Monthly Archives: November 2010

Exelixis Reports Promising Interim Data From Ovarian Cancer Patients Treated With XL184

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Exelixis reports promising interim data from ovarian cancer patients treated with XL184, including:  a  32% confirmed response rate per RECIST in patients with platinum-resistant or platinum-sensitive disease, and a 64% overall week-12 disease control rate.

Ignace Vergote, M.D., Ph.D., Head, Department of Obstetrics & Gynecology and Gynecologic Oncology, Catholic University Hospital, Leuven, Belgium

Exelixis, Inc.  today reported interim data from the cohort of patients with advanced epithelial ovarian cancer, primary peritoneal, or fallopian tube carcinoma treated with XL184 in an ongoing phase 2 adaptive randomized discontinuation trial (RDT) [1]. Ignace Vergote, M.D., Ph.D., Head of the Department of Obstetrics and Gynecology and Gynecologic Oncology at the Catholic University Hospital Leuven, Leuven, Belgium, will present the data in the Molecular-Targeted Therapies-Clinical Trials poster session (Abstract #407) on Thursday, November 18th, at the 22nd EORTC-NCI-AACR [2] Symposium on Molecular Targets and Cancer Therapeutics, being held in Berlin, Germany.

XL184 Activity in Patients with Ovarian Cancer

XL184 is an oral, potent inhibitor of MET, VEGFR2 and RET. MET overexpression has been observed in advanced ovarian cancer, and anti-VEGF pathway agents have shown clinical benefit in ovarian cancer patients. For these reasons, co-targeting of the MET and VEGF signaling pathways using XL184 may represent a promising treatment strategy.

As of the November 1, 2010 cut-off date, a total of 51 patients were enrolled into the ovarian cancer cohort, with 31 evaluable for response, and 41 evaluable for safety. The median number of prior systemic treatments was 2. Tumor shrinkage was observed in 30 of 37 (81%) patients with measurable metastatic lesions. Of 31 patients evaluable for response per RECIST (Response Evaluation Criteria In Solid Tumors), 10 (32%) achieved a confirmed partial response (PR). Stable disease (SD) was reported in 15 patients (48%) including 3 patients who achieved unconfirmed PRs. The overall week-12 disease control rate (DCR)(complete responses + partial responses + stable disease responses = DCR) was 64%.

Upon subset analysis, 5 of 17 platinum–refractory or –resistant patients (29%) evaluable for response per RECIST achieved a confirmed PR. SD was reported in 7 patients (41%) including 2 patients with unconfirmed PRs. The week-12 DCR was 59% in platinum-resistant/refractory patients. Durable responses have been observed, including 2 patients with platinum-refractory or resistant disease who remain on study for 34+ and 36+ weeks, and 3 patients with platinum-sensitive disease on study for 24, 24+, and 28+ weeks. Some patients have experienced reductions in the ovarian cancer blood marker CA125, but in general no clear concordance between CA125 changes and tumor shrinkage has been observed.

Safety data are available for 49 patients who had at least 6 weeks of follow-up. The most common grade greater-than or equal to 3 adverse events, regardless of causality were PPE (Palmar-Plantar Erythrodysesthesia) syndrome (also referred to as “hand-foot syndrome”) (12%), diarrhea (7%), fatigue, vomiting (each 5%), nausea, rash, abdominal pain, hypertension, and hypomagnesemia (each 2%).

“The activity of XL184 in women with both platinum-sensitive and platinum-resistant/refractory disease is unique and encouraging. The response rate and overall disease control rate of this oral agent are impressive especially in the group of patients with platinum refractory/resistant ovarian cancer, and compare favorably to other targeted and systemic agents in development,” said, Dr. Vergote. “I believe these encouraging data warrant further evaluation of XL184 in ovarian cancer.”

Michael M. Morrissey, Ph.D., President & Chief Executive Officer, Exelixis, Inc.

“The high response rate in patients with ovarian cancer is reflective of the broad anti-tumor activity of XL184 observed in multiple tumor types to date,” said Michael M. Morrissey, Ph.D., president and chief executive officer of Exelixis. “The data from the RDT underscore the novel and differentiated clinical activity of XL184 in diverse tumor indications with predominance of either soft tissue or bone involvement.”

To access the clinical data poster mentioned in this press release, please visit www.exelixis.com.

