Heavily pretreated ovarian cancer patients treated by single-agent gemcitabine. A retrospective outcome comparison between platinum-sensitive and platinum-resistant patients

Estimating Treatment-Switching Bias in a Randomized Clinical Trial of Ovarian Cancer Treatment: Combining Causal Inference with Decision-Analytic Modeling

BACKGROUND

Bevacizumab is efficacious in delaying ovarian cancer progression and controlling ascites. The ICON7 trial showed a significant benefit in overall survival for bevacizumab, whereas the GOG-218 trial did not. GOG-218 allowed control group patients to switch to bevacizumab upon progression, which may have biased the results. Lack of data on switching behavior prevented the application of g-methods to adjust for switching. The objective of this study was to apply decision-analytic modeling to estimate the impact of switching bias on causal treatment-effect estimates.

METHODS

We developed a causal decision-analytic Markov model (CDAMM) to emulate the GOG-218 trial and estimate overall survival. CDAMM input parameters were based on data from randomized clinical trials and the published literature. Overall switching proportion was based on GOG-218 trial information, whereas the proportion switching with and without ascites was estimated using calibration. We estimated the counterfactual treatment effect that would have been observed had no switching occurred by denying switching in the CDAMM.

RESULTS

The survival curves generated by the CDAMM matched well with the ones reported in the GOG-218 trial. The survival curve correcting for switching showed an estimated bias such that 79% of the true treatment effect could not be observed in the GOG-218 trial. Results were most sensitive to changes in the proportion progressing with severe ascites and mortality.

LIMITATIONS

We used a simplified model structure and based model parameters on published data and assumptions. Robustness of the CDAMM was tested and model assumptions transparently reported.

CONCLUSIONS

Medical-decision science methods may be merged with empirical methods of causal inference to integrate data from other sources where empirical data are not sufficient. We recommend collecting sufficient information on switching behavior when switching cannot be avoided.

A randomized phase II evaluation of weekly gemcitabine plus pazopanib versus weekly gemcitabine alone in the treatment of persistent or recurrent epithelial ovarian, fallopian tube or primary peritoneal carcinoma

OBJECTIVE

Angiogenesis inhibition is a valuable strategy for ovarian cancer (EOC). Pazopanib (paz) is a potent small molecular inhibitor of VEGF-1, -2, -3, PDGFR, c-kit, and has activity as a single agent in ovarian cancer. We designed a trial to assess the benefit of adding paz to gemcitabine (gem) in patients with recurrent EOC.

METHODS

An open-label, randomized, multi-site, phase 2 trial was conducted (NCT01610206) including patients with platinum resistant or sensitive disease, ≤ 3 prior lines of chemotherapy, and measurable/evaluable disease. Patients were randomly assigned to weekly gem 1000 mg/m² on days 1 and 8 of a 21 day cycle, with or without paz 800 mg QD, stratified by platinum sensitivity and number of prior lines (1 vs 2 or 3). The primary endpoint was PFS.

RESULTS

148 patients were enrolled 2012-2017. Median age was 63 years (30-82); 60% were platinum resistant; median surveillance was 13 months (0.4-54 months). Median PFS was 5.3 (95% CI, 4.2-5.8) vs 2.9 months (95% CI, 2.1-4.1) in the gem arm. The PFS effect was most pronounced in the platinum resistant group (5.32 vs 2.33 months Tarone-Ware p < 0.001). There was no difference in OS. Overall RR (PR 20% vs 11%, Chi-squre p = 0.02) and DCR (80% vs 60%, Chi-square p < 0.001) were higher in the combination. High grade AEs in the combination arm included ≥ Grade 3: hypertension (15%), neutropenia (35%), and thrombocytopenia (12%).

CONCLUSIONS

The addition of paz to gem enhanced anti-tumor activity; those with platinum-resistant disease derived the most benefit from combination therapy, even in the setting of receiving prior bevacizumab.

