Exploratory analysis of serum CA-125 response to surgery and the risk of relapse in patients with FIGO stage IIIC ovarian cancer

Nadir CA-125 has prognostic value for recurrence, but not for survival in patients with ovarian cancer

The objective of this study was to evaluate the nadir CA-125 in patients with epithelial ovarian cancer. A total of 168 patients who achieved complete remission (no clinical and radiological signs, CA-125 ≤ 35 U/ml) after first-line treatment were enrolled in the study. The relationship between CA-125 and survival was examined by applying generalized additive models to the Cox proportional hazards model. The median CA-125 concentration after the treatment was 10 U/ml (2.7–35 U/ml). The nadir CA-125 was related to progression-free survival but not to overall survival. The risk of recurrence in patients with 11–25 U/ml and 26–35 U/ml compared to patients with ≤ 10 U/ml was 1.87 (p < 0.0024) and 2.17 (p < 0.018), respectively. An increased risk of recurrence according to the nadir CA-125 (≤ 10 U/ml vs. 11–25 U/ml and ≤ 10 U/ml vs. 26–35 U/ml) was found in patients with high-grade tumours (hazard ratio, HR = 2.08 and 2.59, respectively), advanced disease (HR = 2.38 and 2.03, respectively), serous histology (HR = 2.08 and 2.43, respectively) and after complete cytoreduction (HR = 2.7 and 2.72, respectively). No correlation between the CA-125 nadir and recurrence risk was found in patients with early-stage disease or those receiving neoadjuvant chemotherapy or bevacizumab.

Prognostic significance of elevated pretreatment serum levels of CEA and CA-125 in epithelial ovarian cancer

BACKGROUND

Epithelial ovarian cancer is a highly lethal gynecological malignancy. Accurate and cost-effective predictive tools to estimate the prognosis of patients with epithelial ovarian cancer before treatment are currently lacking.

OBJECTIVE

The purpose of this study was to evaluate the prognostic significance of pretreatment serum levels of carcinoembryonic antigen (CEA) and carbohydrate antigen-125 (CA-125) in primary epithelial ovarian cancer.

METHODS

Between 2008 and 2016, 326 patients with a diagnosis of primary epithelial ovarian cancer were retrospectively reviewed. We attempted to identify an optimal cut-off value of CEA to predict survival using ROC curve analysis. Cox regression univariate and multivariate analyses were used to evaluate prognostic factors.

RESULTS

The optimal cut-off value of CEA was 2.6 ng/mL. In univariate and multivariate analyses, FIGO stage and pretreatment CA-125 and CEA levels significantly predicted progression-free and overall survival. The 5-year progression-free survival rate for patients with both a CEA level < 2.6 ng/mL and CA-125 level < 35 U/mL was 84%, compared to only 33% for the patients with higher levels of both markers (p< 0.001). The 5-year cancer specific survival rate was 94% in those with a CEA level < 2.6 ng/mL and CA-125 level < 35 U/mL, and only 39% for those with higher levels of both markers (p< 0.001).

CONCLUSIONS

In addition to traditional prognostic factors, a pretreatment serum CEA level ⩾ 2.6 ng/mL and CA-125 level ⩾ 35 U/mL were also independent prognostic factors for epithelial ovarian cancer. Patients with an elevated CEA and/or CA-125 level before treatment should be considered to be at high-risk of recurrence and death.

Perioperative change in CA125 is an independent prognostic factor for improved clinical outcome in advanced ovarian cancer

OBJECTIVE

Despite being the most important prognostic factor for prolonged overall survival in epithelial ovarian cancer (EOC), the measurement of residual disease is hampered by its subjective character. Additional assessment tools are needed to establish the success of cytoreductive surgery in order to predict patients' prognosis more accurately. The aim of this study is to evaluate the independent prognostic value of perioperative CA125 change in advanced stage EOC patients.

STUDY DESIGN

We identified all patients who underwent primary cytoreductive surgery for advanced stage (FIGO IIB-IV) EOC between 2008 and 2015, from the Netherlands Cancer Registry. The relative perioperative change in CA125 was categorized into four groups; increase, <50% decline, 50-79% decline and ≥80% decline. Overall survival (OS) was analyzed using Kaplan-Meier survival curves and multivariable cox regression models.

