PCPro: a clinically accessible, circulating lipid biomarker signature for poor-prognosis metastatic prostate cancer

BACKGROUND

Using comprehensive plasma lipidomic profiling from men with metastatic castration-resistant prostate cancer (mCRPC), we have previously identified a poor-prognostic lipid profile associated with shorter overall survival (OS). In order to translate this biomarker into the clinic, these men must be identifiable via a clinically accessible, regulatory-compliant assay.

METHODS

A single regulatory-compliant liquid chromatography-mass spectrometry assay of candidate lipids was developed and tested on a mCRPC Discovery cohort of 105 men. Various risk-score Cox regression prognostic models of OS were built using the Discovery cohort. The model with the highest concordance index (PCPro) was chosen for validation and tested on an independent Validation cohort of 183 men.

RESULTS

PCPro, the lipid biomarker, contains Cer(d18:1/18:0), Cer(d18:1/24:0), Cer(d18:1/24:1), triglycerides and total cholesterol. Within the Discovery and Validation cohorts, men who were PCPro positive had significantly shorter OS compared to those who were PCPro negative (Discovery: median OS 12.0 months vs 24.2 months, hazard ratio (HR) 3.75 [95% confidence interval (CI) 2.29-6.15], p < 0.001, Validation: median OS 13.0 months vs 25.7 months, HR = 2.13 [95% CI 1.46-3.12], p < 0.001).

CONCLUSIONS

We have developed PCPro, a lipid biomarker assay capable of prospectively identifying men with mCRPC with a poor prognosis. Prospective clinical trials are required to determine if men who are PCPro positive will benefit from therapeutic agents targeting lipid metabolism.

Multi-Omic Integration of Blood-Based Tumor-Associated Genomic and Lipidomic Profiles Using Machine Learning Models in Metastatic Prostate Cancer

PURPOSE

To determine prognostic and predictive clinical outcomes in metastatic hormone-sensitive prostate cancer (mHSPC) and metastatic castrate-resistant prostate cancer (mCRPC) on the basis of a combination of plasma-derived genomic alterations and lipid features in a longitudinal cohort of patients with advanced prostate cancer.

METHODS

A multifeature classifier was constructed to predict clinical outcomes using plasma-based genomic alterations detected in 120 genes and 772 lipidomic species as informative features in a cohort of 71 patients with mHSPC and 144 patients with mCRPC. Outcomes of interest were collected over 11 years of follow-up. These included in mHSPC state early failure of androgen-deprivation therapy (ADT) and exceptional responders to ADT; early death (poor prognosis) and long-term survivors in mCRPC state. The approach was to build binary classification models that identified discriminative candidates with optimal weights to predict outcomes. To achieve this, we built multi-omic feature-based classifiers using traditional machine learning (ML) methods, including logistic regression with sparse regularization, multi-kernel Gaussian process regression, and support vector machines.

RESULTS

The levels of specific ceramides (d18:1/14:0 and d18:1/17:0), and the presence of CHEK2 mutations, AR amplification, and RB1 deletion were identified as the most crucial factors associated with clinical outcomes. Using ML models, the optimal multi-omics feature combination determined resulted in AUC scores of 0.751 for predicting mHSPC survival and 0.638 for predicting ADT failure; and in mCRPC state, 0.687 for prognostication and 0.727 for exceptional survival. The models were observed to be superior than using a limited candidate number of features for developing multi-omic prognostic and predictive signatures.

CONCLUSION

Using a ML approach that incorporates multiple omic features improves the prediction accuracy for metastatic prostate cancer outcomes significantly. Validation of these models will be needed in independent data sets in future.

Targeting lipid metabolism in metastatic prostate cancer

Despite key advances in the treatment of prostate cancer (PCa), a proportion of men have de novo resistance, and all will develop resistance to current therapeutics over time. Aberrant lipid metabolism has long been associated with prostate carcinogenesis and progression, but more recently there has been an explosion of preclinical and clinical data which is informing new clinical trials. This review explores the epidemiological links between obesity and metabolic syndrome and PCa, the evidence for altered circulating lipids in PCa and their potential role as biomarkers, as well as novel therapeutic strategies for targeting lipids in men with PCa, including therapies widely used in cardiovascular disease such as statins, metformin and lifestyle modification, as well as novel targeted agents such as sphingosine kinase inhibitors, DES1 inhibitors and agents targeting FASN and beta oxidation.

