Recommended Best Practices for Lyophilization Validation 2021 Part II: Process Qualification and Continued Process Verification

This work describes the lyophilization process validation and consists of two parts. Part one (Part I: Process Design and Modeling) focuses on the process design and is described in the previous paper, while the current paper is devoted to process qualification and continued process verification. The goal of the study is to show the cutting edge of lyophilization validation based on the integrated community-based opinion and the industrial perspective. This study presents best practices for batch size determination and includes the effect of batch size on drying time, process parameters selection strategies, and batch size overage to compensate for losses during production. It also includes sampling strategies to demonstrate batch uniformity as well as the use of statistical models to ensure adequate sampling. Based on the LyoHUB member organizations survey, the best practices in determining the number of PPQ runs are developed including the bracketing approach with minimum and maximum loads. Standard practice around CQA and CPP selection is outlined and shows the advantages of using control charts and run charts for process trending and quality control. The case studies demonstrating the validation strategy for monoclonal antibody and the impact of the loading process on the lyophilization cycle and product quality as well as the special case of lyophilization for dual-chamber cartridge system are chosen to illustrate the process validation. The standard practices in the validation of the lyophilization process, special lyophilization processes, and their impact on the validation strategy are discussed.

Recommended Best Practices for Lyophilization Validation-2021 Part I: Process Design and Modeling

Abstract

This work describes lyophilization process validation and consists of two parts. Part I focuses on the process design and is described in the current paper, while part II is devoted to process qualification and continued process verification. The intent of these articles is to provide readers with recent updates on lyophilization validation in the light of community-based combined opinion on the process and reflect the industrial prospective. In this paper, the design space approach for process design is described in details, and examples from practice are provided. The approach shows the relationship between the process inputs; it is based on first principles and gives a thorough scientific understanding of process and product. The lyophilization process modeling and scale-up are also presented showing the impact of facility, equipment, and vial heat transfer coefficient. The case studies demonstrating the effect of batch sizes, fill volume, and dose strength to show the importance of modeling as well as the effect of controlled nucleation on product resistance are discussed.

Graphical abstract

Abstract 377: KLF15-TCF7L2-dependent Cardiac Transcriptional Reprogramming Induces Cardiomyocyte and Vascular Cell Remodeling in the Mammalian Heart

Integrative biochemical and omic-based approaches have refined our understanding of how cells integrate the Wnt signal at the chromatin level to yield specific cellular responses. However, this aspect remains unexplored in the heart. Since Wnt/β-catenin signaling activation is a hallmark in pathological cardiac remodeling, we aimed to characterize the specific Wnt cardiac transcriptional network regulation, amenable to therapeutic intervention in the adult heart.

In the adult heart, we found the transcription factor KLF15 occupying regulatory regions of tissue remodeling genes containing Wnt transcriptional activator, TCF7L2, binding sites, which are silenced in the healthy myocardium but are active during pathological remodeling. Supporting KLF15 repressive roles, its loss resulted in cardiac TCF7L2 activation, maladaptive reprograming and failure in vivo . We demonstrated that KLF15 possess transcriptional age-specific repressive functions controlling Wnt signaling, cardiomyocyte de-differentiation and vascular cell (VC) remodeling. Employing different transgenic mouse models we further identified a cooperative program inducing aberrant VC remodeling, caused by a reduction of KLF15 with a concomitant TCF7L2 activation in cardiomyocytes. Furthermore, we characterized a cardiac specific Wnt transcriptional inhibitory complex consisting of KLF15 directly interacting with β-catenin and TCF7L2 and identified the amino acids critical for these interactions. Next, using a CRISPR/Cas9-mediated approach we generated KLF15 knockout (KO) hESC lines differentiated into functional cardiomyocytes and used for engineering human myocardium (EHM) generation. KLF15 KO EHMs showed activation of TCF7L2-dependent transcription as well as impaired function in comparison to control lines, recapitulating the Klf15 KO mouse phenotype.

Altogether, we uncover an exquisite evolutionary conserved cardiac specific regulation mediated by KLF15 on Wnt signaling in myocardium offering a basis for designing highly specific pharmacological intervention for controlling Wnt cardiac-specific gene activation to prevent irreversible heart failure. We also underscore the significance of KLF15-Wnt dynamics in VC remodeling of the adult heart.

Abstract P3-02-08: Association of background parenchymal enhancement with breast cancer risk factors and tumor characteristics

Background: Background Parenchymal Enhancement (BPE) in a dynamic contrast enhanced (DCE)MRI refers to change in morphology and temporal degree of enhancement expressing physiology of breast tissue. Improvements in the analysis and interpretation of BPE have been shown to increase diagnostic accuracy of the MRI. We explored associations of BPE with breast cancer(BC) risk factors and tumor characteristics.

Methods: We conducted a retrospective chart review study of 149 women who were treated for BC at the University of Maryland Medical Center(UMMC) between 2003-2015. Institutional Review Board approval was obtained. Subjects had BI-RADS 4,5 or 6 on their mammograms and/or biopsy proven BC. Women with false positive mammograms (n=2), missing BPE grade in their MRI reports (n=6), metastatic BC at diagnosis (n=2), MRIs done outside of a year of diagnosis (n=3), and who followed up outside UMMC (n=1) were excluded. Final analysis included 135 women. We used 1.5T or 3T scanners for DCE MRI. Standard contrast enhanced MRI protocol, T1, T2, and dynamic series were acquired according to American College of Radiology requirements for breast MRI accreditation and interpreted with Maximum Intensity Projection and subtracted imaging. Fellowship-trained breast imagers performed qualitative BPE assessment as per standard BI-RADS classification. BI-RADS classes were grouped as high BPE (BI-RADS moderate and marked) and low BPE (BI-RADS minimal and mild). Multivariable logistic regression was used to assess associations with predictors including individual and tumor characteristics.

