2011 ASCO: Matching Targeted Therapies To Specific Tumor Gene Mutations Key to Personalized Cancer Treatment

Customizing targeted therapies to each tumor’s molecular characteristics, instead of a “one-size-fits-all” approach by tumor type, may be more effective for some types of cancer, according to research presented today at the American Society of Clinical Oncology annual meeting by the M.D. Anderson Cancer Center. In patients with end-stage disease, matched patients achieved a 27% response rate, versus 5% in those unmatched.

Customizing targeted therapies to each tumor’s molecular characteristics, instead of a “one-size-fits-all approach” by tumor type, may be more effective for some types of cancer, according to research conducted by The University of Texas M.D. Anderson Cancer Center.

Apostolia M. Tsimberidou, M.D., Ph.D., Associate Professor, Department of Investigational Cancer Therapeutics, Division of Cancer Medicine, The University of Texas M.D. Anderson Cancer Center, Houston, Texas

M.D. Anderson’s phase I clinical study findings were presented today on the opening press program of the 47th Annual Meeting of the American Society of Clinical Oncology. Apostolia-Maria Tsimberidou, M.D., Ph.D., associate professor in the M.D. Anderson Department of Investigational Cancer Therapeutics, and the principal investigator of the study, presented the data.

Marking the largest scale on which this approach has been examined to date, the study analyzed the results of matching targeted therapies with specific gene mutations in patients. The data indicated that this strategy was associated with higher rates of response, survival and failure-free survival than observed in non-matched patients.

Pairing Patient and Treatment

“This preliminary study strongly suggests that molecular analysis is needed to use the right drug for the right patient. Up to this point, we have treated tumor types, but this study shows we cannot treat all patients with a tumor type the same way. We need to take into consideration a number of factors, and this study suggests that a personalized approach is needed to improve clinical outcomes for patients with cancer,” said Tsimberidou.

The identification of pathways involved in carcinogenesis, metastasis and drug resistance; new technologies enabling tumor molecular analysis; and the discovery of targeted therapies have stimulated research focusing on the use of targeted agents as part of a personalized medicine approach, she said.

“Over the past decades, a personalized medicine approach using Gleevec has changed the way we treat chronic myeloid leukemia, as well as survival rates,” said Razelle Kurzrock, M.D., professor and chair of the M.D. Anderson Department of Investigational Cancer Therapeutics. “We wanted to apply a similar approach to solid tumors.”

“Ultimately, to best match treatments to patients and offer the most therapeutic benefit, assessing a patient’s molecular markers has to become the standard at diagnosis. … 

This study affirms what we in the cancer community have been talking about for a decade – matching drugs to patients. The time is now. The drugs are here. The technology is here, and with our program at M.D. Anderson we can bring the two together in hopes to offer the most personalized care for our patients. …”

–Razelle Kurzrock, M.D., Professor & Chair, Department of Investigational Cancer Therapeutics, University of Texas M.D. Anderson Cancer Center

Research Methods and Results

In the initial analysis, Tsimberidou analyzed 1,144 patients with metastatic or inoperable cancer who underwent testing for molecular aberrations at M.D. Anderson. Their median age was 58, and the median number of prior treatments was four. Of these patients, 460 had one or more gene aberrations, including:

  • 10 percent with a PIK3CA mutation;
  • 18 percent with a KRAS mutation;
  • 8 percent with a NRAS mutation;
  • 17 percent with a BRAF mutation;
  • 3 percent with an EGFR mutation;
  • 2 percent with a CKIT mutation;
  • 21 percent with a PTEN loss; and
  • 37 percent with a p53 mutation

Patients with gene aberrations were treated on clinical trials with matched targeted agents, when available. Regimens included one or more therapies targeting PIK3CA, mTOR, BRAF, MEK, multikinases, KIT or EGFR. Outcomes of patients with gene aberrations treated with matched therapy were compared with those patients with gene aberrations who were not treated with matched therapy because of issues such as eligibility, study availability; insurance coverage and/or logistical problems with the study calendar.

For the 175 patients with one aberration, the response rate was 27 percent with matched targeted therapy. The response rate was 5 percent in 116 patients when treated with non-matched therapy.

Patients who received matched targeted therapy had median survival of 13.4 months, while median survival for patients treated with unmatched targeted therapy was nine months. Median failure-free survival in patients who received matched targeted therapy was 5.2 months, compared to 2.2 months for patients who received unmatched targeted therapy.

Further Research Needed

These preliminary results merit further investigation and confirmatory, prospective studies are needed, especially because the study was not a randomized study and therefore biases could influence the results.

