Comprehensive characterization of genomic features and clinical outcomes following targeted therapy and secondary cytoreductive surgery in OCCC: a single center experience

OBJECTIVE

Ovarian clear cell carcinoma (OCCC) is associated with chemoresistance. Limited data exists regarding the efficacy of targeted therapies such as immune checkpoint inhibitors (ICI) and bevacizumab, and the role of secondary cytoreductive surgery (SCS).

METHODS

We retrospectively analyzed genomic features and treatment outcomes of 172 OCCC patients treated at our institution from January 2000 to May 2022. Next-generation sequencing (NGS) was performed where sufficient archival tissue was available.

RESULTS

64.0% of patients were diagnosed at an early stage, and 36.0% at an advanced stage. Patients with advanced/relapsed OCCC who received platinum-based chemotherapy plus bevacizumab followed by maintenance bevacizumab had a median first-line progression-free survival (PFS) of 12.2 months, compared with 9.3 months for chemotherapy alone (hazard ratio=0.69; 95% confidence interval [CI]=0.33, 1.45). In 27 patients who received an ICI, the overall response rate was 18.5% and median duration of response was 7.4 months (95% CI=6.5, 8.3). In 17 carefully selected patients with fewer than 3 sites of relapse, median PFS was 35 months (95% CI=0, 73.5) and median overall survival was 96.8 months (95% CI=44.6, 149.0) after SCS. NGS on 58 tumors revealed common mutations in ARID1A (48.3%), PIK3CA (46.6%), and KRAS (20.7%). Pathogenic alterations in PIK3CA, FGFR2, and NBN were associated with worse survival outcomes. Median tumor mutational burden was 3.78 (range, 0-16). All 26 patients with available loss of heterozygosity (LOH) scores had LOH <16%.

CONCLUSION

Our study demonstrates encouraging outcomes with bevacizumab and ICI, and SCS in select relapsed OCCC patients. Prospective trials are warranted.

Triplet maintenance therapy of olaparib, pembrolizumab and bevacizumab in women with BRCA wild-type, platinum-sensitive recurrent ovarian cancer: the multicenter, single-arm phase II study OPEB-01/APGOT-OV4

In this multicenter, open-label, single-arm, Phase II study with Simon two-stage optimum design (NCT04361370), we investigate the efficacy and safety of triplet maintenance (olaparib, pembrolizumab, bevacizumab) in patients with platinum-sensitive recurrent ovarian cancer who are wild-type for BRCA 1/2. A total of 44 patients were enrolled, and the median follow-up duration was 22.9 months (interquartile range: 17.4-24.7). The primary outcome was 6-months progression-free survival (PFS), which was 88.6% (95% confidence interval [CI] 75.4-96.2), meeting the pre-specified primary endpoint. The secondary outcomes reported here include median PFS, 12-months PFS, and overall survival and safety. The median PFS was 22.4 months (20.4-∞), with a 12-months PFS rate of 84.0% (95% CI 69.3-92.0). The median overall survival was 28.6 months (27.3-∞). The combination demonstrated tolerable toxicity with manageable side effects. Other secondary outcomes include time-to-progression, time to subsequent treatment, time to second treatment and PFS2; however, this data is not reported, as treatment is still ongoing in a majority of patients. Exploratory analysis shows that patients who were homologous recombination deficiency-positive or had a programmed death-ligand 1 combined positive score ≥1 showed a favorable response (P = 0.043 and P < 0.001, respectively). Thus, triplet maintenance shows durable efficacy with tolerable safety in patients with platinum-sensitive recurrence.

Weekly versus tri-weekly paclitaxel with carboplatin for first-line treatment in women with epithelial ovarian cancer

BACKGROUND

Epithelial ovarian cancer is the sixth most common cancer worldwide: 295,414 new cases were diagnosed in 2018, with 184,799 deaths. The lack of an effective screening strategy has led to the majority of women being diagnosed at an advanced stage. For these women, intravenous carboplatin combined with paclitaxel for six cycles is widely accepted as the standard first-line treatment for epithelial ovarian cancer, in combination with debulking surgery. However, there is conflicting evidence regarding the optimal dosing schedule of paclitaxel when combined with carboplatin in this setting.

OBJECTIVES

To compare the efficacy and tolerability of intravenous weekly paclitaxel with that of tri-weekly paclitaxel, in combination with intravenous carboplatin, as first-line treatment for epithelial ovarian cancer (defined as epithelial ovarian, primary peritoneal and fallopian tube cancer).

SEARCH METHODS

We searched CENTRAL, MEDLINE, and Embase databases for relevant studies up to 15 November 2021, using keywords and MeSH terms. We additionally handsearched conference libraries, online clinical trial databases and screened through lists of retrieved references.

SELECTION CRITERIA

We Included randomised controlled trials (RCTs) comparing weekly paclitaxel in combination with carboplatin versus tri-weekly paclitaxel in combination with carboplatin, for treatment of newly-diagnosed epithelial ovarian cancer.

