Serum placental-like alkaline phosphatase (PLAP): a novel combined enzyme linked immunoassay for monitoring ovarian cancer

Evaluation of follow-up strategies for women with epithelial ovarian cancer following completion of primary treatment

BACKGROUND

This is an update of a previous Cochrane Review, last updated in 2014. Ovarian cancer is the eighth most common cancer and seventh most common cause of death due to cancer in women worldwide. Traditionally, most women who have been treated for cancer undergo long-term follow-up in secondary care. However, it has been suggested that the use of routine review may not be effective in improving survival, or health-related quality of life (HRQOL), or relieving anxiety. In addition, traditional follow-up may not be cost-effective.

OBJECTIVES

To compare the potential effects of different strategies of follow-up in women with epithelial ovarian cancer, following completion of primary treatment.

SEARCH METHODS

For this update, we searched the Cochrane Gynaecological Cancer Group Trials Register, CENTRAL 2022, Issue 11, MEDLINE, and Embase from August 2013 to November 2022. We also searched review articles and contacted experts in the field.

SELECTION CRITERIA

All randomised controlled trials (RCTs) that evaluated follow-up strategies for women with epithelial ovarian cancer following completion of primary treatment.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methodology. Two review authors independently selected potentially relevant trials, extracted data, and assessed risk of bias. They compared results, and resolved disagreements by discussion. We assessed the certainty of evidence, using the GRADE approach, for the outcomes of interest: overall survival (OS), health-related quality of life (HRQOL), psychological effects, and cost analysis.

MAIN RESULTS

For this update, we included one new RCT, including 112 women with ovarian, fallopian tube, or peritoneal cancer, who had completed primary treatment by surgery, with or without chemotherapy. This study reported the effect of individualised, i.e. individually tailored, nurse-led follow-up versus conventional medical follow-up on HRQOL, psychological outcomes, and cost-analysis. Individualised follow-up improved HRQOL in one of the two scales, with a decrease in mean difference (MD) in the QLQ-C30 discomfort scale following 12 months of individualised treatment compared to 12 months of conventional treatment (MD -5.76 points, 95% confidence interval (CI) -10.92 to -0.60; 1 study, 112 participants; low-certainty evidence; minimal important difference 4 to 10 points). There may be little or no difference in the other HRQOL scale (QLQ-Ov28, MD -0.97 points, 95% CI -2.57 to 0.63; 1 study, 112 participants: low-certainty evidence); psychological outcome, measured with the hospital anxiety and depression scale (HADS; MD 0.10 point, 95% CI -0.81 to 1.02; 1 study, 112 participants: low-certainty evidence), or cost analysis (MD -GBP 695.00, 95% CI -1467.23 to 77.23; 1 study, 112 participants: moderate-certainty evidence). Our previous review included one RCT, with 529 women in a confirmed remission, with normal CA125 concentration and no radiological evidence of disease, after surgery and first-line chemotherapy for ovarian cancer. This study evaluated immediate treatment of ovarian cancer relapse following a rise of serum CA125 levels versus delaying treatment until symptoms developed for OS, and HRQOL. There was little or no difference in OS between the immediate and delayed arms after a median follow-up of 56.9 months (unadjusted hazard ratio (HR) 0.98, 95% CI 0.80 to 1.20; 1 study, 529 participants; moderate-certainty evidence). Time from randomisation to first deterioration in global health score or death was shorter in the immediate treatment group than in the delayed treatment group (HR 0.71, 95% CI 0.58 to 0.88).

AUTHORS' CONCLUSIONS

Limited evidence from one trial suggests that routine surveillance with CA125 in asymptomatic women and treatment at CA125-defined relapse does not seem to offer survival advantage when compared to treatment at symptomatic relapse. However, this study pre-dates the use of PARPi maintenance treatment and the increased use of secondary cytoreductive surgery, so the results may be limited in their applicability to current practice. Limited evidence from one trial suggests that individualised nurse-led follow-up may improve HRQOL in women with ovarian cancer following completion of primary treatment. Large RCTs are needed to compare different types of follow-up, looking at survival, HRQOL, psychological effects, and cost as outcomes.