“M.D. Anderson’s goal is to better understand the biology involved in each patient’s carcinogenesis by testing each tumor for genetic abnormalities driving tumor growth to guide treatment selection. This strategy will lead to the optimization of personalized therapy,” Tsimberidou said.

Another goal is to match targeted therapies to patients earlier in treatment.

“When Gleevec was first introduced, it was tested in patients in blast crisis and the response rate was about 15 percent. In contrast, when tested in the front line setting, and with the introduction of similar but increasingly potent second- and third-generation drugs, patients’ response rate was close to 100 percent, and now their expected survival is 25 years and counting,” said Kurzrock. “Ultimately, to best match treatments to patients and offer the most therapeutic benefit, assessing a patient’s molecular markers has to become the standard at diagnosis.”

About the Phase I Program – The Time is Now

The M.D. Anderson’s Phase I program is the largest of its kind and accounts for the majority – but not all – of the institution’s earliest clinical studies. In 2010, of the 11,000 patients who participated in M.D. Anderson clinical trials, more than 1,150 were enrolled in one of the 120 Phase I trials in the program.

Currently, tumors are tested for up to 12 molecular aberrations, but at the rate technology is rapidly advancing, Kurzrock expects that number to climb to more than 100 in the near future.

Patients treated in the Phase I Program are typically very ill and all other approved therapies have failed them. Yet they are “fighters” who are willing to try anything, including studies not specific to their diagnosis to test the effectiveness of a new drug, drug combination or delivery method, said Kurzrock.

“This study affirms what we in the cancer community have been talking about for a decade – matching drugs to patients,” said Kurzrock. “The time is now. The drugs are here. The technology is here, and with our program at M.D. Anderson we can bring the two together in hopes to offer the most personalized care for our patients.”

In addition to Tsimberidou and Kurzrock, other authors on the all-M.D. Anderson study included N. G. Iskander, David S. Hong, M.D., Jennifer J. Wheler, M.D., Siqing Fu, M.D., Ph.D., Sarina A. Piha-Paul, M.D., Aung Naing, M.D., Gerald Falchook, Filip Janku, M.D., Ph.D., all assistant professors of the Department of Investigational Cancer Therapeutics; Raja Luthra, Ph.D., professor, Department of Hematopathology, Research and Sijin Wen, Ph.D., Division of Quantitative Sciences.

Libby’s H*O*P*E*™ Commentary — Use of Molecular Profiling and Chemosensitivity Testing To Determine Individualized Ovarian Cancer Treatment

It is wonderful that various medical research institutions, including M.D. Anderson, are beginning to match targeted therapies to a patient’s specific molecular tumor characteristics. This approach is generally referred to as “molecular profiling,” and it represents one promising method of matching an individual cancer patient to an effective therapy. As noted in the related Libby’s H*O*P*E*™ postings set forth below, there are several medical and scientific institutions which are pursuing development of molecular profiling for clinical study use. In the most recent related posting listed below, we discuss the molecular profile testing that is commercially available through The Clearity Foundation and Caris Life Sciences.

In the future, it may be helpful to use a form of chemosensitivity testing (e.g., the type of testing provided by Precision Therapeutics, Rational Therapeutics, and the Weisenthal Cancer Group), which is based upon the measurement of actual cancer cell death, as a second method to match a cancer patient to a potential drug or drug combination within the context of a clinical study. In fact, we would like to see a future prospective, randomized ovarian cancer clinical trial in which enrolled women are provided with treatment after assignment to one of three clinical trial arms:  (i) treatment based upon the standard of care (e.g., paclitaxel and carboplatin), (ii) treatment based upon molecular profiling, or (iii) treatment based upon chemosensitivity testing.  This type of study may uncover additional ovarian cancer treatment insights (both molecular and functional) with respect to the most lethal gynecologic cancer, while ultimately helping women with forms of the disease that may not possess a known molecular characteristic that is potentially “targetable” by an existing clinical trial drug or compound.

This combination of “bottom-up” scientific research (i.e., molecular profiling) performed side-by-side with “top-down” research (i.e., chemosensitivity testing) may represent an effective and efficient approach — albeit provocative — for evaluation of optimal personalized ovarian cancer treatment.

It is important to note that Libby’s H*O*P*E*™ and its founder Paul Cacciatore do not receive financial renumeration or benefit of any kind from the companies referred to in the paragraphs above.

About the University of Texas M.D. Anderson Cancer Center

The University of Texas M.D. Anderson Cancer Center in Houston ranks as one of the world’s most respected centers focused on cancer patient care, research, education and prevention. MD Anderson is one of only 40 comprehensive cancer centers designated by the National Cancer Institute. For seven of the past nine years, including 2010, M.D. Anderson has ranked No. 1 in cancer care in “America’s Best Hospitals,” a survey published annually in U.S. News & World Report.