DATA COLLECTION AND ANALYSIS

We used the hazard ratio (HR) to estimate the primary efficacy outcomes progression-free (PFS) and overall survival (OS). We used the risk ratio (RR) to estimate the primary toxicity outcome of severe neutropenia and secondary outcomes of quality of life (QoL) and treatment-related adverse events. Two review authors independently selected studies, extracted data, and assessed risk of bias, using standard Cochrane methodological procedures. We included individual participant data (IPD) from one of the included studies, ICON-8, provided by the study team. We analysed data using a random-effects model in Review Manager 5.4 software. Additionally, we reconstructed IPD for PFS and OS data from published Kaplan-Meier curves from all studies and subsequently pooled these to analyse the two primary efficacy outcomes.

MAIN RESULTS

From 2469 records, we identified four eligible RCTs with data for 3699 participants. All eligible studies were included in the main meta-analysis and reported on PFS and OS. There was likely a slight improvement in PFS when paclitaxel was dosed weekly compared to tri-weekly (HR 0.89, 95% confidence interval (CI) 0.81 to 0.98; 4 studies, 3699 participants; moderate-certainty evidence). We found little to no improvement in OS when paclitaxel was dosed weekly compared to tri-weekly (HR 0.92, 95% CI 0.79 to 1.06; 4 studies, 3699 participants; high-certainty evidence). There was likely little to no difference in high-grade (grade 3 or 4) neutropenia when paclitaxel was dosed weekly compared to tri-weekly (RR 1.11, 95% CI 0.86 to 1.43; 4 studies, 3639 participants; moderate-certainty evidence). However, weekly paclitaxel increased high-grade (grade 3 or 4) anaemia when compared to tri-weekly dosing (RR 1.57, 95% CI 1.12 to 2.20; 4 studies, 3639 participants; high-certainty evidence). There may be little to no difference in high-grade neuropathy when paclitaxel was dosed weekly compared to tri-weekly (RR 1.12, 95% CI 0.64 to 1.94; 4 studies, 3639 participants; low-certainty evidence). The overall risk of detection bias and performance bias was low for OS, but was unclear for other outcomes, as treatments were not blinded. The risk of bias in other domains was low or unclear. We note that OS data were immature for three of the included studies (GOG-0262, ICON-8 and MITO-7).

AUTHORS' CONCLUSIONS

Weekly paclitaxel combined with carboplatin for first-line treatment of epithelial ovarian cancer likely improves PFS slightly (moderate-certainty evidence) but not OS (high-certainty evidence), compared to tri-weekly paclitaxel combined with carboplatin. However, this was associated with increased risk for high-grade anaemia, treatment discontinuation, dose delays and dose omissions (high- to low-certainty evidence). Our findings may not apply to women receiving bevacizumab in first-line therapy, those receiving treatment in the neo-adjuvant setting, or those with rare subtypes of clear cell or mucinous ovarian cancer.

A multi-ethnic analysis of immune-related gene expression signatures in patients with ovarian clear cell carcinoma

Little is known about the immune environment of ovarian clear cell carcinoma (OCCC) and its impact on various ethnic backgrounds. The aim of this OCCC immune‐related gene expression signatures (irGES) study was to address the interaction between tumour and immune environment of ethnically‐diverse Asian and Caucasian populations and to identify relevant molecular subsets of biological and clinical importance. Our study included 264 women from three different countries (Singapore, Japan, and the UK) and identified four novel immune subtypes (PD1‐high, CTLA4‐high, antigen‐presentation, and pro‐angiogenic subtype) with differentially expressed pathways, and gene ontologies using the NanoString nCounter PanCancer Immune Profiling Panel. The PD1‐high and CTLA4‐high subtypes demonstrated significantly higher PD1, PDL1, and CTLA4 expression, and were associated with poorer clinical outcomes. Mismatch repair (MMR) protein expression, assessed by immunohistochemistry, revealed that about 5% of OCCCs had deficient MMR expression. The prevalence was similar across the three countries and appeared to cluster in the CTLA4‐high subtype. Our results suggest that OCCC from women of Asian and Caucasian descent shares significant clinical and molecular similarities. To our knowledge, our study is the first study to include both Asian and Caucasian women with OCCC and helps to shine light on the impact of ethnic differences on the immune microenvironment of OCCC. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

A single-arm phase II study of olaparib maintenance with pembrolizumab and bevacizumab in BRCA non-mutated patients with platinum-sensitive recurrent ovarian cancer (OPEB-01)

Background

The optimal treatment of BRCA wild-type patients with platinum-sensitive recurrent ovarian cancer remains unknown. Recently, there is an increase in the evidence to support the role of the combination of a poly(adenosine diphosphate-ribose) polymerase inhibitor, anti-angiogenic agents, and immunotherapy as maintenance therapy in BRCA wild-type patients with platinum-sensitive recurrence. We hypothesized that adding pembrolizumab and bevacizumab to olaparib maintenance can increase progression-free survival (PFS) in BRCA wild-type patients with platinum-sensitive recurrent ovarian cancer.

Methods

BRCA wild-type patients who received two previous courses of platinum-containing therapy, achieved complete or partial response to last treatment, and the treatment-free interval is >6 months after the penultimate platinum-based chemotherapy offered olaparib maintenance with pembrolizumab and bevacizumab. Forty-four patients will be included from 4 sites across Singapore and Korea. The primary endpoint of the study is 6-month PFS rate.