RESULTS

We included 1232 eligible patients with known pre- and postoperative CA125 serum levels. Patients with a decline of ≥80% in CA125 levels experienced improved OS compared to those with a decline of <50% (univariable Hazard Ratio (HR) 0.45, 95%CI 0.36-0.57). The prognostic effect of perioperative CA125 change was independent of patient- and treatment characteristics, such as the extent of residual disease after cytoreductive surgery (multivariable HR_≥80% 0.52(0.41-0.66)).

CONCLUSIONS

This study shows that the perioperative change in CA125 is an independent prognostic factor for overall survival after primary surgery for EOC patients. This pleads for the use of a combined model, consisting of perioperative CA125 change and the outcome of residual disease, in order to predict the prognosis of EOC patients more accurately.

Phthalocyanine-doped polystyrene fluorescent nanocomposite as a highly selective biosensor for quantitative determination of cancer antigen 125

A novel, simple, sensitive, and precise spectrofluorometric assay of cancer antigen [CA 125] is described. This modality is based on monitoring the quenching of the luminescence intensity at 790 nm of the phthalocyanine fluorophore, in a nanocomposite comprising the fluorophore and cationic polystyrene, which results from interaction with CA 125. The remarkable quenching of the luminescence intensity of the Ni-phthalocyanine complex doped in PS matrix by various concentrations of CA 125 was successfully utilized as an optical sensor for the determination of CA 125 in different serum samples of ovarian disease. The performance of the designed biosensor is determined through monitoring the quenching of the luminescence intensity at 790 nm by cancer antigen 125 after excitation at 685 nm, pH 7.3 in water. The calibration plot was achieved over the concentration range 1.0 × 10^-2 - 127 U mL^-1 CA-125 with a correlation coefficient of 0.99 and detection limit of 1.0 × 10^-4 U mL^-1. The mechanism of the interaction between the nano thin film nickel(II)phthalocyanine and CA-125 was discussed. A significant correlation between the proposed method for the assessment of CA 125 and the standard method was applied to patients and controls.

Treatment of Peritoneal Surface Malignancies with Cytoreductive Surgery and Hyperthermic Intra-peritoneal Chemotherapy (HIPEC): Experience in Israel

The treatment of peritoneal surface malignancies, either primary or secondary (peritoneal metastasis), has evolved over the past two decades. A nihilistic approach of incurable "carcinomatosis" is changing into treatment of peritoneal metastasis with curative intent. The aim of the present study is to review the current practice, past history, and future of peritoneal surface oncology in Israel. A systematic review of all patients treated in institutions performing cytoreductive surgery (CRS) and hyperthermic intra-peritoneal chemotherapy (HIPEC) for the treatment of peritoneal surface malignancies. Each center provided the following data: start year, number of total cases, number of cases performed in 2017, and the method used (open vs. closed technique). Between 1990 and 2018, there were 1462 patients treated by CRS/HIPEC in Israel by eight different surgical groups in six medical centers. Currently, there are seven surgical groups in six medical centers routinely performing CRS/HIPEC. The annual rate of CRS/HIPEC was 171 cases in 2017 with a range of (4-69 cases/center). This is the first step of establishing an Israeli Peritoneal Surface Oncology Group that will have joined database and perform clinical trials in this challenging field of surgical oncology.

High-Grade Serous Ovarian Cancer: Basic Sciences, Clinical and Therapeutic Standpoints

Among a litany of malignancies affecting the female reproductive tract, that of the ovary is the most frequently fatal. Moreover, while the steady pace of scientific discovery has fuelled recent ameliorations in the outcomes of many other cancers, the rates of mortality for ovarian cancer have been stagnant since around 1980. Yet despite the grim outlook, progress is being made towards better understanding the fundamental biology of this disease and how its biology in turn influences clinical behaviour. It has long been evident that ovarian cancer is not a unitary disease but rather a multiplicity of distinct malignancies that share a common anatomical site upon presentation. Of these, the high-grade serous subtype predominates in the clinical setting and is responsible for a disproportionate share of the fatalities from all forms of ovarian cancer. This review aims to provide a detailed overview of the clinical-pathological features of ovarian cancer with a particular focus on the high-grade serous subtype. Along with a description of the relevant clinical aspects of this disease, including novel trends in treatment strategies, this text will inform the reader of recent updates to the scientific literature regarding the origin, aetiology and molecular-genetic basis of high-grade serous ovarian cancer (HGSOC).