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Related Libby’s H*O*P*E* Postings:

Largest Study Matching Genomes To Potential Anticancer Treatments Releases Initial Results

The largest study to correlate genetics with response to anticancer drugs released its first results on July 15. The researchers behind the study, based at Massachusetts General Hospital Cancer Center and the Wellcome Trust Sanger Institute, describe in this initial dataset the responses of 350 cancer samples (including ovarian cancer) to 18 anticancer therapeutics.

U.K.–U.S. Collaboration Builds a Database For “Personalized” Cancer Treatment

The Genomics of Drug Sensitivity in Cancer project released its first results on July 15th. Researchers released a first dataset from a study that will expose 1,000 cancer cell lines (including ovarian) to 400 anticancer treatments.

The largest study to correlate genetics with response to anticancer drugs released its first results on July 15. The researchers behind the study, based at Massachusetts General Hospital Cancer Center and the Wellcome Trust Sanger Institute, describe in this initial dataset the responses of 350 cancer samples (including ovarian cancer) to 18 anticancer therapeutics.

These first results, made freely available on the Genomics of Drug Sensitivity in Cancer website, will help cancer researchers around the world to obtain a better understanding of cancer genetics and could help to improve treatment regimens.

Dr. Andy Futreal, co-leader of the Cancer Genome Project at the Wellcome Trust Sanger Institute, said:

Today is our first glimpse of this complex interface, where genomes meet cancer medicine. We will, over the course of this work, add to this picture, identifying genetic changes that can inform clinical decisions, with the hope of improving treatment.  By producing a carefully curated set of data to serve the cancer research community, we hope to produce a database for improving patient response during cancer treatment.

How a patient responds to anticancer treatment is determined in large part by the combination of gene mutations in her or his cancer cells. The better this relationship is understood, the better treatment can be targeted to the particular tumor.

The aim of the five-year, international drug-sensitivity study is to find the best combinations of treatments for a wide range of cancer types: roughly 1000 cancer cell lines will be exposed to 400 anticancer treatments, alone or in combination, to determine the most effective drug or combination of drugs in the lab.

The therapies include known anticancer drugs as well as others in preclinical development.

To make the study as comprehensive as possible, the researchers have selected 1000 genetically characterized cell lines that include common cancers such as breast, colorectal and lung. Each cell line has been genetically fingerprinted and this data will also be publicly available on the website. Importantly, the researchers will take promising leads from the cancer samples in the lab to be verified in clinical specimens: the findings will be used to design clinical studies in which treatment will be selected based on a patient’s cancer mutation spectrum.

The new data released today draws on large-scale analyses of cancer genomes to identify genomic markers of sensitivity to anticancer drugs.

The first data release confirms several genes that predict therapeutic response in different cancer types. These include sensitivity of melanoma, a deadly form of skin cancer, with activating mutations in the gene BRAF to molecular therapeutics targeting this protein, a therapeutic strategy that is currently being exploited in the clinical setting. These first results provide a striking example of the power of this approach to identify genetic factors that determine drug response.

Dr. Ultan McDermott, Faculty Investigator at the Wellcome Trust Sanger Institute, said:

It is very encouraging that we are able to clearly identify drug–gene interactions that are known to have clinical impact at an early stage in the study. It suggests that we will discover many novel interactions even before we have the full complement of cancer cell lines and drugs screened. We have already studied more gene mutation-drug interactions than any previous work but, more importantly, we are putting in place a mechanism to ensure rapid dissemination of our results to enable worldwide collaborative research. By ensuring that all the drug sensitivity data and correlative analysis is freely available in an easy-to-use website, we hope to enable and support the important work of the wider community of cancer researchers.

Further results from this study should, over its five-year term, identify interactions between mutations and drug sensitivities most likely to translate into benefit for patients: at the moment we do not have sufficient understanding of the complexity of cancer drug response to optimize treatment based on a person’s genome.

Professor Daniel Haber, Director of the Cancer Center at Massachusetts General Hospital and Harvard Medical School, said:

We need better information linking tumor genotypes to drug sensitivities across the broad spectrum of cancer heterogeneity, and then we need to be in position to apply that research foundation to improve patient care.  The effectiveness of novel targeted cancer agents could be substantially improved by directing treatment towards those patients that genetic study suggests are most likely to benefit, thus “personalizing” cancer treatment.

The comprehensive results include correlating drug sensitivity with measurements of mutations in key cancer genes, structural changes in the cancer cells (copy number information) and differences in gene activity, making this the largest project of its type and a unique resource for cancer researchers around the world.

