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Dana-Farber Researchers “OncoMap” The Way To Personalized Treatment For Ovarian Cancer

Posted by Paul Cacciatore on November 16, 2010

Researchers have shown that point mutations – mis-spellings in a single letter of genetic code – that drive the onset and growth of cancer cells can be detected successfully in advanced ovarian cancer using a technique called OncoMap. The finding opens the way for personalized medicine in which every patient could have their tumor screened, specific mutations identified, and the appropriate drug chosen to target the mutation and halt the growth of their cancer.

Researchers have shown that point mutations – mis-spellings in a single letter of genetic code – that drive the onset and growth of cancer cells can be detected successfully in advanced ovarian cancer using a technique called OncoMap. The finding opens the way for personalized medicine in which every patient could have their tumor screened, specific mutations identified, and the appropriate drug chosen to target the mutation and halt the growth of their cancer.

Using mass spectrometry for identifying the genetic make-up of cancer cells, OncoMap can determine the point mutations in tumors by utilizing a large panel of over 100 known cancer-causing genes (referred to as “oncogenes“). In the work to be presented today (Wednesday) at the 22nd EORTC-NCI-AACR [1] Symposium on Molecular Targets and Cancer Therapeutics in Berlin, researchers will describe how they used OncoMap to identify oncogene mutations in tumor samples obtained from women with advanced high-grade serous ovarian cancer. [2] Earlier in the year 76 mutations in 26 different genes had been found but, since then, further work in more tumor samples has found more.

Ursula A. Matulonis, M.D., Medical Director, Gynecologic Oncology, Dana-Farber Cancer Institute; Associate Professor, Medicine, Harvard Medical School

Dr. Ursula Matulonis, director/program leader in medical gynecologic oncology at the Dana-Farber Cancer Institute located in Boston, Massachusetts (USA) and Associate Professor of Medicine at Harvard Medical School, will tell the meeting:

“Epithelial ovarian cancer is the most lethal of all the gynecologic malignancies, and new treatments are needed for both newly diagnosed patients as well as patients with recurrent cancer. The success of conventional chemotherapy has reached a plateau, and new means of characterizing ovarian cancer so that treatment can be personalized are needed.

We know that many human cancers have point mutations in certain oncogenes, and that these mutations can cause cancer cells to have a dependence on just one overactive gene or signalling pathway for the cancer cell’s growth and survival – a phenomenon known as ‘oncogene addiction’. If the mutation that causes the oncogene addiction can be inhibited, then it seems that this often halts the cancer process. Examples of mutations that are successfully inhibited by targeted drugs are HER2 (for which trastuzumab [Herceptin®] is used in breast cancer), EGFR (erlotinib [Tarceva®] in lung cancer) and c-kit (imatinib [Gleevec®] in chronic myeloid leukemia). So if we know the status of specific genes in a tumor, then this enables us to choose specific treatments that are likely to work successfully against the cancer.”

Dr Matulonis and her colleagues used OncoMap to investigate the mutation status of high-grade serous ovarian tumors that were known not to be caused by inherited mutations in the BRCA 1 and BRCA 2 genes. They found mutations previously identified to be involved in ovarian cancer: KRAS, BRAF, CTNNB1 and PIK3CA. The KRAS and PIK3CA mutations were the most common, while BRAF was more rare. The researchers also identified a low frequency of mutations in many other different oncogenes.

Dr. Matulonis further noted:

“This study shows that it’s feasible to use OncoMap to identify whether a patient’s tumor has a mutation in an oncogene for which a known drug is available to target that specific gene, so as to enable us to place her on a clinical study of that drug; for instance, XL147 or GDC-0941 are inhibitors for the P13kinase mutation that are in clinical trials at present.  In addition, someone’s cancer could harbor a mutation (such as ALK) that is not known to be associated with ovarian cancer or has not yet been studied in ovarian cancer – these patients could be matched with a drug that inhibits that protein too. As new drugs get developed, this information would be used to match future drugs with patients and their cancers.”

The researchers hope that OncoMap will become a clinical test for all cancer patients at the Dana-Farber Cancer Institute before long, so that the genetic information obtained can be used to choose the best treatment for them.

Dr. Matulonis said:

“At present, only a few targeted therapies are being used for newly diagnosed ovarian cancer and most are being used to treat recurrent ovarian cancer, but this will change eventually. I have already referred several of our patients who are either newly diagnosed or have recurrent cancer and who have mutations (one with KRAS and one with PIK3CA) to our phase I program for drugs studies specific to these mutations.  For ovarian cancer, understanding mutational analysis is one piece of the genetic puzzle. Our group will also start looking for chromosomal and gene amplifications and deletions in patients’ tumors, which we know are important for ovarian cancer.”