High-Grade Serous Ovarian Cancer: Basic Sciences, Clinical and Therapeutic Standpoints

Among a litany of malignancies affecting the female reproductive tract, that of the ovary is the most frequently fatal. Moreover, while the steady pace of scientific discovery has fuelled recent ameliorations in the outcomes of many other cancers, the rates of mortality for ovarian cancer have been stagnant since around 1980. Yet despite the grim outlook, progress is being made towards better understanding the fundamental biology of this disease and how its biology in turn influences clinical behaviour. It has long been evident that ovarian cancer is not a unitary disease but rather a multiplicity of distinct malignancies that share a common anatomical site upon presentation. Of these, the high-grade serous subtype predominates in the clinical setting and is responsible for a disproportionate share of the fatalities from all forms of ovarian cancer. This review aims to provide a detailed overview of the clinical-pathological features of ovarian cancer with a particular focus on the high-grade serous subtype. Along with a description of the relevant clinical aspects of this disease, including novel trends in treatment strategies, this text will inform the reader of recent updates to the scientific literature regarding the origin, aetiology and molecular-genetic basis of high-grade serous ovarian cancer (HGSOC).

High-Grade Serous Ovarian Cancer: Basic Sciences, Clinical and Therapeutic Standpoints

Among a litany of malignancies affecting the female reproductive tract, that of the ovary is the most frequently fatal. Moreover, while the steady pace of scientific discovery has fuelled recent ameliorations in the outcomes of many other cancers, the rates of mortality for ovarian cancer have been stagnant since around 1980. Yet despite the grim outlook, progress is being made towards better understanding the fundamental biology of this disease and how its biology in turn influences clinical behaviour. It has long been evident that ovarian cancer is not a unitary disease but rather a multiplicity of distinct malignancies that share a common anatomical site upon presentation. Of these, the high-grade serous subtype predominates in the clinical setting and is responsible for a disproportionate share of the fatalities from all forms of ovarian cancer. This review aims to provide a detailed overview of the clinical-pathological features of ovarian cancer with a particular focus on the high-grade serous subtype. Along with a description of the relevant clinical aspects of this disease, including novel trends in treatment strategies, this text will inform the reader of recent updates to the scientific literature regarding the origin, aetiology and molecular-genetic basis of high-grade serous ovarian cancer (HGSOC).

Prognostic significance of CA-125 re-elevation after interval debulking surgery in patients with advanced-stage ovarian cancer undergoing neoadjuvant chemotherapy

AIMS

We evaluated the prognostic significance of postoperative re-elevation of cancer antigen-125 (CA-125) levels in patients with ovarian cancer and preoperative normalization of CA-125 levels after neoadjuvant chemotherapy (NAC).

METHODS

The data of 103 patients with preoperative CA-125 normalization after NAC at the Yonsei Cancer Hospital (2006-2017) were analyzed. We compared the clinical characteristics and survival outcomes among patients with normal postoperative CA-125 levels and those with re-elevated CA-125 levels after interval debulking surgery (IDS). CA-125 elevation was defined as levels >35 U/mL.

RESULTS

Among 103 patients, 52 (50.5%) and 51 (49.5%) had normal and re-elevated CA-125 levels after IDS, respectively. Patients with CA-125 re-elevation underwent more radical surgeries during IDS than those with normal CA-125 levels (p = 0.018). We found no significant differences in progression-free survival (PFS; p = 0.726) or overall survival (OS; p = 0.293) between the two groups. Moreover, patients with persistent CA-125 elevation (3 weeks after IDS) did not have inferior PFS (p = 0.171 and p = 0.208, respectively) or OS (p = 0.128 and p = 0.095, respectively) compared to patients with early normalization (within 3 weeks of IDS) or normal CA-125 levels. Multivariate regression showed that CA-125 re-elevation had no effect on recurrence (hazard ratio [HR], 0.75; 95% confidence interval [CI], 0.43-1.30) or death (HR, 0.99; 95% CI, 0.33-2.98).