Trial Registration

ClinicalTrials.gov Identifier: NCT04361370, Clinical Research Information Service Identifier: KCT0005144

Cost-effectiveness of olaparib versus routine surveillance in the maintenance setting for patients with BRCA-mutated advanced ovarian cancer after response to first-line platinum-based chemotherapy in Singapore

Objective

To evaluate the cost-effectiveness of olaparib as a maintenance treatment versus routine surveillance (RS) in patients with BRCA mutated (BRCAm) advanced ovarian cancer (OC) following response to first-line platinum-based chemotherapy in Singapore.

Methods

A 4-health state partitioned survival model was developed to simulate the lifetime (50 years) incremental cost-effectiveness ratio (ICER) of olaparib versus RS from a healthcare payer perspective. Progression-free survival, time to second disease progression, and overall survival were estimated using SOLO-1 data and extrapolated beyond the trial period using parametric survival models. Any patient who remained progression-free at year 7 was assumed to be no longer at risk of progression. Mortality rates were based on all-cause mortality, adjusted based on BRCA1/2 mutation. Health state utilities and adverse event frequencies were from SOLO-1. Drug costs were from local public healthcare institutions. Healthcare resource usage and costs were from local clinician input and publications. A 3% discount rate was applied to costs and outcomes. Deterministic and probabilistic sensitivity analyses (PSA) were performed to assess the robustness of results.

Results

The base-case analysis of olaparib maintenance therapy versus RS resulted in an ICER of Singapore dollar (SGD) 19,822 per quality-adjusted life-year (QALY) gained. The ICER was most sensitive to variations in the discount rate. PSA demonstrated that olaparib had an 87% probability of being cost-effective versus RS at a willingness-to-pay of SGD 60,000 per QALY gained.

Conclusion

Olaparib has a high potential of being a cost-effective maintenance treatment versus RS for patients with BRCA1/2m advanced OC after response to first-line chemotherapy in Singapore.

Exploiting replicative stress in gynecological cancers as a therapeutic strategy

Elevated levels of replicative stress in gynecological cancers arising from uncontrolled oncogenic activation, loss of key tumor suppressors, and frequent defects in the DNA repair machinery are an intrinsic vulnerability for therapeutic exploitation. The presence of replication stress activates the DNA damage response and downstream checkpoint proteins including ataxia telangiectasia and Rad3 related kinase (ATR), checkpoint kinase 1 (CHK1), and WEE1-like protein kinase (WEE1), which trigger cell cycle arrest while protecting and restoring stalled replication forks. Strategies that increase replicative stress while lowering cell cycle checkpoint thresholds may allow unrepaired DNA damage to be inappropriately carried forward in replicating cells, leading to mitotic catastrophe and cell death. Moreover, the identification of fork protection as a key mechanism of resistance to chemo- and poly (ADP-ribose) polymerase inhibitor therapy in ovarian cancer further increases the priority that should be accorded to the development of strategies targeting replicative stress. Small molecule inhibitors designed to target the DNA damage sensors, such as inhibitors of ataxia telangiectasia-mutated (ATM), ATR, CHK1 and WEE1, impair smooth cell cycle modulation and disrupt efficient DNA repair, or a combination of the above, have demonstrated interesting monotherapy and combinatorial activity, including the potential to reverse drug resistance and have entered developmental pipelines. Yet unresolved challenges lie in balancing the toxicity profile of these drugs in order to achieve a suitable therapeutic index while maintaining clinical efficacy, and selective biomarkers are urgently required. Here we describe the premise for targeting of replicative stress in gynecological cancers and discuss the clinical advancement of this strategy.

A multicenter phase II randomized trial of durvalumab (MEDI-4736) versus physician's choice chemotherapy in recurrent ovarian clear cell adenocarcinoma (MOCCA)

Background

The optimal treatment of recurrent ovarian clear cell carcinoma remains unknown. There is increasing rationale to support the role of immune checkpoint inhibitors targeting the programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) axis in ovarian clear cell carcinoma.

Primary objective

To evaluate the efficacy of durvalumab (MEDI-4736) compared with standard chemotherapy in patients with recurrent ovarian clear cell carcinoma.

Study hypothesis

Patients with recurrent ovarian clear cell carcinoma treated with durvalumab will have improved progression-free survival compared with those treated with chemotherapy of physician’s choice.

Trial design

The MOCCA study is a multicenter, open-label, randomized phase II trial in patients with recurrent ovarian clear cell carcinoma, which recruited from eight sites across Gynecologic Cancer Group Singapore (GCGS), Korean Gynecologic-Oncology Group (KGOG), and Australia New Zealand Gynecological Oncology Group (ANZGOG). Enrolled patients were randomized in a 2:1 ratio to receive durvalumab or physician’s choice of chemotherapy until disease progression, intolerable toxicity, or withdrawal of patient consent.

Major inclusion/exclusion criteria

Eligible patients required histologically documented diagnosis of recurrent ovarian clear cell carcinoma, as evidenced by WT1 negativity. All patients must have been of Eastern Cooperative Oncology Group (ECOG) performance status 2 or better, and have had previous treatment with, and progressed or recurred after prior platinum-based chemotherapy. No more than four prior lines of treatment were allowed and prior immune checkpoint inhibitor treatment was not permitted.

Primary endpoints

The primary endpoint was the median progression-free survival following treatment with durvalumab, compared with physician’s choice of chemotherapy. Progression-free survival was defined as the time from the first day of treatment to the first observation of disease progression, or death due to any cause, or last follow-up.