Matulonis believes that OncoMap and other similar analytical tools will become mainstream practice in all cancer clinics before long. Tools for detecting genes with the incorrect numbers of copies or abnormal expression will also help doctors to choose the best treatment for individual patients.”

Source: Researchers map the way to personalised treatment for ovarian cancer, Abstract no: 35. Oral presentation in plenary session 2.  22nd EORTC-NCI-AACR Symposium on Molecular Targets and Cancer Therapeutics, Berlin, Germany, November 16- 19, 2010.

References:

[1] EORTC [European Organisation for Research and Treatment of Cancer, NCI [National Cancer Institute], AACR [American Association for Cancer Research].

[2] The study was funded by the Madeline Franchi Ovarian Cancer Research Fund, twoAM Fund and the Sally Cooke Ovarian Cancer Research Fund.

Related Information:

Posted in Conferences, Discoveries, Genetics, Medical Study Results, Meeting Highlights, Pipeline Drugs | Tagged: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , | 1 Comment »

European Researchers Find Estrogen Receptor Gene Amplification Occurs Rarely in Ovarian Cancer

Posted by Paul Cacciatore on February 24, 2009

“… ESR1 [gene] amplification is an uncommon mechanism for estrogen receptor overexpression in ovarian cancer occurring in about 2.1% of the total number of ovarian cancers. In general, this frequency parallels the fraction of ovarian cancers reported to show complete response to antiestrogenic [anti-hormonal] therapies. Given the strong predictive power of ESR1 [gene] amplification for response to tamoxifen in breast cancer, an evaluation of such treatments in ESR1 [gene] amplified ovarian cancers appears justified.”

Abstract:

“Amplification of the gene encoding estrogen receptor-alpha occurs in about 20% of breast cancers and is an important mechanism for estrogen receptor overexpression in this tumor type. In ovarian cancer, overexpression of estrogen receptor protein has been described in more than two thirds of cases.

To study a potential role of estrogen receptor-alpha gene amplification for estrogen receptor overexpression in ovarian cancer, a tumor tissue microarray containing 428 ovarian cancers was analyzed by fluorescence in situ hybridization [FISH] for estrogen receptor-alpha gene amplification and immunohistochemistry [IHC] for estrogen receptor expression. The estrogen receptor-alpha gene status was successfully determined in 243 of 428 arrayed cancers.

Estrogen receptor gene amplification was found in 5 of 243 (2%) of tumors. Amplification levels were usually low, with 4-8 estrogen receptor-alpha gene copies. However, one case had a high-level amplification, with more than 30 estrogen receptor-alpha gene copies. All five amplified tumors were estrogen receptor positive, with 3 of 5 tumors showing highest (Allred score, 7-8) estrogen receptor levels. The data demonstrate that estrogen receptor-alpha amplification occurs only rarely in ovarian cancer.”

Article Discussion Points:

