Roshan Agarwal

Ovarian cancer: strategies for overcoming resistance to chemotherapy

Ovarian cancer is responsible for 4% of deaths from cancer in women. Treatment comprises a combination of surgery and chemotherapy, but patients typically experience disease relapse within 2 years of the initial treatment. Further treatment can extend survival, although relapse eventually occurs again. A better understanding of the mechanisms that underlie this drug resistance should allow treatment to be optimized, so that substantial improvements in the outlook for women with this disease can be achieved.

Mechanisms of transcoelomic metastasis in ovarian cancer

Metastasis from epithelial ovarian cancer can occur via the transcoelomic, haematogeneous, or lymphatic route. Of these, transcoelomic metastasis is the most common, and is responsible for the greatest morbidity and mortality in women with this disease. Unfortunately, very little is known about the mechanisms behind this process. This review assesses the current evidence and ideas about the biology of transcoelomic dissemination. The mechanisms of cell detachment, migration, and implantation in transcoelomic metastasis are placed within the context of clinical observations of ovarian cancer to derive a stepwise hypothesis of this process. Evidence for transcoelomic dissemination versus transcoelomic metaplasia in ovarian cancer is presented. Future high throughput microarray studies that compare changes at a genomic and gene expression level between primary ovarian tumours and their peritoneal metastases are hoped to lead to a more conclusive picture of transcoelomic metastasis, and to delineate the key molecular players in this process. These studies might also result in the identification of potential new therapeutic targets in ovarian cancer.

The First-in-Human Study of the Hydrogen Sulfate (Hyd-Sulfate) Capsule of the MEK1/2 Inhibitor AZD6244 (ARRY-142886): A Phase I Open-Label Multicenter Trial in Patients with Advanced Cancer

Purpose: In part A, the aim was to define the maximum tolerated dose (MTD) of the hydrogen sulfate (Hyd-Sulfate) oral capsule formulation of the mitogen-activated protein kinase kinase inhibitor AZD6244 (ARRY-142886). In part B, the aim was to compare the pharmacokinetic profile of the new Hyd-Sulfate capsule with the initial AZD6244 free-base suspension and further characterize the pharmacodynamic profile and efficacy of the new formulation. Experimental Design: In part A, 30 patients received escalating doses of AZD6244 Hyd-Sulfate twice daily. In part B, 29 patients were randomized to a single dose of the Hyd-Sulfate capsule or free-base suspension, followed by a washout, then a single dose of the alternative formulation. Patients received the Hyd-Sulfate capsule twice daily at MTD of part A thereafter. Results: The MTD of the Hyd-Sulfate capsule was 75 mg twice daily. Dose limiting toxicities were Common Terminology Criteria for Adverse Events grade 3 acneiform rash and pleural effusion. Fatigue (65.7%) and acneiform dermatitis (60.0%) were the most frequent adverse events at the MTD. Based on area under curve0-24, exposure of the 75 mg Hyd-Sulfate capsule relative to the 100 mg free-base suspension was 197% (90% confidence interval, 161-242%). Pharmacodynamic analysis showed that inhibition of 12-O-tetradecanoylphorbol-13-acetate–induced extracellular signal-regulated kinase phosphorylation in peripheral blood lymphocytes was related to plasma concentrations of AZD6244, with an estimated IC50 of 352 ng/mL and maximum inhibition (Emax) of ∼91%, showing target inhibition. A patient with metastatic melanoma bearing a V600E BRAF mutation achieved a complete response persisting after 15 months of therapy. Conclusions: The AZD6244 Hyd-Sulfate capsule formulation has shown a favorable toxicity, pharmacokinetic, and pharmacodynamic profile, and is being taken forward in ongoing clinical trials. Clin Cancer Res; 16(5); 1613–23

