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5032 Background: DMXAA (AS1404) is a small-molecule vascular disrupting agent, which in animal models shows additive or supra-additive effects with cytotoxics, including taxanes and platinum agents. This phase II study evaluated DMXAA in combination with carboplatin and paclitaxel in recurrent platinum-sensitive ovarian cancer patients with a progression-free interval of more than 6 months after response to platinum-based chemotherapy. Methods: Patients had first diagnosed disease FIGO stage Ic-IV, with presence of recurrent disease confirmed by imaging. Patients were randomised 1:1 to receive up to 6 cycles of carboplatin (AUC 6 mg/ml × min) and paclitaxel (175 mg/m2) with or without DMXAA (1200 mg/m2). Safety assessments included EKG, adverse events, laboratory screens and ophthalmic exam. Efficacy endpoints are objective response rates, time to progression, duration of response and stable disease, and median and 1-year survival. Results: 55 patients have been enrolled to date from a planned total of ∼70. Initial safety findings in the two arms are comparable. Preliminary investigator-assessed RECIST response data show the following unconfirmed outcomes: of 17 patients in the DMXAA arm, there are 10 with partial responses (PRs), 7 with stable disease (SD) and 0 with progressive disease (PD); of 14 patients in the control arm, there are 8 PRs, 6 SDs and 0 PDs. Conclusions: Initial safety findings suggest that addition of DMXAA to standard doses of carboplatin and paclitaxel did not add significantly to toxicity. Efficacy assessments are ongoing to determine the value of the triple combination in recurrent ovarian cancer. No significant financial relationships to disclose.

5025 Background: Letrozole is a potent oral aromatase inhibitor which rapidly suppresses circulating estrogen levels by 99% in postmenopausal women. By comparison with cytotoxic agents it is very well tolerated. We previously demonstrated an ‘endocrine sensitive’ subgroup of ovarian cancer patients with ER histoscore cutoff of ≥150 (Bowman et al, Clin Can Res 2002). Methods: This was a phase II study with a planned sample size of 33 patients. Eligible patients had relapsed EOC or primary peritoneal cancer with an ER histoscore of ≥150 and a rising CA125 that had progressed according to Rustin’s criteria. Patients were treated with letrozole 2.5mg daily until clinical or marker evidence of disease progression. The primary endpoint was response according to CA125 and RECIST criteria. Biomarker analysis by tissue microarray is also being performed. Results: 46 patients were accrued, 45 of whom were eligible. The median age was 61 (range 39–81). 24, 10 and 10 patients had received 1,2 and >2 previous lines of chemotherapy respectively. Of 43 patients evaluable for CA125 response, 7 (16%) had a response (decrease of >50%) and 16 (37%) patients had not progressed (doubling of CA125) following 12 weeks on treatment. In the CA125 responders, the nadir CA125 ranged from 0.7–49% of baseline (actual % of baseline: 0.7, 2.6, 11.1, 17.6, 23.6, 42.6, 49). Of the 7 responding patients, 5 had received only one previous line of chemotherapy. The time taken to achieve the nadir CA125 value ranged from 10 to 36 weeks, with a median of 13 weeks. Of 33 patients evaluable for radiological response, 3 (9%) had a PR and 14 (42%) had stable disease at 12 weeks. Overall, 11 patients (26%) had a PFS of >6 months and 2 patients (5%) had a PFS of ≥2 years. Conclusions: To our knowledge this is the first study of a hormonal agent in a selected ER +ve population of ovarian cancer patients. Promising efficacy of the agent is demonstrated in this population of pre-treated patients, many with a considerable bulk of disease. Given the median time of 13 weeks to response, we suggest that this strategy should be tested in ER+ve ovarian cancer patients in the adjuvant setting following first line chemotherapy No significant financial relationships to disclose.