Results: Preliminary analyses showed BPE was significantly associated with alcohol intake, with drinkers being more likely to have high BPE compared to non-drinkers [odds ratio (OR) =3.08 (95% confidence interval (CI) = 1.34-7.09; p=0.008]. Women who received adjuvant radiation for their BC were less likely to have high BPE compared to women who did not undergo radiation [OR= 0.37 (95% CI=0.15-0.90); p=0.03] implying higher likelihood of breast conservation surgery in the former group. High BPE was less often observed for invasive ductal carcinoma histology vs. in-situ ductal carcinomas [OR= 0.40 95% CI=0.16-1.00); p=0.05] and in post- vs. premenopausal women [OR=0.47 (95%CI=0.22-1.00); p=0.05]. No association was found between BPE and race, BMI, prior HRT/OCP use, smoking, or ER/PR/HER-2 status.

Conclusion: We observed association between higher BPE and alcohol exposure and lower BPE and, invasive ductal histology, postmenopausal status at diagnosis of BC and adjuvant radiation for BC. Larger studies are needed to corroborate our findings and identify the underlying mechanisms.

Citation Format: Iyer L, Faramand R, Jung S, Rosenblatt P, Campassi C, Dromi S, Dorgan J, Tkaczuk K. Association of background parenchymal enhancement with breast cancer risk factors and tumor characteristics [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-02-08.

Molecular analysis of vibrio cholerae strains isolated in Malaysia: public health implications

The genetic diversity or clonality among Vibrio cholerae O1, O139 and non-O1/ non-O139 of clinical and environmental origin using ribotyping and PFGE was performed in order to ascertain the public health implications of the different genotypes circulating within the Malaysian environment. Using an in-house typing scheme, of the 214 strains included, 202 strains were isolated locally between 1992 and 1998, seven were obtained from Bangladesh and five were reference strains. Amongst the 176 El Tor O1 strains, 152 clinical strains demonstrated five ribotypes--E1a, E1b, E2a, E3 and E1c. E1b was the most predominant ribotype demonstrated by 84% of the El Tor O1 strains and was present in all years demonstrating that this strain was intrinsic to Malaysia. PFGE analysis of these strains demonstrated minimal variation amongst the 15 PFGE profiles obtained. Ribotpye E2a amongst five clinical and two environmental O1 strains, were from one location and had previously been reported in Indonesia and the Philippines, thus demonstrating strong evidence that these strains may have been imported into Malaysia. Among Vibrio cholerae O139 strains, 91.7% were of ribotype A1a similar to the original O139, while two others were of ribotype A1b and one of A1e, corresponding to ribotypes 1, 2 and 3 of Dalsgaard and colleagues' scheme for O139 strains. PFGE analysis demonstrated that 89% of ribotype A1a could be differentiated into three PFGE genotypes which were very closely related. The eight non-O1/non-O139 serogroup strains were heterogeneous in both ribotype and PFGE patterns.

Diagnosis, treatment and follow up of women undergoing conscious pain mapping for chronic pelvic pain: a prospective cohort study

OBJECTIVE

To assess the efficacy of conscious pain mapping in diagnosing and treating chronic pelvic pain (CPP).

DESIGN

Prospective cohort study. Setting Gynaecology Department, UK District General Hospital.

POPULATION

Forty-three women diagnosed with CPP.

METHODS

The cohort was followed up for 18-24 months after diagnosis and treatment based on conscious pain mapping.

MAIN OUTCOME MEASURES

Improvement of pain assessed by using visual analogue scale (VAS) pain scores at 6-month follow up.

RESULTS

Thirty-nine women had successful conscious pain mapping. Pelvic pathology was identified in 18, pelvic congestion in 13 and 8 women had normal pelvic organs. In 35 women (90%), conscious pain mapping identified the cause of pain. Five out of eight women (63%) who were judged to have a normal pelvis had positive findings at pain mapping. VAS scores fell significantly from pre-treatment to post-treatment values at 6-month follow up (P < 0.01). Overall, 26 women (74%) felt that their symptoms had improved after treatment based on findings at pain mapping. However, we concluded that pain mapping only contributed to the diagnosis and treatment in seven women (27%), who may not have received appropriate diagnosis and treatment if they had a laparoscopy under general anaesthetic. Conclusions CONSCIOUS: pain mapping is a useful additional investigation in the management of women with CPP. It can be employed in women with a negative laparoscopy or with visible pathology where the conventional treatment has failed.

UGT1A1*28 polymorphism as a determinant of irinotecan disposition and toxicity

The metabolism of irinotecan (CPT-11) involves sequential activation to SN-38 and detoxification to the pharmacologically inactive SN-38 glucuronide (SN-38G). We have previously demonstrated the role of UGT1A1 enzyme in the glucuronidation of SN-38 and a significant correlation between in vitro glucuronidation of SN-38 and UGT1A1 gene promoter polymorphism. This polymorphism (UGT1A1*28) is characterized by the presence of an additional TA repeat in the TATA sequence of the UGT1A1 promoter, ((TA)7TAA, instead of (TA)6TAA). Here we report the results from a prospective clinical pharmacogenetic study to determine the significance of UGT1A1*28 polymorphism on irinotecan disposition and toxicity in patients with cancer. Twenty patients with solid tumors were treated with a 90 min i.v. infusion of irinotecan (300 mg m(-2)) once every 3 weeks. The frequency of UGT1A1 genotypes was as follows: 6/6--45%, 6/7--35% and 7/7--20%, with allele frequencies of 0.375 and 0.625 for (TA)7TAA and (TA)6TAA, respectively. Patients with the (TA)7TAA polymorphism had significantly lower SN-38 glucuronidation rates than those with the normal allele (6/6>6/7>7/7, P = 0.001). More severe grades of diarrhea and neutropenia were observed only in patients heterozygous (grade 4 diarrhea, n = 1) or homozygous (grade 3 diarrhea/grade 4 neutropenia, n = 1 and grade 3 neutropenia, n = 1) for the (TA)7TAA sequence. The results suggest that screening for UGT1A1*28 polymorphism may identify patients with lower SN-38 glucuronidation rates and greater susceptibility to irinotecan induced gastrointestinal and bone marrow toxicity.