Sample size

The target sample size was 46 patients.

Estimated dates for completing accrual and presenting results

Accrual has been completed and results are expected to be presented by mid-2021.

Trial registration

Clinicaltrials.gov: NCT03405454.

Weekly versus 3-weekly paclitaxel in combination with carboplatin in advanced ovarian cancer: which is the optimal adjuvant chemotherapy regimen?

The 3-weekly regimen of carboplatin and paclitaxel is the backbone of first line adjuvant chemotherapy for advanced ovarian cancer. The landmark Japanese Gynaecologic Oncology Group (JGOG) 3016 study demonstrated significant improvements in progression-free survival and overall survival with dose dense weekly administration of paclitaxel in combination with 3-weekly carboplatin. However, efforts to replicate these benefits have failed in subsequent phase III trials. Weekly paclitaxel is purported to have enhanced antitumor activity, with stronger anti-angiogenic effects, and yet is better tolerated. In this review, we explore the rationale for dose dense weekly paclitaxel, and compare the relevant trials as well as quality of life considerations. Possible reasons for the difference in outcomes between the JGOG 3016 and other studies are reviewed, with a focus on how the addition of bevacizumab, the variations between histological and molecular subtypes of epithelial ovarian cancers, and ethnic pharmacogenetic differences may potentially affect the efficacy of dose dense paclitaxel.

Asian Society of Gynecologic Oncology International Workshop 2018

The Asian Society of Gynecologic Oncology International Workshop 2018 on gynecologic oncology was held in the Ajou University Hospital, Suwon, Korea on the 24th to 25th August 2018. The workshop was an opportunity for Asian doctors to discuss the latest findings of gynecologic cancer, including cervical, ovarian, and endometrial cancers, as well as the future of fertility-sparing treatments, minimally invasive/radical/debulking surgery, radiotherapy, chemotherapy, targeted therapy, and immunotherapy. Clinical guidelines and position statement of Asian countries were presented by experts. Asian clinical trials for gynecologic cancers were reviewed and experts emphasized the point that original Asian study is beneficial for Asian patients. In Junior session, young gynecologic oncologists presented their latest research on gynecologic cancers.

Phase I and biomarker study of OPB-51602, a novel signal transducer and activator of transcription (STAT) 3 inhibitor, in patients with refractory solid malignancies

BACKGROUND

The aim of this study was to determine the maximum-tolerated dose (MTD), safety, pharmacokinetics, and pharmacodynamics of OPB-51602, an oral, direct signal transduction activator of transcription 3 (STAT3) inhibitor, in patients with refractory solid tumors.

PATIENTS AND METHODS

Three cohorts were studied: cohort A, a sequential dose escalation of OPB-51602 administered intermittently (days 1-14 every 21 days); cohort B, an expansion cohort evaluating the dose lower than the MTD; cohort C, evaluating continuous daily dosing.

RESULTS

Fifty-one patients were studied at 2, 4, and 5 mg per day dosing. The MTD was 5 mg; first-cycle dose-limiting toxicities (DLTs) were grade 3 hyponatremia in one patient, and grade 3 dehydration in another. Intermittent dosing of both 2 and 4 mg doses were tolerable, and the recommended phase II dose was 4 mg. Cohort B investigated 4 mg intermittently, whereas cohort C investigated 4 mg continuously. Common toxicities included fatigue, nausea/vomiting, diarrhea, anorexia, and early-onset peripheral neuropathy. Drug-induced pneumonitis occurred in two patients in cohort C. Continuous dosing was associated with a higher incidence of peripheral neuropathy and a lower mean relative dose intensity, compared with intermittent dosing. Steady-state pharmacokinetics was characterized by high oral clearance, mean elimination half-life ranging from 44 to 61 h, and a large terminal-phase volume of distribution. An active metabolite, OPB-51822, accumulated to a greater extent than OPB-51602. Flow cytometry of peripheral blood mononuclear cells demonstrated pSTAT3 (Tyr(705)) inhibition following exposure. Two patients achieved partial responses at 5 mg intermittently and 4 mg continuously; both had epidermal growth factor receptor (EGFR) mutation-positive non-small-cell lung cancer (NSCLC) with prior EGFR tyrosine kinase inhibitor exposure.

CONCLUSION

OPB-51602 demonstrates promising antitumor activity, particularly in NSCLC. Its long half-life and poorer tolerability of continuous dosing, compared with intermittent dosing, suggest that less frequent dosing should be explored.

CLINICALTRIALSGOV IDENTIFIER

NCT01184807.

Ligand discovery using encoded combinatorial libraries

Solid-phase combinatorial synthesis using split-pool or direct divide methods allows large libraries of complex molecules to be generated. Encoding techniques used during synthesis allow the identities of the products to be determined readily. An overview of this process and its application to ligand discovery are presented, along with comparisons to alternative approaches. Libraries are classified depending upon their intended use as discovery libraries (for broad screening), targeted libraries (for structure-based screening) and optimization libraries (for activity improvement). Biological assays can be performed on the solid support that is used in synthesis, or in solution under in vitro or in vivo conditions, with readouts indicative of either receptor binding or biological activity. This approach has led to numerous examples of successful ligand discovery.