The pattern of c-myc gene organization and expression has been examined in resected colonic tumors and in the adjacent normal colon from 15 patients undergoing radical surgery. DNA hybridization showed no evidence of gene amplification or rearrangement. Transcripts of the c-myc messenger ribonucleic acid (mRNA) were elevated up to 32-fold in 12 of 15 tumors. The gene product, p62c-myc, was detected by both immunoblotting and immunohistology using a monoclonal antibody raised against a synthetic peptide immunogen. There was close correlation between c-myc mRNA copy number and p62c-myc abundance. Three well differentiated tumors contained high levels of transcript and protein, whereas four poorly differentiated tumors had the lowest levels. The assay of oncogene products may provide new biologically relevant tumor markers for determining prognosis and guiding treatment.

We have studied the utility of the c-myc oncogene product as tumour marker using a set of monoclonal antibodies raised against synthetic peptides constructed from sequence data of the human c-myc oncoprotein. One antibody, Myc1 - 9E10, raised against the C-terminal 32 amino acids, has been shown to detect specifically the 62 kDa c-myc gene product in tumour cells. Immunoblotting of sera and urine with this antibody consistently revealed a single 40 kDa band (p40). Quantitative analysis using dilution dot immunoblotting demonstrated a considerable increase in the titre of p40 in the sera of 51 patients with a wide range of advanced solid tumours when compared with 17 healthy controls and 50 patients with non-malignant diseases. Serial measurement of the p40 titre in 12 patients with resected colorectal carcinoma shows a gradual return to normal with a half-life of 7 days. Our data suggests that p40 may be a useful new marker for monitoring tumour activity.

We have performed representational difference analysis (RDA) on DNA from tumor cells and normal fibroblasts isolated from the ascites of a patient with ovarian cancer. Five of six products of the RDA were homozygously deleted from the tumor DNA. One of these products has been characterized and identifies a homozygous deletion of approximately 6.9 Mb at chromosome 9p21 in the original ovarian tumor material. This deletion encompasses CDKN2A (p16), CDKN2B (p15), and IFN-alpha. PCR analysis of other tumor cell lines using the novel STS based on the RDA product has shown it to lie between IFN-alpha and p16, and to identify the distal extent of a homozygous deletion in another ovarian cancer cell line. These data provide further evidence for a tumor suppressor locus distinct from, but mapping close to, p16 on 9p21. Cytogenetic analysis using comparative genomic hybridization (CGH) performed on the same primary tumor confirmed a loss of material from chromosome 9p. However, the CGH technique had neither the resolution nor the sensitivity to define a subregion of homozygous loss.

2531 Background: Acelarin (NUC-1031) is a first-in-class nucleotide designed to overcome key cancer cell resistance by having nucleoside transporter-independent cellular uptake, activity independen...

Here, we sought to obtain evidence that the progesterone receptor (PR) may be functional in ovarian cancer and regulated by estrogen. Megestrol acetate inhibited growth of the PR-positive PE04 ovarian carcinoma xenograft but not the PR-negative HOX 60 xenograft. PR concentration was higher in early-stage (I/II) tumors than in advanced-stage (III/IV) tumors (P = 0.007) and in tumors of endometrioid histology compared to other carcinoma subtypes (P = 0.009). Patients with a tumor PR concentration of40 fmol/mg protein had significantly improved survival over those patients whose tumors contained40 fmol/mg (P = 0.0007; log-rank). Evidence of PR regulation by estrogen was obtained by endocrine manipulation of the PE04 xenograft. PR content of PE04 xenografts fell from 145 to 7 fmol/mg protein in ovariectomized mice and was 2 fmol/mg in male mice. Administration of 17-beta-estradiol increased PR content to 745 fmol/mg. In primary ovarian carcinomas, PR was significantly associated with ER concentrations (P0.0001), suggesting regulation of PR levels by estrogen. This association was present for tumors of endometrioid histology (P0.0001) but not for those with serous histology (P = 0.31). These data point to the regulation of PR levels by estrogen in ovarian cancer and to a mediatory role for PR in the inhibition of growth induced by progestin.