Professor Michael Stratton, co-leader of the Cancer Genome Project and Director of the Wellcome Trust Sanger Institute, said:

“This is one of the Sanger Institute’s first large-scale explorations into the therapeutics of human disease.  I am delighted to see the early results from our partnership with the team at Massachusetts General Hospital. Collaboration is essential in cancer research: this important project is part of wider efforts to bring international expertise to bear on cancer.”

Ovarian Cancer Sample Gene Mutation Prevalence

As part of the Cancer Genome Project, researchers identified gene mutations found in 20 ovarian cancer cell lines and the associated prevalence of such mutations within the sample population tested. For purposes of this project, a mutation — referred to by researchers as a “genetic event” in the project analyses description — is defined as (i) a coding sequence variant in a cancer gene, or (ii) a gene copy number equal to zero (i.e., a gene deletion) or greater than or equal to 8 (i.e., gene amplification).  The ovarian cancer sample analysis thus far, indicates the presence of mutations in twelve genes. The genes that are mutated and the accompanying mutation prevalence percentage are as follows:  APC (5%), CDKN2A (24%), CTNNB1 (5%), ERBB2/HER-2 (5%), KRAS (10% ), MAP2K4 (5%), MSH2 (5%), NRAS (10%), PIK3CA (10%), PTEN (14%), STK11 (5%), and TP53 (62%). Accordingly, as of date, the top five ovarian cancer gene mutations occurred in TP53, CDKN2A, CDKN2a(p14)(see below), PTEN, and KRAS.

Click here to view the Ovary Tissue Overview.  Click here to download a Microsoft Excel spreadsheet listing the mutations in 52 cancer genes across tissue types. Based upon the Ovary Tissue Overview chart, the Microsoft Excel Chart has not been updated to include the following additional ovarian cancer sample mutations and associated prevalence percentages: CDKN2a(p14)(24%), FAM123B (5%), FBXW7 (5%), MLH1 (10%), MSH6 (5%).

18 AntiCancer Therapies Tested; Next 9 Therapies To Be Tested Identified

As presented in the initial study results, 18 drugs/preclinical compounds were tested against various cancer cell lines, including ovarian. The list of drugs/preclinical compounds that were tested for sensitivity are as follows:  imatinib (brand name: Gleevec),  AZ628 (C-Raf inhibitor)MG132 (proteasome inhibitor), TAE684 (ALK inhibitor), MK-0457 (Aurora kinase inhibitor)sorafenib (C-Raf kinase & angiogenesis inhibitor) (brand name: Nexavar), Go 6976 (protein kinase C (PKC) inhibitor), paclitaxel (brand name: Taxol), rapamycin (mTOR inhibitor)(brand name: Rapamune), erlotinib (EGFR inhibitor)(brand name: Tarceva), HKI-272 (a/k/a neratinib) (HER-2 inhibitor), Geldanamycin (Heat Shock Protein 90 inhibitor), cyclopamine (Hedgehog pathway inhibitor), AZD-0530 (Src and Abl inhibitor), sunitinib (angiogenesis & c-kit inhibitor)(brand name:  Sutent), PHA665752 (c-Met inhibitor), PF-2341066 (c-Met inhibitor), and PD173074 (FGFR1 & angiogenesis inhibitor).

Click here to view the project drug/preclinical compound sensitivity data chart.

The additional drugs/compounds that will be screened by researchers in the near future are metformin (insulin)(brand name:  Glucophage), AICAR (AMP inhibitor), docetaxel (platinum drug)(brand name: Taxotere), cisplatin (platinum drug)(brand name: Platinol), gefitinib (EGFR inhibitor)(brand name:  Iressa), BIBW 2992 (EGFR/HER-2 inhibitor)(brand name:  Tovok), PLX4720 (B-Raf [V600E] inhibitor), axitinib (angiogenesis inhibitor)(a/k/a AG-013736), and CI-1040 (PD184352)(MEK inhibitor).

Ovarian cancer cells dividing. (Source: ecancermedia)

Ovarian Cancer Therapy Sensitivity

Targeted molecular therapies that disrupt specific intracellular signaling pathways are increasingly used for the treatment of cancer. The rational for this approach is based on our ever increasing understanding of the genes that are causally implicated in cancer and the clinical observation that the genetic features of a cancer can be predictive of a patient’s response to targeted therapies. As noted above, the goal of the Cancer Genome Project is to discover new cancer biomarkers that define subsets of drug-sensitive patients. Towards this aim, the researchers are (i) screening a wide range of anti-cancer therapeutics against a large number of genetically characterized human cancer cell lines (including ovarian), and (ii) correlating drug sensitivity with extensive genetic data. This information can be used to determine the optimal clinical application of cancer drugs as well as the design of clinical trials involving investigational compounds being developed for the clinic.