A study of symptoms described by ovarian cancer survivors

OBJECTIVEnA cross-sectional, observational study to evaluate physical and psychological symptoms experienced by patients following completion of treatment for ovarian cancer and compared to symptoms documented in their hospital notes.nnnMETHODSnWomen attending follow-up clinic at Hammersmith Hospital having undergone treatment for primary or relapsed ovarian cancer were asked to complete two validated questionnaires (EORTC QLQ-C30 and QLQ-OV28) and a wellbeing thermometer. Results were assessed and stratified by patient age, tumour stage, relapse status, type of chemotherapy received and treatment-free interval. Symptoms reported in questionnaires were compared to those documented in patients hospital notes.nnnRESULTSnOf 116 women approached, 100 (86%) participated in this study and had received chemotherapy for ovarian cancer between 2003 and 2010. The most frequently described and severe symptoms reported in the questionnaires were emotional symptoms, negative feelings about treatment or prognosis, fatigue and pain. Dyspareunia, cognitive impairment and peripheral neuropathy were also frequently described. Symptom severity was independent of variables such as disease stage, type of chemotherapy received and relapse status. The wellbeing thermometer scores closely correlated with pain, fatigue, weakness, gastrointestinal symptoms and attitude to disease or treatment (p<0.001). There was a marked discordance between questionnaire-reported symptoms and those recorded in hospital notes.nnnCONCLUSIONSnThe majority of women surveyed experienced persistent psychological and physical symptoms following ovarian cancer treatment; in particular: psychological concerns, sexual inactivity and fatigue, all potentially reversible with appropriate interventions. Our results highlight the extent of symptoms described by ovarian cancer survivors and the need for them to be adequately acknowledged and addressed.

Flow Cytometric Method for Determining Folate Receptor Expression on Ovarian Carcinoma Cells

The α‐folate receptor (α‐FR) is a folate transporter with restricted expression levels in normal tissues. It is over‐expressed in several cancers, particularly epithelial carcinomas, including nonmucinous ovarian carcinoma. It offers a novel therapeutic target for selective imaging and cytotoxic agents. Measurement of the receptor could be a valuable tool in selecting patients more likely to respond to new drugs that target the α‐FR, and monitoring them while on treatment. While tumor samples are often unavailable, a number of patients who relapse develop ascites, which are often rich in tumor cells. We have therefore developed a triple antibody flow cytometric method to assess α‐FR expression on tumor cells from ascites. An antibody to BerEP4, an epithelial cell marker expressed on >90% ovarian cancers, labeled with fluorescein, and an α‐FR antibody labeled with antimouse‐phycoerythrin have been used to label tumor cells, with a CD45‐phycoerythrin‐cyanine5 antibody used to exclude white blood cells from the analysis. The method was optimized using human carcinoma cell lines (JEG‐3, IGROV‐1, and KB cells). Calibrated beads were used to quantify the number of antibodies bound per cell. The triple antibody protocol successfully measured α‐FR expression levels in cell lines spiked with blood. Tumor cells were obtained from ascites in 25 patients with relapsed ovarian cancer. In each case sufficient cells were harvested to identify an epithelial cell population to estimate the number of binding sites/cell. All the samples contained a single population of BerEP4, α‐FR positive cells between 5 × 103 and 5 × 105 antibody binding sites/cell. The method can be used to determine the number of anti‐α‐FR antibodies bound per epithelial cell in ascites from patients with ovarian carcinoma. The results obtained were reproducible and the method could be applied to specimens that had been stored at −80°C.

Eligibility of patients with brain metastases for phase I trials: time for a rethink?

Since the inception of phase I clinical trials in cancer, patients with symptomatic brain metastases have commonly been excluded from participation because of a poor outlook. However, patients with asymptomatic brain metastases pose an increasingly frequent challenge for clinicians: more sensitive brain imaging can identify clinically silent brain metastases; frequency of detection might have increased because of changes in the natural history of many tumour types as a result of more effective systemic treatment; and routine brain imaging as a screening procedure before entry into a clinical trial can show lesions which are of questionable clinical importance, but which frequently preclude trial enrolment. Evidence suggests that delaying whole-brain radiotherapy until symptomatic progression has no adverse effect on prognosis. Safety and efficacy data are accumulating for targeted agents to treat brain metastases. We think that a subset of patients with asymptomatic brain metastases might be appropriately entered into phase I trials, and we present our approach for their stratification. As a consequence, patients might have increased access to experimental treatments and thus effective interventions for brain metastases might be developed more promptly.