Cell cycle proteins do not predict outcome in grade I infiltrating ductal carcinoma of the breast

Infiltrating ductal mammary carcinomas are histologically graded according to their extent of differentiation. Well-differentiated, grade I, tumours have low proliferative activity, usually form tubules and exhibit little nuclear pleomorphism. Despite an apparently reassuring morphology, 10-15% of grade I ductal carcinomas metastasize, albeit after a prolonged period. Recent evidence supports the view that evolution to higher grade malignancies occurs rarely and that grade I tumours are biologically distinct from grade III tumours. We have examined a series of 148 grade I ductal carcinomas in order to ascertain whether information about the level of expression of cyclin D1, p27, p53, oestrogen receptor status (ER) or proliferative activity could be used to identify those patients with a poor outcome. The majority of tumours expressed high levels of cyclin D1, p27 and ER, low levels of p53 and had low Ki-67 expression and mitotic counts. Cyclin D1, p27 and ER expression were all significantly correlated with each other but not with p53 (cyclin D1 correlation with ER, p = 0.01; cyclin D1 correlation with p27 and ER correlation with p27 both p < 0.0001). Cyclin D1 and ER were also both correlated with Ki-67 (p = 0.01 and p < 0.0001) but not with mitotic count. Our results suggest that cyclin D1, ER and p27 are all markers of well-differentiated tumours and that their detection is related to proliferative activity in a manner reflecting their functional role within the normal cell cycle. However, none of the proteins or markers of proliferative activity were sensitive enough to predict which patients were likely to have a poor outcome.

Cell cycle proteins do not predict outcome in grade I infiltrating ductal carcinoma of the breast

Infiltrating ductal mammary carcinomas are histologically graded according to their extent of differentiation. Well-differentiated, grade I, tumours have low proliferative activity, usually form tubules and exhibit little nuclear pleomorphism. Despite an apparently reassuring morphology, 10-15% of grade I ductal carcinomas metastasize, albeit after a prolonged period. Recent evidence supports the view that evolution to higher grade malignancies occurs rarely and that grade I tumours are biologically distinct from grade III tumours. We have examined a series of 148 grade I ductal carcinomas in order to ascertain whether information about the level of expression of cyclin D1, p27, p53, oestrogen receptor status (ER) or proliferative activity could be used to identify those patients with a poor outcome. The majority of tumours expressed high levels of cyclin D1, p27 and ER, low levels of p53 and had low Ki-67 expression and mitotic counts. Cyclin D1, p27 and ER expression were all significantly correlated with each other but not with p53 (cyclin D1 correlation with ER, p = 0.01; cyclin D1 correlation with p27 and ER correlation with p27 both p < 0.0001). Cyclin D1 and ER were also both correlated with Ki-67 (p = 0.01 and p < 0.0001) but not with mitotic count. Our results suggest that cyclin D1, ER and p27 are all markers of well-differentiated tumours and that their detection is related to proliferative activity in a manner reflecting their functional role within the normal cell cycle. However, none of the proteins or markers of proliferative activity were sensitive enough to predict which patients were likely to have a poor outcome.

The biological and prognostic significance of cell polarity and E-cadherin in grade I infiltrating ductal carcinoma of the breast

Grading of breast cancer based on the modified Scarff, Bloom, and Richardson system provides invaluable prognostic information. Recent evidence suggests that most tumours do not usually progress between grades and that groups of tumours within each grade are biologically distinct. This study has explored one potential aspect of biological tumour heterogeneity within grade by examining the relationship between cell polarity, the cell adhesion molecule E-cadherin, a major effector of cell polarity, and outcome, in 149 grade I infiltrating ductal breast carcinomas. Polarity was evaluated by studying the degree to which three features of polarized epithelial cells-nuclear ordering, basal positioning of nuclei within cells, and apical snouting/blebbing-were present in these tumours. E-cadherin expression was investigated using the antibody HECD-1. A low degree of tubule formation was correlated with poor nuclear ordering ( p< 0.01). The three histological features-nuclear ordering, basal nuclei, and apical blebbing-were all correlated with each other (all p< 0.0001). Polarity measurements did not correlate with survival. E-cadherin expression did not correlate with polarity and negative tumours were still able to form tubules. Surprisingly, strong E-cadherin immunostaining correlated with poor survival, tumour size, and nodal status. On univariate parametric (Weibull) survival models, high E-cadherin scores and tumour size were both significant predictors of survival in this group.

Involvement of a third histidine in the ferrous active site of isopenicillin N synthase of Cephalosporium acremonium repudiated by recombinant double histidine mutants

Site-directed mutagenesis studies have shown that the isopenicillin N synthase of Cephalosporium acremonium (cIPNS) requires two essential histidine residues (H216, H272) for activity. The determination of iron bound to the wildtype cIPNS and its absence in the mutants lacking histidine at positions 216 and 272 clearly supports the essential role these two histidines play in iron binding. However, nuclear magnetic resonance (NMR) studies have indicated that there could be three histidine residues that possibly coordinate the essential iron at the active site. To search for a presumed third histidine ligand, mutant cIPNS genes containing mutations at two histidine codons were created by in vitro cloning of fragments from the expression vectors bearing the respective cIPNS genes each with a single histidine mutation at positions H49, H64, H116, H126 and H137. All ten possible double histidine mutant cIPNS constructs were subsequently expressed in Escherichia coli. If a third histidine had a participatory role in the iron active centre of cIPNS, then one of the constructed double histidine mutants would have lost its enzymatic activity. However, analysis of the cIPNS activities of these recombinant double histidine mutants indicated that none of them was totally inactivated. Thus, the involvement of a third histidine can be repudiated.