Epidemiology and molecular characterization of nosocomially transmitted multidrug-resistant Klebsiella pneumoniae

OBJECTIVES

To describe the epidemiology, antimicrobial susceptibility, genomic profiles, and control of a nosocomial outbreak of multidrug-resistant Klebsiella pneumoniae (MRKP) that occurred in the pediatric oncology unit of the University of Malaya Medical Centre in Kuala Lumpur.

MATERIALS AND METHODS

A prospective epidemiologic and microbiologic study was conducted of MRKP isolated from the blood and wound of a boy with necrotizing fasciitis after a 7-day course of ceftazidime and amikacin. In the following 2 weeks, phenotypically similar MRKP were isolated from the blood cultures of four other patients and rectal swabs of another three patients and two liquid soap samples located in the same ward.

RESULTS

Antimicrobial profiles demonstrated that all the isolates were resistant to ceftazidime, sensitive to imipenem and ciprofloxacin, and confirmed to be extended-spectrum beta-lactamase producers. Plasmids of varying molecular weights were present in all isolates. In eight of these isolates, which included four from blood, there were common large molecular weight plasmids ranging from 80 kb to 100 kb. Pulsed-field gel electrophoresis analysis using XbaI demonstrated six different DNA profiles, A to F. Profile A was shared by two blood culture isolates and were related by 91%. Profile B was found in one rectal swab isolate and one isolate from liquid soap and were related by 94%. Profile C was shared by one blood isolate and one liquid soap isolate and showed 100% relatedness. Profiles D, E, and F each were demonstrated by one blood isolate and two rectal swab isolates, respectively. These showed only 65% relatedness.

CONCLUSIONS

The MRKP strains in this outbreak were not clonal in origin. The decline of the outbreak after 4 weeks was attributed to the reemphasis of standard infection control procedures and the implementation of a program that addressed sites of environmental contamination.

Epirubicin glucuronidation is catalyzed by human UDP-glucuronosyltransferase 2B7

Epirubicin is one of the most active agents for breast cancer. The formation of epirubicin glucuronide by liver UDP-glucuronosyltransferase (UGT) is its main inactivating pathway. This study aimed to investigate epirubicin glucuronidation in human liver microsomes, to identify the specific UGT isoform for this reaction, and to correlate epirubicin glucuronidation with other UGT substrates. Microsomes from human livers were used. UGTs specifically expressed in cellular systems, as well as two UGT2B7 variants, were screened for epirubicin glucuronidation. Epirubicin, morphine, and SN-38 glucuronides were measured by high-pressure liquid chromatography. The mean +/- S.D. formation rate of epirubicin glucuronide in human liver microsomes (n = 47) was 138 +/- 37 pmol/min/mg (coefficient of variation, 24%). This phenotype was normally distributed. We screened commercially available UGT1A1, UGT1A3, UGT1A4, UGT1A6, UGT1A9, UGT2B7, and UGT2B15 for epirubicin glucuronidation. Only UGT2B7 converted epirubicin to its glucuronide. No differences in epirubicin glucuronidation were found in HK293 cells expressing the two UGT2B7 variants at position 268. Catalytic efficiency (V(max)/K(m)) of epirubicin glucuronidation was 1.4 microl/min/mg, a value higher than that observed for morphine, a substrate of UGT2B7. Formation of epirubicin glucuronide was significantly related to that of morphine-3-glucuronide (r = 0.76, p < 0.001) and morphine-6-glucuronide (r = 0.73, p < 0.001). No correlation was found with SN-38, a substrate of UGT1A1 (r = 0.04). UGT2B7 is the major human UGT catalyzing epirubicin glucuronidation, and UGT2B7 is the candidate gene for this phenotype. The reported tyrosine to histidine polymorphism in UGT2B7 does not alter the formation rate of epirubicin glucuronide, and undiscovered genetic polymorphisms in UGT2B7 might change the metabolic fate of this important anticancer agent.

Phase I clinical and pharmacogenetic study of weekly TAS-103 in patients with advanced cancer

PURPOSE

TAS-103 is an inhibitor of both topoisomerase I and II enzymes with broad antitumor activity. It is metabolized to TAS-103-glucuronide (TAS-103-G) predominantly by uridine diphosphate glucuronosyltransferase isoform 1A1 (UGT1A1). We conducted a phase I study to determine the maximum-tolerated dose (MTD) and dose-limiting toxicity (DLT) of TAS-103 when administered on a weekly schedule to patients with advanced cancer. In addition, we evaluated the influence of UGT1A1 genotype on the pharmacokinetics and toxicity of TAS-103.

PATIENTS AND METHODS

Thirty-two patients were treated with escalating doses (50 to 200 mg/m(2)) of TAS-103, administered intravenously over 1 hour each week for 3 weeks. Pharmacokinetic analysis was performed at the 130-, 160-, and 200-mg/m(2) dose levels. UGT1A1 genotypes were determined using reverse-transcription polymerase chain reaction techniques.

RESULTS

DLT (grade 3 neutropenia) was observed in 5 of 12 patients at 160 mg/m(2) and in 3 of 6 patients at 200 mg/m(2). At 160 mg/m(2), there was a significant correlation between areas under the curve (AUCs) for TAS-103 and TAS-103-G (r = 0.76, P <.05) and an apparent relationship between TAS-103 AUC and D 15 absolute neutrophil count (r = -0.63, P <.05, n = 11, one outlier excluded). UGT1A1 genotype did not influence clearance of TAS-103.