When the researchers tested the 18 anticancer therapies against the 20 ovarian cancer cell lines, they determined that the samples were sensitive to many of the drugs/compounds. The initial results of this testing indicate that there are at least six ovarian cancer gene mutations that were sensitive to eight of the anticancer therapies, with such results rising to the level of statistical significance.  We should note that although most (but not all) of the ovarian cancer gene mutations were sensitive to several anticancer therapies, we listed below only those which were sensitive enough to be assigned a green (i.e., sensitive) heatmap code by the researchers.

Click here to download a Microsoft Excel spreadsheet showing the effect of each of the 51 genes on the 18 drugs tested. Statistically significant effects are highlighted in bold and the corresponding p values for each gene/drug interaction are displayed in an adjacent table.  A heatmap overlay for the effect of the gene on drug sensitivity was created, with the color red indicating drug resistance and the color green indicating drug sensitivity.

The mutated genes present within the 20 ovarian cancer cell line sample that were sensitive to anticancer therapies are listed below.  Again, only statistically significant sensitivities are provided.

  • CDKN2A gene mutation was sensitive to TAE684, MK-0457, paclitaxel, and PHA665752.
  • CTNNB1 gene mutation was sensitive to MK-0457.
  • ERBB2/HER-2 gene mutation was sensitive to HKI-272.
  • KRAS gene mutation was sensitive to AZ628.
  • MSH2 gene mutation was sensitive to AZD0530.
  • NRAS gene mutation was sensitive to AZ628.

We will provide you with future updates regarding additional ovarian cancer gene mutation findings, and new anticancer therapies tested, pursuant to the ongoing Cancer Genome Project.

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About The Genomics of Drug Sensitivity In Cancer Project

The Genomics of Drug Sensitivity In Cancer Project was launched in December 2008 with funding from a five-year Wellcome Trust strategic award. The U.K.–U.S. collaboration harnesses the experience in experimental molecular therapeutics at Massachusetts General Hospital Cancer Center and the expertise in large scale genomics, sequencing and informatics at the Wellcome Trust Sanger Institute. The scientists will use their skills in high-throughput research to test the sensitivity of 1000 cancer cell samples to hundreds of known and novel molecular anticancer treatments and correlate these responses to the genes known to be driving the cancers. The study makes use of a very large collection of genetically defined cancer cell lines to identify genetic events that predict response to cancer drugs. The results will give a catalogue of the most promising treatments or combinations of treatments for each of the cancer types based on the specific genetic alterations in these cancers. This information will then be used to empower more informative clinical trials thus aiding the use of targeted agents in the clinic and ultimately improvements in patient care.

Project leadership includes Professor Daniel Haber and Dr. Cyril Benes at Massachusetts General Hospital Cancer Center and Professor Mike Stratton and Drs. Andy Futreal and Ultan McDermott at the Wellcome Trust Sanger Institute.

About Massachusetts General Hospital

Massachusetts General Hospital (MGH), established in 1811, is the original and largest teaching hospital of Harvard Medical School. The MGH conducts the largest hospital-based research program in the United States, with an annual research budget of more than $600 million and major research centers in AIDS, cardiovascular research, cancer, computational and integrative biology, cutaneous biology, human genetics, medical imaging, neurodegenerative disorders, regenerative medicine, systems biology, transplantation biology and photomedicine.

About The Wellcome Trust Sanger Institute

The Wellcome Trust Sanger Institute, which receives the majority of its funding from the Wellcome Trust, was founded in 1992 as the focus for U.K. gene sequencing efforts. The Institute is responsible for the completion of the sequence of approximately one-third of the human genome as well as genomes of model organisms such as mouse and zebrafish, and more than 90 pathogen genomes. In October 2005, new funding was awarded by the Wellcome Trust to enable the Institute to build on its world-class scientific achievements and exploit the wealth of genome data now available to answer important questions about health and disease. These programs are built around a Faculty of more than 30 senior researchers. The Wellcome Trust Sanger Institute is based in Hinxton, Cambridge, U.K.

About The Wellcome Trust

The Wellcome Trust is a global charity dedicated to achieving extraordinary improvements in human and animal health. It supports the brightest minds in biomedical research and the medical humanities. The Trust’s breadth of support includes public engagement, education, and the application of research to improve health. It is independent of both political and commercial interests.

