Innovations in understanding the biology of cervical cancer

Human Papillomavirus Vaccines

Objective:

TO review the pharmacology, efficacy, safety, tolerability, and pharmacoeconomics of Cervarix and Gardasil, 2 human papillomavirus (HPV) vaccines.

Data Sources:

English-language articles were obtained by MEDLINE search (1966–February 2006) using the key words human papillomavirus vaccine, Cervarix, and Gardasil. Bibliographies of selected articles were used to identify additional sources.

Study Selection and Data Extraction:

All available published articles or abstracts reporting the results of human studies of HPV vaccines were reviewed for inclusion in this article. Additional information about ongoing clinical trials was obtained from manufacturers' Web sites.

Data Synthesis:

Cervarix and Gardasil are recombinant vaccines against HPV. Cervarix targets HPV-16 and -18, which are responsible for 70% of cervical cancers. Gardasil also targets HPV-16 and -18, plus the HPV-6 and -11 types responsible for more than 80% of genital warts. Both vaccines have been effective in preventing persistent infection with targeted HPV types and in preventing cervical intraepithelial lesions, while Gardasil has also been effective in preventing vulvar and vaginal neoplasia and genital warts. Both vaccines have been well tolerated, with the most common adverse effects occurring at the injection site. Phase III trials are ongoing to further evaluate vaccine efficacy.

Conclusions:

Cervarix and Gardasil are effective for prevention of HPV infection and cervical lesions. Issues remaining to be addressed include duration of protection, efficacy for prevention of cervical cancer, optimal age for vaccination, feasibility of application to the developing world, the ideal combination of HPV subtypes, and the most efficient combination of vaccination and cervical cancer screening.

Cervical cancer: A comprehensive approach towards extermination

Human Papilloma Virus (HPV) is one of the most common sexually transmitted pathogen, globally. Oncogenic types of HPV are the causative agents of many neoplastic diseases, including cervical cancer, which ranks as the most common cancer affecting females in developing countries. HPV infection of the cervical epithelium and the subsequent integration of viral DNA into the host genome are the major risk factors for cervical cancer. The scientific discovery of HPV as the causal agent of cervical cancer has led to the development of HPV-based diagnostic tools. Prophylactic vaccines, based on the oncogenic HPV type virus-like particles have been introduced in several developed countries as a preliminary preventive approach. Nevertheless, it remains a continuous threat to women in developing countries, where the prophylactic vaccines are unaffordable and organized screening programmes are lacking. This warrants implementation of prevention strategies that will reduce cervical cancer-related mortality. In this review, we have discussed molecular pathogenesis of HPV infection and the risk factors associated with it. The diagnosis, treatment and prevention strategies of HPV-related cervical cancer have also been discussed.

Generation of K14-E7/∆N87βcat double transgenic mice as a model of cervical cancer

Nearly all cervical cancers are initiated by a subset of high-risk human papilloma viruses (HPVs). However, cervical cancers develop only in a small fraction of women who are infected with these viruses. HPV is required, but not sufficient for developing cervical cancer. Activation of complementary signaling pathways appears to be necessary for malignant transformation of cervical epithelial cells that are immortalized by HPV. Here, we describe the creation and maintenance of a double transgenic mouse model that is based on constitutively active Wnt/β-catenin signaling in cervical epithelial cells expressing the HPV oncoprotein E7. These mice develop invasive cervical squamous carcinomas within 6 months with an average penetrance of 94 %.