Broad Clinical Activity of XL184 – Randomized Discontinuation Trial

XL184 has demonstrated anti-tumor activity in 9 of 12 indications studied to date. In ongoing trials, compelling activity has been observed in medullary thyroid cancer, glioblastoma, and clear cell renal cancer. In the RDT, XL184 is being evaluated in nine different tumor types, with clear signals of activity in six: prostate, ovarian, hepatocellular, breast, non-small cell lung cancer and melanoma. The adaptive RDT design allowed for rapid simultaneous assessment of the activity of XL184 across nine different tumor indications. As of the November 1, 2010 cut-off date, a total of 397 patients have been enrolled into the nine disease-specific cohorts, with 273 evaluable for response, and 312 evaluable for safety. Of 273 patients evaluable for response per RECIST, 39 achieved a PR (either confirmed or unconfirmed) and 100 had SD at week 12. The week-12 DCR for the overall population was 49%, with the highest rates occurring in hepatocellular cancer (75%), castration-resistant prostate cancer (71%), ovarian cancer (64%), melanoma (45%), non-small cell lung cancer (42%) and breast cancer (42%). Of note, a breast cancer patient with evidence of bone metastasis on bone scan demonstrated evidence of resolution on bone scan accompanied by 29% reduction in tumor size. XL184 has been generally well tolerated with a consistent adverse event profile across the nine different RDT tumor types.

About XL184

XL184, an inhibitor of tumor growth, metastasis and angiogenesis, simultaneously targets MET and VEGFR2, key kinases involved in the development and progression of many cancers, including ovarian cancer. It has recently been shown in preclinical models that treatment with selective inhibitors of VEGF signaling can result in tumors that are more invasive and aggressive compared to control treatment. In preclinical studies, upregulation of MET has been shown to occur in concert with development of invasiveness after selective anti-VEGF therapy, and may constitute a mechanism of acquired or evasive resistance to agents that target VEGF signaling. Accordingly, treatment with XL184 in similar preclinical studies resulted in tumors that were less invasive and aggressive compared to control or selective anti-VEGF treatment. Therefore, XL184 has the potential for improving outcomes in a range of indications, including those where selective anti-VEGF therapy has shown minimal or no activity.

About Exelixis

Exelixis, Inc. is a development-stage biotechnology company dedicated to the discovery and development of novel small molecule therapeutics for the treatment of cancer. The company is leveraging its biological expertise and integrated research and development capabilities to generate a pipeline of development compounds with significant therapeutic and commercial potential for the treatment of cancer. Currently, Exelixis’ broad product pipeline includes investigational compounds in phase 3, phase 2, and phase 1 clinical development. Exelixis has established strategic corporate alliances with major pharmaceutical and biotechnology companies, including Bristol-Myers Squibb Company, sanofi-aventis, GlaxoSmithKline, Genentech (a wholly owned member of the Roche Group), Boehringer Ingelheim, and Daiichi-Sankyo. For more information, please visit the company’s web site at http://www.exelixis.com.

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1/Rosner GL, Stadler W, Ratain MJ. et. al.  Randomized discontinuation design: Application to cytostatic antineoplastic agents. J Clin Oncol 20:4478-4484, 2002.  Pursuant to this design, all patients receive the investigational drug for an initial period of time. Patients with standard radiologic tumor shrinkage within that timeframe would continue investigational therapy, while those with radiologic progression or unacceptable toxicity would discontinue therapy. All patients with radiologic stable disease after the initial therapy period are then randomized to continuing or discontinuing therapy in a double-blind placebo-controlled manner. This is an enrichment strategy in which patients with the end point of interest are preferentially enrolled in the randomized portion and in which the heterogeneity of the randomized population is decreased. These two factors result in an increased power for detecting a clinically relevant difference and decrease the number of patients exposed to placebo. Importantly, the enrichment is driven by the properties of the investigational drug as opposed to clinical prognostic factors identified in historical untreated patients or patients treated with a different class of agents. In addition, the statistical behavior of the trial is not highly dependent on investigators’ assumptions regarding the “no dose effect” (i.e., non-receipt of drug = no effect)  for time to progression or stable disease rate, and thus effectively deals with uncertainty in this variable. Finally, patients may find such a trial design more appealing, resulting in brisk accrual.

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

PARP Inhibitor MK-4827 Shows Anti-Tumor Activity in First Human Clinical Study

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MK-4827, a new drug that targets proteins responsible for helping cancer cells repair their damaged DNA, has shown promising anti-tumor activity in its first human clinical trial.

MK-4827, a new drug that targets proteins responsible for helping cancer cells repair their damaged DNA, has shown promising anti-tumour activity in its first human clinical trial. Some patients with a range of solid tumors, many of whom had been treated unsuccessfully for their cancer with other therapies, have seen their tumors shrink or stabilize for periods of between 46 days to more than a year. The research will be presented today (Thursday) at the 22nd EORTC–NCI–AACR [1] Symposium on Molecular Targets and Cancer Therapeutics, which is being held in Berlin, Germany.