Overview of Optical and Electrochemical Alkaline Phosphatase (ALP) Biosensors: Recent Approaches in Cells Culture Techniques

Alkaline phosphatase (ALP), which catalyzes the dephosphorylation process of proteins, nucleic acids, and small molecules, can be found in a variety of tissues (intestine, liver, bone, kidney, and placenta) of almost all living organisms. This enzyme has been extensively used as a biomarker in enzyme immunoassays and molecular biology. ALP is also one of the most commonly assayed enzymes in routine clinical practice. Due to its close relation to a variety of pathological processes, ALP's abnormal level is an important diagnostic biomarker of many human diseases, such as liver dysfunction, bone diseases, kidney acute injury, and cancer. Therefore, the development of convenient and reliable assay methods for monitoring ALP activity/level is extremely important and valuable, not only for clinical diagnoses but also in the area of biomedical research. This paper comprehensively reviews the strategies of optical and electrochemical detection of ALP and discusses the electrochemical techniques that have been addressed to make them suitable for ALP analysis in cell culture.

Placental type alkaline phosphatase tissue expression in ovarian serous carcinoma

OBJECTIVE

To analyze the expression profile of placental type alkaline phosphatase (PLAP), cancer antigen 125 (CA125), and human epididymis protein 4 (HE4) in serous ovarian cancer and to correlate their expression with the tumor aggressiveness and progression.

METHODS

Retrospective study considering a tissue microarray of 82 women affected by ovarian serous cancer. Protein expression was assessed by immunohistochemistry on ovarian serous cancer tissue samples. Immunohistochemical staining was semiquantitatively evaluated as H-score.

RESULTS

Median H-score values were lower for PLAP, 1 (IQR 0-4) than CA125, 10 (IQR 6-12) or HE4, 8 (IQR 5-12). Even if PLAP was less expressed in the cells of serous ovarian cancer than CA125 or HE4 it was relatively more expressed in the fourth quartile of its H-score distribution among cases with low CA125 or HE4 expression. Furthermore, PLAP and HE4 high expression resulted to be significantly correlated with a better prognosis.

CONCLUSIONS

PLAP could be an additional marker for early detection of serous ovarian carcinoma, together with the established CA125 and HE4. In addition, PLAP expression is correlated with prognosis, giving, in this way, an additional tool for improving treatment approach.

Evaluation of follow-up strategies for patients with epithelial ovarian cancer following completion of primary treatment

BACKGROUND

Ovarian cancer is the sixth most common cancer and seventh commonest cause of death in women worldwide. Traditionally, many people who have been treated for cancer undergo long-term follow-up in secondary care. However, it has been suggested that the use of routine review may not be effective in improving survival, quality of life (QoL), or relieving anxiety, or both. In addition, traditional follow-up may not be cost-effective.

OBJECTIVES

To compare the potential benefits of different strategies of follow-up in patients with epithelial ovarian cancer following completion of primary treatment.

SEARCH METHODS

For this update we searched the Cochrane Gynaecological Cancer Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) Issue 7, 2013, MEDLINE and EMBASE from November 2010 to July 2013. We also searched reference lists of review articles and contacted experts in the field.

SELECTION CRITERIA

All relevant randomised controlled trials (RCTs) that evaluated follow-up strategies for women with epithelial ovarian cancer following completion of primary treatment.

DATA COLLECTION AND ANALYSIS

Two review authors independently abstracted data and assessed risk of bias.

MAIN RESULTS

The authors did not identify any new studies that were eligible for inclusion in this update of the review. The search for the original review identified only one RCT that met the inclusion criteria, which included 529 women. This study reported data on immediate treatment of ovarian cancer relapse following rise of serum CA125 levels versus delaying treatment until symptoms developed. All the women participating had previous confirmation of remission, with normal CA125 concentration and no radiological evidence of disease, after surgery and first-line chemotherapy for ovarian cancer.Overall survival between the immediate and delayed arms showed no difference after a median follow-up of 56.9 months (unadjusted hazard ratio (HR) 0.98, 95% confidence interval (CI) 0.80 to 1.20; P value 0.85). Time from randomisation to first deterioration in global health score or death was shorter in the immediate treatment group than in the delayed treatment group (HR 0.71, 95% CI 0.58 to 0.88; P value < 0.01). The trial was at low risk of bias.