Required Cancer Genome Project Disclaimer:

The data above was obtained from the Wellcome Trust Sanger Institute Cancer Genome Project web site, http://www.sanger.ac.uk/genetics/CGP. The data is made available before scientific publication with the understanding that the Wellcom Trust Sanger Institute intends to publish the initial large-scale analysis of the dataset. This publication will include a summary detailing the curated data and its key features.  Any redistribution of the original data should carry this notice: Please ensure that you use the latest available version of the data as it is being continually updated.  If you have any questions regarding the sequence or mutation data or their use in publications, please contact cosmic@sanger.ac.uk so as to obtain any updated or additional data.  The Wellcome Trust Sanger Institute provides this data in good faith, but makes no warranty, express or implied, nor assumes any legal liability or responsibility for any purpose for which the data are used.

PI3K Pathway: A Potential Ovarian Cancer Therapeutic Target?

…[T]here are several PI3K signaling pathway targeting drugs in clinical development for use against ovarian cancer and solid tumors, including GDC-0941, BEZ235, SF1126, XL-147, XL-765, BGT226, and PX-866.  The results of two recent medical studies suggest that the use of PI3K-targeted therapies may offer an effective therapeutic approach for patients with advanced-stage and recurrent ovarian cancer, including a generally chemotherapy-resistant histological subtype of epithelial ovarian cancer known as “ovarian clear cell cancer” (OCCC).  The targeting of the PI3K pathway in endometrial, ovarian, and breast cancer is also being investigated by a Stand Up To Cancer “Dream Team.” …

PI3K Cellular Signaling Pathway — An Overview

PI3K/AKT cellular signaling pathway (Photo: Cell Signaling Technology(R))

In 2004 and 2005, multiple researchers identified mutations in the PIK3CA  gene with respect to multiple cancers.[1]  The PIK3CA gene encodes the PI3K catalytic subunit p110α. PI3K (phosphoinositide 3- kinase) proteins have been identified in crucial signaling pathways of ovarian cancer cells. PI3Ks are also part of the PI3K-AKT-mTOR signaling pathway which promotes cellular glucose metabolism, proliferation, growth, survival, and invasion and metastasis in many cancers. PIK3CA gene mutations can increase PI3K signaling, thereby activating the PI3K-AKT-mTOR pathway within cancer cells.

As of this writing, there are several PI3K signaling pathway targeting drugs in clinical development for use against ovarian cancer and solid tumors, including GDC-0941, BEZ235, SF1126, XL-147, XL-765, BGT226, and PX-866. [2]  The results of two recent medical studies suggest that the use of PI3K-targeted therapies may offer an effective therapeutic approach for patients with advanced-stage and recurrent ovarian cancer, including a generally chemotherapy-resistant histological subtype of epithelial ovarian cancer known as “ovarian clear cell cancer” (OCCC).  The targeting of the PI3K pathway in endometrial, ovarian, and breast cancer is also being investigated by a Stand Up To CancerDream Team.”

Frequent Mutation of PIK3CA Gene In Recurrent & Advanced Clear Cell Ovarian Cancer

OCCC is one of the five major subtypes of epithelial ovarian cancer. OCCC accounts for only 4% to 12% of epithelial ovarian cancer in Western countries and, for unknown reasons, it comprises more than 20% of such cancers in Japan [3,4,5]. OCCC possesses unique clinical features such as a high incidence of stage I disease, a large pelvic mass, an increased incidence of venous thromboembolic complications, and hypercalcemia. It is frequently associated with endometriosis.  Compared to serous ovarian cancer, OCCC is relatively resistant to conventional platinum and taxane-based chemotherapy. For these reasons, new effective therapies are desperately needed for OCCC.

Researchers from Johns Hopkins and the University of California, Los Angeles (UCLA) analyzed 97 OCCC tumors for genetic sequence mutations in KRAS (v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog), BRAF (v-raf murine sarcoma viral oncogene homolog B1), PIK3CA (phosphoinositide-3-kinase, catalytic, alpha polypeptide), TP53 (tumor protein p53), PTEN (phosphatase and tensin homolog), and CTNNB1 (Catenin, Beta-1) as these mutations frequently occur in other major types of ovarian cancers.[6] The samples tested included the following:

  • 18 OCCCs for which affinity-purified tumor cells from fresh specimens were available;
  • 10 OCCC tumor cell lines.

Upon test completion, the researchers discovered that sequence mutations of PIK3CA, TP53, KRAS, PTEN, CTNNB1, and BRAF occurred in 33%, 15%, 7%, 5%, 3%, and 1% of OCCC cases, respectively.

