Co-administration Of Tamoxifen Research Articles

Modulation of SIRT6 related signaling pathways of p-AKT/mTOR and NRF2/HO-1 by memantine contributes to curbing the progression of tamoxifen/HFD-induced MASH in rats

Metabolic dysfunction-associated steatohepatitis (MASH) is a chronic liver disorder marked by hepatic fat accumulation and inflammatory infiltrates which may evolve to cirrhosis. Clinical studies have demonstrated the higher risk of MASH development after tamoxifen (TAM) therapy, especially in obese patients. Therefore, we aimed to evaluate MASH induction by TAM combined with high fat diet (HFD) and the potential interference of memantine (MEMA) with MASH progression via modulation of SIRT6 and its related signaling pathways. MASH was induced in female Wistar rats by co-administration of TAM (25 mg/kg/day, p.o.) and HFD for 5 weeks. Liver function biomarkers, tissue triglyceride and cholesterol, MASH scoring, SIRT6 with its related signals, and lipid synthesis/oxidation markers were estimated. By comparison to MASH group, MEMA improved liver function indices (ALT, AST, ALP, albumin) and reduced the progression of MASH, evidenced by decreased accumulation of lipids in hepatic tissue, improved histological features, and reduced MASH scoring. MEMA enhanced hepatic SIRT6 and downregulated p-AKT/mTOR signaling, that subsequently reduced expressions of the lipid synthesis biomarkers (SREBP1c, SCD), while elevating the lipid oxidation markers (PPAR-α, CPT1). Moreover, MEMA enhanced NRF2/HO-1 signaling, with subsequently improved antioxidant defense and pro-inflammatory/anti-inflammatory cytokines balance. Analysis of SIRT6 correlations with p-AKT/mTOR, NRF2/HO-1, SREBP1c, and PPAR-α further confirmed our results. Consequently, we conclude that MEMA could interfere with MASH progression, at least in part, via enhanced SIRT6 expression and modulation of its related p-AKT/mTOR and NRF2/HO-1 signaling pathways, eventually reducing liver steatosis and inflammation. That could be a promising therapeutic modality for curbing MASH progression.

P-367 Letrozole or Tamoxifen co-administration during fertility preservation of breast cancer patients: a retrospective cohort study

Abstract Study question How do fertility preservation (FP) outcomes differ between breast cancer patients stimulated with FSH and Tamoxifen versus FSH and Letrozole? Summary answer Letrozole and Tamoxifen co-administration yielded similar number of retrieved and cryopreserved oocytes/embryos, as well as similar oocyte maturation and fertilization and rates. What is known already Oocyte/embryo cryopreservation is recommended before initiation of chemotherapy in cancer patients. The co-administration of Tamoxifen, a selective estrogen receptor modulator, or Letrozole, an aromatase inhibitor, during ovarian stimulation with gonadotropins, are used to limit the potentially harmful effects of a supra-physiological rise in estrogen levels on hormone-sensitive cancers. However, the optimal choice between the two is still unclear and with no sound evidence. Study design, size, duration Retrospective cohort study of all FP treatments of newly diagnosed breast cancer patients in two tertiary centers between 2000-2022. Collected data included 354 FP cycles of 290 patients and compared treatment parameters and outcomes of Tamoxifen or Letrozole co-administration. Participants/materials, setting, methods Breast cancer patients who underwent FP before chemotherapy were included. Patients with a history of radiation or gonadotoxic treatment, as well as those undergoing other fertility preservation treatments, such as ovarian tissue cryopreservation were excluded. Main results and the role of chance Overall, 215 Letrozole and 139 Tamoxifen treatment cycles were compared, with no significant demographic differences. Treatments with Letrozole had higher FSH dosages (3970IU vs. 2839IU, p < 0.001) but shorter duration (9.7 vs. 10.5 days, p < 0.001). The Letrozole group achieved lower peak E2 levels and endometrial thickness (1508pmol/L, 8.1mm vs. 8760pmol/L, 9.5mm, p < 0.001). The mean number of retrieved oocytes was comparable between the groups (13.6 with Letrozole vs 14.7 with Tamoxifen, p = 0.06). In 122 Letrozole and 46 Tamoxifen patients that underwent strictly oocytes cryopreservation the mean number of cryopreserved oocytes was comparable (11 vs. 12.1, p = 0.21). Moreover, in embryo cryopreservation cycles of 71 patients treated with Letrozole compared to 76 patients with Tamoxifen, no difference was observed in the number of cryopreserved embryos (6.2 vs. 7.0, p = 0.12). Oocyte maturation rate among strictly oocyte preservation cycles was comparable (86% with Letrozole vs. 83% with Tamoxifen, p = 0.80), as were fertilization rates in embryo cryopreservation cycles (62% vs. 63%, p = 0.8 and 71% vs. 76%, p = 0.3 in IVF and ICSI with Letrozole and Tamoxifen, respectively). Multivariate analysis, controlling for potential confounders showed no significant correlations between Tamoxifen or Letrozole co-administration and the number of retrieved oocytes or oocyte maturation rate. Limitations, reasons for caution The primary limitation of our study is its retrospective design and the variation in treatment duration and gonadotrophin dosages among groups. Wider implications of the findings This study provides reassurance that both Tamoxifen and Letrozole are equally effective options when co-administered in FP treatments of breast cancer patients. Trial registration number not applicable