Modulation of Plasma Lipidomic Profiles in Metastatic Castration-Resistant Prostate Cancer by Simvastatin

Elevated circulating sphingolipids are associated with shorter overall survival and therapeutic resistance in metastatic castration-resistant prostate cancer (mCRPC), suggesting that perturbations in sphingolipid metabolism promotes prostate cancer growth. This study assessed whether addition of simvastatin to standard treatment for mCRPC can modify a poor prognostic circulating lipidomic profile represented by a validated 3-lipid signature (3LS). Men with mCRPC (n = 27) who were not on a lipid-lowering agent, were given simvastatin for 12 weeks (40 mg orally, once daily) with commencement of standard treatment. Lipidomic profiling was performed on their plasma sampled at baseline and after 12 weeks of treatment. Only 11 men had the poor prognostic 3LS at baseline, of whom five (45%) did not retain the 3LS after simvastatin treatment (expected conversion rate with standard treatment = 19%). At baseline, the plasma profiles of men with the 3LS displayed higher levels (p < 0.05) of sphingolipids (ceramides, hexosylceramides and sphingomyelins) than those of men without the 3LS. These plasma sphingolipids were reduced after statin treatment in men who lost the 3LS (mean decrease: 23−52%, p < 0.05), but not in men with persistent 3LS, and were independent of changes to plasma cholesterol, LDL-C or triacylglycerol. In conclusion, simvastatin in addition to standard treatment can modify the poor prognostic circulating lipidomic profile in mCRPC into a more favourable profile at twice the expected conversion rate.

GUIDE: a randomised non-comparative phase II trial of biomarker-driven intermittent docetaxel versus standard-of-care docetaxel in metastatic castration-resistant prostate cancer (clinical trial protocol)

Objective:

To determine the efficacy and safety of intermittent docetaxel chemotherapy guided by circulating methylated glutathione S-transferase Pi-1 (mGSTP1) in men with metastatic castration-resistant prostate cancer (CRPC).

Patients and Methods:

GUIDE (NCT04918810) is a randomised, two-arm, non-comparative phase-2 trial recruiting 120 patients at six Australian centres. Patients with Prostate Cancer Working Group-3 defined metastatic CRPC who are commencing docetaxel 75 mg/m² q3w will be pre-screened for detectable mGSTP1 at baseline ± following two cycles of treatment. Those with detectable plasma mGSTP1 at baseline that becomes undetectable after two cycles of chemotherapy will be eligible for GUIDE. Prior to Cycle 4 of docetaxel, these patients are randomised 2:1 to one of two treatment arms: Arm A (cease docetaxel and reinstitute if mGSTP1 becomes detectable) or Arm B (continue docetaxel 75 mg/m² q3w in accordance with clinician’s usual practice). The primary endpoint is radiographic progression-free survival. Secondary endpoints include time on treatment holidays, safety, patient-reported outcomes, overall survival, health resource use, and cost associated with treatment. Enrolment commenced November 2021.

Results and Conclusion:

The results of this trial will generate data on the clinical utility of mGSTP1 as a novel biomarker to guide treatment de-escalation in metastatic CRPC.

Combined impact of lipidomic and genetic aberrations on clinical outcomes in metastatic castration-resistant prostate cancer

BACKGROUND

Both changes in circulating lipids represented by a validated poor prognostic 3-lipid signature (3LS) and somatic tumour genetic aberrations are individually associated with worse clinical outcomes in men with metastatic castration-resistant prostate cancer (mCRPC). A key question is how the lipid environment and the cancer genome are interrelated in order to exploit this therapeutically. We assessed the association between the poor prognostic 3-lipid signature (3LS), somatic genetic aberrations and clinical outcomes in mCRPC.

METHODS

We performed plasma lipidomic analysis and cell-free DNA (cfDNA) sequencing on 106 men with mCRPC commencing docetaxel, cabazitaxel, abiraterone or enzalutamide (discovery cohort) and 94 men with mCRPC commencing docetaxel (validation cohort). Differences in lipid levels between men ± somatic genetic aberrations were assessed with t-tests. Associations between the 3LS and genetic aberrations with overall survival (OS) were examined using Kaplan-Meier methods and Cox proportional hazard models.