Beta-catenin accelerates human papilloma virus type-16 mediated cervical carcinogenesis in transgenic mice

Human papilloma virus (HPV) is the principal etiological agent of cervical cancer in women, and its DNA is present in virtually all of these tumors. However, exposure to the high-risk HPV types alone is insufficient for tumor development. Identifying specific collaborating factors that will lead to cervical cancer remains an unanswered question, especially because millions of women are exposed to HPV. Our earlier work using an in vitro model indicated that activation of the canonical Wnt pathway in HPV-positive epithelial cells was sufficient to induce anchorage independent growth. We therefore hypothesized that constitutive activation of this pathway might function as the "second hit." To address this possibility, we developed two double-transgenic (DT) mouse models, K14-E7/ΔN87βcat and K14-HPV16/ΔN87βcat that express either the proteins encoded by the E7 oncogene or the HPV16 early region along with constitutively active β-catenin, which was expressed by linking it to the keratin-14 (K14) promoter. We initiated tumor formation by treating all groups with estrogen for six months. Invasive cervical cancer was observed in 11% of the K14-ΔN87βcat mice, expressing activated β-catenin and in 50% of the animals expressing the HPV16 E7 oncogene. In double-transgenic mice, coexpression of β-catenin and HPV16 E7 induced invasive cervical cancer at about 7 months in 94% of the cases. We did not observe cervical cancer in any group unless the mice were treated with estrogen. In the second model, K14-HPV16 mice suffered cervical dysplasias, but this phenotype was not augmented in HPV16/ΔN87βcat mice. In summary, the phenotypes of the K14-E7/ΔN87βcat mice support the hypothesis that activation of the Wnt/β-catenin pathway in HPV-associated premalignant lesions plays a functional role in accelerating cervical carcinogenesis.

Overcoming Barriers to Cervical Cancer Screening Among Asian American Women

Significant disparities in cervical cancer incidence and mortality exist among ethnic minority women, and in particular, among Asian American women. These disparities have been attributed primarily to differences in screening rates across ethnic/racial groups. Asian American women have one of the lowest rates of screening compared to other ethnic/racial groups. Yet Asian Americans, who comprise one of the fastest growing populations in the United States, have received the least attention in cancer control research. Studies suggest that various factors, including lack of knowledge, psychosocial and cultural beliefs, and access barriers, are associated with cervical cancer screening behaviors among Asian American women. Indeed, the few interventions that have been developed for Asian American women demonstrate that targeting these factors can yield significant increases in screening rates. It is important to note, however, that the effectiveness of educational interventions is often attenuated if access barriers are not adequately addressed. Hence, interventions that include key essential components, such as the use of community individuals as lay health workers, culturally-tailored and linguistically-appropriate educational materials, and navigation assistance to overcome access barriers, are more likely to be successful in enhancing screening rates. As the benefits of community-based cervical cancer prevention programs become more apparent, it will be essential to identify effective approaches for disseminating such programs more broadly. In conclusion, community-based cervical cancer screening programs have demonstrated promise in addressing existing cervical cancer disparities by increasing awareness and knowledge and promoting recommended screening behaviors. These findings will be instrumental in guiding future community-based programs to reduce cervical cancer health disparities among Asian American women.

Behavioral correlates of HPV vaccine acceptability in the 2007 Health Information National Trends Survey (HINTS)

The development of a prophylactic vaccine to prevent infection with oncogenic subtypes of human papillomavirus (HPV) is an important step in reducing cervical cancer incidence and mortality. However, national data indicate that only 37% of 13- to 17-year-old females have initiated the vaccine series. Prior studies have examined demographic, medical history, and psychosocial variables associated with parental HPV vaccine acceptability, although few have investigated the behavioral correlates of vaccine acceptability. The primary purpose of the current study is to report on national acceptability of the HPV vaccine among U.S. adults with female children in the household and to investigate the health behavior correlates of vaccine acceptability. Data were drawn from the 2007 Health Information National Trends Survey (HINTS). The study sample comprised 1,383 adults who reported having a female child under the age of 18 in their household (52% female, 59% white; mean age = 40 years). More than half (58%) reported they would have a daughter get the HPV vaccine, 25% were not sure, and 18% would not have a daughter vaccinated. Behavioral factors significantly associated with lower acceptance of the HPV vaccine included lack of physical activity in the past month (P = 0.002), past year use of complementary or alternative therapies (P = 0.021), and no history of smoking (P = 0.005). These results suggest that behavioral health factors may be associated with vaccine acceptability and further our understanding of how behavioral patterns may contribute to the uptake of new cancer prevention strategies.