AUTHORS' CONCLUSIONS

Limited evidence from a single trial suggests that routine surveillance with CA125 in asymptomatic patients and treatment at CA125 relapse does not seem to offer survival advantage when compared to treatment at symptomatic relapse. RCTs are needed to compare different types of follow-up, looking at survival, QoL, cost and psychological effects as outcomes.

Evaluation of follow-up strategies for patients with epithelial ovarian cancer following completion of primary treatment

BACKGROUND

Ovarian cancer is the sixth most common cancer and seventh cause of cancer death in women worldwide. Traditionally, many patients who have been treated for cancer undergo long-term follow up in secondary care. Recently however it has been suggested that the use of routine review may not be effective in improving survival, quality of life (QoL), and relieving anxiety. In addition, it may not be cost effective.

OBJECTIVES

To compare the potential benefits of different strategies of follow up in women with epithelial ovarian cancer following completion of primary treatment.

SEARCH STRATEGY

We searched the Cochrane Gynaecological Cancer Group Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, 2010, Issue 4), MEDLINE and EMBASE (to November 2010). We also searched CINAHL, PsycLIT, registers of clinical trials, abstracts of scientific meetings, reference lists of review articles, and contacted experts in the field.

SELECTION CRITERIA

All relevant randomised controlled trials (RCTs) that evaluated follow-up strategies for patients with epithelial ovarian cancer following completion of primary treatment.

DATA COLLECTION AND ANALYSIS

Two review authors independently abstracted data and assessed risk of bias.

MAIN RESULTS

We found only one RCT (Rustin 2010) that met our inclusion criteria. This trial included 529 women and reported data on immediate treatment versus delayed treatment in women with confirmation of remission and with normal CA125 concentration and no radiological evidence of disease after surgery and first-line chemotherapy.Overall survival showed no significant difference between the immediate and delayed arms after a median follow up of 56.9 months (unadjusted hazard ratio (HR) = 0·98, 95% confidence interval (CI) 0·80 to 1·20; P = 0·85). Time from randomisation to first deterioration in global health score or death was significantly shorter in the early group compared with the delayed group (HR 0·71, 95% CI 0·58 to 0·88; P < 0·01). The trial was at low risk of bias.

AUTHORS' CONCLUSIONS

There is a lack of randomised studies on most aspects of follow-up care after treatment for epithelial ovarian cancers. Limited evidence from a single trial suggests that routine surveillance with CA125 in asymptomatic patients, with treatment at CA125 relapse, does not seem to offer survival advantage when compared to treatment at symptomatic relapse. Randomised controlled trials are needed to compare different types of follow up on the outcomes of survival, quality of Life, cost and psychological effects.

Specific immunoassays for placental alkaline phosphatase as a tumor marker

Human placental (hPLAP) and germ cell (PLAP-like) alkaline phosphatases are polymorphic and heat-stable enzymes. This study was designed to develop specific immunoassays for quantifying hPLAP and PLAP-like enzyme activity (EA) in sera of cancer patients, pregnant women, or smokers. Polyclonal sheep anti-hPLAP antibodies were purified by affinity chromatography with whole hPLAP protein (ICA-PLAP assay) or a synthetic peptide (aa 57–71) of hPLAP (ICA-PEP assay); the working range was 0.1–11 U/L and cutoff value was 0.2 U/L EA for nonsmokers. The intra- and interassay coefficients of variation were 3.7%–6.5% (ICA-PLAP assay) and 9.0%–9.9% (ICA-PEP assay). An insignificant cross-reactivity was noted for high levels of unheated intestinal alkaline phosphatase in ICA-PEP assay. A positive correlation between the regression of tumor size and EA was noted in a child with embryonal carcinoma. It can be concluded that ICA-PEP assay is more specific than ICA-PLAP, which is still useful to detect other PLAP/PLAP-like phenotypes.