PARP is a key signaling enzyme involved in triggering the repair of single-strand DNA damage. PARP inhibition has been demonstrated to selectively kill tumor cells lacking components of the homologous recombination (HR) DNA repair pathway while sparing normal cells. Known defects in HR repair include the well-characterized hereditary BRCA1 and BRCA2 mutations in breast and ovarian cancer, as well as nonhereditary BRCA mutations. (Photo Credit: AstraZeneca Oncology)

Laboratory studies of the drug, MK-4827, have shown that it inhibits proteins called PARP1 and PARP2 (poly(ADP)-ribose polymerase). PARP is involved in a number of cellular processes and one of its important functions is to assist in the repair of single-strand breaks in DNA. Notably, if one single-strand DNA break is replicated (replication occurs before cell division), then it results in a double-strand break.  By inhibiting the action of PARP, double-strand breaks occur, which in turn, lead to cell death. Tumors that are caused by a mutation in the BRCA1 or BRCA2 genes are susceptible to cell death through PARP inhibition because correctly functioning BRCA genes assist in repairing double-strand DNA breaks via a process called homologous-recombination-dependent DNA repair, whereas mutated versions are unable to perform this role. Normal cells do not replicate as often as cancer cells and they still have homologous repair operating; this enables them to survive the inhibition of PARP and makes PARP a good target for anti-cancer therapy.

In a Phase I trial [2] conducted at the H. Lee Moffitt Cancer Center (Tampa Florida, USA), University of Wisconsin-Madison (Madison, USA) and the Royal Marsden Hospital (London, UK), MK-4827 was given to 59 patients (46 women, 13 men) with a range of solid tumors such as non-small cell lung cancer (NSCLC), prostate cancer, sarcoma, melanoma and breast and ovarian cancers. Some patients had cancers caused by mutations in the BRCA1/2 genes, such as breast and ovarian cancer, but others had cancers that had arisen sporadically.

Robert M. Wenham, M.D., MS, FACOG, Clinical Director, Gynecologic Oncology, Department of Women's Oncology, H. Lee Moffitt Cancer Center

The drug was given in pill form once a day, and the researchers found that the maximum tolerated dose was 300 mg per day. Dr. Robert Wenham, Clinical Director for Gynecologic Oncology in the Department of Women’s Oncology at the Moffitt Cancer Center, who is presenting data on behalf of the participating investigators, said: “MK-4827 is generally well tolerated, with the main dose-limiting toxicity being thrombocytopenia – an abnormal decrease in the number of platelets in the circulatory blood. The most common side effects are mild nausea, vomiting, anorexia and fatigue.”

The researchers saw anti-tumor responses in both sporadic (non-inherited) and BRCA1/2 mutation-associated cancers [emphasis added]. Ten patients with breast and ovarian cancers had partial responses, with progression-free survival between 51-445 days, and seven of these patients are still responding to treatment. Four patients (two with ovarian cancer and two with NSCLC) had stable disease for between 130-353 days.

Dr. Wenham said: “Most patients in the trial had exhausted standard therapies and those who responded to this drug have benefited. Several patients have been receiving treatment for more than a year. The responses mean that MK-4827 is working as hoped and justify additional studies. Just how well MK-4827 works compared to other treatments is the goal of the next set of studies.”

He gave a possible explanation as to why patients with cancers that were not caused by BRCA1 or BRCA 2 gene mutations also responded to the PARP inhibition. “BRCA is a tumor suppressor gene that assists in repairing double stranded DNA breaks. In BRCA-mutation related cancers, loss of both copies of the gene results in a non-functional protein and thus BRCA deficiency. Because BRCA works with other proteins, BRCA-pathway related deficiency can be seen in the absence of two mutated copies of the BRCA genes. This may explain why responses have been reported for this class of drugs in non-BRCA mutant cancers.”

Dr. Wenham and his colleagues are recruiting more patients for additional studies and an expansion of the existing trial. “We want to understand what types of cancers will respond best to treatment with MK-4827,” he said. “Cohorts are currently open for patients with ovarian cancer, patients without germ-line BRCA mutations, and prostate cancer patients. Cohorts will open soon for patients with T-cell prolymphocytic leukemia, endometrial cancer, breast cancer and colorectal cancer. MK-4827 is also being studied in combination with conventional chemotherapy drugs.”

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References:

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

[2] This study was funded by Merck & Co., Inc. MK-4827 is owned by Merck & Co., Inc.

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

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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:

Ovarian Cancer Drug AMG 386 Shows Promise With Move To Phase 3 Trials In Australia, Canada & Europe

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A new drug (AMG 386) designed to arrest ovarian cancer cell growth by inhibiting blood vessel formation is being readied for a phase 3 trial in Australia, Canada and Europe.

AMG 386, a new drug designed to arrest ovarian cancer cell growth by inhibiting blood vessel formation, is being readied for a phase 3 trial in Australia, Canada and Europe.