CONCLUSION

We recommend a dose of 130 to 160 mg/m(2), or 250 to 300 mg administered using the above weekly schedule for phase II studies. Further studies to characterize the pharmacodynamics and pharmacogenetics of TAS-103 are warranted.

Pharmacogenetics of anticancer agents: lessons from amonafide and irinotecan

Amonafide and irinotecan are anticancer drugs representative of the clinical relevance of N-acetyltransferase (NAT) and uridine diphosphate glucuronosyltransferase (UGT) polymorphisms in cancer chemotherapy, respectively. Amonafide, a substrate for the polymorphic NAT2, has an active metabolite, N-acetyl-amonafide. Using caffeine as a probe, slow and rapid acetylators of amonafide were identified. Fast acetylators experienced greater myelosuppression than did slow acetylators, and a reduced dose of amonafide for fast acetylators has been recommended. A pharmacodynamic model based on acetylator phenotype, pretreatment white blood cell count, and gender has been proposed for dose individualization. The strategy adopted for amonafide is a model for future investigations in pharmacogenetics, although amonafide is no longer in clinical development. SN-38, the active metabolite of irinotecan, is glucuronidated to the inactive SN-38 glucuronide by UGT1A1, the isoform catalyzing bilirubin glucuronidation. Genetic defects in UGT1A1 determine Crigler-Najjar and Gilbert's syndromes characterized by unconjugated hyperbilirubinemia. Gilbert's syndrome often remains undiagnosed and occurs in up to 19% of individuals. Gilbert's syndrome is due to a homozygous TA insertion in the TATAA promoter of UGT1A1, leading to the mutated (TA)(7) allele. Irinotecan toxicity depends on the individual glucuronidation rate of SN-38. Decreased SN-38 glucuronidating activity has been found in livers obtained from individuals carrying the (TA)(7) allele. A phenotyping procedure for UGT1A1 has not been identified and genotyping of the UGT1A1 promoter in patients receiving irinotecan may identify patients at increased risk of toxicity. A clinical trial at the University of Chicago is ongoing to demonstrate the predictive significance of UGT1A1 genotyping for irinotecan pharmacodynamics.

Platelet APP isoform ratios in asymptomatic young adults expressing an AD-related presenilin-1 mutation

The Alzheimer's disease (AD) related amyloid precursor protein (APP) is stored, cleaved and released similarly from neurons and from platelets. We have reported that the proportion of 120-130 to 110 kDa carboxyl-cleaved APP present in the platelets of AD patients is significantly lower than that of platelets of age-matched controls. This reduced APP isoform ratio, not seen in several other disease groups, is further reduced as the severity of AD increases. Since the neuropathology of AD is believed to begin many years before the onset of cognitive loss, we have also compared platelet APP ratios of four pre-symptomatic young adults carrying a presenilin-1 mutation to seven siblings homozygous for the normal PS-1 gene in an effort to determine whether reduced APP ratios are present before apparent cognitive loss in familial AD. Decreased platelet APP ratios were not seen in any of these subjects at this time. We will continue to monitor these subjects as they near the mean age of AD onset in these families. As the magnitude of the APP ratio reduction is proportional to the severity of cognitive loss in sporadic AD, these cognitively normal incipient AD subjects would not be expected to present significant reductions in this AD severity index at this time. Alternatively, the absence of platelet APP ratio reductions may result from a failure of platelets from familial PS-1 AD subjects to manifest altered APPs, as has been reported for PS-2 AD subjects, unlike those of sporadic AD patients. Continued monitoring of cognitive status in our sub-set of controls with AD-like low APP ratios may yet validate the ability of this assay to detect incipient sporadic AD.

Pharmacogenetics: a tool for individualizing antineoplastic therapy

This article reviews the clinical relevance of pharmacogenetics in cancer chemotherapy, with emphasis on drugs for which genetic differences in enzyme metabolism have been demonstrated to affect patient outcome. About 10% of children with leukaemia are intolerant to mercaptopurine (6-mercaptopurine) because of genetic defects in mercaptopurine inactivation by thiopurine S-methyltransferase. However, mercaptopurine dose intensity, a critical factor for outcome in patients deficient in thiopurine S-methyltransferase, can be maintained by means of thiopurine S-methyltransferase phenotyping or genotyping. Patients with reduced fluorouracil (5-fluorouracil) catabolism are more likely to be exposed to severe toxicity. The measurement of dihydropyrimidine dehydrogenase activity in patients cannot be considered fully predictive, and the role of dihydropyrimidine dehydrogenase gene variants in this syndrome has yet to be clarified. With regard to irinotecan, patients with Gilbert's syndrome phenotype have reduced inactivation of the active topoisomerase I inhibitor 7-ethyl-10-hydroxycamptothecin (SN-38) caused by a mutation in the UDP-glucuronosyltransferase 1A1 gene promoter. This subset of patients is more likely to be exposed to irinotecan toxicity and could be identified by genotyping for gene promoter variants. Finally, the experience with amonafide represents a model for dose individualization approaches that use simple phenotypic probes.

Flavopiridol metabolism in cancer patients is associated with the occurrence of diarrhea

