The KRAS-Variant and Cetuximab in HPV-Positive Oropharyngeal Cancer in NRG/RTOG 1016

PURPOSE/OBJECTIVE(S)

NRG/RTOG 1016 was a non-inferiority phase III trial comparing radiation with cisplatin versus cetuximab monotherapy for patients with HPV-positive oropharyngeal squamous cell carcinoma (SCC). The trial did not meet the non-inferiority criteria for overall survival (OS) and had significantly worse progression-free survival (PFS) and locoregional failure (LRF) in patients treated with cetuximab. Based on prior evidence that HNSCC patients with a germ-line mutation in KRAS (the KRAS-variant) had a positive response to radiation with cisplatin plus cetuximab without increased toxicity, samples from RTOG 1016 were used to test the protocol-specified hypothesis that KRAS-variant patients will have better outcomes when receiving IMRT + cetuximab monotherapy compared to IMRT + cisplatin.

MATERIALS/METHODS

The KRAS-variant was tested in 562 samples at MiraDx, a CLIA-certified laboratory. OS, PFS, LRF, and distant metastases (DM) were as defined per the RTOG 1016 protocol, and hazard ratios (HRs) were estimated by (cause-specific) Cox models. Negative binomial regression was used to model the number of treatment-related acute and late (≤ and > 180 days from end of treatment, respectively) grade 3-5 adverse events. To assess the predictive role of the KRAS-variant, all models included KRAS, assigned treatment, and their interaction, with the interaction tested at two-sided 0.05. HRs and toxicity ratios are expressed as IMRT + cetuximab / IMRT + cisplatin.

RESULTS

The prevalence of the KRAS-variant was 16% with similar patient and tumor characteristics and well-balanced treatment arms for variant and non-variant patients. Median follow-up was 8.6 years. There was no significant interaction between KRAS and treatment for OS (p = 0.99), PFS (p = 0.56), LRF (p = 0.09), or DM (p = 0.19) (Table 1). In KRAS-variant patients the mean acute and late toxicity ratios were 0.53 (95% CI 0.36, 0.80) and 1.62 (95% CI 0.57, 4.62). In non-variant patients, the mean acute and late toxicity ratios were 0.80 (95% CI 0.67, 0.95) and 0.55 (95% CI 0.35, 0.87), respectively. The interaction of KRAS and treatment was not significant for acute (p = 0.07) or late toxicity (p = 0.07).

CONCLUSION

While this study does not directly refute prior evidence that KRAS-variant patients benefit from radiation + cisplatin and cetuximab, this study does not support the hypothesis that the KRAS-variant is a predictive biomarker of improved outcome in HPV+ oropharyngeal SCC patients treated with IMRT + cetuximab alone, and suggests that for KRAS-variant patients, potential benefits in LRF and acute toxicity with cetuximab may be offset by worse DM and worse late toxicity.

HER-2/neu oncogene amplification in cervical cancer studied by fluorescent in situ hybridization

Oncogene amplification, such as HER-2/neu (C-erbB-2), is a manifestation of genetic instability often associated with the genesis and progression of cancer, including cervical cancer. Oncogene overexpression is traditionally studied using immunohistochemistry. We previously reported studies of oncogene amplification in breast cancer using fluorescent in situ hybridization (FISH), where the data support the hypothesis that HER-2/neu is a prognostic marker of poor outcome. To explore further the possible significance of HER-2/neu oncogene amplification in cervical cancer, we conducted a pilot study of 24 cervical cancer cases. The HER-2/neu FISH probe (Vysis, Inc., Downers Grove, IL) was used to measure gene amplification, with a chromosome 17 centromeric probe as an internal control. Out of 24 cases studied, 23 were informative. Of the 23 informative cases, 2 (8.7%) were found to be amplified. The rest (21 out of 23 or 91.3%) were nonamplified. Both amplified cases were invasive adenocarcinoma. Although the sample size of this pilot study may be somewhat small, the data obtained so far clearly demonstrated that detection of oncogene amplification in cervical cancer is not only feasible but is very sensitive, and suggest that further exploration using a larger sample size may be warranted.