Clear cell carcinoma of the ovary (Photo: Geneva Foundation For Medical Education & Research)

The sequence analysis of the 18 affinity purified OCCC tumors and the 10 OCCC cell lines showed a PIK3CA mutation frequency of 46%. Based upon these findings the researchers concluded that the use of PIK3CA-targeting drugs may offer a more effective therapeutic approach compared with current chemotherapeutic agents for patients with advanced-stage and recurrent OCCC. As noted above, there are several PI3K-targeting drugs in clinical development for use against ovarian cancer and solid tumors.[2]

Notably, one of the researchers involved with this OCCC study is Dennis J. Slamon, M.D., Ph.D. Dr. Slamon serves as the Director of Clinical/Translational Research, and as Director of the Revlon/UCLA Women’s Cancer Research Program at the Jonsson Comprehensive Cancer Center. Dr. Slamon is also a professor of medicine, chief of the Division of Hematology/Oncology and Executive Vice Chair of Research for UCLA’s Department of Medicine. Dr. Slamon is a co-discoverer of the breast cancer drug Herceptin®. Herceptin is a monoclonal antibody targeted therapy used against HER-2 breast cancer, an aggressive breast cancer subtype that affects 20% to 30% of women with the disease. Herceptin’s development was based, in part, upon the unique genetic profile of HER-2 breast cancer as compared to other forms of breast cancer. Herceptin® revolutionized the treatment of HER-2 postive breast cancer and is recognized worldwide as the standard of care for that subtype of breast cancer.  The approach taken by Johns Hopkins and UCLA researchers in this study — the identification of  a subtype within a specific form of cancer that may be susceptible to a targeted therapy –  bears a striking similarity to the overarching approach taken in the development of Herceptin®.

Ovarian Cancer & Other Solid Tumors With PIK3CA Gene Mutations Respond To PI3K-AKT-mTOR Pathway Inhibitors In Phase I Clinical Testing.

Testing patients with cancer for PIK3CA gene mutations is feasible and may allow targeted treatment of the PI3K-AKT-mTOR cellular signaling pathway, according to the results of a University of  Texas, M.D. Anderson Cancer Center study presented on November 17, 2009 at the 2009 AACR (American Association for Cancer Research)-NCI (National Cancer Institute)-EORTC (European Organization For Research & Treatment of Cancer) International Conference on Molecular Targets and Cancer Therapeutics.[7]

mTOR cellular signaling pathway (Photo: Cell Signaling Technology(R))

Filip Janku, M.D., Ph.D, a clinical research fellow with the M.D. Anderson Cancer Center’s department of investigational cancer therapeutics, and colleagues conducted a mutational analysis of exon 9 and exon 20 of the PI3KCA gene using DNA from the tumors of patients referred to targeted therapy clinical trials. Patients with PIK3CA mutations were preferably treated whenever possible with regimens utilizing PI3K-AKT-mTOR signaling pathway inhibitors.

As part of this study 117 tumor samples were analyzed. PIK3CA mutations were detected in 14 (12%) patients.  In tumor types with more than 5 patients tested, PIK3CA mutations were identified in endometrial cancer (43%, 3 out of 7 patients), ovarian cancer (22%, 5 out of 23 patients), squamous head and neck cancer (14%, 1 out of 7 patients), breast cancer (18%, 2 out of 11 patients), and colon cancer (15%, 2 out of 13 patients). No mutations were identified in patients with melanoma or cervical cancer.

Of the 14 patients found to possess PIK3CA mutations, 10 were treated based upon a clinical trial protocol that included a drug targeting the PI3K-AKT-mTOR pathway.  A partial response to treatment was experienced by 4 (40%) patients. Although the total number of patients is small, there were 2 (67%) patient responses in 3 endometrial cancer cases, 1 (25%) patient response in 4 ovarian cancer cases, 1 (100%) patient response in 1 breast cancer, and no patient response in 1 colorectal cancer case.  Although the total number of study patients is small, the researchers conclude that the response rate appears high (40%) in tumors with PIK3CA mutations treated with PI3K-AKT-mTOR pathway inhibitors.

“The implications of this study are twofold,” said Dr. Janku.  “We demonstrated that PIK3CA testing is feasible and may contribute to the decision-making process when offering a patient a clinical trial. Although this study suffers from low numbers, the response rate observed in patients treated with inhibitors of PI3K/AKT/mTOR pathway based on their mutational status was well above what we usually see in phase-1 clinical trials.”  “These results are intriguing but at this point should be interpreted with caution,” said Janku. “The promising response rate needs to be confirmed in larger groups of patients. We expect to learn more as this project continues to offer PIK3CA screening to patients considering a phase-1 clinical trial.”

