhibitors with strong anti-T. cruzi activity have been reported (3, 8, 24, 44, 45).Inhibitors of CYP51 are in the pipeline for preclinical and clinical development for treatment of Chagas’ disease (11). Although earlier commercially available inhibitors, like ketoconazole and itraconazole, were not powerful enough to eradicate T. cruzi from infected animals or human patients (28), the recently approved inhibitor posaconazole (Noxafil; Schering-Plough) is capable of inducing parasitological cure in murine models of both acute and chronic Chagas’ disease (18). Posaconazole cured 50 to 100% of animals in the acute phase and 50 to 60% of chronically infected animals (2). Very recently, posaconazole cured an immunosuppressed patient with concomitant Chagas’ disease and systemic lupus erythematosus (34). However, the use of posaconazole as an anti-chagasic agent may be limited by the requirement for simultaneous intake of a fatty meal or a nutritional supplement to enhance absorption, the drug''s high cost, and the need for clinical monitoring during treatment (31). Another complication is the rapid appearance of laboratory-induced resistance to azoles in T. cruzi, which may predict the occurrence of drug resistance in chagasic patients (4). Although no data on the development of posaconazole resistance in patients with Chagas’ disease are available, studies of fungal infections indicate that posaconazole resistance occurs mainly by a mechanism involving mutation of the cyp51 gene (23, 33, 35). Posaconazole appears to be less susceptible to the efflux pumps that confer resistance to some other azoles (7, 25, 35). Mapping mutations in cyp51 genes in clinical posaconazole-resistant isolates on the CYP51-posaconazole structure (9) points to the mouth of the posaconazole binding tunnel as a mutation hot spot. Mutations of G54, P216, and M220 in clinical isolates of Aspergillus fumigatus (10, 12, 13, 23, 27, 32) (corresponding to G49, P210, and F214, respectively, in T. cruzi CYP51 [CYP51_Tc]) and of A61 (46) and P230 (25) in clinical isolates of Candida albicans (I45 and P210, respectively, in CYP51_Tc) map directly to the tunnel mouth, where amino acids interact with the dangling long substituent tail of posaconazole extending into the tunnel (9). Mutations of G54 in A. fumigatus to arginine or tryptophan associate with moderate and high levels of resistance, respectively, and confer cross-resistance between itraconazole and posaconazole (27). Mutations of M220 confer cross-resistance to all azole drugs tested, including itraconazole, voriconazole, ravuconazole, and posaconazole (30, 39), and therefore may interfere with the entry of the drugs. In accordance with this assumption, posaconazole is reported to induce resistance to all azole drugs in Candida parapsilosis in vitro (35). The alarming perspective emerging from antifungal therapy efforts must be taken into consideration when designing antichagasic drugs targeting CYP51_Tc. While antifungal azoles do show promise, the less than 30% sequence identity between fungal and protozoan CYP51 targets suggests that a more direct approach may be a better route toward developing novel potent therapeutic CYP51 inhibitors.Using clues from our previous work on CYP51 from Mycobacterium tuberculosis (CYP51_Mt), we focused on rationally designed nonazole inhibitors of CYP51_Tc. These inhibitors were based on an experimental hit obtained from screening a small-molecule-compound library against CYP51_Mt (36). Analysis of the X-ray structure revealed that the N-[4-pyridyl]-formamide scaffold group (Fig. ​(Fig.1A,1A, highlighted in gray) binds in the CYP51 active site via conserved residues and the heme prosthetic group. Structural characterization confirmed that these interactions in the complexes were preserved between CYP51_Mt and five different compounds (8, 36), suggesting that this scaffold could be used efficiently instead of the azole or triazole groups to target a variety of chemotypes to the CYP51 active site. Based on the similarity of the chemical structures, the expanded-spectrum compound LP10 (Fig. ​(Fig.1B)1B) was selected for its nanomolar binding affinity to CYP51_Tc and its potent efficacy against T. cruzi in mammalian cells (8). As the pyridyl group of LP10 presumably coordinates to the heme iron, the indole substituent may fill the space occupied by the 2,4-difluorophenyl ring of fluconazole or posaconazole in their structurally characterized complexes with CYP51 (9).Open in a separate windowFIG. 1.Screen hit (A) and the expanded-spectrum compound LP10 (B) containing the N-[4-pyridyl]-formamide scaffold (highlighted in gray), which unvaryingly binds in the CYP51 active site. The chiral center is labeled with an asterisk.In the present work, we evaluated the efficacy of LP10 in an animal model of acute Chagas’ disease. The curative effect of LP10 in vivo was comparable to that of the protease inhibitor K777, an antichagasic drug in preclinical development, used as a positive control (15, 16). Electron microscopy and gas chromatography-mass spectrometry (GC-MS) analysis demonstrated that treatment with LP10 disrupted cell membranes in T. cruzi amastigotes and altered sterol composition via accumulation of the C-14-methylated precursors lanosterol and 24-methylene-dihydrolanosterol (eburicol). There was concomitant reduction of 14-desmethylated fecosterol and episterol. LP10-induced alterations are consistent with the inhibition of T. cruzi CYP51.     

NMDA-receptor activation and nitroxidative regulation of the glutamatergic pathway during nociceptive processing

The role of peroxynitrite (PN) as a mediator of nociceptive signaling is emerging. We recently reported that the development of central sensitization that follows the intraplantar injection of carrageenan in rats is associated with spinal PN synthesis. We now demonstrate that a significant pathway through which spinal PN modulates central sensitization is post-translational tyrosine nitration of key proteins involved in the glutamatergic pathway, namely glutamate transporter GLT-1 and glutamine synthetase (GS). We also reveal that spinal activation of the N-methyl-d-aspartate (NMDA) receptor provides a source of PN in this setting. Intraplantar injection of carrageenan led to the development of thermal hyperalgesia as well as nitration of GLT-1 and GS in dorsal horn tissues. Pretreatment with the PN decomposition catalyst FeTM-4-PyP⁵⁺ [Fe(III)5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrin] or the NMDA receptor antagonist MK-801 blocked the development of hyperalgesia. Carrageenan-induced hyperalgesia was also associated with nitration and inactivation of spinal mitochondrial superoxide dismutase (MnSOD) known to provide a critical source of PN during central sensitization. Nitration of GLT-1 and GS contributes to central sensitization by enhancing glutamatergic neurotransmission. Our results support the critical role of nitroxidative stress in the development of hyperalgesia and suggest that post-translational nitration of enzymes and transporters linked to glutamatergic neurotransmission represent a novel mechanism of central sensitization.