RESULTS

The 3LS was associated with shorter OS in the discovery (hazard ratio [HR] 2.15, 95% confidence interval [CI] 1.4-3.3, p < 0.001) and validation cohorts (HR 2.32, 95% CI 1.59-3.38, p < 0.001). Elevated plasma sphingolipids were associated with AR, TP53, RB1 and PI3K aberrations (p < 0.05). Men with both the 3LS and aberrations in AR, TP53, RB1 or PI3K had shorter OS than men with neither in both cohorts (p ≤ 0.001). The presence of 3LS and/or genetic aberration was independently associated with shorter OS for men with AR, TP53, RB1 and PI3K aberrations (p < 0.02). Furthermore, aggressive-variant prostate cancer (AVPC), defined as 2 or more aberrations in TP53, RB1 and/or PTEN, was associated with elevated sphingolipids. The combination of AVPC and 3LS predicted for a median survival of ~12 months. The relatively small sample size of the cohorts limits clinical applicability and warrants future studies.

CONCLUSIONS

Elevated circulating sphingolipids were associated with AR, TP53, RB1, PI3K and AVPC aberrations in mCRPC, and the combination of lipid and genetic abnormalities conferred a worse prognosis. These findings suggest that certain genotypes in mCRPC may benefit from metabolic therapies.

Modulation of the plasma lipidomic profile with simvastatin in metastatic castration-resistant prostate cancer (mCRPC)

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Background: Elevated circulating sphingolipids are associated with poorer outcomes across the natural history of prostate cancer (PC), including metastatic relapse in localised PC, earlier androgen deprivation failure in metastatic hormone-sensitive PC, and shorter overall survival (OS) in mCRPC. We have derived and validated a poor prognostic 3-lipid signature (3LS) [consisting of ceramide Cer(d18:1/24:1), sphingomyelin SM(d18:2/16:0) and phosphatidylcholine PC(16:0/16:0)], which was independently associated with shorter radiographic progression-free survival (rPFS) and OS in men with mCRPC commencing taxanes or androgen receptor signaling inhibitors (ARSI). Statins significantly reduce plasma levels of ceramides, sphingomyelin and cholesterol in cardiovascular disease. We hypothesised that this therapy could change the poor prognostic lipid profile of patients with mCRPC. This study assessed whether the addition of simvastatin to standard treatment for mCRPC modulates the circulating lipidomic profile. Methods: This investigator-initiated, multi-centre, single arm, pilot study enrolled men with mCRPC commencing taxanes or ARSI for disease progression, who were not on a lipid-lowering agent. Men were treated with simvastatin 40mg orally once daily for 12 weeks, commencing on day 1 of treatment for mCRPC. Plasma was taken at baseline and after 12 weeks of simvastatin, and underwent lipidomic profiling of ̃800 lipids. Differences in lipid levels between baseline and post-simvastatin samples and between those with and without the 3LS were assessed using t-tests. Results: 27 men (74% on taxanes, 26% on ARSI) were recruited between May 2018 to March 2021. 46% of the men had the poor prognostic 3LS at baseline, of whom 45% lost the 3LS after simvastatin. Comparison between all paired baseline and post-simvastatin samples showed significant reduction (p < 0.05) in free cholesterol, cholesteryl esters and some sphingolipids (sphingomyelins, hexosylceramides) with simvastatin treatment. Baseline profiles with the 3LS displayed significantly higher levels (p < 0.05) of ceramides, hexosylceramides and sphingomyelins, relative to baseline profiles without the 3LS. Men who lost the 3LS after treatment (n = 5) demonstrated significant reductions in ceramides (23-45%, p≤0.046), hexosylceramides (27-52%, p≤0.049) and sphingomyelins (28-44%, p≤0.047). These changes were not seen in men with persistent 3LS after treatment (n = 6). Conclusions: Simvastatin in addition to standard treatment for mCRPC can modulate the circulating lipidomic profile and eliminate the presence of a poor prognostic 3LS in 45% of participants with the 3LS. Further prospective randomised control studies are required to determine if modulation of the 3LS by simvastatin can improve clinical outcomes. Clinical trial information: ACTRN12617000965303.

Overcoming enzalutamide resistance in metastatic prostate cancer by targeting sphingosine kinase

Background

Intrinsic resistance to androgen receptor signalling inhibitors (ARSI) occurs in 20–30% of men with metastatic castration-resistant prostate cancer (mCRPC). Ceramide metabolism may have a role in ARSI resistance. Our study's aim is to investigate the association of the ceramide-sphingosine-1-phosphate (ceramide-S1P) signalling axis with ARSI resistance in mCRPC.