Functional analysis of conserved histidine residues in Cephalosporium acremonium isopenicillin N synthase by site-directed mutagenesis

The isopenicillin N synthase of Cephalosporium acremonium (cIPNS) involves a catalytically important non-heme iron which is coordinated credibly to histidine residues. A comparison of the IPNS genes from various microbial sources indicated that there are seven conserved histidine residues. These were individually replaced by leucine residues through site-directed mutagenesis, and the sites of mutation were confirmed by DNA sequencing. The seven mutant genes were cloned separately into the vector pET24d for expression in Escherichia coli BL21 (DE3), and the proteins were expressed as soluble enzymes. All the resulting mutant enzymes obtained have mobilities of approximately 38 kDa, identical with the wild-type enzyme on SDS-polyacrylamide gel electrophoresis, and were also reactive to cIPNS antibodies. The enzymes were purified by ammonium sulfate precipitation and DEAE-Sephadex A-50 ion exchange chromatography, and these were analyzed for enzyme activity. A group of mutant enzymes, H49L, H64L, H116L, H126L, and H137L, were found to be enzymatically active with reduced activities of 16-93.7%, indicating that they are not essential for catalysis. Two of the mutant enzymes, H216L and H272L, were found to have lost their enzymatic activity completely, indicating that both His-216 and His-272 are crucial for catalysis. It is suggested that these histidines are likely to serve as ligands for binding to the non-heme iron in the IPNS active site. Alignment of the amino acid sequence of IPNS to related non-heme Fe(2+)-requiring enzymes indicated that the two essential histidine residues correspond to two invariant residues located in highly homologous regions. The conservation of the two closely located histidine residues indicates the possible conservation of similar iron-binding sites in these enzymes.

Biophysical factors affecting the expression of isopenicillin N synthase isozymes in Escherichia coli

The influence of biophysical factors over the production of isozymes of isopenicillin N synthase (IPNS) from fungal and bacterial sources in Escherichia coli was examined. The effect of these parameters on the expression of Cephalosporium acremonium IPNS was determined by using two expression vectors containing the lac- or the T7-promoter. Under the lac-promoter, IPNS expressed in E. coli reached 5-15% of total soluble proteins and under the T7 promoter, the level reached approximately 50% of total soluble proteins. Furthermore the high level of expression did not affect aggregation of IPNS proteins. Analysis of the hydrophobicity of the C. acremonium IPNS and site-specific mutant enzymes relative to other IPNS isozymes suggested that proteins of low gravy scores (< or = -0.515) tend to be soluble whereas higher gravy scores (> or = -0.512) form aggregates. Neither the GC content of the gene nor the relative percentage proline content of the protein affected the expression of the IPNS isozymes in E. coli.

Histidine-272 of isopenicillin N synthase of Cephalosporium acremonium, which is possibly involved in iron binding, is essential for its catalytic activity

Amino acid sequence alignment of the Cephalosporium acremonium isopenicillin N synthase (cIPNS) to similar non-heme Fe(2+)-containing enzymes from 28 different sources (bacterial, fungal, plant and animals) revealed a homologous region of high sequence conservation containing an invariant histidine residue at position 272 in cIPNS. The importance of this histidine residue in cIPNS was investigated through site-directed mutagenesis by replacing the histidine residue with leucine. The mutated gene was verified by DNA sequence analysis and expressed in Escherichia coli. When analyzed by denaturing gel electrophoresis and immunoblotting, the mutant cIPNS had identical mobility as that of the wild-type enzyme. Enzyme studies on the mutant enzyme showed loss of enzymatic activity indicating that His272 is essential for the catalytic function of cIPNS, possibly as a ligand for iron binding.

The role of cytomegalovirus (CMV) infection in congenital diseases in Malaysia

A previous cross-sectional serological survey of various age groups (0-55 years) of the Malaysian normal population showed that cytomegalovirus (CMV) infection is highly endemic in Malaysia. A total of 1,688 infants (0-4 months) with congenital abnormalities were screened for evidence of congenital CMV infection and the rest of the TORCHES (TOxoplasmosis, Rubella, Cytomegalovirus, HErpes simplex, Syphilis) group of congenital infections. Congenital CMV infection was detected in 193 (11.4%) infants which is significantly higher than the prevalence of congenital syphilis (4%), congenital rubella infection (3.7%), congenital toxoplasma (1.0%) and congenital herpes simplex virus infection (0%). Of the 193 cases, 10.4 per cent had CNS defects. We concluded that 1) congenital CMV appears to be the most important cause of congenital infections among the TORCHES diseases in Malaysia; and 2) secondary rather than primary infections or reactivation is responsible for most of the intrauterine CMV infection in Malaysia, as primary infection is usually associated with neurological involvement.