The attendees at the Clinical Oncological Society of Australia Annual Scientific Meeting were told on November 10th that AMG 386 offers benefits over existing treatments, extending survival in advanced ovarian cancer patients with fewer side-effects.

AMG 386 is a first-in-class investigational “peptibody” (i.e., a combination of a peptide + an antibody) that is designed to block angiogenesis by inhibiting angiopoietin-1 and -2 (Ang1 & Ang2). Angiopoietins interact with the Tie2 receptor, which mediates vascular remodeling. Ang1 and Ang2 are thought to play opposing roles, and the maturation of blood vessels appears to be controlled by their precise balance.

Gary E. Richardson, M.D., Associate Professor of Medicine, Monash University, Victoria, Australia

Associate Professor of Medicine at Monash University, Gary Richardson, presented updated data from phase 2 clinical trials (first reported in June at the American Society of Clinical Oncology) showing that AMG 386 in combination with paclitaxel not only extends survival, but is well tolerated and reduces the risk of serious complications such as bowel perforation.

“Currently the prognosis for ovarian cancer patients is poor,” Professor Richardson said. “Over 75% of patients diagnosed with ovarian cancer present with advanced disease. Current treatments will cure only about a quarter of these patients.”

“The phase 2 trials show that AMG 386 combined with paclitaxel extends survival of heavily pre-treated patients by almost two thirds (4.6 to 7.2 months). In practical terms, this does not add significantly to survival time for terminal patients, but importantly indicates real potential as a first line treatment immediately following surgery.”

Professor Richardson said the treatment worked by inhibiting angiogenesis, the process by which new blood vessels grow from existing blood vessels. “By starving the cancer cells of blood supply, they will die in greater numbers. This form of therapy is complementary to current chemotherapy treatment as it uses a different mechanism to target the cancer.”

Professor Richardson said the phase 3 trial would commence by the end of this year and involve more than 1,000 patients in Australia, Canada and western Europe.

Bruce Mann, M.D., President, Clinical Oncological Society of Australia

Clinical Oncological Society of Australia President, Professor Bruce Mann, said clinicians had been frustrated by the lack of progress in treatment for ovarian cancer. “We don’t want to get ahead of ourselves, but novel approaches like this have the potential to make a real difference in patient survival from this devastating disease.”

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New Assay Test Predicts That 50% of Ovarian Cancers Will Respond To In Vitro PARP Inhibition

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U.K. researchers develop a new test that could be used to select ovarian cancer patients who will benefit from a new class of drugs called “PARP inhibitors.”

U.K. researchers have developed a new test that could be used to select which patients with ovarian cancer will benefit from a new class of drugs called “PARP (poly (ADP-ribose) polymerase) inhibitors,” according to preclinical research presented at the National Cancer Research Institute (NCRI) Cancer Conference held in Liverpool on November 8th.  According to the test results, approximately 50 percent of all patients with ovarian cancer may benefit from PARP inhibitors.

Dr. Asima Mukhopadhyay Discusses Her Research Into A More Tailored Treatment For Ovarian Cancer

PARP Inhibition & BRCA Gene Mutations: Exploiting Ovarian Cancer’s Inherent Defects

  • Genetics 101

DNA (deoxyribonucleic acid) is the genetic material that contains the instructions used in the development and functioning of our cells. DNA is generally stored in the nucleus of our cells. The primary purpose of DNA molecules is the long-term storage of information. Often compared to a recipe or a code, DNA is a set of blueprints that contains the instructions our cells require to construct other cell components, such as proteins and RNA (ribonucleic acid) molecules. The DNA segments that carry this genetic information are called “genes.”

A gene is essentially a sentence made up of the bases A (adenine), T (thymine), G (guanine), and C (cytosine) that describes how to make a protein. Any change in the sequence of bases — and therefore in the protein instructions — is a mutation. Just like changing a letter in a sentence can change the sentence’s meaning, a mutation can change the instruction contained in the gene. Any changes to those instructions can alter the gene’s meaning and change the protein that is made, or how or when a cell makes that protein.

Gene mutations can (i) result in a protein that cannot carry out its normal function in the cell, (ii) prevent the protein from being made at all, or (iii) cause too much or too little of a normal protein to be made.

  • Targeting DNA Repair Through PARP Inhibition

Targeting DNA repair through PARP inhibition in BRCA gene-mutated cancer cells. "DSB" stands for DNA "Double Stand Break." (Photo Credit: AstraZeneca Oncology)

Normally functioning BRCA1 and BRCA2 genes are necessary for DNA repair through a process known as “homologous recombination” (HR).  HR is a form of genetic recombination in which two similar DNA strands exchange genetic material. This process is critical to a cell’s ability to repair its DNA in the event that it becomes damaged, so the cell can continue to function.