A phase 1/2a, dose-escalation, safety, pharmacokinetic, and preliminary efficacy study of intraperitoneal administration of BC-819 (H19-DTA) in subjects with recurrent ovarian/peritoneal cancer

BACKGROUND

H19 is a paternally imprinted, oncofetal gene expressed in various embryonic tissues and in 85% of the ovarian tumors. H19-DTA (BC-819) is a DNA plasmid that drives the expression of the diphtheria toxin gene under the regulation of the H19 promoter sequence and therefore is a potential treatment for various tumors that overexpress the H19 gene, among them-ovarian cancer.

OBJECTIVE

To assess the safety and efficacy of intra-peritoneal (IP) instillations of H19-DTA (BC-819) plasmid in treating ovarian/peritoneal cancer patients with advanced recurrent disease.

METHODS

A phase 1-2A multi-centric trial included 14 eligible patients who were either platinum-refractory or platinum-resistant with positive H19 expression. Patients were treated IP with escalating weekly doses of BC-819 for a maximum of 6-9 weeks. Dose-limiting toxicities (DLT) were assessed after the first course of treatment for each patient and each subsequent cohort was enrolled once each subject had completed the first course of treatment and its 4-week follow-up period. The occurrence of adverse events (AEs) and response to treatment were assessed after the induction course and then periodically.

RESULTS

During the study, no DLTs were observed. Only 5 grade 1 and 2 AEs, which occurred in 4 patients were considered as possibly related to BC-819. The best tumor response seen was stable disease. Median survivals of 3.2, 5.3 and 6.5 months were observed for the 60, 120 and 240 mg cohorts, respectively.

CONCLUSIONS

BC-819 can be considered safe and well tolerated in intraperitoneal doses up to 240 mg. Hybridization of intraperitoneal chemotherapy with the biological treatment of BC-819 should be further evaluated in phase 2 and 3 studies.

Response to and toxicity of gemcitabine for recurrent ovarian cancer according to number of previous chemotherapy regimens

AIM

Gemcitabine is used not only as a second-line, but also as a third-line or higher regimen for taxane/platinum-resistant recurrent ovarian cancer. The purpose of this study was to clarify the response to and toxicity of gemcitabine for recurrent ovarian cancer according to the number of previous chemotherapy regimens.

METHODS

The subjects were patients with taxane/platinum-resistant recurrent ovarian cancer on gemcitabine treatment at the present hospital between June 2007 and September 2013. We retrospectively reviewed the medical records. Response and adverse events were assessed using the Response Evaluation Criteria in Solid Tumors version 1.1. and the Common Terminology Criteria for Adverse Events v4.0, respectively.

RESULTS

The subjects consisted of 65 patients. The median number of previous chemotherapy regimens was 3 (range, 1-7). Overall response rate was 4.6%, and disease control rate (DCR) was 40.0%. DCR versus one, two, three, and ≥four previous chemotherapy regimens was 83.3%, 45.0%, 36.4%, and 23.5%, respectively. Grade 3/4 neutropenia, anemia, and thrombocytopenia occurred in 52.3%, 9.2%, and 9.2% of patients, respectively. Prevalence of grade 3/4 neutropenia according to one, two, three, and ≥four previous chemotherapy regimens was 66.7%, 55.0%, 54.5%, and 41.2%, respectively. Prevalence of anemia, thrombocytopenia, and almost all the non-hematological toxicities also did not increase with an increase in the number of previous chemotherapy regimens.

CONCLUSIONS

Although DCR decreased as the number of previous chemotherapy regimens increased, the toxicities did not increase. Gemcitabine may be relatively safe in heavily pretreated ovarian cancer patients.

Metronomic oral cyclophosphamide (MOC) in the salvage therapy of heavily treated recurrent ovarian cancer patients: a retrospective, multicenter study

BACKGROUND

The aim of this multicenter, retrospective study was to evaluate the efficacy and safety of metronomic oral cyclophosphamide (MOC) in heavily treated, relapsed ovarian cancer (ROC) patients.

METHODS

oral cyclophosphamide (Endoxan®, Baxter, Italy) was administered at the dose of 50 mg daily, continuously. Treatment-related toxicity and response to treatment were assessed by the NCI-CTC criteria, and RECIST criteria, respectively. Progression-free (PFS), and overall survival (OS) were also assessed.

