Tamoxifen synergizes the antiproliferative effect of cisplatin in human ovarian cancer cells: enhancement of DNA platination as a possible mechanism

Estrogen- and estrogen receptor (ER)-mediated cisplatin chemoresistance in cancer

Cisplatin is a platinum-based chemotherapeutic drug used in the standard treatment of various solid cancers including testicular, bladder, head and neck, cervical and ovarian cancer. Although successful clinical responses are observed in patients following initial cisplatin treatment, resistance to cisplatin ultimately develops in most patients, leading to therapeutic failure. Multiple molecular mechanisms contributing to cisplatin resistance in cancer cells have been identified to date. In this review, we discuss the effect of estrogen, estrogen receptors (ERs) and estrogen-related receptors (ERRs) on cisplatin resistance in various cancer types. We highlight that estrogen treatment or increased expression of ERs or ERRs are generally associated with higher cisplatin resistance in cancer in vitro, mostly due to decreased caspase activity, increased anti-apoptotic protein levels such as BCL-2, higher drug efflux and higher levels of antioxidant enzymes. Targeted inhibition of ERs or estrogen production in combination with cisplatin treatment thus can be a useful strategy to overcome chemoresistance in certain cancer types. Estrogen levels and ER status can also be considered to identify cancer patients with a high potential of therapy response against cisplatin. A better mechanistic understanding of the involvement of estrogen, ERs and ERRs in the development of cisplatin resistance is needed to improve the management of cancer treatment.

Sphingolipid metabolism and drug resistance in ovarian cancer

Despite progress in understanding molecular aberrations that contribute to the development and progression of ovarian cancer, virtually all patients succumb to drug resistant disease at relapse. Emerging data implicate bioactive sphingolipids and regulation of sphingolipid metabolism as components of response to chemotherapy or development of resistance. Increases in cytosolic ceramide induce apoptosis in response to therapy with multiple classes of chemotherapeutic agents. Aberrations in sphingolipid metabolism that accelerate the catabolism of ceramide or that prevent the production and accumulation of ceramide contribute to resistance to standard of care platinum- and taxane-based agents. The aim of this review is to highlight current literature and research investigating the influence of the sphingolipids and enzymes that comprise the sphingosine-1-phosphate pathway on the progression of ovarian cancer. The focus of the review is on the utility of sphingolipid-centric therapeutics as a mechanism to circumvent drug resistance in this tumor type.

FTY720 enhances the anti-tumor activity of carboplatin and tamoxifen in a patient-derived xenograft model of ovarian cancer

Ovarian cancer is the fifth leading cause of cancer-related deaths among women in the United States. Although most patients respond to frontline therapy, virtually all patients relapse with chemoresistant disease. This study addresses the hypothesis that carboplatin or tamoxifen + FTY720, a sphingosine analogue, will minimize or circumvent drug-resistance in ovarian cancer cells and tumor models. In vitro data demonstrate that FTY720 sensitized two drug-resistant (A2780. cp20, HeyA8. MDR) and two high-grade serous ovarian cancer cell lines (COV362, CAOV3) to carboplatin, a standard of care for patients with ovarian cancer, and to the selective estrogen receptor modulator tamoxifen. FTY720 + tamoxifen was synergistic in vitro, and combinations of FTY720 + carboplatin or + tamoxifen were more effective than each single agent in a patient-derived xenograft model of ovarian carcinoma. FTY720 + tamoxifen arrested tumor growth. FTY720 + carboplatin induced tumor regressions, with tumor volumes reduced by ∼86% compared to initial tumor volumes. Anti-tumor efficacy was concomitant with increases in intracellular proapoptotic lipid ceramide. The data suggest that FTY720 + tamoxifen or carboplatin may be effective in treating ovarian tumors.