The combined use of high performance liquid chromatography and immuno-biochemical techniques for protein isolation: a new approach for identification of an individual protein from a pool of proteins

HPLC was used in combination with immuno-bead separation technique for identification of an individual protein from a pool of proteins. This was carried out using an in-house monoclonal antibody (ATC2) specific for placental alkaline phosphatase (PLAP) as a primary antibody for conjugation to CNBr beads. The phosphatase activity (ALP) of PLAP was measured by colorimetric assay (MEDC). The data from this study has so far indicated that: 1. HPLC analysis of molecules following isolation with ATC2-conjugated beads showed high degree of purity. This could be achieved using protein mixtures prepared from lysates of tumour cell lines or tumour fragments. 2. HPLC-isolated PLAP maintained phosphatase activity. 3. Out of the four dissociation reagents used, diethyl amine (DEA) was found to be the best reagent for dissociation of antigen, ie PLAP, but not mAb from CNBr beads. 4. The profile of ALP activity was different for samples prepared from testis and kidney fragments, both in terms of the HPLC peak profile as well as the sensitivity. These data confirmed that the immuno-bead separation technique in conjunction with HPLC were powerful tools for identifying an individual protein from a pool of proteins. These approaches are being used for the identification of PLAP molecules, as a tumour marker in patients suspected of testicular malignancies with equivocal ultrasound.

Elevated serum alkaline phosphatase may enable early diagnosis of ovarian cancer

A case of endometrioid ovarian carcinoma associated with elevated levels of serum placental-like alkaline phosphatase (PLAP) is presented. Two and a half years before a final diagnosis was made following explorative laparotomy, an incidental blood test revealed elevated alkaline phosphatase in the patient's serum. A thorough investigation for the source of this elevation was negative. Postoperative immunohistochemical staining of the tumor, showed diffuse stain with PLAP, along with gradual decline to normal values of serum total alkaline phosphatase. It is suggested, that whenever serum alkaline phosphatase is elevated due to unknown reason, an investigation including alkaline phosphatase isoenzymes, serum Ca-125, trans-vaginal pelvic sonogram and even diagnostic laparoscopy, should be considered in a search for early preclinical ovarian cancer.

Immunohistochemical expression of placental alkaline phosphatase and vimentin in epithelial ovarian neoplasms

The immunohistochemical expression of PLAP and vimentin was assessed in 23 benign, 6 borderline malignant and 31 malignant epithelial ovarian neoplasms. PLAP and vimentin were expressed in some benign (3/23 and 5/23 respectively) and borderline malignant (2/6 for both markers) tumours and they were often expressed in malignant tumours (16/31 and 17/31 respectively). There was a significantly increased expression of PLAP and vimentin in serous cystadenomas and serous carcinomas compared to their mucinous counterparts. Although there was no significant correlation between PLAP expression and histologic grade of carcinomas there was a trend towards increased expression in more differentiated carcinomas. No correlation was found between vimentin expression and degree of differentiation.

Serum placental-type alkaline phosphatase activity in women with squamous and glandular malignancies of the reproductive tract

AIM

To investigate serum placental-type alkaline phosphatase (PLAP-type) activities in women with squamous and glandular malignancies of the reproductive tract using an immunoradiometric assay.

METHODS

PLAP-type immunoreactivity was measured in 180 women with non-ovarian malignancies of the reproductive tract and the values were compared with those from 334 controls. The cases comprised 18 vulval, nine vaginal, 103 cervical, 46 endometrial, and five fallopian tube cancers.

RESULTS

Serum PLAP-type activities were no different from controls in patients with squamous cell tumours. Women with adenocarcinoma of the cervix, endometrium, and fallopian tube had increased values: women with endometrial cancer had a median value nearly four times greater than that of controls. There was no direct correlation between PLAP-type activities and stage of disease in patients with endometrial cancer, but values reverted to normal after treatment.

CONCLUSIONS

Serum PLAP-type measurements are of no value in the management of patients with squamous cell tumours of the female reproductive tract. Raised activities can, however, be found in glandular tumours, in particular endometrial cancer where serum PLAP-type measurements may be of value in predicting remission.

Radioimmunodetection of ovarian cancer

Radioimmunoscintigraphy (RIS) is a potentially valuable method for the detection of primary, secondary and recurrent malignant tumours. Antigens that have been used for monitoring as well as for RIS of ovarian carcinomas include CA 125, PLAP, HMFG, and CA 19-9. Between 70 and 100% of the tumours have been detected at RIS when these antigens have been used. Conventional methods, e.g., computerized tomography (CT) and ultrasonography (US), demonstrate similar or lower detection rate than RIS for tumour diagnosis. RIS gives additional information to conventional radiological methods (CT and US) for the detection of occult ovarian carcinomas. A review of earlier investigations is given and our own recent results using PLAP as a target antigen are presented. The future potential of the technology is discussed.