Squamous cell carcinoma associated with intralesional injection of cidofovir for recurrent respiratory papillomatosis

Recurrent respiratory papillomatosis is a common neoplasm of the larynx that may lead to severe, recurrent lesions. Intralesional injection of cidofovir has shown promise as an adjuvant therapy. There is concern for possible malignant transformation with its use but, to our knowledge, this has not been documented in the literature. We report a case of invasive squamous cell cancer arising from squamous papilloma in a patient treated with multiple injections of cidofovir. Although causation is not shown, we believe the association presented is a valuable addition to the literature and an important consideration in the use of cidofovir.

Perceived stress is associated with impaired T-cell response to HPV16 in women with cervical dysplasia

BACKGROUND

Infection with high-risk subtypes of human papillomavirus (HPV) is a central factor in the development of cervical neoplasia. Cell-mediated immunity against HPV16 plays an important role in the resolution of HPV infection and in controlling cervical disease progression. Research suggests that stress is associated with cervical disease progression, but few studies have examined the biological mechanisms that may be driving this association.

PURPOSE

This study examines whether stress is associated with immune response to HPV16 among women with cervical dysplasia.

METHODS

Seventy-four women presenting for colposcopy completed measures of health behaviors, stressful life events and perceived stress. A blood sample was obtained to evaluate proliferative T-cell response to HPV16, and a cervical sample was obtained during gynecologic exam for HPV-typing.

RESULTS

More than 55% tested positive for one or more HPV subtypes. Women who did not show proliferative responses to HPV (i.e. non-responders) were more likely to be HPV(+) compared to women who had a response (i.e. responders). Consistent with study hypotheses, logistic regression revealed that higher levels of perceived stress were associated with a non-response to HPV16, controlling for relevant covariates. Stressful life events were not associated with T-cell response to HPV.

CONCLUSIONS

Higher levels of perceived stress are associated with impaired HPV-specific immune response in women with cervical dysplasia, suggesting a potential mechanism by which stress may influence cervical disease progression.

Detection and genotyping of human papillomavirus DNA in samples from healthy Sardinian patients: a preliminary study

The human papillomavirus (HPV) is involved in the development of different benign and malignant lesions that include in particular squamous tumours of the cervix, skin and the respiratory tracts. In particular, the 'high risk' HPV type 16 (HPV 16) causes genito-rectal epithelial cancers and is suspected of causing epithelial cancers of the head and neck. To determine the presence and genotypes of HPV was determined in saliva samples from 164 subjects recruited from the Department of Surgery and Odontostomatological Sciences (University of Cagliari). For this study a sensitive seminested polymerase chain reaction (PCR) method was used to detect HPV-DNA; moreover in all positive samples, HPV genotyping was based on sequencing of the HPV genome L1 region. The results obtained with these patients (who were ethnically homogeneous), showed an interesting percentage of positive samples for HPV-DNA (30 samples out of 164-18.3%). Only two HPV genotypes have been identified in these patients, HPV 16 and HPV 31 with 76.7% and 23.3% of the positive specimens, respectively, both correlating with high carcinogenic risk. This preliminary result leads us to reflect on the presence of HPV in saliva, in particular in young asymptomatic subjects (15.38%), and its prognostic value for the possible incidence in Sardinia of oral carcinoma.

Participation of patients with gynecological cancer in phase I clinical trials: two years experience in a major cancer center

OBJECTIVES

This study aims at analyzing the clinico-demographic features that influence the recruitment of gynecological cancer (GC) patients to phase I trials. The possible clinical benefit to patients resulting from the participation in these trials has been also investigated.

METHODS

We performed a retrospective analysis of GC patients referred to the Phase I Unit of the Royal Marsden Hospital in Sutton (Surrey, UK), over 2 years.