Methods

Lipidomic analysis (∼700 lipids) was performed on plasma collected from 132 men with mCRPC, before commencing enzalutamide or abiraterone. AR gene aberrations in 77 of these men were identified by deep sequencing of circulating tumour DNA. Associations between circulating lipids, radiological progression-free survival (rPFS) and overall survival (OS) were examined by Cox regression. Inhibition of ceramide-S1P signalling with sphingosine kinase (SPHK) inhibitors (PF-543 and ABC294640) on enzalutamide efficacy was investigated with in vitro assays, and transcriptomic and lipidomic analyses of prostate cancer (PC) cell lines (LNCaP, C42B, 22Rv1).

Findings

Men with elevated circulating ceramide levels had shorter rPFS (HR=2·3, 95% CI=1·5–3·6, p = 0·0004) and shorter OS (HR=2·3, 95% CI=1·4–36, p = 0·0005). The combined presence of an AR aberration with elevated ceramide levels conferred a worse prognosis than the presence of only one or none of these characteristics (median rPFS time = 3·9 vs 8·3 vs 17·7 months; median OS time = 8·9 vs 19·8 vs 34·4 months). SPHK inhibitors enhanced enzalutamide efficacy in PC cell lines. Transcriptomic and lipidomic analyses indicated that enzalutamide combined with SPHK inhibition enhanced PC cell death by SREBP-induced lipotoxicity.

Interpretation

Ceramide-S1P signalling promotes ARSI resistance, which can be reversed with SPHK inhibitors.

Aberrations in circulating ceramide levels are associated with poor clinical outcomes across localised and metastatic prostate cancer

BACKGROUND

Dysregulated lipid metabolism is associated with more aggressive pathology and poorer prognosis in prostate cancer (PC). The primary aim of the study is to assess the relationship between the plasma lipidome and clinical outcomes in localised and metastatic PC. The secondary aim is to validate a prognostic circulating 3-lipid signature specific to metastatic castration-resistant PC (mCRPC).

PATIENTS AND METHODS

Comprehensive lipidomic analysis was performed on pre-treatment plasma samples from men with localised PC (N = 389), metastatic hormone-sensitive PC (mHSPC)(N = 44), or mCRPC (validation cohort, N = 137). Clinical outcomes from our previously published mCRPC cohort (N = 159) that was used to derive the prognostic circulating 3-lipid signature, were updated. Associations between circulating lipids and clinical outcomes were examined by Cox regression and latent class analysis.

RESULTS

Circulating lipid profiles featuring elevated levels of ceramide species were associated with metastatic relapse in localised PC (HR 5.80, 95% CI 3.04-11.1, P = 1 × 10^-6), earlier testosterone suppression failure in mHSPC (HR 3.70, 95% CI 1.37-10.0, P = 0.01), and shorter overall survival in mCRPC (HR 2.54, 95% CI 1.73-3.72, P = 1 × 10^-6). The prognostic significance of circulating lipid profiles in localised PC was independent of standard clinicopathological and metabolic factors (P < 0.0002). The 3-lipid signature was verified in the mCRPC validation cohort (HR 2.39, 95% CI 1.63-3.51, P = 1 × 10^-5).

CONCLUSIONS

Elevated circulating ceramide species are associated with poorer clinical outcomes across the natural history of PC. These clinically actionable lipid profiles could be therapeutically targeted in prospective clinical trials to potentially improve PC outcomes.

Evaluation of a Mainstream Model of Genetic Testing for Men With Prostate Cancer

PURPOSE

To identify the approximately 12% with inherited cancer predisposition, all men with metastatic prostate cancer (mPC) should be offered germline genetic testing. This guides treatment choices and impacts cancer prevention in the family. Limited genetic services globally present a barrier to testing. This study tested a potential solution, "mainstreaming," where counseling and testing are performed by the patient's oncologist.

PATIENTS AND METHODS

Men with mPC at three Australian sites were offered germline genetic testing at their medical oncology appointment. Panel testing (ATM, BRCA1, BRCA2, BRIP1, CHEK2, EPCAM, FANCA, HOXB13, MLH1, MSH2, MSH6, NBN, PALB2, PMS2, RAD51D, and TP53) was performed on saliva/blood (Invitae, San Francisco, CA). Primary outcomes were clinician and patient satisfaction. Secondary outcomes included mutation rates and resource allocation.