A Study to Evaluate the Cause of Bone Demineralization in Gynecological Cancer Survivors

BACKGROUNDnAn association between treatment for gynecological cancers and risk of osteoporosis has never been formally evaluated. Women treated for these cancers are now living longer than ever before, and prevention of treatment-induced morbidities is important. We aimed to distinguish, in gynecological cancer survivors, whether cancer therapy has additional detrimental effects on bone health above those attributable to hormone withdrawal.nnnMETHODSnWe performed a retrospective cross-sectional analysis of dual energy x-ray absorptiometry (DEXA) scan results from 105 women; 64 had undergone bilateral salpingo-oophorectomy (BSO) followed by chemotherapy or radiotherapy for gynecological malignancies, and 41 age-matched women had undergone BSO for benign etiologies. All were premenopausal prior to surgery.nnnRESULTSnThe median age at DEXA scan for the cancer group was 42 years, and 66% had received hormonal replacement therapy (HRT) following their cancer treatment. For the benign group, the median age was 40 years, and 87% had received HRT. Thirty-nine percent of cancer survivors had abnormal DEXA scan results compared to 15% of the control group, with the majority demonstrating osteopenia. The mean lumbar spine and femoral neck bone mineral densities (BMDs) were significantly lower in cancer patients. A history of gynecological cancer treatment was associated with significantly lower BMD in a multivariate logistic regression.nnnCONCLUSIONSnWomen treated for gynecological malignancies with surgery and adjuvant chemotherapy have significantly lower BMDs than age-matched women who have undergone oophorectomy for noncancer indications. Prospective evaluation of BMD in gynecological cancer patients is recommended to facilitate interventions that will reduce the risk of subsequent fragility fractures.