Preclinical Evaluation of Intravesical Cisplatin Nanoparticles for Non-Muscle-Invasive Bladder Cancer

Purpose: Prior clinical trials evaluating cisplatin for non-muscle-invasive bladder cancer (NMIBC) were stopped due to local and systemic toxicity. Currently, there is still a need for improved intravesical therapies, and nanoparticle-based CDDP may be efficacious without the toxicity of free cisplatin observed in the past.Experimental Design: Cisplatin nanoparticles (CDDP NPs) were developed using biocompatible poly(l-aspartic acid sodium salt; PAA), both with and without low and high grafting density of methoxy-polyethylene glycol (PEG). In vitro cytotoxicity studies confirmed activity of CDDP NPs and CDDP solution against a papillary bladder cancer cell line. Local toxicity was assessed by three weekly intravesical administrations of CDDP formulations. CDDP NPs and CDDP solution were evaluated for bladder absorption in murine models 1 and 4 hours after intravesical administration. In vivo efficacy was evaluated in an immunocompetent carcinogen model of NMIBC.Results: CDDP NPs showed decreased local toxicity, as assessed by bladder weight, compared with CDDP solution. Furthermore, >2 μg/mL of platinum was observed in mouse serum after intravesical administration of CDDP solution, whereas serum platinum was below the limit of quantification after intravesical administration of CDDP NPs. CDDP NPs provided significantly increased (P < 0.05) drug levels in murine bladders compared with CDDP solution for at least 4 hours after intravesical administration. In vivo, CDDP NPs reduced cancer cell proliferation compared with untreated controls, and was the only treatment group without evidence of invasive carcinoma.Conclusions: Cisplatin-loaded PAA NPs have the potential to improve intravesical treatment of NMIBC while reducing local and systemic side effects. Clin Cancer Res; 23(21); 6592-601. ©2017 AACR.

Interaction of current cancer treatments and the immune system: implications for breast cancer therapeutics

Early diagnosis and treatment of breast cancer may account for the current improvement in the mortality of breast cancer. However, achieving a complete 'cure' is the holy grail of cancer medicine and, in many cases, cancer patients still succumb to their ultimate fate. There is therefore a need to devise innovative therapies to overcome this problem. To this end, many emerging therapies utilizing the immune system to eradicate the residues of disease have been described in the preclinical and clinical arenas. However, there is very little work examining the impact of immunotherapy on the existing natural immunity. The relationship between antitumor immunity, in the form of immunotherapy (either passive or active), and current strategies of treatment also needs to be explored. If we are to improve the success of cancer treatment, we must understand how current therapies interact with the immune system and with the emerging immunotherapies. For breast-cancer treatment to be successful, therapeutics should be tailored towards antitumor immunity; they should also avoid tumor-specific tolerance. The sources of information used to prepare this paper were obtained through published work on Pubmed/Medline and materials published on the US/UK governmental agencies' websites.

Pharmaceutical management of ovarian cancer : current status

Over recent decades, truly impressive progress has been made in the outcome associated with the pharmacological antineoplastic management of women with advanced ovarian cancer. Following initial surgery, the large majority of patients with this malignancy will receive a chemotherapy regimen that includes a platinum drug (carboplatin or cisplatin) and a taxane (paclitaxel or docetaxel). Currently, objective responses are observed in approximately 60-80% of patients treated in the front-line setting, with documented improvements in overall survival compared with prior non-platinum and taxane programmes. Unfortunately, despite the high response rate to initial chemotherapy, the majority of women with advanced disease will experience recurrence of the malignant process and be candidates for a variety of possible second-line therapeutic options. It is well recognized that ovarian cancer patients who are documented to experience an initial response to platinum-based chemotherapy but where the disease recurs approximately 6 or more months following the completion of primary therapy, may have another clinically meaningful response (both objective and subjective) to a second platinum-based strategy. However, an optimal management approach in this setting remains to be defined. Furthermore, the malignant cell populations in all ovarian cancer patients who experience an initial relapse of the disease process will eventually be resistant to the platinum agents. In this setting, multiple drugs have been shown to be biologically active. Again, an optimal strategy to be employed in the platinum-resistant setting has yet to be demonstrated through the conduct of evidence-based trials. Reasonable goals of therapy in women with recurrent or resistant ovarian cancer are to improve overall survival, reduce the severity (and delay the occurrence) of symptoms and optimize overall quality of life.