Flavopiridol, a cyclin-dependent kinase inhibitor currently undergoing clinical evaluation, has a dose-limiting toxicity of diarrhea. Preclinical data on flavopiridol metabolism indicate that flavopiridol undergoes hepatic glucuronidation. The purpose of this study is to evaluate whether the occurrence of diarrhea is related to the systemic glucuronidation of flavopiridol. Parent drug and metabolite concentrations in plasma were measured by high-pressure liquid chromatography in 22 metastatic renal cancer patients treated on a Phase II trial of 50 mg/m2/day of flavopiridol administered every 2 weeks as a 72-h continuous infusion. Pharmacokinetics of flavopiridol and its glucuronide were assessed during the first cycle at 23, 47, and 71 h during the infusion. Flavopiridol concentrations at 23, 47, and 71 h were 389 nM (296-567 nM), 412 nM (297-566 nM), and 397 nM (303-597 nM) [median (interquartile range)], respectively. Flavopiridol glucuronide reached a plateau of 358 nM (196-553 nM) at 47 h. Metabolic ratios of flavopiridol glucuronide:flavopiridol at 71 h showed an apparent bimodal distribution with an antimode of 1.2. Thirteen patients experienced diarrhea and had lower metabolic ratios [0.72 (0.53-0.86)] than patients without diarrhea [2.24 (1.76-2.3); P = 0.002]. Eight of 11 extensive glucuronidators (ratio > 1.2) did not develop diarrhea, whereas 10 of 11 poor glucuronidators (ratio < 1.2) developed diarrhea (P = 0.008). The glucuronidation of flavopiridol is apparently polymorphic, suggesting a genetic etiology. The systemic glucuronidation of flavopiridol is inversely associated with the risk of developing diarrhea.

Detection of virulence associated genes, haemolysin and protease amongst Vibrio cholerae isolated in Malaysia

Eighty-four strains of Vibrio cholerae O1, O139 and non-O1/non-O139 from clinical and environmental sources were investigated for the presence of the toxin co-regulated pilus gene, tcpA, the virulence cassette genes ctxA, zot, ace and cep and also for their ability to elaborate haemolysin and protease. The ctxA and zot genes were detected using DNA-DNA hybridization while the ace, cep and tcpA genes were detected using PCR. Production of haemolysin and protease was detected using mammalian erythrocytes and an agar diffusion assay respectively. Analysis of their virulence profiles showed six different groups designated Type I to Type VI and the major distinguishing factor among these profiles was in the in vitro production of haemolysin and/or protease. Clinical O1, O139 and environmental O1 strains were similar with regard to presence of the virulence cassette genes. All environmental O1 strains with the exception of one were found to possess ctxA, zot and ace giving rise to the probability that these strains may actually be of clinical origin. One strain which had only cep but none of the toxin genes may be a true environmental isolate. The virulence cassette and colonization factor genes were absent in all non-O1/non-O139 environmental strains but production of both the haemolysin and protease was present, indicating that these may be putative virulence factors. These findings suggest that with regard to its pathogenic potential, only strains of the O1 and O139 serogroup that possess the tcpA gene which encodes the phage receptor, have the potential to acquire the CTX genetic element and become choleragenic.

Platelet APP isoform ratios correlate with declining cognition in AD

BACKGROUND

Platelets and neurons both contain large quantities of two carboxyl-truncated 120 to 130 and 110 kDa Alzheimer amyloid precursor proteins (APPs). Platelets taken from patients with AD have been reported to contain a reduced ratio of these APPs.

OBJECTIVE

To further study the AD specificity of reduced platelet APP ratios and to determine whether, after 3 years, cognitive losses in AD are accompanied by similarly reduced platelet APP ratios.

METHODS

To test the AD specificity of reduced platelet APP ratios, we quantitated these APPs in eight patients with PD and six patients with hemorrhagic stroke (HS). To determine whether further cognitive losses correlate with platelet APP ratio reductions in patients with AD, the authors re-examined platelet APPs and Mini-Mental State Examination (MMSE) scores of 10 patients with AD and 11 controls, who were tested 3 years ago. APP ratios were determined by the average of six assays using Western blotting with m22C11 monoclonal antibody, enhanced chemoluminescence, and digital scanning of autoradiographs.

RESULTS

APP ratios were normal in the patients with PD and HS, further supporting the AD specificity of this assay. After 3 years, the MMSE scores and APP ratios of our control subjects changed by <4%. However, the average MMSE scores of our patients with AD declined from 16.4 to 8.3, and their average 120 to 130/110 kDa APP ratios declined from 5.8 to 3.6. The difference between AD and control APP ratios, with no overlap, is significant and the correlation between the 3-year decline in AD MMSE scores and reduced APP ratios (r = 0.69) was significant.

CONCLUSIONS

Although the number of subjects analyzed was limited, reduced platelet APP ratios appear to be a specific biological marker of AD and a biological index of the severity of cognitive loss in AD.

Molecular evidence of clonality amongst Vibrio cholerae O1 biotype El Tor during an outbreak in Malaysia

Forty-three clinical strains of V. cholerae O1 biotype E1 Tor were isolated between 3 May and 10 June 1998 during an outbreak in the metropolitan area of Kuala Lumpur and its suburbs. With the exception of three Inaba strains that were restricted to three members of a family, all the others belonged to the Ogawa serotype. The strains were analysed for clonality using ribotyping and pulsed-field gel electrophoresis (PFGE). Two ribotypes, V/B21a and B27, were identified among 40 Ogawa isolates using BglI restriction endonuclease. Ribotype V/B21a has been described previously from Taiwan and Colombia and several Asian countries while B27 has been reported among isolates from Senegal. The three Inaba strains belonged to one ribotype, designated type A, not previously reported. PFGE analysis using NotI revealed that all isolates within a ribotype had identical profiles demonstrating clonality amongst the strains. Dice coefficient analysis of the two Ogawa genotypes revealed 89% similarity on ribotype patterns and 91.3% on PFGE profiles. Ribotype V/B21a isolates were associated with cases from dispersed areas of Kuala Lumpur and its suburbs while ribotype B27 was restricted to cases from one particular area suggesting a common-source outbreak.

Inherited variations in drug-metabolizing enzymes: significance in clinical oncology

Pharmacogenetics has emerged as a novel and challenging area of interest in oncology. Cancer chemotherapy is characterized by major intersubject variability in tumor responses and host toxicity. This variation may be caused by genetic differences in the enzymes involved in the metabolism of anticancer agents. Anticancer agents, such as 6-mercaptopurine, 5-fluorouracil, and irinotecan, have a narrow therapeutic index that can sometimes result in severe life-threatening toxicities. The impact of polymorphisms in metabolizing enzymes (thiopurine S-methyltransferase, dihydropyrimidine dehydrogenase, and uridine diphosphate glucuronosyltransferase) that participate significantly in the disposition of these anticancer agents is discussed.