Effects of letrozole or tamoxifen coadministered with a standard stimulation protocol on fertility preservation among breast cancer patients.

To assess the effects of letrozole or tamoxifen coadministration on fertility preservation treatment outcomes. Retrospective cohort study of 118 breast cancer patients undergoing fertility preservation treatment between 2008 and 2018. Patients who received letrozole (n = 36) or tamoxifen (n = 30) were compared to controls (n = 52) who underwent standard ovarian stimulation protocols. The primary outcome measures included the number of retrieved oocytes, mature oocytes (MII), fertilization, and top-quality embryo rates. The secondary outcome measures included duration of stimulation, gonadotropin dose and peak estradiol level. The number of oocytes retrieved, MII oocytes, fertilization rate, duration of stimulation, or gonadotropin dose were similar inthe letrozole and tamoxifen groups, compared to controls. Top-quality embryo rate was lower in the tamoxifen group compared to controls (25% vs 39.4%, respectively, P = 0.034). The abnormal fertilization rate was higher in the letrozole group compared to controls (7.8% vs 3.60%, respectively, P = 0.015). A stepwise logistic regression analysis revealed that letrozole and peak estradiol were significantly associated with abnormal fertilization (OR 11.94; 95% CI 2.35-60.4, P = 0.003 for letrozole and OR 1.075; 95% CI 1.024-1.12, P = 0.004 per 100 unit change in estradiol). There may be a negative effect of letrozole or tamoxifen on fertilization and embryo quality, in fertility preservation cycles. Further studies are needed to confirm these findings.

Effect of the Single Oral Combination Treatment of Tamoxifen with Gamisoyo-san on the Pharmacokinetics Profiles of Tamoxifen

The effects of Gamisoyo-san (GMSYS) co-administration within 5 min on the pharmacokinetics (PK) of tamoxifen were observed. After 50 mg/kg of tamoxifen oral treatment, GMSYS 100 mg/kg was orally administered within 5 min to 7-wk old male SPF.VAF Outbred Crl:CD [Sprague-Dawley (SD)] rats. The plasma were collected at 30 min before administration, 30 min, 1, 2, 3, 4, 6, 8 and 24 hrs after end of GMSYS treatment, and plasma concentrations of tamoxifen were analyzed using LC-MS/MS methods. Tmax, Cmax, AUC, t1/2 and MRTinf of tamoxifen were analysis as compared with tamoxifen single administered rats. Although co-administration with GMSYS did not critically influenced on the pharmacokinetic parameters of oral tamoxifen, they induced increased trends of plasma tamoxifen concentrations, especially significant (p0.05) increases of plasma tamoxifen concentrations were demonstrated at 0.5 hr after end of co-administration with GMSYS as compared with tamoxifen single formula treated rats, at dosage levels of tamoxifen 10 mg/kg and GMSYS 100 mg/kg within 5 min. It is considered that pharmacokinetic studies should be tested like the effects of GMSYS on the pharmacokinetics of tamoxifen, when they were co-administered with prolonger intervals than Tmax of tamoxifen oral administration (about 2.5 hr-intervals), to achieve the optimal dosing regimen of GMSYS and tamoxifen co-administration.