A Phase III Trial Evaluating the Combination of Cisplatin, Etoposide, and Radiation Therapy With or Without Tamoxifen in Patients With Limited-Stage Small Cell Lung Cancer

Based on both clinical and laboratory data that suggested that tamoxifen (TAM) enhanced the effectiveness of cisplatin (DDP)-based chemotherapy regimens, the Cancer and Leukemia Group B (CALGB) designed and initiated a prospective, randomized phase III trial to test the efficacy of the addition of high-dose TAM to a standard chemoradiation regimen of DDP and etoposide (VP-16) in patients with limited-stage small cell lung cancer (LS-SCLC). Between August 6, 1993, and January 15, 1999, 319 patients with LSSCLC were accrued to CALGB 9235. Patients were randomized to receive chemotherapy with or without high-dose TAM. Treatment on the non-TAM containing arm (arm 1) included DDP (80 mg/m2 intravenously day 1 only) and VP-16 (80 mg/m2 intravenously days 1-3) given every 3 weeks for a total of 5 cycles. Patients treated on arm 2 received the identical chemotherapy regimen as described here with the addition of high-dose TAM (80 mg orally twice per day), which was given for 5 days each cycle starting 1 day before the DDP. Thoracic radiation (XRT) given at 200 cGy 5 days per week to a total dose of 50 Gy began on day 1 of cycle 4 of chemotherapy and overlapped with cycle 5. Prophylactic cranial irradiation was offered to all patients who achieved a complete response or near-complete response. A total of 307 patients are evaluable for response. After the completion of the chemoradiation portion of the treatment, the overall response rate (ORR) was 88% for 154 patients treated without tamoxifen and 84% for 153 patients treated with tamoxifen with complete response (CR) rates of 49% and 50%, respectively. The median failure-free survivals of 12.3 months and 10.5 months and the overall survivals of 20.6 months and 18.4 months, respectively, were not statistically significant between the 2 arms. Toxicity was similar with and without tamoxifen. This phase III trial failed to demonstrate a positive effect on either the response or survival for the addition of TAM to standard etoposide-cisplatin-radiation management for patients with LS-SCLC. However, these data continue to support a positive effect of chemoradiation in the treatment of patients with LS-SCLC.

Phase I trial of high-dose tamoxifen in combination with cisplatin in patients with lung cancer and other advanced malignancies

BACKGROUND

Tamoxifen has been reported to enhance the antitumor activity of cisplatin in preclinical models by modulation of protein kinase C signal transduction and apoptosis-related pathways.

METHODS

We conducted a phase I study of high-dose oral tamoxifen in combination with intravenous cisplatin, with two objectives: 1) to determine tolerability, and 2) to determine the daily tamoxifen dose required to achieve serum levels equivalent to in vitro concentrations reported to enhance cisplatin cytotoxicity in preclinical models. Tamoxifen was administered days one through seven at escalating daily doses of 160 mg/m2 (n = 5), 200 mg/m2 (n = 6), and 250 mg/m2 (n = 4) by patient cohort, followed by cisplatin at 100 mg/m2 on day eight. Serum concentrations of tamoxifen and its hydroxylated metabolite N-desmethyltamoxifen were determined by high-performance liquid chromatography (HPLC) on day eight of the first treatment cycle in seven patients.