A cell’s DNA structure can be damaged by a wide variety of intentional (i.e., select cancer treatments) or unintentional (ultraviolet light, ionizing radiation, man-made chemicals, etc.) factors.  For example, chemotherapy regimens used in the treatment of cancer, including alkylating agents, topoisomerase inhibitors, and platinum drugs, are designed to damage DNA and prevent cancer cells from reproducing.

In approximately 10 percent of inherited ovarian cancers, the BRCA 1 or BRCA2 gene is damaged or mutated.  When the BRCA1 or BRCA2 gene is mutated, a backup type of DNA repair mechanism called “base-excision repair” usually compensates for the lack of DNA repair by HR.  Base-excision repair represents a DNA “emergency repair kit.” DNA repair enzymes such as PARP, whose activity and expression are upregulated in tumor cells, are believed to dampen the intended effect of chemotherapy and generate drug resistance.

When the PARP1 protein – which is necessary for base-excision repair – is inhibited in ovarian cancer cells possessing a BRCA gene mutation, DNA repair is drastically reduced, and the cancer cell dies through so-called “synthetic lethality.”  In sum, PARP inhibitors enhance the potential of chemotherapy (and radiation therapy) to induce cell death.  Healthy cells are unaffected if PARP is blocked because they either contain one or two working BRCA1 or BRCA2 genes which do an effective DNA repair job through use of HR.

  • PARP Inhibitors: A New Class of Targeted Therapy

PARP inhibitors represent a new, targeted approach to treating certain types of cancers. PARP inhibition has the potential to overwhelm cancer cells with lethal DNA damage by exploiting impaired DNA repair function inherent in some cancers, including breast and ovarian cancers with defects in the BRCA1 gene or BRCA 2 gene, and other DNA repair molecules. Inhibition of PARP leads to the cell’s failure to repair single strand DNA breaks, which, in turn, causes double strand DNA breaks. These effects are particularly detrimental to cancer cells that are deficient in repairing double strand DNA breaks and ultimately lead to cancer cell death.

PARP inhibitors are the first targeted treatment to be developed for women with inherited forms of breast and ovarian cancer carrying faults or mutations in a BRCA gene. Early results from clinical trials are showing promise for patients with the rare inherited forms of these cancers.

Study Hypothesis: PARP Inhibitors May Be Effective Against a Large Proportion of Non-Inherited Ovarian Cancers

As noted above, PARP inhibitors selectively target HR–defective cells and have shown good clinical activity in hereditary breast and ovarian cancers associated with BRCA1 or BRCA2 mutations. The U.K. researchers hypothesized that a high proportion (up to 50%) of sporadic (non-inherited) epithelial ovarian cancers could be deficient in HR due to genetic or epigenetic inactivation of the BRCA1, BRCA2, or other HR-related genes, which occur during a woman’s lifetime. Therefore, PARP inhibitors could prove beneficial to a larger group of ovarian cancer patients, assuming a patient’s HR status can be properly identified.

To test this hypothesis, the U.K. researchers developed a functional assay to test the HR status of primary ovarian cancer cultures derived from patients’ ascitic fluid. The test, referred to as the “RAD51 assay,” scans the cancer cells and identifies which tumor samples contain defective DNA repair ability (i.e., HR-deficient) which can be targeted by the PARP inhibitor. The researchers tested the HR status of each culture, and then subjected each one to in vitro cytotoxicity testing using the potent PARP inhibitor PF-01367338 (formerly known as AG-14699).

Study Results: 90% of HR-Deficient Ovarian Cancer Cultures Respond to PARP Inhibition

Upon testing completion, the U.K. researchers discovered that out of 50 primary cultures evaluated for HR status and cytotoxicity to the PARP inhibitor, approximately 40% of the cultures evidenced normal HR activity, while 60 percent of the cultures evidenced deficient HR activity. Cytotoxicity to PARP inhibitors was observed in approximately 90 percent of the HR deficient cultures, while no cytotoxicity was seen in the cultures that evidenced normal HR activity. Specifically, the PARP inhibitor PF-01367338 was found to selectively block the spread of ovarian tumor cells with low RAD51 expression.

Conclusion

Based upon the findings above, the U.K. researchers concluded that HR-deficient status can be determined in primary ovarian cancer, and that such status correlates with in vitro response to PARP inhibition.  Accordingly, the researchers concluded that potentially 50 to 60 percent of ovarian cancers could benefit from PARP inhibitors, but they note that use of the RAD51 assay as a biomarker requires additional clinical trial testing.  Although the RAD51 assay test that was used by the U.K. researchers to examine tumor samples in the laboratory is not yet suitable for routine clinical practice, the U.K. research team hopes to refine it for use in patients.