RESULTS

Of 66 men offered testing, 63 (95%) accepted. Four pathogenic variants were identified (two BRCA2, one NBN, and one MSH6). Fifty patients and nine clinicians completed questionnaires. Satisfaction was high. All patients were pleased to have had testing overall, 98% (46 of 47) to have had testing at their usual oncology appointment, and all to receive results from their usual specialist, rather than a separate genetics appointment. A total of 88% (7 of 8) of clinicians felt confident, and all were satisfied with mainstreaming. Mainstreaming was resource efficient, requiring 87% fewer genetic consultations than traditional genetic counseling.

CONCLUSION

This study demonstrates that mainstreaming of men with mPC is feasible, resource efficient, and satisfactory for clinicians and patients. Widespread implementation as standard of care would facilitate timely access to genetic testing for men with mPC.

Abstract 4761: Lipidomic analysis of circulating lipids across the natural history of prostate cancer identifies aberrant ceramide metabolism

Background: Obesity is a well established risk factor not only for increased prostate cancer incidence, but for poorer survival from prostate cancer. However, there is limited knowledge on the role of the circulating lipidome in prostate cancer. In order to target lipid metabolism optimally, it is critical to understand the spectrum of changes in circulating lipid profiles and the association with clinical outcome across the natural history of prostate cancer.

Aim: To assess the relationship between the plasma lipidome and clinical outcome in localized and metastatic prostate cancer.

Methods: Liquid chromatography-tandem mass spectrometry was used to quantitate over 500 lipid species in plasma samples from 3 cohorts (1) 389 men with localized prostate cancer, (2) 44 men with metastatic hormone-sensitive prostate cancer (mHSPC), and (3) 137 men with metastatic castration-resistant prostate cancer (CRPC). Associations between circulating lipids with metastatic relapse, androgen-deprivation therapy (ADT) failure or overall survival for each relevant disease stage were examined by latent class analysis and cox regression.

Results: Circulating lipid profiles displaying elevated levels of ceramides were associated with metastatic relapse in localized prostate cancer (HR 5.8, 95% CI 3.0-11, P 1 × 10−6), early ADT failure in mHSPC (HR 2.4, 95% CI 1.1-5.3, P 0.03), and shorter overall survival in CRPC (HR 2.5, 95% CI 1.7-3.7, P 2 × 10−6). ADT failure in mHSPC and shorter overall survival in CRPC were also associated with elevated levels of other sphingolipids (sphingomyelins, hexosylceramides). The prognostic significance of the high risk lipid profiles in localized prostate cancer was independent of clinicopathological characteristics (lipid profile HR 4.7, 95%CI 2.4-9.3, P 7 × 10−6) when modeled with Gleason score (P&lt;0.0001) and pathological stage (P&lt;0.0001). Furthermore, the circulating lipid profiles were independent of metabolic factors (localized prostate cancer lipid profile HR 8.2, 95% CI 2.6-25, P 0.0003 when modeled with diabetes, statin, hypertension, body mass index [BMI]; CRPC lipid profile HR 2.6, 95% CI 1.7-3.8, P x10−6 when modeled with BMI).

Conclusion: Elevated circulating ceramides are associated with poorer clinical outcomes across the natural history of prostate cancer (from localized to metastatic hormone-sensitive to metastatic castration resistant prostate cancer). This demonstrates that aberrant lipid metabolism in the patients occurs early in prostate cancer and could be therapeutically targeted in prospective clinical trials to improve prostate cancer outcomes.

Citation Format: Lisa Glen Horvath, Hui-Ming Lin, Blossom Mak, Kate Mahon, Nicole Yeung, Maria Docanto, Peter Sutherland, andrew Shepherd, Winston Tan, Arun Azad, Manish Kohli, Peter Meikle, Lisa Butler. Lipidomic analysis of circulating lipids across the natural history of prostate cancer identifies aberrant ceramide metabolism [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4761.