RESULTS

Fifteen patients with advanced malignancies received treatment with tamoxifen at 160 mg/m2, 200 mg/m2, and 250 mg/m2 per cycle, respectively. Serum concentrations of tamoxifen and N-desmethyltamoxifen on day eight of the first cycle ranged from 1.75-8.22 microM (mean 4.72 microM) and 3.62-10.85 microM (mean 3.87 microM), respectively. Toxicity analysis demonstrated that grade 3/4 nonhematological toxicity occurred in 0/5 at a tamoxifen dose of 160 mg/m2, 1/6 at a tamoxifen dose of 200 mg/m2, and in 1/4 patients at the 250 mg/m2 dose level. No grade 4 hematological toxicity occurred. Classic dose-limiting toxicity was not observed; the trial was closed to further accrual after documentation that targeted tamoxifen levels (around 5 microM) were achieved with daily tamoxifen doses > or = 160 mg/m2 in combination with cisplatin.

CONCLUSIONS

This regimen of high-dose tamoxifen in combination with cisplatin can be safely administered. Serum tamoxifen levels comparable to concentrations required for enhancement of cisplatin sensitivity in vitro are clinically achievable with acceptable toxicity. The level of antitumor activity in nonsmall cell lung cancer NSCLC is encouraging (partial response in 4/10 patients). Based on these data, a Phase II study of high-dose tamoxifen in combination with cisplatin in patients with metastatic NSCLC is being conducted through the Southwest Oncology Group.

A combination of platinum and tamoxifen in advanced ovarian cancer failing platinum-based chemotherapy: results of a Phase II study

The treatment of recurrent or progressive ovarian cancer has limited therapeutic potential. The clinical outcome of second-line therapy largely depends on the potential chemo-sensitivity of the tumor expressed during up-front chemotherapy, as well as on the treatment-free interval from the last course of cytotoxic therapy. However, the identification of agents such as tamoxifen (TAM) at nontoxic doses, able to act synergistically with standard chemotherapy, may be useful to overcome resistance. Fifty patients with recurrent or progressive ovarian cancer following platinum (P)-based chemotherapy (28 platinum-resistant and 22 platinum-sensitive) entered a Phase II trial to evaluate the efficacy and toxicity of P re-challenge with the addition of TAM as a chemotherapy response modulator. The choice of the P compound (100 mg/m2 cisplatin or 400 mg/m2 carboplatin, q3 weeks) was made on the basis of the prior total cisplatin dose and the presence of neurotoxicity. TAM was administered at the doses of 80 mg/day for 30 days followed by 40 mg/day for the remaining period of treatment. Toxicity consisted mainly of mild to moderate nausea and vomiting (76%), peripheral neuropathy (43%), nephrotoxicity (4%), anemia (16%), leukopenia (58%) and thrombocytopenia (16%). The overall response to the P-TAM combination was 50% (complete response 30%; partial response 20%) with a median duration of 8.5 months (3-42). Sixty-four percent of the P-sensitive and 39% of the P-resistant patients responded (59% and 33%, respectively, for those bearing measurable disease). The overall median survival was 23 (3-48) and 19 months for the patients with measurable disease (20 months for the P-resistant group). This phase II trial confirmed the activity for a re-challenge employing a P compound and TAM in clinically defined P-resistant ovarian cancer patients. The mild toxicity profile and the relatively low cost of the treatment render further investigations on the P-TAM regimen worthwhile.

Management of adenocarcinoma of unknown primary with a 5-fluorouracil-cisplatin chemotherapy regimen (CFTam)

BACKGROUND

Adenocarcinoma of unknown primary comprises up to 10% of metastatic malignant disease. With few exceptions this diagnosis carries a very poor prognosis of a few months with minimal survival advantage to chemotherapy. However there is the possibility that chemotherapy can improve symptom control and quality of life.

PATIENTS AND METHODS

Forty-four patients with adenocarcinoma of unknown primary received CFTam chemotherapy regimen (5-FU 750 mg/m2/day by protracted infusion for five days, cisplatin 60 mg/m2 once and tamoxifen 20 mg daily on a 21-day cycle). Disease response and toxicity were collected and survival compared to patients who were not treated or who received different chemotherapy regimens.

RESULTS

Overall response to CFTam was 27% with a median duration of 10 months (range 4-26 months). The chemotherapy was well tolerated with no grade 4 non-haematological toxicity and only three patients (7%) grade 4 neutropaenia with only two (5%) patients developing sepsis. There were no toxic deaths. Performance status was maintained or improved in responders.