Stand Up 2 Cancer Dream Team: Targeting the PI3K Pathway in Women’s Cancers

The potential importance of the PI3K pathway in the treatment of ovarian cancer is emphasized by the two medical studies above.  This issue is also receiving considerable attention from one of the Stand Up 2 Cancer (SU2C) “Dream Teams,” which is going to evalute  the potential for targeting the PI3K pathway in women’s cancer.  SU2C assigned $15 million of cancer research funding to this critical issue.  The scientists involved in this SU2C Dream Team are the pioneers who discovered the PI3K pathway and validated its role in human cancers, and they will focus on breast, ovarian and endometrial cancers, all of which possess the PI3K mutation.

The leader and co-leaders of the PI3K pathway SU2C team are set forth below.

Leader:

Lewis C. Cantley, Ph.D., Director, Cancer Center at Beth Israel Deaconess Medical Center.

Co-Leaders:

Charles L. Sawyers, M.D., Director, Human Oncology and Pathogenesis Program, Memorial Sloan-Kettering Cancer Center.

Gordon B. Mills, M.D., Ph.D., Chair, Department of Systems Biology, University of Texas, M.D. Anderson Cancer Center.

The specific SU2C Dream Team research goal with respect to targeting the PI3K pathway in women’s cancers is stated as follows:

The PI3K pathway is mutated in more cancer patients than any other, and these mutations are the most frequent events in women’s cancers, making it an attractive molecular target for agents that inhibit these genetic aberrations. If successful, this project will allow clinicians to use biomarkers and imaging techniques to predict which patients will benefit from PI3K pathway inhibitors and lead to the development of therapeutic combinations that will hit multiple targets in the complex pathways that contribute to cancer cell growth.  This work will help assure that these therapies are given to patients who will benefit from them, and it will also increase the overall pace of clinical trials targeting PI3K inhibitors.

Based upon the two studies discussed, and the creation and funding of the SU2C Dream Team for the purpose of targeting the PI3K pathway in women’s cancer, the future holds great promise in the battle against ovarian cancer (including OCCC).  It is our hope that more clinical study investigators will offer PI3K pathway mutation screening to all ovarian cancer patient volunteers.  Libby’s H*O*P*E*™ will continue to monitor the clinical development of PI3K pathway inhibitors, and make our readers aware of all future developments.

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References:

1/Yuan TL, Cantley LC. PI3K pathway alterations in cancer: variations on a theme. Oncogene. 2008 Sep 18;27(41):5497-510. PubMed PMID: 18794884
Samuels Y, Ericson K. Oncogenic PI3K and its role in cancer. Curr Opin Oncol. 2006 Jan;18(1):77-82. PubMed PMID: 16357568.
Levine DA, Bogomolniy F, Yee CJ, et. al. Frequent mutation of the PIK3CA gene in ovarian and breast cancers. Clin Cancer Res. 2005 Apr 15;11(8):2875-8. PubMed PMID: 15837735.
Samuels Y, Wang Z, Bardelli A, et. al. High frequency of mutations of the PIK3CA gene in human cancers. Science. 2004 Apr 23;304(5670):554. Epub 2004 Mar 11. PubMed PMID: 15016963.

2/For open ovarian cancer clinical trials using a PI3K-targeted therapy; CLICK HERE; For open solid tumor clinical trials using a PI3K-targeted therapy, CLICK HERE.

3/ Itamochi H, Kigawa J & Terakawa N.  Mechanisms of chemoresistance and poor prognosis in ovarian clear cell carcinoma. Can Sci 2008 Apr;99(4):653-658. [PDF Document]

4/Schwartz DR, Kardia SL, Shedden KA, et. alGene Expression in Ovarian Cancer Reflects Both Morphology and Biological Behavior, Distinguishing Clear Cell from Other Poor-Prognosis Ovarian CarcinomasCan Res 2002 Aug; 62, 4722-4729.

5/Sugiyama T & Fujiwara K.  Clear Cell Tumors of the Ovary – Rare Subtype of Ovarian Cancer, Gynecologic Cancer, American Society of Clinical Oncology (ASCO) Educational Book, 2007 ASCO Annual Meeting, June 2, 2007 (Microsoft Powerpoint presentation).

6/Kuo KT, Mao TL, Jones S, et. al. Frequent Activating Mutations of PIK3CA in Ovarian Clear Cell Carcinoma. Am J Pathol. 2009 Apr 6. [Epub ahead of print]

7/Janku F, Garrido-Laguna I, Hong D.S.  PIK3CA mutations in patients with advanced cancers treated in phase I clinical trials, Abstract #B134, Molecular Classification of Tumors, Poster Session B, 2009 AACR-NCI-EORTC Molecular Targets and Cancer Therapeutics Conference. [PDF Document].