Evaluation of a mainstream model of genetic testing for men with prostate cancer

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Background: In order to identify the ∼12% with inherited cancer predisposition, it is recommended that all men with metastatic prostate cancer (mPC) be offered testing. This has implications for treatment choices and cancer prevention in family. Limited geneticists/genetic counsellors globally present a major barrier to testing. We tested a potential solution, mainstreaming, where testing is performed by the patient’s oncologist. Methods: Men with mPC at three Australian sites were offered germline genetic testing at their medical oncology appointment. Panel testing ( ATM, BRCA1, BRCA2, BRIP1, CHEK2, EPCAM, FANCA, HOXB13, MLH1, MSH2, MSH6, NBN, PALB2, PMS2, RAD51D and TP53) was performed on saliva/blood (Invitae). Primary outcomes were clinician and patient acceptability (modified Royal Marsden Satisfaction Questionnaires). Secondary outcomes included mutation rates and cost-effectiveness. A sample size of 44 provided 90% power, with a one-sided alpha of 5%, to distinguish a proportion of men happy with mainstreaming of 80% vs. 60% or less. Allowing for 25% drop-out, we aimed to recruit 60 men. Results: Of 66 men offered testing from April to November 2019, 63 (95%) accepted. Four pathogenic variants were identified (2 BRCA2, 1 NBN, 1 MSH6). 48 patients and eight clinicians completed questionnaires. Acceptability was high. All (48/48) patients were happy to have been tested, and 45/48 (94%) were happy to have been tested at their oncology appointment. All were happy to receive their results from their oncologist. All clinicians were satisfied mainstreaming and 88% (7/8) felt confident doing so. Mainstreaming was cost-effective, requiring 87% fewer genetic consultations than traditional genetic counselling. Conclusions: This study shows that mainstreaming of men with mPC is feasible, resource efficient and acceptable to both clinicians and patients. Widespread implementation as a new standard of care would facilitate timely access to genetic testing for men with mPC.

Modulation of plasma lipidomic signature in metastatic castration-resistant prostate cancer (mCRPC)

TPS331

Background: Altered lipid metabolism and its impact on prostate cancer (PC) is increasingly recognised, in light of the association between obesity and worse PC outcomes. Our exploratory study was the first to identify baseline plasma lipidomic profiles in men with mCRPC commencing docetaxel that were associated with survival. A prognostic three-lipid signature was derived, consisting of ceramide, sphingomyelin and phosphatidylcholine (HR 4.8, 95% CI 2.06-11.1, p = 0.0003). This signature was independently prognostic when modelled with clinicopathological factors and metabolic characteristics. A key question is whether therapeutic modulation of a patient’s lipid profile is possible. Statins significantly reduce the plasma levels of ceramides, sphingomyelin and cholesterol in cardiovascular disease, suggesting that this therapy could change the poor prognostic lipid profile of mCRPC patients. This trial assesses whether addition of simvastatin to docetaxel for mCRPC can reverse the poor prognostic lipid signature with the aim of developing a precision medicine strategy for metabolic targeting. Methods: This investigator-initiated, multi-centre, open-label, single arm, pilot study enrols patients with mCRPC commencing docetaxel for disease progression, not already receiving a lipid-lowering agent. Patients are treated with simvastatin 40mg orally once daily for 12 weeks, commencing on day 1 of the first cycle of docetaxel. Blood is taken at baseline and after 12 weeks of simvastatin and the plasma lipidomic profile is determined using liquid chromatography and electrospray ionisation-tandem mass spectrometry. The lipidomic profile is classified as either good or poor prognostic as per our three-lipid signature model derived by logistic regression. The primary objective is to assess the rates of conversion from a poor prognostic lipid signature to good prognostic after simvastatin. A sample size of 60 men provides over 90% power, with a 1-sided type 1 error of 10%, to detect conversion to the good prognostic signature in 50% of patients, assuming 25% of patients have the poor prognostic signature at baseline as previously detected. To date, 6 patients have been enrolled to the trial. Clinical trial information: ACTRN12617000965303.

Utility of the Health Belief Model in predicting compliance of screening in patients with chronic hepatitis B

BACKGROUND

Regular surveillance is recommended for patients with chronic hepatitis B, to select candidates for anti-viral therapy and detect early complications. However, factors that determine compliance are not well studied.

AIM

To determine the utility of the Health Belief Model in explaining non-compliance, among a group of chronic hepatitis B patients for screening.

METHODS

A total of 192 chronic hepatitis B patients who responded to advertisement for free screening took part in a telephonic interview study. Subjects were asked about the five constructs of the Health Belief Model, and factors associated with recent screening were analysed.