A recent Japanese Gynecologic Oncology Group phase III clinical trial in patients with ovarian cancer receiving the conventional paclitaxel-carboplatin combination once every 3 weeks or "dose-dense" paclitaxel once a week with carboplatin once every 3 weeks has reported a large progression free survival advantage for the dose-dense therapy. Recent advances in the molecular understanding of ovarian cancer point to molecular differences between paclitaxel and carboplatin sensitivity which link to the status of BRCA genes--so called familial and sporadic "BRCAness." It may be that the change in the way we use paclitaxel allows us to more effectively target the heterogeneity of such intrinsic sensitivity/resistance to these agents in the adjuvant therapy of ovarian cancer, leading to significant improvement in the management of the disease.

WWOX is a candidate tumour suppressor gene that exhibits LOH or homozygous deletion in several tumour types. As well as the predominant full-length transcript (variant 1) there also exist alternatively spliced transcripts found previously only in malignant tissue. It has been suggested that proteins encoded by these variants may interfere with normal WWOX function in a dominant negative fashion. The most prevalent alternate transcript demonstrated in ovarian cancer is variant 4, which lacks exons 6-8. Here, we report the first comparison of the mRNA expression of WWOX variants 1 and 4 in human ovarian tumours and normal ovaries, and correlate expression with clinical data. We demonstrate significantly lower WWOX variant 1 expression in tumours than in normal ovaries. This reduction was not associated with any specific clinical subgroup. Variant 4 was expressed at low levels, and significantly associated with high grade and advanced stage ovarian cancer. Furthermore, tumours co-expressing variant 4 and relatively high levels of variant 1 showed significantly worse survival than tumours expressing variant 1 alone. However, variant 4 was also frequently identified in non-malignant ovarian tissue. These results support the role of WWOX variant 1 as a suppressor of ovarian tumouri-genesis, but the role of variant 4 remains speculative.

2514 Background: NUC-1031 is a first-in-class nucleotide analogue utilising phosphoramidate chemistry to enhance anti-cancer efficacy and safety. In preclinical studies NUC-1031 demonstrated potent...

2576 Background: NUC-1031 is a novel nucleotide (ProTide) that evades all three key cellular resistance mechanisms associated with gemcitabine (dFdC). NUC-1031 bypasses nucleoside transporters, is activated independent of deoxycytidine kinase and is resistant to cytidine deaminase-mediated degradation. NUC-1031 has demonstrated broad antiproliferative activity in vitro and in vivo. Methods: Patients with relapsed/refractory advanced solid tumors entered in sequential cohorts of up to 6 patients, with escalating doses of NUC-1031 administered as a 5-10 minute IV injection weekly or twice-weekly. Ongoing objectives are to determine recommended phase II dose, safety profile, pharmacokinetics (PK) and preliminary anti-tumor activity. Results: 8 patients (5 female, 3 male) with pancreatic (2), colorectal (2), breast (1), and ovarian (1) cancers; cholangiocarcinoma (1) and unknown primary (1) have been enrolled. Two dose levels - 500mg/m2 (4) and 1000mg/m2 (1) weekly and one dose level - 375 mg/m2(3) twice-weekly. No DLTs have been observed. Mean AUC (0 - 24 h) for NUC-1031 was 150.3 ± 84.8 µM/h (n=5). dFdC and dFdU were detected in plasma up to 24 h (range of 0 - 5.8 µM for dFdC and 0 - 14.9 µM for dFdU). NUC-1031 excreted in urine mainly as dFdU. The Table shows rapid elimination of NUC-1031 from plasma and high intracellular levels of the active gemcitabine triphosphate at 2 and 24 h. Stable disease achieved in 1 patient with rapidly progressing breast cancer. Two further patients had symptomatic relief and improved QOL, including a dramatic reduction in ascites and pain. Conclusions: PK data show NUC-1031 has ≥ 10x higher intracellular levels of the active compound, dFdCTP, and significantly lower plasma Cmax levels of the toxic metabolite, dFdU, compared to equivalent levels of gemcitabine. NUC-1031 has shown better intracellular delivery and toxicity profile than gemcitabine with some promising early indicators of clinical efficacy. Clinical trial information: NCT01621854. [Table: see text]