Phenotype-genotype correlation of in vitro SN-38 (active metabolite of irinotecan) and bilirubin glucuronidation in human liver tissue with UGT1A1 promoter polymorphism

BACKGROUND

Hepatic uridine diphosphate glucuronosyltransferase (UGT) isoform 1A1 (UGT1A1) is primarily responsible for the glucuronidation of SN-38 (7-ethyl-10-hydroxycamptothecin), the active metabolite of the anticancer agent irinotecan. UGT1A1, also catalyzing the glucuronidation of bilirubin, has been shown to have reduced activity in Gilbert's syndrome. The presence of an additional TA repeat [(TA)7TAA] in the TATA sequence of UGT1A1 has been associated with Gilbert's syndrome.

OBJECTIVE

To evaluate the relationship between UGT1A1 phenotypic activity and UGT1A1 promoter polymorphism.

METHODS

Phenotypic measurements included in vitro SN-38 and bilirubin glucuronidation in human liver microsomes (n = 44). A recently developed genotyping test was used to determine TATA sequence polymorphisms in UGT1A1. Genotypes were assigned as follows: 7/7, homozygous for the (TA)7TAA allele; 6/6, homozygous for the (TA)6TAA allele; and 6/7, heterozygous with 1 of each allele.

RESULTS

Nine percent of screened liver samples were found to be homozygous for allele 7 (7/7), 43% were homozygous for allele 6 (6/6), and 48% were heterozygous (6/7). Frequencies of (TA)7TAA and (TA)6TAA alleles were 0.33 and 0.67, respectively. A significant trend toward a decrease in SN-38 and bilirubin glucuronidation rates was found as the number of TA repeats increased (6/6 > 6/7 > 7/7). Glucuronidation rates of both substrates were significantly lower in the 7/7 and 6/7 groups compared with the 6/6 group.

CONCLUSIONS

The results indicate a significant association of UGT1A1 phenotype and genotype based on in vitro phenotypic measurements. The clinical significance of our finding remains to be established.

Clinical pharmacology of camptothecins

Camptothecins (CPTs) are a unique class of chemotherapeutic agent which inhibit DNA synthesis by inhibiting topoisomerase I activity. Structure-activity studies on the original CPT alkaloid led to the development of the new analogues irinotecan (CPT-11), topotecan, and 9-aminocamptothecin, which have improved water solubility and lower toxicity. CPT analogues exhibit interesting pharmacokinetic/pharmacodynamic and metabolic properties that are of major research and clinical interest. This review describes the clinical pharmacology of these 3 CPT analogues. Specific areas such as absorption after extravascular administration, pharmacokinetic/pharmacodynamic variability, metabolism, and administration in special populations are discussed.

Pharmacogenetics and cancer chemotherapy

Cancer chemotherapy is limited by significant inter-individual variations in responses and toxicities. Such variations are often due to genetic alterations in drug metabolising enzymes (pharmacokinetic polymorphisms) or receptor expression (pharmacodynamic polymorphisms). Pharmacogenetic screening prior to anticancer drug administration may lead to identification of specific populations predisposed to drug toxicity or poor drug responses. The role of polymorphisms in specific enzymes, such as thiopurine S-methyltransferases (TPMT), dihydropyrimidine dehydrogenase (DPD), aldehyde dehydrogenases (ALDH), glutathione S-transferases (GST), uridine diphosphate glucuronosyl-transferases (UGTs) and cytochrome P450 (CYP 450) enzymes in cancer therapy are discussed in this review.

Phase I clinical and pharmacokinetic study of oral 9-aminocamptothecin (NSC-603071)

PURPOSE

9-Aminocamptothecin (9-AC) is a topoisomerase I inhibitor with high antitumor activity but poor solubility in conventional vehicles. The purpose of this study was to evaluate the toxicities and pharmacokinetics of a colloidal dispersion (CD) formulation of 9-AC when administered orally on a 5 days per week every 2 weeks schedule.

METHOD

This formulation, which was developed for intravenous administration, was orally administered in 20 ml orange juice. A group of 16 cancer patients were treated at doses of 0.2-0.68 mg/m2 daily.

RESULTS

Grade 1-2 nausea (n = 9) was common, usually occurring during the last 2 days of dosing. No objective responses or cumulative toxicities were observed. Pharmacokinetic analysis of total 9-AC showed highly variable apparent oral 9-AC clearance and half-life. There was marked interpatient variability at each dose level in the 9-AC AUC and Cmax, and these parameters showed a poor correlation with dose (r2 = 0.07 and 0.38, respectively).

CONCLUSIONS

We conclude that this formulation is not suitable for further clinical development because of poor bioavailability and highly variable and/or saturable absorption or elimination. Another formulation developed for oral administration is under study elsewhere.

Genetic predisposition to the metabolism of irinotecan (CPT-11). Role of uridine diphosphate glucuronosyltransferase isoform 1A1 in the glucuronidation of its active metabolite (SN-38) in human liver microsomes