RESULTS

The mean age of the subjects was 42.1 +/- 0.7 years; 77% white male, and 97% Chinese. About 108 patients (56%) had recent screening. At multivariate analysis, only the ability to remember date of follow-up (OR: 4.37; 95% CI: 2.07-9.17) and the perception of having to wait a long time for venepuncture (OR: 0.38; 95% CI: 0.19-0.79) were significantly associated with recent screening.

CONCLUSION

Future public health measures should include improving the logistics of follow-up procedures and providing reminders for screening to improve compliance.

The majority of hepatitis B carriers are not on regular surveillance in Singapore

INTRODUCTION

Carriers of hepatitis B virus (HBV) are at risk of developing long-term complications. Regular surveillance helps detect treatable chronic hepatitis, cirrhosis and liver cancer, and is recommended by practice guidelines in the United States, Europe and Singapore. However, there have been few studies evaluating the follow-up of HBV carriers. This study seeks to determine the proportion of HBV carriers on regular follow-up in Singapore and the impact on hepatitis B disease.

METHODS

An advertisement was taken in local newspapers advertising for free screening to HBV carriers. 387 persons answered the advertisement. The screening comprised history-taking, physical examination, blood tests (liver panel, alphafoetoprotein, hepatitis B surface antigen (Ag) and hepatitis B eAg) and ultrasonography of liver. Further evaluation was conducted if the screening results were abnormal.

RESULTS

Of the 387 HBV carriers, 346 (89 percent) were male and 375 (97 percent) were Chinese. Their mean age was 39 years (range 20-60 years) and 36 percent were positive for HBeAg. 247 (64 percent) were not on regular screening over the past 12 months. 19 (5.4 percent) patients were diagnosed to have complications, namely: 13 had HBeAg-positive chronic hepatitis, two had HBeAg-negative chronic hepatitis, one had early liver cancer who recovered well after a curative resection and three had compensated cirrhosis.

CONCLUSION

Our screening programme diagnosed 5.4 percent of complications among 387 asymptomatic HBV carriers. However, 64 percent of the study subjects were not screened regularly and may pose an important public health threat if they develop long-term complications. Further studies are needed to evaluate and improve patient compliance for screening.

Paclitaxel (Taxol) attenuates clinical disease in a spontaneously demyelinating transgenic mouse and induces remyelination

Treatment with paclitaxel by four intraperitoneal injections (20 mg/kg) 1 week apart attenuated clinical signs in a spontaneously demyelinating model, if given with onset of clinical signs. If given at 2 months of age (1 month prior to clinical signs), disease was almost completely prevented The astrogliosis, prominent in our model, was reversed by paditaxel as determined by astrocyte counts and quantitation of GFAP. Electron microscopic examination of affected regions at 2.5 months demonstrated that the myelin was generally normal. By 4 months of age, demyelination was common in the superior cerebellar peduncle, maximal at 6 months, but continued to 8 months. In addition to myelin vacuolation and nude axons, the presence of many thin myelin sheaths suggested remyelination or partial demyelination. Although no evidence of oligodendrocyte loss was seen, nuclear changes were observed. To substantiate that remyelination was occurring, we measured MBP (18.5 kDa), MBP-exon II, Golli-MBP, TP8, Golli-MBP-J37, platelet-derived growth factor alpha (PDGFR alpha) and sonic hedgehog (SHH). Of these TP8, PDGFR alpha and SHH were up-regulated in the untreated transgenic. After paditaxel treatment, MBP-Exon II, TP8, PDGFR alpha and SHH were further up-regulated. We concluded that some of the effects of paditaxel were to stimulate proteins involved in early myelinating events possibly via a signal transduction mechanism.

Mechanism of demyelination in DM20 transgenic mice involves increased fatty acylation

Transgenic mice (ND4) containing 70 copies of the transgene encoding DM20 were clinically normal up to 3 months of age, spontaneously demyelinated there-after and died in 8-10 months. Whereas the myelin fraction from normal mice increased in amount from 1-4 months as expected, the corresponding fraction in ND4 mice remained constant over this period. In order to study the mechanism by which decreased myelin synthesis was manifest in the ND4 mouse, we investigated the amounts of proteolipids at various ages. The amount of proteolipid protein (PLP) was greatly decreased after 1-2 months in the ND4 mice. Although the message for DM20 was increased (transgene mRNA), very little DM20 was found in myelin at 1 month. It subsequently increased so that at 3-4 months the amount of DM20 in myelin isolated from transgenic animals was much higher than in normal mice. Characterization of the DM20 and PLP at 1 month of age showed that the amount of fatty acid (stearate and palmitate) was increased and the N-terminal glycine was methylated. These data suggested that high copy numbers of the cDNA for DM20 affected post translational events which we postulate affected the proper insertion of both DM20 and PLP in the myelin bilayer.