Forty-seven epithelial ovarian cancers were analyzed for loss of heterozygosity (LOH) at D11S35 (11q22), close to the progesterone receptor (PR) gene, and for tumoral estrogen receptor (ER) and PR content. Thirty-eight of 47 tumors were informative, and, of these, 14 exhibited LOH. There was a significant association (P = 0.014) between D11S35 LOH and low tumoral PR content. For all informative tumors, there was no correlation between ER and PR; however, exclusion of tumors with LOH from the informative series revealed a linear correlation between tumoral ER and PR (P = 0.013), and established ER (P = 0.025) and PR (P = 0.05) content as significant factors in relation to patient survival. Patients with ER-rich tumors with D11S35 LOH had particularly poor survival compared with ER-rich, D11S35 heterozygous, no loss patients (P = 0.014). Analysis of the same tumors using two other microsatellites, D11S935 (11p13) and NM23 (17q22), showed no statistically significant relationships, although there were nonsignificant trends for the correlation of ER and PR expression in informative tumors without allele loss at these loci. We propose that genomic structural alteration at or close to the PR gene locus has biological and clinical sequelae in ovarian cancer.

Many regions of the genome exhibit loss of heterozygosity (LOH) in epithelial ovarian cancer (EOC) suggesting sites of recessive genetic elements such as tumor suppressor genes. We performed detailed LOH studies of chromosomes 17 and 11 using 24 microsatellite repeat markers in a population of 47 patients with EOC. Univariate statistical analysis revealed that significant co-losses of chromosomal loci occurred between 17p and 17q whole arms (p=0.0003), NME1 (17q21) with D11S922 (11p15.5) (p=0.0067) and D11S912 (11q24) with D11S935 (11p13) (p=0.0073). Statistical analysis of the relationship between LOH on particular chromosomal arms and clinicopathological factors revealed a significant association between serous histological subtype of ovarian adenocarcinoma and chromosome 17p (p=0.0052) and telomeric 17q (p=0.0007) LOH. An analysis of specific polymorphic chromosomal loci demonstrated that adverse survival was significantly associated with LOH at 11q24 (p=0.0067) and 17q21 (p=0.0076). There were nonsignificant trends suggesting a relationship between chromosome 17p LOH and poorly differentiated (p=0.025) and advanced FIGO stage (p=0.031) tumours. Considering these statistical associations, a preliminary multistep model for involvement of chromosomes 11 and 17 in ovarian neoplasia can be constructed.

Clinical resistance to chemotherapy is a frequent event in cancer treatment and is closely linked to poor outcome. High-grade serous (HGS) ovarian cancer is characterized by p53 mutation and high levels of genomic instability. Treatment includes platinum-based chemotherapy and initial response rates are high; however, resistance is frequently acquired, at which point treatment options are largely palliative. Recent data indicate that platinumresistant clones exist within the sensitive primary tumor at presentation, implying resistant cell selection after treatment with platinum chemotherapy. The AKT pathway is central to cell survival and has been implicated in platinum resistance. Here, we show that platinum exposure induces an AKT-dependent, prosurvival, DNA damage response in clinically platinum-resistant but not platinum-sensitive cells. AKT relocates to the nucleus of resistant cells where it is phosphorylated specifically on S473 by DNA-dependent protein kinase (DNA-PK), and this activation inhibits cisplatin-mediated apoptosis. Inhibition of DNA-PK or AKT, but not mTORC2, restores platinum sensitivity in a panel of clinically resistant HGS ovarian cancer cell lines: we also demonstrate these effects in other tumor types. Re-sensitization is associated with prevention of AKT-mediated BAD phosphorylation. Strikingly, in patient-matched sensitive cells, we do not see enhanced apoptosis on combining cisplatin with AKT or DNA-PK inhibition. Insulin-mediated activation of AKT is unaffected by DNA-PK inhibitor treatment, suggesting that this effect is restricted to DNA damage–mediated activation of AKT and that, clinically, DNA-PK inhibition might prevent platinum-induced AKT activation without interfering with normal glucose homeostasis, an unwanted toxicity of direct AKT inhibitors.