CONCLUSION

Among patients with preoperative CA-125 normalization after NAC, postoperative CA-125 re-elevation had no prognostic value. Novel and reliable biomarkers reflecting the tumor response after IDS should be identified.

Predictive equation of metastasis in patients with malignant ovarian epithelial tumors with the Ca-125 marker

Background

Cancer antigen (CA) 125 (CA-125) is used in ovarian cancer detection and monitoring, whose serum level has a positive correlation with tumor stage. The aim of this study was to obtain a prediction metastasis equation in a group of patients with ovarian cancer based on Ca-125.

Methods

A 2-group comparative observational study was conducted at a single oncologic institution (SOLCA) in Cuenca-Ecuador. All patients who were diagnosed with ovarian cancer between January 1996 and December 2016 were included in the current study. Group 1 (G1) patients with the I and II International Federation of Gynecology and Obstetrics (FIGO) stage and Metastasis Group (MG), with III and IV stage, were subdivided. A logistic regression equation was performed to predict metastasis based on Logarithm of serum Ca-125 levels.

Results

We included 85 cases in G1 and 64 patients in MG, with 47.8 ± 15 years (G1) and 57.5 ± 13.6 years (MG) of age (P < 0.001). Mortality in G1 was 2 cases (3.1%) and 53 cases (62.4%) in MG (P < 0.001). The CA-125 serum level was 163.5 ± 236 in G1 and 1220.9 ± 1940 u / ml in MG (P < 0.001). The equation to predict metastasis = (Age*0.053) + [(Logarithm Ca-125 value) * 1.078] − 8.163 with an OR 2.940 (CI 95% 2.046–4.223) P < 0.001. The sensitivity of the equation was 82.4% and the specificity was 79.7%.

Conclusions

It is possible to predict the presence of metastasis in a group of patients with ovarian cancer based on Ca-125.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4499-y) contains supplementary material, which is available to authorized users.

Postoperative human epididymis protein 4 predicts primary therapy outcome in advanced epithelial ovarian cancer

Primary chemotherapy treatment response monitoring in advanced epithelial ovarian cancer (EOC) is currently based on CT-imaging and serum CA125 values. Serum HE4 profile during first line chemotherapy has not been previously studied. We evaluated the HE4 profile during first line chemotherapy after primary (PDS) and interval debulking surgery (IDS). In total, 49 FIGO stage III/IV EOC patients were included in the study. 22 patients underwent PDS and 27 patients neoadjuvant chemotherapy (NACT) followed by IDS. Serial HE4 and CA125 serum samples were taken during first line chemotherapy. The association of postoperative tumor markers to surgery outcome, primary therapy outcome and progression free survival (PFS) were determined. The lowest HE4 and CA125 values during chemotherapy were compared to primary therapy outcome and PFS. The postoperative HE4 was associated to residual tumor after surgery (p = 0.0001), primary therapy outcome (p = 0.004) and PFS (p = 0.03) in all patients (n = 40). The postoperative CA125 was associated to PFS after IDS (n = 26, p = 0.006), but not after PDS. In multivariate analysis with FIGO stage (III/IV), residual tumor (0/>0) and postoperative CA125, the postoperative HE4 was the only statistically significant prognostic variable predicting PFS. Both HE4 and CA125 nadir corresponded to primary therapy outcome (HE4 p < 0.0001, CA125 p < 0.0001) and PFS (HE4 p = 0.009, CA125 p < 0.0001). HE4 is a promising candidate for EOC response monitoring. In our study, the performance of HE4 in response monitoring of first line chemotherapy was comparable to that of CA125. Of the postoperative values, only HE4 was statistically significantly associated to primary therapy outcome.

Perioperative changes in serum CA125 levels: a prognostic factor for disease-specific survival in patients with ovarian cancer

Objective

In patients with advanced stage epithelial ovarian cancer (EOC) the volume of residual tumor after debulking is known as prognostic factor for survival. We wanted to examine the relationship between postoperative decline in serum CA125 and residual disease after cytoreductive surgery and evaluate perioperative changes in serum CA125 levels as predictor for disease-specific survival.