  • “The results of this study show that ESR1 amplification is rare in ovarian cancers (2.1%). More than one-third of ovarian tumors showed immunohistochemically detectable estrogen receptor protein expression, most abundant in serous and endometroid subtypes. This is in line with previous studies done on the classical paraffin blocks. The good concordance between our data and previous studies demonstrates the representation of our tumor tissue microarray data obtained on a 0.6 mm tissue spot per tumor and enhances the results of other studies used in this method.”
  • “A small subset of ESR1 [gene] amplified estrogen receptor-positive cases was indeed found in ovarian cancers. In comparison, some other genes showed higher rates of amplifications in these cancers. For example, the amplification of ERBB2 ranges (0-66%),  EGFR (3.65-12%),  CCND1 (0-19%), C-MYC up to 54.5,  and KRAS (31%).”
  • “The significant frequency of estrogen receptor positivity in ovarian cancers had prompted treatment efforts using hormonal therapy early on. In addition their relatively little toxicity was another provoking factor to continue going on to achieve more advance in this therapeutic field. Monotherapy studies using tamoxifen, aromatase inhibitors, and GnRH analogues had yielded variable results with objective response rates ranging between 0 and 56%.  Combinatorial treatment regimens combining tamoxifen and goserelin or tamoxifen and Gefitinib had obtained results with objective response rates of up to 11.5%.”
  • “The role of estrogen receptor expression for response prediction to anti-hormonal drugs has been much better studied in breast cancer, where a strong association between estrogen receptor positivity and response to anti-hormonal drugs is well established. … More than 20% of breast cancers had amplified or at least elevated ESR1 [gene] copy number. Possible explanations for the predictive effect of ESR1 [gene] amplification could be a particularly high expression of amplified as compared to non-amplified cancers. Alternatively, it could be speculated, that ESR1 [gene] amplified are more dependent on the estrogen receptor pathway than other tumors that express estrogen receptors together with many other growth receptors. If this latter hypothesis was true, visualization of ESR1 [gene] amplification would pinpoint toward an ‘Achilles tendon‘ of a tumor that could be most successfully targeted.”
  • “The frequency of ESR1 [gene] amplified ovarian cancers (2.1%) is much lower than that in breast cancer. Interestingly, this fraction somehow parallels the percentage of ovarian cancers reported to show strong responses to hormonal therapies.”
  • “For example, in retrospective analysis was conducted of patients who received tamoxifen at a dose 20 mg twice daily for the treatment of advanced epithelial ovarian cancer,
    • Karagol et al found that out of 29 eligible patients included in the study, there were 1 (3%) complete response, 2 (7%) partial response, 6 (21%) stable disease, and 20 (69%) progressive disease.
    • Papadimitriou et al have studied response rate in 27 patients treated with letrozole at a dose of 2.5 mg once a day. Patients with measurable or evaluable disease (n=21) and those with only increasing CA-125 serum levels (n=6) were eligible. Among the 21 patients with measurable or evaluable disease, 1 complete response (5%) and 2 partial responses were observed (10%) for an objective response rate of 15%.
    • Other studies, in which the combined regiment had been implicated, patients were given oral tamoxifen 20 mg twice daily on a continuous basis and subcutaneous goserelin 3.6 mg once a month until disease progression. In total, 26 patients entered this study, of which 17 had platinum-resistant disease, using the definition of endocrine response that included patients with stable disease of 6 months or greater, the overall response rate (clinical benefit rate) was 50%. This included one complete response (3.8%), two partial responses (7.7%), and 10 patients with stable disease (38.5%).”
  • “In summary, ESR1 [gene] amplification is an uncommon mechanism for estrogen receptor overexpression in ovarian cancer occurring in about 2.1% of the total number of ovarian cancers. In general, this frequency parallels the fraction of ovarian cancers reported to show complete response to antiestrogenic [anti-hormonal] therapies. Given the strong predictive power of ESR1 [gene] amplification for response to tamoxifen in breast cancer, an evaluation of such treatments in ESR1 [gene] amplified ovarian cancers appears justified.”

Quoted SourceEstrogen receptor gene amplification occurs rarely in ovarian cancer, Issa RM et. al., Mod Pathol. 2009;22(2):191-196, reprinted in From Modern Pathology, Medscape Today, February 18, 2009. [Free Medscape subscription required to view full text article.]

Comment:  This study indicates that the occurrence of estrogen positivity (ER+)/ESR1 gene amplification with respect to ovarian cancer is significantly lower than such occurrence in the breast cancer area.  Nevertheless, it is prudent to request your doctor to have your ovarian cancer tumor tissue tested by a pathologist for estrogen positivity or ESR1 gene amplification (through IHC or FISH testing, respectively).  If your ovarian cancer tissue tests ER+, you may respond to anti-estrogen drugs.  Although this type of pathology testing is commonplace in the breast cancer area, it is not in the ovarian cancer area due to the much lower percentage of ER+ ovarian cancer tumors.  As the study above notes, further research of anti-estrogen therapy use within the area of ovarian cancer is needed, especially given the potential high effectiveness and low toxicity of such therapies.

Posted in Anti-Estrogen Therapy, Medical Study Results | Tagged: , , , , , , , , , , , , , , , , , , , , , , , , , | 2 Comments »

Avastin/Tarceva Combination May Be No More Effective Than Avastin Monotherapy

Posted by Paul Cacciatore on April 23, 2008

The purpose of this single arm, multicenter Phase II clinical trial was to assess the activity and tolerability of the combination of bevacizumab (Avastin®) and erlotinib (Tarceva®) in patients with recurrent ovarian, primary peritoneal or fallopian tube cancer. Eligible patients received two or fewer prior chemotherapy regimens for recurrent or refractory disease and no prior anti-VEGF or anti-EGFR drugs. Between July and October 2005, 13 patients were enrolled.

There were two major objective responses — one complete response of 16+ month duration and one partial response of 11 month duration, representing an overall response rate of 15%. Two patients had fatal gastrointestinal perforations, and therefore, the study was discontinued. The trial investigators concluded that there was no strong suggestion that the Avastin®/Tarceva® combination was superior to single agent Avastin®, and noted that the rate of gastrointestinal perforation was of concern. The investigators believe that identification of risk factors for gastrointestinal perforation will be important with respect to the use of Avastin in the treatment of ovarian cancer.

[Source: “Efficacy and safety of bevacizumab plus erlotinib for patients with recurrent ovarian, primary peritoneal, and fallopian tube cancer: A trial of the Chicago, PMH, and California Phase II consortia;” Nimeiri HS, et. al., Gynecol Oncol. 2008 Apr 17 (Epublication ahead of print).]

Posted in Clinical Trial Results | Tagged: , , , , , , , , | Leave a Comment »

 
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