Co-Administration of Tamoxifen and Letrozole: Does it Increase Endometrial Thickness and Pregnancy Rate in Cases of Ovulation Induction?

Co-Administration of Tamoxifen and Letrozole: Does it Increase Endometrial Thickness and Pregnancy Rate in Cases of Ovulation Induction?

Protective effects of Vitex agnus-castus in ovariectomy mice following permanent middle cerebral artery occlusion.

Objective(s):Previous studies have indicated that phytoestrogens induce estrogenic as well as anti-inflammatory effects, and they are found in high abundance in the extracts of some herbs such as Vitex Agnus Castus (VAC). Therefore, we investigated the effect of VAC extract on ovariectomized mice after the induction of permanent middle cerebral artery occlusion (PMCAO) model. Materials and Methods:In this study, 50 mice ranging from 25 to 35 g were divided into five experimental groups as follows: Control, VAC, Estrogen, Tamoxifen, and Tamoxifen-VAC. Animals were ovariectomized, and after 30 days of treatment, they were given PMCAO induction. Behavioral assessment (adhesive removal and wire hanging tests) was evaluated 24 hr, 48 hr, and one week after induction of stroke. The infarct volume, as well as serum levels of matrix metalloproteinase-9 (MMP-9) and interleukin-10 (IL-10), were measured one week after stroke.Results:One week after stroke, in both VAC and estrogen groups, the infarct size reduced in comparison with the control group. Estrogen and VAC extract improved adhesive removal and wire hanging test, increased the level of IL-10, and decreased the level of MMP-9 compared with the control group. In addition, co-administration of tamoxifen and VCA extract had no significant effect on measured indices compared with control and tamoxifen groups. Conclusion:Based on our findings, VAC extract has neuroprotective properties and can reduce stroke injuries in PMCAO-induced ovariectomized mice via anti-inflammatory and estrogenic properties.

Abstract 5629: Modeling cyclophosphamide induced ovarian toxicity in a novel translational canine model

Abstract Reproductive failure following chemotherapy and/or ionizing radiation is a major adverse event, for which there are no established preventive measures. In previous studies, our laboratory has documented that the selective estrogen receptor modulator, tamoxifen (TAM) is effective in both prevention and reversal of ovarian toxicity from cyclophosphamide (CTX) in rodent models. To validate the effectiveness of this approach in a more relevant model system, we have developed a canine ovarian explant tissue model system. Dogs present with many cancers spontaneously and their pathology and treatment approaches mirror those of the human cancers. Thus, canine cancers and their treatments are excellent translational models for human diseases. Furthermore, dogs share the same environment as humans and have longer life spans than rodents. Our laboratory has recently established a dog ovarian explant tissue model system using fresh ovaries collected at the time of ovariohysterectomy. In the current study, we hypothesized that ovarian toxicity induced by CTX will be reduced by co-administration of TAM. Using this system, freshly prepared ovarian cortical tissue sections are cultured in the presence of TAM and CTX. Ovarian tissue viability is assessed by primordial and primary follicle morphometry, where the number of primordial, primary and apoptotic follicles were counted in 9 sections of 1 mm3 of ovarian cortical tissue from each dog, using CTX (at 0, 1 and 10µM) concentrations combined with TAM (0 and10µM). The number and percentage of each follicle was assessed. In addition, granulosa cells proliferation is assessed using bromodeoxyuridine (BrdU) incorporation. Further, we show that, as in women, anti-mullerian hormone (AMH) can be used as an indicator of follicle reserves in the dog, thereby establishing their use as an in-vivo monitoring system to test ovarian viability in future clinical studies. This study is intended to underpin a subsequent canine clinical trial testing TAM as a countermeasure against infertility from cancer treatment in dogs. Note: This abstract was not presented at the meeting. Citation Format: Puja Basu, Rebecca Egbert, Evan Pasternak, Brian Petroff, Nucharin Songsasen. Modeling cyclophosphamide induced ovarian toxicity in a novel translational canine model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5629. doi:10.1158/1538-7445.AM2017-5629

The effects of soy and tamoxifen on apoptosis in the hippocampus and dentate gyrus in a pentylenetetrazole-induced seizure model of ovariectomized rats.