Measurement of placental alkaline phosphatase activity in benign and malignant pleural effusions

The usefulness of placental alkaline phosphatase (PLAP) as a diagnostic marker of malignancy was assessed in pleural fluid from 60 patients with effusions. Pleural fluid PLAP activities were measured by an enzyme linked immunoassay (ELISA) using the two monoclonal antibodies H17E2 and H317. Similar values were found in groups of patients with primary bronchial tumours (n = 12), secondary malignancies (n = 23), and "benign" conditions (n = 25). The highest values were found in a small subgroup of patients with metastatic ovarian carcinoma. However, the production of this enzyme by normal lung makes the measurement of PLAP in pleural fluid unhelpful as a diagnostic aid to distinguish "benign" from malignant effusions.

The expression of placental alkaline phosphatase (PLAP) and PLAP-like enzymes in normal and neoplastic human tissues. An immunohistological survey using monoclonal antibodies

The immunohistological expression of placental alkaline phosphatase (PLAP) and PLAP-like enzyme was studied in frozen sections from a wide variety (n = 254) of normal and malignant tissues using monoclonal antibodies reactive with PLAP (H317) and PLAP/PLAP-like enzyme (H17E2; H315). PLAP/PLAP-like reactivity was seen in normal thymus, and foetal and neonatal testis, and in 21 out of 22 malignant germ cell tumours (GCTs), but was also found in normal endocervix, normal Fallopian tube and in 28 out of 167 non-GCTs (particularly in ovarian and proximal gastrointestinal tract tumours). Positivity for true PLAP (as demonstrated with H317) was seen in term placenta, in endocervix, and in Fallopian tube (but not in other normal tissues) and was commonly found in ovarian and proximal gastrointestinal tract tumours. Reactivity with H317 was unusual in malignant GCTs (2 out of 22 cases). These findings confirm that PLAP/PLAP-like positivity is a highly sensitive immunohistological marker for malignant GCTs, but one which by itself is of only moderate specificity. Furthermore, expression of true PLAP is rare in GCTs and favours instead an origin from the ovary or proximal gastrointestinal tract. The results also indicate that the predominant heat-stable alkaline phosphatase species in normal foetal and neonatal testis, and in thymus has a similar immunohistological profile to that found in malignant GCTs, and is a PLAP-like enzyme ("germ cell alkaline phosphatase") distinct from true PLAP. The occurrence of this marker in GCTs would appear to reflect increased eutopic production of an enzyme present in trace amount in corresponding normal tissues rather than a genuine example of ectopic expression.

Is placental alkaline phosphatase (PLAP) a useful marker for seminoma?

The usefulness of placental alkaline phosphatase (PLAP) as a tumour marker was assessed in 1578 serum samples from 236 patients with seminoma. Smoking habits were known for all but 7 patients (22 samples). Smoking was associated with significantly higher mean levels of PLAP in disease-free patients (28.8 [S.E. 2.1] U/l vs. 15.9 [1.3] U/l in non-smokers). Mean PLAP levels were higher in patients with active disease (78.6 [23.5] U/l in non-smokers and 47.2 [18.5] U/l in smokers). The median values showed a similar trend. However, there was considerable overlap between the various groups and differences between mean and median values indicated that PLAP values were distributed asymmetrically. The predictive value of PLAP as a tumour marker was consequently much less than superficial inspection of these values might suggest. In 97 patients on surveillance, only 2 out of 11 patients who relapsed had elevated PLAP at the time of clinically detectable relapse. With the upper limit of normal PLAP quoted by our laboratory (35 U/l), specificity and sensitivity were, respectively, 88% and 45% (all patients) and 96% and 47% (non-smokers). The sensitivity and specificity of PLAP were assessed in more detail for a series of threshold values (normal vs. abnormal) with a graphical method. Only in non-smokers did PLAP seem useful and even in this group the positive predictive value of an "abnormal" test may be low; less than 50% in clinically relevant circumstances. Serum PLAP assay cannot usefully stand alone as a marker for seminoma and its routine estimation contributes little to follow-up.