Methods

A retrospective study was conducted of patients with FIGO stage IIb-IV EOC treated with cytoreductive surgery, followed by chemotherapy between 1996 and 2010 in three hospitals in the Southeastern region of the Netherlands. Data were analyzed with the use of multilevel linear regression and Cox-proportional hazard regression models.

Results

A postoperative decline in serum CA125 level of ≥80% was associated with complete primary cytoreduction (p=0.035). Univariate analyses showed favorable associations with survival for both the degree of decline in serum CA125 and residual tumor after primary cytoreduction. In multivariate analyses the decline in serum CA125 but not the outcome of surgery remained significantly associated with better survival (HR_50%–79%=0.52 [95% CI: 0.28–0.96] and HR_≥80%=0.26 [95% CI: 0.13–0.54] vs. the serum CA125 decline of <50% [p<0.001]).

Conclusion

The current study, although hampered by possible biases, suggests that the perioperative decline in serum CA125 is an early biomarker that predicts disease-specific survival in patients who underwent primary cytoreductive surgery for advanced stage EOC. If confirmed prospectively, the perioperative change in serum CA125 could be a better marker for residual tumor volume after primary cytoreductive surgery (and therewith disease-specific survival) than the surgeons’ estimation of residual tumor volume.

Hormone receptor, HER2/NEU and EGFR expression in ovarian carcinoma--is here a prognostic phenotype?

PURPOSE

We aimed to evaluate the effects of hormone receptor, HER2, and epidermal growth factor receptor (EGFR) expression on epithelial ovarian cancer (EOC) prognosis and investigate whether or not phenotypic subtypes might exist.

MATERIALS AND METHODS

The medical records of 82 patients who were diagnosed with EOC between 2003 and 2012 and treated by platinum-based chemotherapy were retrospectively evaluated. Expression of EGFR, oestrogen (ER), progesterone (PR), and cerbB2 (HER2) receptors were assessed immunohistochemically on paraffin-embedded tissues of these patients. Three phenotypic subtypes were defined according to ER, PR, and HER2 expression and associations of these with EGFR expression, clinicopathologic features, platinum sensitivity, and survival were investigated.

RESULTS

When we classified EOC patients into three subtypes, 63.4% had hormone receptor positive (HR(+)) (considering breast cancer subtypes, luminal A), 18.3% had triple negative, and 18.3% had HER2(+) disease. EGFR positivity was observed in 37 patients (45.1%) and was significantly more frequent with advanced disease (p=0.013). However, no significant association with other clinicopathologic features and platinum sensitivity was observed. HER2(+) patients had significantly poorer outcomes than HER2(-) counterparts (triple negative and HR positive patients) (p=0.019). Multivariate analysis demonstrated that the strongest risk factor for death was residual disease after primary surgery.

CONCLUSIONS

Triple negative EOC may not be an aggressive phenotype as in breast cancer. The HER2 positive EOC has more aggressive behaviour compared to triple negative and HR(+) phenotypes. EGFR expression is more frequent in advanced tumours, but is not related with poorer outcome. Additional ovarian cancer molecular subtyping using gene expression analysis may provide more reliable data.

Treatment monitoring of patients with epithelial ovarian cancer using invasive circulating tumor cells (iCTCs)

GOALS

Contemporary management of epithelial ovarian cancer (EOC) uses biomarkers to monitor response to therapy. This study evaluates the role of invasive circulating tumor cells (iCTCs) in monitoring EOC treatment in comparison with serum cancer antigen 125 (CA125).

METHODS

Molecular and microscopic analyses were used to identify seprase and CD44 as tumor progenitor (TP) markers. The iCTC flow cytometry assay was optimized using blood donated by 64 healthy donors, 49 patients with benign abdominal diseases and 123 EOC patients. Serial changes in iCTCs and CA125 were measured in 129 blood and 169 serum samples, respectively, from 31 EOC patients to assess their concordance during therapy and their relationship with risk of progressive disease (PD).

