Different antigenic nature in apparently healthy women with high serum CA 125 levels compared with typical patients with ovarian cancer

Risk communication in genetic testing for cancer susceptibility

Risk communication is an integral part of genetic counseling and testing for cancer susceptibility. This paper reviews the emerging literature on this topic. Three relevant aspects of risk communication are addressed: communication of individual risk, communication of the risks inherent in genetic testing, and family communications related to risk. These studies suggest that (a) most individuals with some family history of cancer, including those at low to moderate risk, overestimate their personal cancer risk; (b) awareness of the risks of genetic testing is limited; (c) decision making about genetic testing is influenced strongly by exaggerated perceptions of personal cancer risk and less so by perceptions of the risks of genetic testing; (d) perceptions of personal risk of cancer are resistant to standard education and counseling approaches; (e) psychologic distress and coping processes influence the processing of risk information and subsequent decision making in genetic testing; and (f) family influences play an important role in risk awareness, genetic testing decisions, and outcomes. To study these issues further, new theoretical models and measures of risk perceptions need to be developed. Both observational and experimental methods should be used to examine both the content and process of risk communication in cancer genetic counseling and testing. Emotional, familial, and sociocultural influences on the risk communication process require special attention.

Prophylactic surgery decisions and surveillance practices one year following BRCA1/2 testing

BACKGROUND

Although genetic testing for breast cancer risk is clinically available, its impact on health-related behaviors is unknown. This study examined prophylactic surgery and surveillance behavior during the year following BRCA1/2 gene testing.

METHODS

Participants were female members (n = 216) of hereditary breast-ovarian cancer families (84 mutation carriers, 83 noncarriers and 49 test decliners). In this prospective observational study, utilization of prophylactic surgery and surveillance behavior were assessed 1-year following BRCA1/2 testing.

RESULTS

Only 3% of the unaffected carriers obtained prophylactic mastectomy during the 1-year follow-up period. Among the remaining females, carriers had significantly higher rates of mammography (68%) than noncarriers (44%); (OR = 7.1; C.I. = 1.36-37.1; P = 0.02). However, the adherence rate in carriers was unchanged from baseline, suggesting that this difference is attributable to a reduction in screening among noncarriers. Women ages 25-39 years were significantly less likely to obtain mammograms than those aged 40 years and older. Cancer-related distress had a positive but nonsignificant (P < 0.07) association with adherence in bivariate but not multivariate analysis. With regard to ovarian risk, only 13% of carriers obtained prophylactic oophorectomy; of the remaining female carriers, only 21% reported a CA125 and 15% reported a transvaginal ultrasound.

CONCLUSION

The vast majority of BRCA1/2 carriers may not opt for prophylactic surgery, and many do not adhere to surveillance recommendations. Greater attention to risk communication and medical decision-making is warranted.

Intraperitoneal photoimmunotherapy of ovarian carcinoma xenografts in nude mice using charged photoimmunoconjugates

OBJECTIVE

The objective of this study was to compare the efficacy of photoimmunoconjugates with cationic and anionic molecular charges on intraperitoneal photoimmunotherapy of ovarian cancer xenografts in nude mice.

METHODS

The photosensitizer chlorin(e6) (c(e6)) was conjugated via a poly-l-lysine linker to the F(ab')(2) fragment of the murine anti-ovarian cancer monoclonal antibody OC125, resulting in a photoimmunoconjugate with a pronounced cationic charge. Alternatively, by succinylating the poly-l-lysine conjugate, a photoimmunoconjugate with a pronounced anionic charge was obtained. A murine model of ovarian cancer derived from intraperitoneal inoculation of NIH:OVCAR-5 cells was employed. The conjugate was injected intraperitoneally followed after 3 h by red light delivered through a fiber into the peritoneal cavity. These photoimmunotherapy treatments were repeated three times, and the results obtained with the anionic and cationic photoimmunoconjugates were compared with those obtained with free c(e6) and control. The extent of residual macroscopic disease and death from disease were the evaluable outcomes for tumoricidal and survival studies, respectively.

RESULTS

In contrast to other intraperitoneal photosensitizers, mice showed no systemic toxicity or morbidity from the treatment. In this initial study the mean residual tumor weights in all treatment groups ranged from 33 to 73 mg, as compared with 330 mg in untreated controls (P < 0.0001), and the response to the cationic conjugate was significantly better than that to the anionic conjugate or free c(e6) (P < 0.005). The median survival for mice treated with cationic photoimmunoconjugate was 41 days, compared with 35 days in controls (P = 0.009).

CONCLUSION

Photoimmunotherapy with a cationic photoimmunoconjugate produces results superior to those obtained with an anionic conjugate, and further optimization of the treatment regimen may lead to a potential treatment for advanced ovarian cancer.

Combination photoimmunotherapy and cisplatin: effects on human ovarian cancer ex vivo

BACKGROUND

Patients with ovarian cancer that is clinically resistant to cisplatin-based chemotherapy have little hope of a cure of their disease. Photoimmunotherapy, which involves the antibody-targeted delivery of a nontoxic photosensitizer that is activated to a cytotoxic state with visible light, may offer a new treatment option. Photoimmunotherapy may be applied intraperitoneally to target disseminated tumor. We tested the hypothesis that this treatment in combination with cisplatin potentiates cytotoxicity in ovarian cancer cell lines and primary cultures of human tumors.