Irinotecan (CPT-11) is a promising antitumor agent, recently approved for use in patients with metastatic colorectal cancer. Its active metabolite, SN-38, is glucuronidated by hepatic uridine diphosphate glucuronosyltransferases (UGTs). The major dose-limiting toxicity of irinotecan therapy is diarrhea, which is believed to be secondary to the biliary excretion of SN-38, the extent of which is determined by SN-38 glucuronidation. The purpose of this study was to identify the specific isoform of UGT involved in SN-38 glucuronidation. In vitro glucuronidation of SN-38 was screened in hepatic microsomes from normal rats (n = 4), normal humans (n = 25), Gunn rats (n = 3), and patients (n = 4) with Crigler-Najjar type I (CN-I) syndrome. A wide intersubject variability in in vitro SN-38 glucuronide formation rates was found in humans. Gunn rats and CN-I patients lacked SN-38 glucuronidating activity, indicating the role of UGT1 isoform in SN-38 glucuronidation. A significant correlation was observed between SN-38 and bilirubin glucuronidation (r = 0.89; P = 0.001), whereas there was a poor relationship between para-nitrophenol and SN-38 glucuronidation (r = 0.08; P = 0.703). Intact SN-38 glucuronidation was observed only in HK293 cells transfected with the UGT1A1 isozyme. These results demonstrate that UGT1A1 is the isoform responsible for SN-38 glucuronidation. These findings indicate a genetic predisposition to the metabolism of irinotecan, suggesting that patients with low UGT1A1 activity, such as those with Gilbert's syndrome, may be at an increased risk for irinotecan toxicity.

Study of pathogenicity markers of staphylococci isolated from clinical specimens

A total of 165 strains of coagulase positive staphylococci (CPS) and 39 strains of coagulase negative Staphylococci (CNS) isolated from various clinical specimens studied for biochemical and enzyme profile showed overlapping of the key characters of pathogenicity. Anaerobic mannitol fermentation (69.20%), phosphatase (58.97%) and penicillinase (58.97%) production was remarkable amongst CNS. Both CPS and CNS showed increased resistance to penicillin and other antimicrobials. Besides increased frequency of isolation of CNS from pathological specimens, they elaborate singly or in combination, the recognized virulence factors.

Colonisation factors amongst clinical isolates of enterotoxigenic Escherichia coli

The production of heat-labile (LT) and heat-stable (ST) enterotoxins, colonisation factor antigens (CFAs) and haemagglutinins was investigated amongst 310 Escherichia coli (E. coli) isolates obtained from 62 children under the age of five, with diarrhoea. Twenty-one isolates were found to produce enterotoxins, of which fifteen (71%) isolates produced ST only, 2 (10%) produced LT only and 4 (19%) produced both LT and ST. However, none of the isolates demonstrated any of the common CFAs identified to date, but 8 out of the 21 isolates demonstrated haemagglutination with rabbit, sheep or human group A erythrocytes, suggesting the presence of putative CFAs, yet unidentified.

Development and validation of two enzyme-linked immunosorbent assay (ELISA) methods for recombinant hirudin

Recombinant hirudin is currently being developed as a potential prophylactic and therapeutic antithrombotic drug in various clinical indications such as angina and deep venous thrombosis. In this report, we have discussed the production of specific polyclonal antibodies to recombinant hirudin (rH) and the development of two ELISA methods to measure rH concentrations in biological fluids: a sandwich and a competitive ELISA method. Intra- and inter-assay variations in the two methods are extremely low (3-7%). The competitive ELISA method is rapid, simple and highly reproducible. Saturation binding curves, selection of appropriate incubation times, recovery of different hirudin variants and reactivity in the presence of thrombin are discussed. The methods can be easily adapted to monitor hirudin concentrations in the clinical laboratory for diagnostic purposes as well as for performing pharmacokinetic studies.

Impact of biotechnology in the diagnostic and therapeutic management of cardiovascular disorders

Although biotechnology has been useful in the development of new diagnostic methods and drugs for the management of cardiovascular disorders, there are several issues which raise certain questions on the global use of biotechnology based drugs and diagnostic methods (Piascik, 1991; Fareed, 1993a; Fareed, 1994a). The cost is rather prohibitive in the development of this type of technology. Most diagnostic methods and drugs developed utilizing biotechnology based methods are relatively expensive. The second important consideration is the equivalence of the newer biotechnology derived drugs to the natural products. Many of the biotechnology derived drugs are obtained in prokaryotic systems (E. coli). Post-transcriptional modifications such as glycosylation are often important in determining the function of various proteins. On the other hand, biotechnology based diagnostic methods exhibit somewhat different specificity in comparison to conventional methods. Thus, it is rather important to assess the developments in this area in a careful manner. Furthermore, validation of the clinical, diagnostic and therapeutic efficacy of biotechnology derived diagnostic devices and drugs is a prerequisite for their use in cardiovascular medicine.

Studies on the pharmacokinetics and pharmacodynamics of recombinant hirudin (rHV2-Lys 47) after intravenous and subcutaneous administration in dogs

In recent years, the pharmacological and biochemical characterization of hirudins has taken a major upswing due to the availability of this natural polypeptide in recombinant form. Despite this, the current knowledge on the pharmacokinetics and pharmacodynamics of recombinant hirudin (rH) appears to be incomplete. The present study was designed to investigate the relationship between plasma concentrations of rH with corresponding antithrombin responses after intravenous (i.v.) and subcutaneous (s.c.) administration in dogs. Four male, Mongrel dogs were each injected with an i.v. (bolus) dose (1 mg/kg) of one specific variant of rH, i.e. rH with a lysine residue in position 47 (rHV2-Lys 47). The dogs were injected with a s.c. dose (1 mg/kg) of rHV2-Lys 47 after one week. After each dose, blood was collected at different time intervals, plasma separated and stored at -70 degrees C. Plasma concentrations of rHV2-Lys 47 were determined using an enzyme-linked immunosorbent assay (ELISA) method and pharmacokinetic parameters were determined using standard non-compartmental methods. The ex vivo antithrombin activity of the drug was measured using activated partial thromboplastin time (APTT), calcium-thrombin time (Ca++TT) and a chromogenic anti-IIa assay. The results from this study indicate that the pharmacokinetic behavior of rHV2-Lys 47 is strongly influenced by the route of administration. In all three functional assays used, a significant correlation was obtained after i.v. administration between plasma concentrations and corresponding responses over the time period of the study when compared to s.c. administration. The results are indicative of a probable structural and functional modification of this rH variant after s.c. administration which may be responsible for the altered pharmacokinetics and pharmacodynamics after s.c. dosing.