Modifications of myelin basic protein in DM20 transgenic mice are similar to those in myelin basic protein from multiple sclerosis

Transgenic mice containing different numbers of transgenes (2-70) of the myelin proteolipid protein DM20 were phenotypically normal up to 3 mo of age, after which the mice containing 70 copies of the transgene spontaneously demyelinated and died at 10-12 mo. Since we demonstrated that demyelination in multiple sclerosis involved specific chemical changes in myelin basic protein (MBP), we investigated the MBP in our transgenic line for similar changes. Both the total amount of MBP in brain and the MBP mRNA levels were unaffected at the different ages. All the isoforms (14-21 kD) of MBP were present, but the microheterogeneity (a posttranslational event) was changed resulting in a higher proportion of the less cationic components reminiscent of the changes in MBP found in multiple sclerosis. An increased amount of the citrullinated form of MBP was found by Western blot analysis. Immunogold labeling of cryosections of brain revealed a greater density of particles with the anticitrulline antibody at 10 mo and that the levels of peptidylarginine deiminase (which deiminates protein-bound arginine to citrulline) were increased. This stable transgenic line represents a useful animal model for the human disease multiple sclerosis.

The value of ultrasound mammography in palpable breast masses

Between January 1987 and May 1988 a prospective study was carried out on 232 women with a palpable breast mass. They underwent physical examination, x-ray mammography and ultrasound mammography. The results of each study were interpreted independently by separate observers, and consensus was achieved. From all solid tumours histology was available. Compared to x-ray mammography, ultrasound mammography proved to be significantly (p less than 0.025) more sensitive in diagnosing malignant palpable breast masses (98.7% versus 86.8%). However there was no statistical significant difference in specificity between ultrasound mammography and x-ray mammography. Using ultrasound mammography we classified 9 histological proven malignant tumours as such which were negative on plain x-ray mammography. Despite the good results of ultrasound mammography in diagnosing palpable breast lesions it can never replace x-ray mammography in cases of malignancy, because the results of ultrasound mammography with non-palpable synchronous tumours with or without microcalcifications are poor. In some cases of benign lesions diagnosed with ultrasound mammography no x-ray mammography is necessary.

An operative choledochoscopy using the flexible choledochoscope

In a prospective study, the value of operative choledochoscopy as a completion procedure after standard instrumental exploration of the common bile duct is evaluated. The technique of examination using the flexible scope is described. Operative choledochoscopy was performed upon 320 patients. Retained stones of the biliary tract missed by exploration were detected in 23 patients (7.1 per cent). Stones retained in spite of endoscopic examination were found in five (1.6 per cent) of the patients. The comparison of the personal experience (158 patients) with the experience of other surgeons and registrars performing the biliary tract operations on their own at our institutions (178 patients) allows a conclusion that, if the technique of choledochoscopy is well standardized and correctly learned, no difference in results achieved is to be expect. Operative choledochoscopy is a reliable method of examination supporting valuable diagnostic information, contributing to the operative decision making and reducing efficiently the incidence of retained biliary tract stones.

Postoperative choledochoscopy. A five-year experience

In a five-year period postoperative choledochoscopy was used in 85 consecutive patients for therapeutic or diagnostic interventions in the biliary tract. Seventy-three patients underwent postoperative choledochoscopy for removal of retained biliary stones; 67 (92%) had successful removal of 94 retained stones; in 11 stones were located in the intrahepatic ducts; in six postoperative choledochoscopy failed; and in 12 postoperative choledochoscopy was performed for diagnostic or other therapeutic reasons. No serious complications were encountered in this series. The advantage of this simple and effective technique over other instrumental or so-called radiologic techniques is discussed. In our opinion, postoperative choledochoscopy is now the method of choice for diagnostic and therapeutic (re)interventions in the biliary tract by patients with a T tube still in situ.