METHODS

Five human cancer cell lines (ovarian and breast) and 19 primary cultures were studied. The primary cultures were from solid and ascites tumor samples obtained from 14 patients with ovarian cancer who were undergoing primary surgery. The photosensitizer chlorin e(6) was conjugated to the F(ab')(2) fragment of the murine monoclonal antibody OC-125, which is directed against the antigen CA 125. Cytotoxicity was measured by the microculture tetrazolium assay. Treatments consisted of cisplatin alone, photoimmunotherapy alone, and photoimmunotherapy followed by cisplatin. The fractional product method was used to assess synergy in treatment effects. Ex vivo cultured human cells exhibiting 80% or greater survival at cisplatin concentrations of 10 microM for 24 hours were defined as cisplatin resistant for this study.

RESULTS

When all cell types (cisplatin sensitive and cisplatin resistant) were considered together, combination treatment yielded cytotoxicity that was, on average, 6.9 times (95% confidence interval = 1.86-11.94) greater than that of cisplatin alone (two-sided P =.023). Cisplatin-resistant cells showed a synergistic effect of the two treatments (two-sided P =.044), while cisplatin-sensitive cells showed an additive effect.

CONCLUSION

These ex vivo data suggest that platinum resistance in human ovarian cancer cells may be reversible by pretreatment with OC-125-targeted photoimmunotherapy. Further studies are required to confirm the efficacy of this approach in vivo.

Biodistribution of charged F(ab')2 photoimmunoconjugates in a xenograft model of ovarian cancer

The effect of charge modification of photoimmunoconjugates (PICs) on their biodistribution in a xenograft model of ovarian cancer was investigated. Chlorin(e6)c(e6) was attached site specifically to the F(ab')2 fragment of the murine monoclonal antibody OC125, directed against human ovarian cancer cells, via poly-1-lysine linkers carrying cationic or anionic charges. Preservation of immunoreactivity was checked by enzyme-linked immunosorbent assay (ELISA). PICs were radiolabelled with 125I and compared with non-specific rabbit IgG PICs after intraperitoneal (i.p.) injection into nude mice. Samples were taken from normal organs and tumour at 3 h and 24 h. Tumour to normal 125I ratios showed that the cationic OC125F(ab')2 PIC had the highest tumour selectivity. Ratios for c(e6) were uniformly higher than for 125I, indicating that c(e6) became separated from 125I. OC125F(ab')2 gave highest tissue values of 125I, followed by cationic OC125F(ab')2 PIC; other species were much lower. The amounts of c(e6) delivered per gram of tumour were much higher for cationic OC125F(ab')2 PIC than for other species. The results indicate that cationic charge stimulates the endocytosis and lysosomal degradation of the OC125F(ab')2-pl-c(e6) that has bound to the i.p. tumour. Positively charged PICs may have applications in the i.p. photoimmunotherapy of minimal residual ovarian cancer.

Screening for Ovarian Cancer

Ovarian cancer is difficult to manage because the disease is most often diagnosed at an advanced stage when survival chances are poor. Early detection of ovarian cancer would increase long-term survival, since effective treatment modalities are available for early-onset disease. Screening with transvaginal ultrasound and serum CA 125 suggests promising results, but studies comparing mortality rates for screened vs unscreened populations are needed, and strategies must be developed for prevention or early diagnosis in order to control this disease process.

Similarity and co-expression of tumour-associated antigens recognised by different monoclonal antibodies

The concentration of carcinoembryonic antigen (CEA), CA130, CA125, SLX, CA19-9, SPan1, and tumour-associated glycoprotein 72 (TAG-72) in the culture supernatant of 15 cancer cell lines and in the sera of 58 cancer patients was measured, and the co-expression of these antigens was examined by double determinant immunoradiometric assays. The high correlation coefficient of the concentrations and significant binding in the double determinant assays indicated a close relationship between CA125 and CA130 and between CA19-9 and SPan1. There was variable binding of the 125I-labelled anti-SLX, anti-CA19-9, and anti-SPan1 antibodies to anti-CA130 beads that had been pre-incubated with the culture supernatants, suggesting the presence of the epitopes of SLX, CA19-9, and SPan1 on the molecule expressing CA130. Similarly, the epitopes of SLX, CA19-9, and SPan1 could be present on the molecule expressing CEA. 125I-labelled anti-CA19-9, anti-SLX, and anti-TAG-72 antibodies were bound in variable proportions to anti-CA130 beads or to anti-CEA beads that had been pre-incubated with patients' sera. However, CEA and CA130 were not expressed on the same molecule, either in the culture supernatant, or in patients' sera. In conclusion, the carbohydrate epitopes of CA19-9, SPan1, SLX, and TAG-72 could be present on the molecule recognised by the anti-CA130 or anti-CEA antibody; however, the epitopes of CA130 and CEA did not co-exist on the same molecule.