RESULTS

The assay had 97% specificity and 83% sensitivity for detecting iCTCs in blood of EOC patients. iCTCs were detected in each monitoring patient (31/31, 100%) and in 110 of the 129 blood samples (85.3%). The concordance between changes in iCTCs/CA125 levels and changes in the intervals associated with no evidence of disease (NED) were markedly stronger (specificity: CA125 93.8%; iCTCs 90.6%), whereas increases in iCTCs (79.5%) were more sensitive than increases in CA125 (67.6%) to predict PD or relapse. Among the six patients who had greater than 6 measurements, iCTCs but not CA125 antedated changes in clinical status from PD to NED during and after chemotherapy and predated relapse.

CONCLUSION

Serial measurements of iCTCs could predict therapeutic responsiveness in 31 EOC patients who underwent standard taxol/carboplatin therapy.

Prognostic analysis of invasive circulating tumor cells (iCTCs) in epithelial ovarian cancer

GOALS

Circulating tumor cells (CTCs) have been introduced as a biomarker in detecting advanced epithelial ovarian cancer (EOC). The goals are to examine the prevalence of the invasive subpopulation of CTCs (iCTCs) in patients at high risk of EOC and to compare this biomarker to serum CA125.

METHODS

We used a unique cell adhesion matrix (CAM)-based, functional cell enrichment and identification platform to isolate iCTCs from 129 preoperative patients. We confirmed the identity of iCTCs using positive epithelial (Epi+) markers and negative hematopoietic lineage (HL-) markers. Sensitivity and specificity of the assays were examined and iCTCs/CA125 were correlated with overall survival (OS), progression-free survival (PFS) and clinical parameters.

RESULTS

We found a 41.2% sensitivity, 95.1% specificity and 77.8% positive predictive value (PPV) of the iCTC assay in detecting patients with stage I and II EOC malignancy, and a 83% sensitivity and 97.3% PPV in detecting all stages of EOC malignancy. However, a positive CA125 test provided weak evidence to detect stage I and II malignancy (61.6% PPV) and all EOC (92.1% PPV), because of its 76.2% specificity. A significantly stronger concordance in OS and PFS of clinical factors (tumor stage, debulking and platinum sensitivity) was noted for elevated iCTCs than for serum CA125.

CONCLUSION

The CAM-initiated CTC enrichment/identification method enabled the detection of early stage EOC. iCTCs were better correlated with worse OS and PFS, more specific and better PPV than CA125 in detecting EOC malignancy in patients at high risk of EOC.

Changes in serum CA-125 can predict optimal cytoreduction to no gross residual disease in patients with advanced stage ovarian cancer treated with neoadjuvant chemotherapy

OBJECTIVE

To evaluate the predictive power of serum CA-125 changes in the management of patients undergoing neoadjuvant chemotherapy followed by interval debulking surgery (NACT-IDS) for a new diagnosis of epithelial ovarian carcinoma (EOC).

METHODS

Using the Cancer Registry databases from our institutions, a retrospective review of patients with FIGO stage IIIC and IV EOC who were treated with platinum-based NACT-IDS between January 2006 and December 2009 was conducted. Demographic data, CA-125 levels, radiographic data, chemotherapy, and surgical-pathologic information were obtained. Continuous variables were evaluated by Student's t test or Wilcoxon-Mann-Whitney test.

RESULTS

One hundred-three patients with stage IIIC or IV EOC met study criteria. Median number of neoadjuvant cycles was 3. Ninety-nine patients (96.1%) were optimally cytoreduced. Forty-seven patients (47.5%) had resection to no residual disease (NRD). The median CA-125 at diagnosis and before interval debulking was 1749U/mL and 161U/mL, respectively. Comparing patients with NRD v. optimal macroscopic disease (OMD), there was no statistical difference in the mean CA-125 at diagnosis (1566U/mL v. 2077U/mL, p=0.1). There was a significant difference in the mean CA-125 prior to interval debulking, 92 v. 233U/mL (p=0.001). In the NRD group, 38 patients (80%) had preoperative CA-125≤100U/mL compared to 33 patients (63.4%) in the OMD group (p=0.04).