Assessment of chromosome 8 copy number in cervical cancer by fluorescent in situ hybridization

Cervical carcinoma is a malignancy which typically occurs at the transformation zone between squamous and glandular epithelium. The vast majority falls into two histologic types, squamous cell and adenocarcinoma. In an effort to identify a subset of cervical cancer characterized by chromosome 8 trisomy, a biomarker extensively explored by this laboratory, we conducted a study of formalin-fixed, paraffin-embedded materials of cervical cancer. A total of 24 cases of cervical cancer were identified from the archives of the Rhode Island Hospital. Fluorescent in situ hybridization (FISH) using a chromosome 8 centromere enumeration probe was conducted to assess the chromosome 8 copy number in these specimens. Hybridization signals were scored among tumor cells in a blinded fashion. Tumors with >/=15% of cells with three signals were scored as trisomic. Of 24 cases studied, 23 were informative. Of the 23 informative cases, 12 (52.2%) were found to be trisomic. Eleven cases (47.8%) were disomic. The frequency of trisomy in a control chromosome 17 probe was 13.0% (3/23). Selected clinicopathologic characteristics of the tumors were also reviewed. The frequency of trisomy 8 among cases of invasive squamous cell carcinoma was 44.4% (8 of 18 tumors) and that of invasive adenocarcinoma was 80% (4 of 5 tumors). The sole tumor which was both trisomic 8 and amplified for the HER-2/neu oncogene was found to be an invasive adenocarcinoma. While the sample size in this pilot study is not large, the data obtained thus far clearly demonstrate that FISH is an appropriate technique for detecting chromosomal trisomies and that a subset of cervical cancer exists that is characterized by chromosome 8 trisomy. Further exploration of this biomarker is warranted.

Integration of human papillomavirus sequences in cervical tumor cell lines

The establishment of three cell lines from keratinizing and nonkeratinizing cervical carcinomas was previously reported. These cell lines were analyzed for growth properties in vitro and in vivo. Metaphases prepared from tissue culture of these cell lines were cytogenetically characterized using GTG-banding and fluorescent in situ hybridization (FISH) using chromosome-specific alpha-satellite probes. Although the karyotypes of most cells were extremely complex, nonrandom karyotypic abnormalities could be identified. Molecular data had suggested that TC140, derived from a keratinizing cervical tumor, may contain HPV 16 in the episomal state, while TC146, derived from a nonkeratinizing large-cell cervical carcinoma, contained HPV 16 in the integrated state. Therefore, a fluorescent in situ hybridization study was undertaken using biotinylated HPV 16 DNA as a probe on order to confirm and to corroborate the original molecular study, as FISH is the most direct approach for mapping cellular and viral sequences in mammalian chromosomes. The results previously reported in abstract demonstrated the presence of positive hybridization signals on the long arms of the apparent homologs of a human D-group chromosome in cell line TC146. The results of recently completed experiments clearly indicated that while the predominant state of viral existence in the TC140 cell line was apparently episomal, consistent viral integration was found in the TC146 cell line. Furthermore, where viral sequences of HPV 16 integration were observed in cells of TC146, integration was apparently nonrandom. Fluorescent in situ hybridization using various chromosome-specific alpha-satellite and HPV 16 probes clearly indicated that viral integration occurred nonrandomly and at a specific site on chromosome 13. By chromosome morphometry, the viral integration site was localized to 13q14, also the mapped locus of the retinoblastoma (Rb) tumor suppressor gene.

A new technique for the rapid dissolution of retained ductal gallstones with monoctanoin in T-tube patients

Retained gallstones in the biliary ducts have been therapeutically managed with monoctanoin (Moctanin; Ethitek Pharmaceuticals Company, Skokie, IL) since Food and Drug Administration approval in 1985. The clinical usefulness of monoctanoin therapy has previously been regarded by some investigators as limited because of the length of time required to achieve complete dissolution (2 to 10 days) and less than optimal results (50% to 86% efficacy). Here, the authors describe a safe technique for the rapid dissolution of retained stones that they have used successfully in four patients. This technique eliminates the need for pressure monitoring in the T-tube patient and is suitable for short-stay hospitalization. Representative case histories are presented.

Fostering a spirit of inquiry in pediatric staff nurses

Research-based practice is essential if nursing is to meet its mandate to society for effective and efficient patient care. The involvement of the clinical nurse is key to the conduct of research.