RESULTS

54 patients were analyzed: 20 patients (37.0%) were considered primarily platinum refractory/resistant, while 34 patients (63.0%) were defined as platinum sensitive; 79.6% of patients had received ≥2 previous lines before starting MOC. The objective response rate (ORR) was 20.4%. Eleven patients (20.4%) experienced stable disease and 8 of them had a response duration ≥6 months. A total of 32 patients (59.2.%) progressed during treatment. Median PFS was 4 months, and the 12-month PFS rate was 19.6%; median OS was 13 months, and the 12-month OS rate was 51.5% . Patients responding to MOC showed a more favorable PFS (median = 17 months) compared to patients with stabilization (median = 6 months) or progression of disease (median = 3 months) (p value = 0.0001). Median OS of responding patients was 30 months compared to 11 months in cases achieving stabilization, or progression of disease (median = 8 months) (p value = 0.0001). Only 1 patient experienced grade 3 anemia. Non-hematological grade 3 toxicity was registered in 2 patients.

CONCLUSIONS

MOC could provide a valid alternative in terms of risk/benefit ratio in the palliative treatment of heavily treated ROC patients.

Overcoming platinum resistance in ovarian carcinoma

IMPORTANCE OF THE FIELD

Ovarian cancer remains a deadly malignancy because most patients develop recurrent disease that is resistant to chemotherapy, including platinum. Because response rates for current treatment regimens are relatively similar and unfortunately low, no standard chemotherapy for platinum-resistant ovarian cancer exists.

AREAS COVERED IN THIS REVIEW

A systematic literature review of clinical studies published between January 2005 and March 2010 was conducted using search engines, PubMed and MEDLINE with the entry keywords 'ovarian cancer' and 'platinum resistance'. This search revealed 40 clinical trials (1793 patients).

WHAT THE READER WILL GAIN

Gemcitabine was the most common drug used in clinical trials reporting higher response rates, ≥ +1 SD of overall response rate (5 out of 8). Gemcitabine-based combination therapy showed an average response rate of 27.2% (95% CI, 22.4-32.0). Combination of gemcitabine and pegylated liposomal doxorubicin (PLD) was the most common regimen (n = 3) and was associated with possible additive effects in platinum-resistant ovarian cancer patients: response rate, gemcitabine alone 6.1%, PLD alone 19.8%, and gemcitabine with PLD 28.7% (95% CI, 20.4-37.0), respectively.

TAKE HOME MESSAGE

Analysis of recent clinical trials showed that gemcitabine-based combination chemotherapy was associated with the highest antitumor effects in platinum-resistant ovarian cancer patients during the study period.

A heavily pretreated patient with recurrent clear cell adenocarcinoma of the ovary in whom carcinomatous peritonitis was controlled successfully by salvage therapy with gemcitabine

INTRODUCTION

Advanced clear cell adenocarcinoma of the ovary is a histologic type with an extremely poor prognosis. No reports have been published concerning useful drugs for salvage chemotherapy for this type of cancer. We performed salvage therapy with gemcitabine in a patient with multiple-drug- resistant, unresectable recurrent clear cell adenocarcinoma of the ovary and succeeded in stabilizing recurrent lesions and controlling carcinomatous peritonitis.

CASE REPORT

A 55-year-old woman was in Stage IIIc of clear cell adenocarcinoma of the ovary. She had recurrent tumors after primary cytoreductive surgery, which were unresectable and also resistant to paclitaxel, carboplatin, irinotecan, and oral etoposide. After three courses of fourth-line chemotherapy with gemcitabine for the treatment of carcinomatous peritonitis and hepatic and splenic metastatic lesions, serum CA-125 and the severity of ascites showed marked decreases, and its efficacy for the hepatic and splenic metastatic lesions was classified as 5-month stable disease. The toxicity of this drug was in the acceptable range.

CONCLUSION

Gemcitabine is also useful for heavily pretreated clear cell adenocarcinoma of the ovary. It is necessary to consider the use of drugs without cross resistance to platinum and taxanes in the selection of drugs for this cancer.