Quinone Oxidoreductase-2-Mediated Prodrug Cancer Therapy

An oxidoreductase enzyme, abundant in tumors, can be catalytically activated by a synthetic cofactor to convert a prodrug to a cytotoxic DNA binding species in human subjects. A Lethal Combination for Liver Cancer? Undergoing chemotherapy to treat cancer is a dreaded—and often grueling—experience. Many chemotherapeutic drugs are double-edged swords: Used with the aim of destroying rapidly dividing cancer cells, they also kill normal cells that exhibit this behavior, sometimes resulting in debilitating side effects. For example, destruction of the quickly multiplying cells that line the gastrointestinal tract can lead to painful ulcerations; loss of proliferating bone marrow cells reduces immune system function and can cause anemia. Ideally, chemotherapeutic drugs display greater specificity toward cancer cells, thus reducing toxicity to healthy tissue. Now, Middleton and colleagues describe their work on a chemotherapy regime that shows promise for specifically destroying liver cancer. The system in question is based on the weak alkylating agent CB1954. Monofunctional alkylating agents such as CB1954 react with a single DNA residue, whereas the more potent bifunctional alkylating agents can react with two residues on different DNA strands, cross-linking them and preventing the strands from uncoiling during replication. Rapidly proliferating cells that duplicate their DNA frequently are more sensitive than others to such damage. CB1954 can be converted to a far more cytotoxic bifunctional agent by the oxidoreductase enzyme NQO2—which is ubiquitously expressed in human tissues—but only in the presence of a cofactor. Middleton and co-workers investigated how this chemotherapy system might be used most effectively. Using structural data, they modeled how CB1954 and a synthetic cofactor bind to NQO2, which indicated that the cofactor should saturate NQO2 before CB1954 is added to maximize conversion of CB1954 to its cytotoxic form. On the basis of these data, a phase I clinical study was performed, during which first the cofactor and then CB1954 were administered to patients with several types of cancer, and a maximum tolerated dose for the drug combination was determined. As predicted, DNA cross-links were observed in tumors after treatment. The researchers also compared the fates of the cofactor and CB1954 when they were administered separately or in combination, and saw a striking interaction: The plasma concentration of CB1954 dropped much more sharply in the presence than in the absence of the cofactor, indirectly indicating activation of NQO2 by the cofactor. However, side effects from the drug combination were similar to those caused by CB1954 alone. NQO2 activity was generally elevated in tumors and was low in bone marrow, blood cells, and epithelial cells from the colon, providing an explanation for the lack of additional side effects caused by use of the cofactor. NQO2 activity in liver cancer was higher than in other cancers by a factor of 6, suggesting that the CB1954-cofactor drug combination might be especially effective for treating liver cancer. Moreover, normal liver cells are relatively resistant to the effects of DNA cross-links, probably because of their low rates of cell division. Thus, the authors propose that a phase II efficacy trial for liver cancer patients is in order for this chemotherapeutic agent. DNA-damaging agents are widely used in cancer treatment despite their lack of tumor specificity. Human NQO2 (quinone oxidoreductase-2) is an atypical oxidoreductase because no endogenous electron donor has been identified to date. The enzyme converts CB1954 [5-(aziridin-1-yl)-2,4-dinitrobenzamide], in the presence of the synthetic nicotinamide cofactor analog EP0152R, to a cytotoxic bifunctional alkylating agent. NQO2 activity in hepatocellular tumor tissue is higher than that in other cancer types by a factor of 6 and higher than that in bone marrow by a factor of 20. Structural data from x-ray crystallography and nuclear magnetic resonance spectroscopy allowed us to construct a model of CB1954 and EP0152R binding to NQO2, which suggested an optimal infusion schedule for a phase I trial combining the two agents. Thirty-two patients were treated, and diarrhea and serum transaminase concentrations defined a maximum tolerated dose for the drug combination. There was a clear pharmacokinetic interaction, with EP0152R inducing a marked increase in clearance of CB1954, in keeping with model predictions. We detected DNA interstrand cross-links caused by nitroreduced CB1954 in tumor biopsies from treated patients, demonstrating that the activated prodrug exerts its cytotoxic properties through DNA base alkylation.

Feasibility of trials in ovarian cancer by line of therapy and platinum sensitivity.

Background To rapidly evaluate the significant numbers of novel therapies entering clinical development requires maximization of clinical trial capacity. To enable this, we evaluated the profile of patients with epithelial ovarian cancer (EOC) in clinical practice, compared with those targeted in clinical trials. Methods Patients with EOC treated between March–September 2009 (cohort A, n = 115 patients) and January–July 2012 (cohort B, n = 109 patients), in the North West London Cancer Network with a catchment of 1.2 million, were identified. Patient characteristics were compared with phase II/III EOC studies identified using clinicaltrials.gov (85 trials; 54,603 patients). Results In cohort A, comparing the proportion of patients in clinical practice with those in trials, 40% versus 55% (P = 0.0006) were chemotherapy-naive, 20% versus 9% (P < 0.0001) had platinum-resistant disease (platinum-free interval, <6 months), 16.2% versus 39% (P < 0.0001) were receiving second line, and 43.8% versus 5% (P < 0.0001) third-line chemotherapy or greater, respectively. Ninety-eight percent of treated patients had a performance status of 2 or less. These results were validated in cohort B, UK National Cancer Research Network and US Gynecologic Oncology Group trial databases. Conclusions These results provide the data to enable EOC trial portfolios to be balanced to clinical practice and suggest an increase in emphasis on trials for patients with platinum-resistant disease and third-line chemotherapy or greater, to address an area of clinical need and maximize recruitment.