Alteration of pharmacokinetics and pharmacodynamics of recombinant hirudin (rHV2-Lys 47) after repeated intravenous administration in dogs

Native hirudin is a heterogenous polypeptide obtained from the medicinal leech, Hirudo medicinalis. Recent advances in molecular biological techniques have led to the availability of large amounts of hirudin in the recombinant form. Recombinant hirudins (rH) are currently being investigated for potential use in the prophylaxis and treatment of deep venous thrombosis (DVT), in disseminated intravascular coagulation (DIC) and during cardiovascular bypass surgery. In this study, one specific variant of rH with a lysine residue in position 47 (rHV2-Lys 47) was administered in dogs in a multiple dose regimen of 2 mg/kg (i.v. bolus) for three weeks with a dosing interval of one week. After each dose, blood samples were collected at regular time intervals, plasma separated and stored at -4 degrees C. Concentrations of rHV2-Lys 47 in each sample were determined using an enzyme-linked immunosorbent assay (ELISA). Ex vivo antithrombin responses measured included activated partial thromboplastin time (APTT), calcium-thrombin time (Ca++TT-10 NIH units/ml) and a chromogenic anti-IIa assay. It was the purpose of this study to detect any sensitization or desensitization of antithrombin responses when rHV2-Lys 47 is used in a repeated fashion such as would be expected in the prophylaxis of DVT. The results indicated that there was no attenuation in the responses; however, there was a sensitization of response as measured by the Ca++TT (10 NIH units/ml). These findings could have major implications in the clinical use of rH where this drug is expected to be used in a multiple dose regimen.

Prior chronic exposure to cocaine inhibits the serotonergic stimulation of ACTH and secretion of corticosterone

The effect of long-term pretreatment with cocaine on serotonergic regulation of ACTH (adrenocorticotropic hormone; corticotropin) and secretion of corticosterone in rats was investigated. The following observations were made: (1) Pretreatment with cocaine had no significant effect on basal levels of ACTH and corticosterone in plasma. However, cocaine caused a reduction in the ability of the 5-HT (5-hydroxytryptamine, serotonin) releaser p-chloroamphetamine (PCA) to increase corticosterone in plasma, 42 hr after the last injection of cocaine. (2) Exposure to cocaine for 7 days was sufficient to produce a maximal inhibition of the PCA-induced increase in ACTH in plasma. (3) The inhibitory effect of cocaine on PCA-induced release of ACTH was more marked than on corticosterone. (4) Conversely, the dose-dependent stimulatory effect of two 5-HT1 agonists, RU 24969 (5-methoxy-3-(1,2,3,4-tetrahydro-4-pyridinyl)-1H-indole) and m-CPP (m-chlorophenylpiperazine), on ACTH and corticosterone was not reduced by 7 days of exposure to cocaine. Taken together, these findings indicate that pretreatment with cocaine reduced the function of serotonergic nerve-terminals but not postsynaptic receptors, that stimulate ACTH and secretion of corticosterone.

An objective perspective on recombinant hirudin: a new anticoagulant and antithrombotic agent

Leeches have been in medical use for many years. Hirudin, the anticoagulant obtained from the medicinal leech has been purified, characterized and can now be produced by recombinant (r) technology. R-hirudin is a potent inhibitor of thrombin and is therefore a potentially valuable anticoagulant and antithrombotic drug. This article reviews the current status of r-hirudin in this role and compares the pharmacokinetics, mechanism of action and clinical efficacy of this agent with heparin. The methods available for laboratory assessment and clinical monitoring of r-hirudin and the possible ways of antagonizing its effects are also discussed. Finally, the potential clinical applications of r-hirudin are outlined, although further laboratory and clinical studies, together with a fall in the cost of this compound are required before r-hirudin can be more widely accepted as an anticoagulant and antithrombotic agent.

The genotoxicity of 2-bromoacrolein and 2,3-dibromopropanal

2-Bromoacrolein (2-BA) and 2,3-dibromopropanal (2,3-DBPA), an identified and a postulated reactive metabolite of tris(2,3-dibromopropyl)phosphate (Tris-BP), respectively, were found to cause mutations in Salmonella typhimurium TA 100 both in the absence and presence of a metabolic system. 2-BA, as well as 2,3-DBPA, caused extensive DNA single-stranded breaks as evidenced by alkaline elution of DNA from exposed Reuber hepatoma cells in culture. The data with Syrian hamster embryo cells suggest that both 2-BA and 2,3-DBPA were more potent than Tris-BP in transforming these cells in culture. On the other hand, neither 2-BA, nor 2,3-DBPA, was found to cause increased unscheduled DNA repair synthesis in isolated rat hepatocytes in monolayer cultures, whereas Tris-BP had a significant effect at low concentrations (10-50 microM). There was no correlation between the observed mutagenic effects of 2-BA and 2,3-DBPA and their alkylating activities using the nitrobenzyl-pyridine test. The genotoxic effects associated with 2-BA and its detection in microsomal incubations makes it a likely candidate for a role in the mutagenicity of Tris-BP.

Activation mechanism of tris(2,3-dibromopropyl)phosphate to the potent mutagen, 2-bromoacrolein

The potent mutagen 2- bromoacrolein is formed from the carcinogenic flame retardant tris(2,3-dibromopropyl)phosphate (Tris-BP) on incubation with hepatic microsomes. Substitution of deuterium for hydrogen at the terminal carbon atoms (C-3) of Tris-BP significantly decreased both the mutagenic response and the formation rate of 2- bromoacrolein . Mass spectral analysis of the 2- bromoacrolein that was formed from the selectively deuterated analogs of Tris-BP revealed that the primary mechanism for the formation of 2- bromoacrolein involves an initial oxidative dehalogenation at C-3 followed by a beta-elimination reaction.