RESULTS

Overall 68 GC patients were referred, and subsequently 32 (47.1%) enrolled. The percentage of patients enrolled increased as the distance to travel between the patient's residence and the hospital shortened (8.3% through 47.8% to 60.8%, for travel time >2, 1-2 or < or =1 h, respectively; p=0.008). Better performance status (PS) was found to be associated with higher enrollment rate with percentages increasing from 0 through 51.2 to 58.8 in cases with PS> or =2, PS=1, PS=0, respectively (p=0.015). Among the biochemical parameters, only hepatobiliary dysfunction was found to be associated with lower enrollment (p=0.012). Minimal response/disease stabilization was observed in 11 patients (34.4%). An increased median survival following the first visit was observed in patients enrolled compared to those not enrolled (8 versus 4 months, respectively, p=0.0055). In the multivariate analysis, only PS and enrollment in trials retained an independent prognostic role (p=0.031 and p=0.040, respectively).

CONCLUSIONS

This study, suggesting liver function and PS as important factors influencing the recruitment of GC patients to phase I trials could guide referral of patients to phase I Units. Moreover, the practical limitations imposed by long distance travel, together with the potential clinical benefit due to the participation to these trials, should encourage more investigators to develop phase I units in major cancer centers.

Gynecologic oncology group trials of chemotherapy for metastatic and recurrent cervical cancer

Because only 16% of patients with metastatic cervical cancer are alive 5 years after diagnosis, the Gynecologic Oncology Group (GOG) has carefully designed and conducted many phase II studies to identify promising drugs. Cisplatin has emerged as the most active single agent with overall response rates of 19%. Recent phase III trials have documented response rates of 27% and 39% when cisplatin has been combined with either paclitaxel or topotecan, respectively. The comparison of cisplatin to cisplatin plus topotecan in GOG-179 has yielded the first study to show a statistically significant impact on the overall response rate, median progression-free survival, and median survival, with all outcome measures favoring the two-drug regimen. Despite these encouraging results, however, most of the responses are partial and of short duration. The need for novel combinations and the implementation of active biologic agents is implicit. The accumulated data in this disease setting, as evidenced by the experience of the GOG, are presented in this review.

Prevalence of human papillomavirus cervical infection in an Italian asymptomatic population

Background

In the last decade many studies have definitely shown that human papillomaviruses (HPVs) are the major cause of cervical carcinogenesis and, in the last few years, HPV testing has been proposed as a new and more powerful tool for cervical cancer screening. This issue is now receiving considerable attention in scientific and non scientific press and HPV testing could be considered the most important change in this field since the introduction of cervical cytology. This paper reports our prevalence data of HPV infection collected in the '90s, while a follow up of these patients is ongoing.

Methods

For this study we used polymerase chain reaction (PCR) to search HPV DNA sequences in cervical cell scrapings obtained from 503 asymptomatic women attending regular cervical cancer screening program in the city of Genova, Italy. All patients were also submitted to a self-administered, standardized, questionnaire regarding their life style and sexual activity. On the basis of the presence of HPV DNA sequences women were separated into two groups: "infected" and "non infected" and a statistical analysis of the factors potentially associated with the infection group membership was carried out.

Results

The infection rate was 15.9% and the most frequent viral type was HPV 16.

Conclusion

Our HPV positivity rate (15.9%) was consistent to that reported by other studies on European populations.