Upon presentation of the testing results, Dr. Asima Mukhopadhyay said:

“Our results show that this new test is almost 100 percent effective in identifying which ovarian cancer patients could benefit from these promising new drugs.  We have only been able to carry out this work because of the great team we have here which includes both doctors and scientists.”

The team based at Queen Elizabeth Hospital, Gateshead and the Newcastle Cancer Centre at the NICR, Newcastle University collaborated with Pfizer to develop the new assay to test tumor samples taken from ovarian cancer patients when they had surgery.

Dr. Mukhopadhyay added:

“Now we hope to hone the test to be used directly with patients and then carry out clinical trials. If the trials are successful we hope it will help doctors treat patients in a personalised and targeted way based on their individual tumour. It is also now hoped that PARP inhibitors will be useful for a broad range of cancers and we hope this test can be extended to other cancer types.”

Dr. Lesley Walker, Cancer Research UK’s director of cancer information, said:

“It’s exciting to see the development of promising new ‘smart’ drugs such as PARP inhibitors. But equally important is the need to identify exactly which sub-groups of patients will benefit from these new treatments. Tests like this will become invaluable in helping doctors get the most effective treatments quickly to patients, sparing them from unnecessary treatments and side effects.”

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About The Researchers

Dr. Asima Mukhopadhyay is a doctor and clinical research fellow working at the Queen Elizabeth Hospital, Gateshead and the Northern Institute for Cancer Research at Newcastle University. Queen Elizabeth Hospital is run by Gateshead Health NHS Foundation Trust and is the home for gynecological oncology for the North East of England and Cumbria. She received a bursary to attend the conference, which was awarded on the merit of her work.

Key researchers on the study included Dr. Richard Edmondson, who was funded by the NHS, and Professor Nicola Curtin, who was funded by the Higher Education Funding Council. Dr Asima Mukhopadhyay is funded by the NHS.

Dr Richard Edmondson is a consultant gynecological oncologist at the Northern Gynaecological Oncology Centre, Gateshead and a Senior Lecturer at the Newcastle Cancer Centre at the Northern Institute for Cancer Research, Newcastle University, and is a member of the research team.

Nicola Curtin is Professor of Experimental Cancer Therapeutics at Newcastle University and is the principal investigator of this project.

Current and future work involves working closely with Pfizer. Pfizer developed one of the PARP inhibitors and supported this project.

About The Newcastle Cancer Centre

The Newcastle Cancer Centre at the Northern Institute for Cancer Research is jointly funded by three charities: Cancer Research UK, Leukaemia and Lymphoma Research, and the North of England Children’s Cancer Research Fund.  Launched in July 2009, the Centre is based at the Northern Institute for Cancer Research at Newcastle University.  The Centre brings together some of the world’s leading figures in cancer research and drug development. They play a crucial role in delivering the new generation of cancer treatments for children and adults by identifying new drug targets, developing new drugs and verifying the effectiveness and safety of new treatments. This collaborative approach makes it easier for researchers to work alongside doctors treating patients, allowing promising new treatments to reach patients quickly.

About the NCRI Cancer Conference

The National Cancer Research Institute (NCRI) Cancer Conference is the UK’s major forum for showcasing the best British and international cancer research. The Conference offers unique opportunities for networking and sharing knowledge by bringing together world leading experts from all cancer research disciplines. The sixth annual NCRI Cancer Conference was held from November 7-10, 2010 at the BT Convention Centre in Liverpool. For more information visit www.ncri.org.uk/ncriconference.

About the NCRI

The National Cancer Research Institute (NCRI) was established in April 2001. It is a UK-wide partnership between the government, charity and industry which promotes cooperation in cancer research among the 21 member organizations for the benefit of patients, the public and the scientific community. For more information visit www.ncri.org.uk.

NCRI members include: the Association of the British Pharmaceutical Industry (ABPI); Association for International Cancer Research; Biotechnology and Biological Sciences Research Council; Breakthrough Breast Cancer; Breast Cancer Campaign; CancerResearch UK; CHILDREN with LEUKAEMIA, Department of Health; Economic and Social Research Council; Leukaemia & Lymphoma Research; Ludwig Institute for Cancer Research; Macmillan Cancer Support; Marie Curie Cancer Care; Medical Research Council; Northern Ireland Health and Social Care (Research & Development Office); Roy Castle Lung Cancer Foundation; Scottish Government Health Directorates (Chief Scientist Office);Tenovus; Welsh Assembly Government (Wales Office of Research and Development for Health & Social Care); The Wellcome Trust; and Yorkshire Cancer Research.