Prevalence of hepatitis delta virus infection in Malaysia

The prevalence of coinfection, superinfection and chronic infection with the hepatitis delta virus (HDV) was studied in 324 hepatitis B surface antigen (HBsAg)-positive Malaysians. Of these, 10.0% (5/50) had coinfection, 5.7% (11/194) had superinfection, but none of the 80 patients with chronic liver disease (CLD) or primary hepatocellular carcinoma (PHC) had chronic infection with HDV. The overall HDV infection was 4.9% (16/324). One of the coinfection cases acquired the HDV infection as early as 1982. HDV superinfection was detected mainly among IV drug abusers (20% or 7/35) and promiscuous males and females (13.6% or 3/22). They were all asymptomatic. Only 0.8% (1/125) apparently healthy blood donors was infected with HDV. None of the 12 multi-transfused patients examined were positive. Malaysia is the only Southeast Asian country examined so far in which HDV infection was detected. The reason could be that the IV drug abusers and the sexually promiscuous groups missed being examined in the other countries. Comparing the HDV infection rates in 4 categories of infected Malaysians (viz. acute hepatitis B patients, IV drug abusers, blood donors and CLD patients) with those of other countries, it was noted that the Malaysian rates were similar to the lowest in the range of prevalence rates of each category in the latter group. The rate of coinfection in a preliminary study in 1982-84 (9.0% or 1/11) was not very different from that obtained to date (10.0% or 5/50).(ABSTRACT TRUNCATED AT 250 WORDS)

Markers of hepatitis B virus infection in asymptomatic drug abusers in Malaysia

Sera from 200 Malaysian male drug abusers were tested for markers of Hepatitis B virus (HBV) infection, viz. HBsAg, HBeAg, anti-HBs and anti-HBc using commercially available enzyme immunoassay (EIA) kits supplied by Abbot Laboratories, Chicago. Of these, 103 (51.5%) were positive for at least one HBV marker, 11 (5.5%) were positive for HBsAg; 4 (2%) for HBeAg, 74 (37%) for anti-HBs and 85 (42.5%) for anti-HBc. The HBsAg carrier rate was roughly the same as the carrier rate in the general population of Malaysia. The majority of drug abusers (95%) have had subclinical, asymptomatic HBV infection. Racially the Malay drug abusers had the highest exposure rate (54.2%). The HBsAg carrier rate was highest in the Chinese drug abusers (15.3%) and lowest in the Indians (0%). The mean age for the HBsAg carriers was found to be 26 years with a mean duration of drug abuse of 72 months. The Malaysian Anti-Narcotics Task Force of the National Security Council reported in the Malay Mail (July 13, 1985) that there were about 106,000 identified drug abusers in Malaysia and that 63% of these were in the 20-29 age groups. It appears from our study that this age group also coincides with the period of high HBsAg carrier rate. Age wise, those less than 21 years old had the highest HBsAg (11%) and HBeAg (5.6%) prevalence rates indicating high infectivity. After the age of 30 years, nearly 50% of the drug abusers appear to be immune with the HBe prevalence of 0%.(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatitis B markers in non-icteric medical patients in Malaysia

Sera were obtained from 494 non-icteric patients admitted with illnesses other than overt hepatitis into the medical wards of the rural and urban hospitals in Malaysia. They were tested for HBsAg, HBeAg, and anti-HBs by enzyme immunoassay. The overall HBsAg carrier rate was 18.0% ranging from 9.6% in children, (10 years and under), to a maximum of 23.5% in the adolescents (11 to 20 years), the rates decreasing subsequently to 16.5% and 20.8% in the adult and middle-age groups, respectively. The Chinese (18.6%) and Malays (19.9%) had similar HBsAg carrier rates but the rate in the Indians (9.0%) was distinctly lower. Similar rates were observed in the males (16.5%) and the females (19.8%). The carrier rate was 17.1% in rural patients compared with 21.4% in the urban ones. The 'e' antigen was found in 14 of the 89 HBsAg carriers (15.7%). The overall prevalence was 14/494 (2.8%) rising sharply from childhood (2.9%) to adolescence (5.3%), subsequently declining with advancing age. The Chinese had the highest rate (6.2%) followed by the Indians (1.5%) and the Malays (1.1%). Males had a rate of 3.3% compared to the females with 2.3%. Anti-HBs was found in 33.8% of the patients, increasing steadily from childhood (18.3%) to middle-age (46.4%). The Chinese had a higher prevalence rate (41.6%) than the Indians (32.8%) and the Malays (29.3%). The rates were similar for the males (35.6%) and the females (31.5%). Rural patients (46.1%) had a higher rate than urban patients (35.7%). Both areas showed rising prevalence with increasing age.(ABSTRACT TRUNCATED AT 250 WORDS)

Delta hepatitis in Malaysia

Sera from one hundred and fifty nine Malaysian individuals were screened for the prevalence of delta markers. These included 15 HBsAg positive homosexuals, 16 acute hepatitis B cases, 9 chronic hepatitis B patients, 13 healthy HBsAg carriers and 106 intravenous (i.v.) drug abusers, of whom 27 were positive for HBsAg only and the rest were anti-HBc IgG positive but HBsAg negative. The prevalence of delta markers in the homosexuals was found to be 6.7%, in the HBsAg positive drug abusers 17.8%, in acute hepatitis B cases 12.5%. No evidence of delta infection was detected in healthy HBsAg carriers, chronic hepatitis B cases and HBsAg negative i.v. drug abusers. With reference to i.v. drug abusers, the prevalence of delta markers was higher in Malays (23%) than in Chinese (7%) although the latter had a higher HBsAg carrier rate. Although the HBsAg carrier rate in the homosexuals was high, their delta prevalence rate was low as compared to drug abusers. In Malaysia, as in other non-endemic regions, hepatitis delta virus transmission appeared to occur mainly via the parenteral and sexual routes. This is the first time in Malaysia that a reservoir of delta infection has been demonstrated in certain groups of the population at high risk for hepatitis B.