Increased risk of cervical cancer associated with cyclin D1 gene A870G polymorphism

Human papillomavirus (HPV) plays a major role in the etiology of cervical cancer. However, a complex correlation between viral and cellular genes is necessary for cell cycle control deregulation in the progression to invasive cervical cancer (ICC). Cyclin D1 (CCND1) is an important positive regulator of the G1/S phase of the cell cycle. The CCND1 gene is located at 11q13 and is often altered in human cancers. We analyzed the A870G CCND1 polymorphism by polymerase chain reaction/restriction fragment length polymorphism analysis in 246 women including 50 cases with high-grade squamous intraepithelial lesions of the cervix (HSIL), 93 with ICC, and 103 healthy women. The GG genotype was associated with a 4.32-fold higher risk for the development of HSIL [adjusted odds ratio (aOR)=4.32, 95% confidence interval (CI) 1.50-12.46, P=0.0067), and a 3.26-fold increased risk for the development of ICC (aOR=3.26, 95% CI 1.42-7.53, P=0.006). The proportion of cervical cancer cases attributable to the GG CCND1 genotype was 17.26%. This study indicates that the A870G CCND1 polymorphism could act as a cofactor of HPV in the initiation of cervical carcinogenesis, particularly in the transformation zone of HPV-infected women, supporting evidence for a genetic factor in ICC risk.

The role of human telomerase catalytic subunit mRNA expression in cervical dysplasias

Telomerase activity and human telomerase reverse transcriptase (hTERT) mRNA expression were investigated in cervical specimens and were correlated with cytologic findings and the presence of human papilloma virus (HPV) infection. Telomerase activity was evaluated by the telomeric repeat protocol assay and hTERT mRNA expression was evaluated by reverse transcriptase polymerase chain reaction (PCR). HPV DNA was detected by PCR, as well as restriction endonuclease digestion. HPV DNA was detected in all 82 specimens with abnormal cytologic findings and in 4 of 34 normal samples. Low-grade squamous intraepithelial lesions (LGSILs) were present in 74 of 82 specimens (90.2%) and high-grade squamous intraepithelial lesions (HGSILs) were present in 8 of 82 (9.75%) specimens. Seven of the eight HGSIL (87.5%) and 26 of 74 LGSIL (35.1%) specimens were hTERT positive, whereas all normal specimens were hTERT mRNA negative. Telomerase activity was detected in 21 of 74 (28.4%) LGSIL/atypical squamous epithelial cells of undetermined significance (ASCUS) and in five of eight (62.5%) HGSIL samples. A correlation was observed among telomerase activity, hTERT mRNA expression, and high-risk HPV infection in HGSIL samples (P < 0.001). High-risk HPV infection assessment showed 75% sensitivity and 72.2% specificity for HGSILs. Telomerase activity assessment in cervical smears showed sensitivity and negative predictive value (NPV) for HGSILs 62.5% and 96.7%, whereas specificity and positive predictive value (PPV) were 80.5% and 19.2%, respectively. hTERT mRNA expression assessment showed 87.5% sensitivity and 98.7% NPV for HGSILs, whereas specificity and PPV were 76% and 21.2%, respectively. Based on the above-described telomerase assessment values, it is suggested that the telomerase system might not be an appropriate diagnostic marker for cytology, given that the final evaluation must rely on a combination of all available test assessment data, clinical diagnosis, as well as the follow-up of all LGSIL samples that were positive for telomerase activation.

Identification using phage display of peptides promoting targeting and internalization into HPV-transformed cell lines

'High-risk' human papilloma viruses (HPVs) cause cervical tumours. In order to treat these tumours therapeutic approaches must be developed that efficiently target the tumour cells. Using phage display, we selected tumour-targeting peptides from a library of constrained nonamer peptides presented multivalently on pVIII of M13. Three different consensus peptide sequences were isolated by biopanning on HPV16-transformed SiHa cells. The corresponding phage-peptides targeted and were internalized in HPV16 transformed SiHa and CaSki cells as well as in HPV18-transformed HeLa cells, but failed to bind a panel of normal or transformed cell lines. Two of the three selected peptides targeted cells only when presented on phage particles in a constrained conformation. However, all three peptides retained their targeting capacity when presented on the reporter protein enhanced green fluorescent protein (EGFP) in a monovalent form. These peptides may be useful for the design of drug or gene delivery vectors for the treatment of cervical cancer.