Access Pharma Commences European Phase II Study of ProLindac™ + Paclitaxel In Platinum-Sensitive Ovarian Cancer Patients

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Access Pharmaceuticals announces commencement of a Phase 2 combination trial for its second generation DACH-platinum cancer drug, ProLindac™ (formerly known as AP5346), in platinum-sensitive ovarian cancer patients. This trial is an open-label, Phase 2 study of ProLindac™ given intravenously with paclitaxel. The combination trial will be conducted in up to eight European participating centers.

Access Pharmaceuticals, Inc., a biopharmaceutical company leveraging its proprietary drug-delivery platforms to develop treatments in the areas of oncology, cancer supportive care and diabetes, announces commencement of a Phase 2 combination trial for its second generation DACH-platinum [the active part of the currently-marketed drug, oxaliplatin] cancer drug, ProLindac™ (formerly known as AP5346), in platinum-sensitive ovarian cancer patients. This trial is an open-label, Phase 2 study of ProLindac™ given intravenously with paclitaxel. The combination trial will be conducted in up to eight European participating centers.

“We are very pleased to be able to begin this trial, which will be the first of several ProLindac-based combination studies in a variety of indications,” said Prof. Esteban Cvitkovic, Vice Chairman Europe and Senior Director Clinical Oncology R&D, Access Pharmaceuticals, Inc. He continued, “The ambitious two-step design of the study will allow us to rapidly benchmark ProLindac/paclitaxel in a clinical setting where there is a clear need to establish an improved standard for long-term tumor responses. When treated using the current first-line combination of carboplatin/paclitaxel, more than half of patients with advanced ovarian cancer will relapse. There are very few second-line options. Approved agents for second-line and later therapy are currently focused primarily on the palliation of more resistant tumors. This lack of valid second-line options presents an opportunity to prove the role of ProLindac-based combinations in ovarian cancer.”

“After optimizing ProLindac’s scaled-up manufacturing process, we are pleased to be moving forward with its clinical development,” said Jeff Davis, President and CEO, Access Pharmaceuticals, Inc. He continued, “We think there is a significant clinical need and commercial opportunity for safer, more effective platinum drugs.”

Access Pharmaceuticals previously announced positive safety and efficacy results from its Phase 2 monotherapy clinical study of ProLindac™ in late-stage, heavily pretreated ovarian cancer patients. In this study, 66% of patients who received the highest dose achieved clinically meaningful disease stabilization according to RECIST [Response Evaluation Criteria in Solid Tumors] criteria, including sustained significant reductions in CA-125 (the established specific serum marker for ovarian cancer) observed in several patients. No patient in any dose group exhibited signs of acute neurotoxicity, which is a major adverse side-effect of the approved DACH platinum, Eloxatin®. ProLindac was very well tolerated, with only minor sporadic hematologic toxicity.

Access Pharmaceuticals is evaluating various indications where DACH platinum-based combinations have been proven active, such as hepatocarcinoma, biliary tree cancer and pancreatic cancer before deciding on an expanded Phase 2 program.

About ProLindac:

ProLindac™ is a novel DACH platinum prodrug that has completed a phase 2 monotherapy study in ovarian cancer patients. It is a polymer therapeutic that utilizes a safe, water-soluble nanoparticulate system to deliver DACH platinum to tumors, while reducing delivery to normal tissue, resulting in an increase in drug effectiveness and a significant decrease in toxic side-effects seen in the currently marketed DACH platinum, Eloxatin®.

For more information, please visit http://www.accesspharma.com/product-programs/prolindac/.

Source: Access Pharmaceuticals Commences ProLindac Phase 2 Combination Clinical Trial – Multicenter, Open-Label Trial to Target Platinum-Sensitive Ovarian-Cancer Patients, News Release, Access Pharmaceuticals, Inc., November 3, 2010.

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Peptide Being Tested for Atherosclerosis Inhibits Ovarian Cancer Growth; Clinical Trial Planned

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A drug in testing to treat atherosclerosis significantly inhibited growth of ovarian cancer in both human cell lines and mouse models, marking the first such report of a peptide being used to fight malignancies, according to a study by researchers at UCLA’s Jonsson Comprehensive Cancer Center.

A drug in testing to treat atherosclerosis significantly inhibited growth of ovarian cancer in both human cell lines and mouse models, marking the first such report of a peptide being used to fight malignancies, according to a study by researchers at UCLA’s Jonsson Comprehensive Cancer Center.

The study follows a previous discovery by the same group showing that a protein called apolipoprotein A-I (apoA-I) may be used as a biomarker to diagnose early stage ovarian cancer in patients, when it typically is asymptomatic and much easier to treat. These earlier findings could be vital to improving early detection, as more than 85 percent of ovarian cancer cases present in the advanced stages, when the cancer has already spread and patients are more likely to have a recurrence after treatment, said Dr. Robin Farias-Eisner, chief of gynecologic oncology and co-senior author of the study with Dr. Srinu Reddy, a professor of medicine.