Aetiology of acute hepatitis in Malaysia

Icteric patients with clinical and biochemical evidence of liver disease, admitted into various hospitals in Malaysia, were investigated to determine the cause of their infection. Of these patients, 11.0% (16/145) were found positive for IgM anti-HAV (EIA), 4.1% (6/145) for IgM anti-HBc (EIA), 1.0% (1/102) for IgM anti-CMV (ELISA), 17.2% (16/64) for rising titres of leptospiral agglutinin, and none for heterophile antibody of EBV. Hepatitis NANB accounted for 67.9% of cases. The mean serum transaminases (ALT and AST) values in patients with hepatitis A and B were higher (more than 500IU) than in patients with leptospirosis or non-A, non-B hepatitis, whereas serum bilirubin levels were higher in patients with hepatitis A and leptospirosis than in patients with hepatitis B.

A seroepidemiologic study of hepatitis A in Malaysia

Sera from 494 non-icteric patients admitted with illnesses other than overt hepatitis into the various hospitals in rural and urban Malaysia were tested for IgG antibody to hepatitis A virus. The overall antibody prevalence rate was 67.0% with rates increasing steadily from childhood 10 years old and under (39.4%) to middle-age and above (96.0%). No significant differences were noted between males (68.4%) and females (65.3%). The highest rate was in the Indians (80.6%), the lowest in the Chinese (55.9%) with Malays occupying intermediate position (70.3%). The rate in the rural patients (74.7%) was higher than that in the urban patients (65.5%) especially in the 21 to 40 year age-group where the rural patients had a rate of 96.7% compared with that in urban patients (61.1%). A comparison of antibody prevalence rates in different countries was made.

The role of toxoplasmosis in congenital disease in Malaysia

Toxoplasmosis was found not to be an important cause of intrauterine infection in Malaysia as the rate of toxoplasma-specific IgM in 1,060 congenitally defective Malaysian children, 0 to 4 months old (0.4%) was lower than that in 405 normal children of the same age group (2.0%). A total of 8.2 intra-uterine toxoplasmic infections per 1,000 live births was detected of which one-third (2.7 per 1,000 live births) was overt, manifesting symptoms more of liver damage, than eye or brain damage. A comparison was made with the rates in U.S.A. and Europe. The role of toxoplasmosis in abortion needs to be studied.

A serological study of cytomegalovirus and herpes simplex virus infections in Peninsular Malaysia

Healthy Malaysians from various parts of Peninsular Malaysia were examined for CF antibodies against cytomegalovirus (CMV) and herpes simplex virus (HSV) type 2. CMV antibodies were detected in 1114 out of 1556 persons (71.6%) and HSV antibodies were detected in 954 persons out of 1554 (61.4%). The age distribution patterns were similar for the two infections, with maximum prevalence at 5 - 14 years of age. Prevalence was higher in women than in men. There were no significant differences among the Malay, Chinese, and Indian groups of the population with respect to CMV, 72 - 78% possessing antibodies, but in the case of HSV, 76% of the Chinese had antibodies, compared with 57 - 60% of the Malays and Indians. More than 90% of newborn infants had CMV and HSV CF antibodies, confirming the highly immune status of childbearing women in Malaysia. No CMV-specific IgM was detected in the Malaysian neonates examined but this does not exclude the possibility of congenital infection.

An outbreak of acute conjunctivitis caused by coxsackievirus A24 in Kuala-Lumpur, Malaysia, 1978

An investigation of an outbreak of acute conjunctivitis in Kuala Lumpur from May to August 1978 was made. A total of 2,133 cases was involved, most of whom were adult Malay males of low income status from the surrounding villages and low-cost flats. The majority of cases had bilateral conjunctivitis with clear discharge. Pain and subconjunctival haemorrhage were not common and recovery, mostly without complications, occurred within 1 week. Eye scrapings and paired sera specimens were examined and the causal agent was found to be Coxsackievirus A24 (CA24).

Enterovirus survey before and after poliomyelitis vaccination in Kuala Lumpur, Malaysia

Stool samples from healthy children mainly of the low income group aged 0 to 7 years of age from five Maternal and Child Health Centres in Kuala Lumpur were obtained for isolation of enteroviruses. The specimens were collected before and after the mass vaccination given in the face of polio type 1 epidemic which started in October, 1971. The prevelance rate of enteroviruses was 11.9% (3.0% polioviruses, 8.9% non-polio enteroviruses) before the vaccination and essentially the same after. Coxsackie A viruses predominated over the other enteroviruses in the pre- and post-vaccination phases. The highest isolation rate of enteroviruses was observed in children 0 to 2 years age. No significant differences in distribution by sex, race and month were noted. A sharp fall in the prevalence rates of total enteroviruses and polioviruses was noted shortly after the mass vaccination campaign However, the rates reverted to the pre-vaccination state during the next successive years.