CONCLUSIONS

Patients who undergo NACT-IDS achieve a high rate of optimal cytoreduction. In our series, after treatment with taxane and platinum-based chemotherapy, patients with a preoperative CA-125 of ≤100U/mL were highly likely to be cytoreduced to no residual disease.

Synthesis of a covalent gemcitabine-(carbamate)-[anti-HER2/neu] immunochemotherapeutic and its cytotoxic anti-neoplastic activity against chemotherapeutic-resistant SKBr-3 mammary carcinoma

Gemcitabine is a potent chemotherapeutic that exerts cytotoxic activity against several leukemias and a wide spectrum of carcinomas. A brief plasma half-life in part due to rapid deamination and chemotherapeutic-resistance frequently limit the utility of gemcitabine in clinical oncology. Selective 'targeted' delivery of gemcitabine represents a potential molecular strategy for simultaneously prolonging its plasma half-life and minimizing exposure of innocent tissues and organ systems.

MATERIALS AND METHODS

Gemcitabine was combined in molar excess with N-[p-maleimidophenyl]-isocyanate (PMPI) so that the isocyanate moiety of PMPI which exclusively reacts with hydroxyl groups preferentially created a carbamate covalent bond at the terminal C(5)-methylhydroxy group of gemcitabine. Monoclonal immunoglobulin with binding-avidity specifically for HER2/neu was thiolated with 2-iminothiolane at the terminal ε-amine group of lysine amino acid residues. The gemcitabine-(carbamate)-PMPI intermediate with a maleimide moiety that exclusively reacts with reduced sulfhydryl groups was then combined with thiolated anti-HER2/neu monoclonal immunoglobulin. Western-blot analysis was utilized to delineate the molecular weight profile for gemcitabine-(carbamate)-[anti-HER2/neu] while cell binding characteristics were determined by cell-ELISA utilizing SKBr-3 mammary carcinoma which highly over-expresses HER2/neu receptors. Cytotoxic anti-neoplastic potency of gemcitabine-(carbamate)-[anti-HER2/neu] between the gemcitabine-equivalent concentrations of 10(-12) and 10(-6)M was determined utilizing vitality staining analysis of chemotherapeutic-resistant SKBr-3 mammary carcinoma.

RESULTS

Gemcitabine-(carbamate)-[anti-HER2/neu] was synthesized at a molar incorporation index of 1:1.1 (110%) and had a molecular weight of 150kDa that was indistinguishable from reference control immunoglobulin fractions. Cell-ELISA detected progressive increases in SKBr-3 mammary carcinoma associated immunoglobulin with corresponding increases in covalent gemcitabine immunochemotherapeutic concentrations. The in vitro cytotoxic anti-neoplastic potency of gemcitabine-(carbamate)-[anti-HER2/neu] was approximately 20% and 32% at 10(-7) and 10(-6)M (gemcitabine-equivalent concentrations) after a 182-h incubation period.

DISCUSSION

The investigations describes for the first time a methodology for synthesizing a gemcitabine anti-HER2/neu immunochemotherapeutic by creating a covalent bond structure between the C(5)-methylhydroxy group of gemcitabine and thiolated lysine amino acid residues of monoclonal antibody or other biologically active protein fractions. Gemcitabine-(carbamate)-[anti-HER2/neu] possessed binding-avidity at HER2/neu receptors highly over-expressed by chemotherapeutic-resistant SKBr-3 mammary carcinoma. Alternatively, gemcitabine can be covalently linked at its C(5)-methylhydroxy group to monoclonal immunoglobulin fractions that possess binding-avidity for other receptors and membrane complexes uniquely highly over-expressed by a variety of neoplastic cell types. Compared to chemotherapeutic-resistant SKBr-3 mammary carcinoma, gemcitabine-(carbamate)-[anti-HER2/neu] immunochemotherapeutic is anticipated to exert higher levels of cytotoxic anti-neoplastic potency against other neoplastic cell types like pancreatic carcinoma, small-cell lung carcinoma, neuroblastoma, glioblastoma, oral squamous cell carcinoma, cervical epithelioid carcinoma, or leukemia/lymphoid neoplastic cell types based on their reportedly greater sensitivity to gemcitabine and gemcitabine covalent conjugates.