Robin Farias-Eisner, M.D., Ph.D., Chief of Gynecologic Oncology, UCLA Jonsson Comprehensive Cancer Center

“The vast majority of ovarian cancer patients are diagnosed with advanced disease and the vast majority of those, after surgery and chemotherapy, will eventually become resistant to standard therapy,” Farias-Eisner said. “That’s the reason these patients die. Now, with this peptide as a potential therapy, and if successful in clinical trials, we may have a novel effective therapy for recurrent, chemotherapy-resistant ovarian cancer, without compromising the quality of life during treatment.”

The study was published Nov. 1, 2010 in the early online edition of the peer-reviewed journal Proceedings of the National Academy of Sciences.

In their previous work, Farias-Eisner, Reddy and their research teams identified three novel biomarkers that they used to diagnose early stage ovarian cancer. In September 2009, the U.S. Food and Drug Administration cleared the first laboratory test that can indicate the likelihood of ovarian cancer, OVA1™ Test, which includes the three biomarkers identified and validated by Farias-Eisner, Reddy and their research teams.

They observed that one of the markers, apoA-I, was decreased in patients with early stage disease. They wondered why the protein was decreased and set out to uncover the answer. They speculated that the protein might be protective, and may be preventing disease progression.

The protein, apoA-I, is the major component of HDL [high-density lipoprotein], the good cholesterol, and plays an important role in reverse cholesterol transport by extracting cholesterol and lipids from cells and transferring it to the liver for extraction. The protein also has anti-inflammatory and antioxidant properties. Because lipid transport, inflammation and oxidative stress are associated with the development and progression of cancer, Farias-Eisner and Reddy hypothesized that the reduced levels of apoA-I in ovarian cancer patients may be causal in disease progression.

Mice that were engineered to have many copies of human apoA-I gene showed very little cancer development when induced with ovarian cancer, while the mice without the extra copies of apoA-I showed much more disease. The mice with extra copies of the apoA-I gene also lived 30 to 50 percent longer than those who didn’t receive it.

Farias-Eisner and Reddy wanted to treat the mice that had more cancer with the protein apoA-I, but it was too large to conveniently administer, having 243 amino acids. The researchers then turned to apoA-I mimetic peptides—only 18 amino acids in length—that are being tested for cardiovascular diseases. That project had been ongoing for a number of years at UCLA, said Reddy, who is also a part of the cardiovascular research team led by Dr. Alan M. Fogelman, executive chair of the Department of Medicine.

Srinivasa T. Reddy, Ph.D., M.Sc., Professor, Division of Cardiology, Depart. of Molecular & Medical Pharmacology, David Geffen School of Medicine, University of California at Los Angeles

“The smaller peptides mimic the larger apoA-I protein and provided us with agents we could give to the mouse to see if it was effective in fighting ovarian cancer,” said Reddy. “One of the peptides was being tested as an experimental therapy for atherosclerosis, so we already have some information on how it’s being tolerated in humans, which would be vital information to have if we progressed to human studies in ovarian cancer.”

The peptide, thus far, has caused little to no side effects in atherosclerosis patients, Reddy said, a hopeful sign that it might be well tolerated in ovarian cancer patients.

The mice that were given the peptide by injection had about 60 percent less cancer than the mice that did not receive the peptide, Farias-Eisner said. The peptide also was given in drinking water or in mouse food and proved to be as effective when administered that way.

“It was an exciting result,” Farias-Eisner said. “It looked like we had something that could be ingested or injected that might be very effective against ovarian cancer progression.”

Farias-Eisner said the peptide avidly binds oxidized lipids, one of which is known to stimulate cancer cells to survive and multiply. In the mouse studies, the mice that received peptide had significantly lower levels of this cancer promoting lipid.

An early phase clinical trial is being planned testing the peptide in patients with aggressive ovarian cancers that are resistant to chemotherapy, a group of patients whose median survival is just 40 months. Farias-Eisner hopes the study will be started and completed within two years.

The study was funded by the Womens Endowment, the Carl and Roberta Deutsch Family Foundation, the Joan English Fund for Women’s Cancer Research, the National Institutes of Health and the West Los Angeles Veterans Affairs Medical Center.

UCLA’s Jonsson Comprehensive Cancer Center has more than 240 researchers and clinicians engaged in disease research, prevention, detection, control, treatment and education. One of the nation’s largest comprehensive cancer centers, the Jonsson center is dedicated to promoting research and translating basic science into leading-edge clinical studies. In July 2010, the Jonsson Cancer Center was named among the top 10 cancer centers nationwide by U.S. News & World Report, a ranking it has held for 10 of the last 11 years. For more information on the Jonsson Cancer Center, visit our website at http://www.cancer.ucla.edu.

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