CONCLUSIONS

CFTam is a well tolerated chemotherapy regimen with similar efficacy to other regimens described in the treatment of adenocarcinoma of unknown primary. In the absence of a significant survival advantage there is a need to conduct randomised trials of chemotherapy versus best supportive care to quantify any improvement in quality of life or symptom control.

Effects of the Bowman-Birk inhibitor on clonogenic survival and cisplatin- or radiation-induced cytotoxicity in human breast, cervical, and head and neck cancer cells

Bowman-Birk inhibitor (BBI) is a soybean-derived anticarcinogenic protease inhibitor previously shown to potentiate cisplatin-induced cytoxicity in human lung and ovarian cancer cells. To further assess the potential of BBI as a sensitizing agent for cancer radiotherapy and chemotherapy, we evaluated the effects of BBI and a soybean concentrate enriched in BBI known as BBI concentrate (BBIC) on clonogenic survival and radiation- or cisplatin-induced cell killing in MCF7 human breast carcinoma cells, SCC61 and SQ20B human head and neck carcinoma cells, HeLa, HeLa-R1, and HeLa-R3 human cervical carcinoma cells, MCF10 nontumorigenic human epithelial cells, HTori-3 nontumorigenic human thyroid epithelial cells, and C3H10T1/2 mouse fibroblast cells. BBI and BBIC significantly suppressed the clonogenic survival of MCF7 and SCC61 cells. BBIC also suppressed the survival of SQ20B cells and enhanced radiation-induced cell killing in SCC61 and SQ20B cells and cisplatin-induced cell killing in HeLa, HeLa-R1, and HeLa-R3 cells. In contrast, BBI and/or BBIC did not enhance radiation-induced cell killing in MCF10 cells or cisplatin-induced cell killing in C3H10T1/2 cells. BBI did not significantly affect the survival of SQ20B cells or enhance radiation-induced cell killing in SCC61 and SQ20B cells. The clonogenic survivals of MCF10 and C3H10T1/2 cells were not adversely affected by treatment with BBI or BBIC. The clonogenic survival of HTori-3 cells was only moderately suppressed by treatment with BBIC at > or = 80 micrograms/ml. These results suggest that BBIC could be a useful agent for the potentiation of radiation- and cisplatin-mediated cancer treatment without significant adverse effects on surrounding normal tissues.

Hormonal interactions in ovarian cancer

According to the epidemiologic literature and the laboratory characterization of receptor content and molecular interactions, there is a relationship between the microenvironment of ovarian cancer and steroid hormones. Advances in our knowledge of the molecular-hormonal nature of ovarian cancer will help in designing a rationale for clinical trials in appropriate subsets of patients. However, currently, development of successful therapies and prevention strategies for women at risk remains a true challenge.

Growth inhibition and cytotoxicity induced by Bowman-Birk inhibitor concentrate in cisplatin-resistant human ovarian cancer cells

Bowman-Birk inhibitor (BBI) is a soybean-derived anticarcinogenic protease inhibitor that was shown to potentiate the cytotoxicity of cisplatin in our previous studies. To assess the potential of BBI as a sensitizing agent for the chemotherapy of cisplatin-resistant cancers, we evaluated the effects of a soybean concentrate enriched in BBI (known as BBI concentrate or BBIC) on cell growth and clonogenic survival of a human ovarian cancer cell line, A2780, and its cisplatin-resistant sublines, C30, and C200. The presence of BBI and BBIC in the cell culture, medium reduced the clonogenic survival of the A2780, C30, and C200 cells in a dose-dependent manner and enhanced cisplatin-induced growth inhibition and/or cytotoxicity. BBIC alone showed greater inhibitory effects on growth in the cisplatin-resistant cell lines. These results suggest that BBI and BBIC could be useful agents for the treatment of cancers, especially with cisplatin, in tumors resistant to this important anticancer agent.