The effects of tamoxifen and soy on apoptosis of the hippocampus and dentate gyrus of ovariectomized rats after repeated seizures were investigated. Female rats were divided into: (1) Control, (2) Sham, (3) Sham-Tamoxifen (Sham-T), (4) Ovariectomized (OVX), (5) OVX-Tamoxifen (OVX-T), (6)OVX-Soy(OVX-S) and (7) OVX-S-T. The animals in the OVX-S, OVX-T and OVX-S-T groups received soy extract (60mg/kg; i.p.), tamoxifen (10mg/kg) or both for 2 weeks before induction of seizures. The animals in these groups additionally received the mentioned treatments before each injection of pentylenetetrazole (PTZ; 40mg/kg) for 6days. The animals in the Sham and OVX groups received a vehicle of tamoxifen and soy. A significant decrease in the seizure score and TUNEL-positive neurons was seen in the OVX group compared to the Sham (P<0.001). The animals in both the OVX-T and OVX-S groups had a significantly higher seizure score as well as number of TUNEL-positive neurons compared to the OVX group (P<0.01-P<0.001). Co-treatment of the OVX rats by the extract and tamoxifen decreased the seizure score and number of TUNEL-positive neurons compared to OVX-S (P<0.001). Treatment of the OVX rats by either soy or tamoxifen increased the seizure score as well as the number of TUNEL-positive neurons in the hippocampal formation. Co-administration of tamoxifen and soy extract inhibited the effects of the soy extract and tamoxifen when they were administered alone. It might be suggested that both soy and tamoxifen have agonistic effects on estrogen receptors by changing the seizure severity.

Topical tamoxifen in the therapy of cutaneous leishmaniasis.

The aims of the present work were to test the effect of tamoxifen administered topically and the therapeutic efficacy of tamoxifen and pentavalent antimonial combinations in an experimental model of cutaneous leishmaniasis. BALB/c mice infected with a luciferase expressing line of Leishmania amazonensis were treated with topical tamoxifen in two different formulations (ethanol or oil-free cream) as monotherapy or in co-administration with pentavalent antimonial. Treatment efficacy was evaluated by lesion size and parasite burden, quantified through luminescence, at the end of treatment and 4 weeks later. Topical tamoxifen, formulated in ethanol or as a cream, was shown to be effective. The interaction between tamoxifen and pentavalent antimonial was additive in vitro. Treatment with combined schemes containing tamoxifen and pentavalent antimonial was effective in reducing lesion size and parasite burden. Co-administration of tamoxifen and pentavalent antimonial was superior to monotherapy with antimonial.

The safety and efficacy of controlled ovarian hyperstimulation for fertility preservation in women with early breast cancer: a systematic review.

Can controlled ovarian hyperstimulation (COH) for fertility preservation be effectively conducted in women with breast cancer without worsening their prognosis? COH with co-administration of letrozole suppresses oestradiol levels without significantly impacting oocyte yield or decreasing disease-free survival rates. Oestradiol has the capacity to stimulate the proliferation of breast cancer cells. COH can cause oestradiol levels to rise by an order of magnitude above physiological levels. Concern exists regarding the effect of supra-physiological oestradiol levels in women with a recent diagnosis of breast cancer. A systematic review of the literature was performed using MEDLINE (PubMed database), EMBASE and the Cochrane Library. The search was restricted to articles written in English. No restrictions regarding the date of publication were applied. Safety was assessed in terms of relapse rates and cancer-related mortality rates. Peak oestradiol concentrations were recorded for different stimulation protocols. Efficacy was measured in terms of the total number of oocytes collected and proportion of mature oocytes. The primary outcome was mortality/recurrence in premenopausal women with Stage I-IIIB breast cancer who underwent COH in the immediate post-operative period, prior to chemotherapy. This is a systematic review of randomized control trials (RCTs), case control and cohort studies reporting on the primary outcome of mortality/recurrence after COH in women with early breast cancer, or secondary outcomes of oocyte yield and peak oestrogen concentration. Owing to the small number of RCTs available, other study types were included. The last electronic search was run in April 2016. Two prospective non-randomized studies reported relapse and breast cancer-related mortality rates in 397 women with breast cancer, of whom 149 underwent COH. Twelve studies reported the peak oestradiol concentrations of 882 women undergoing COH with letrozole co-administration. Four studies compared the oocyte yield of 248 women who underwent COH plus letrozole with 254 women who underwent standard COH. Two studies compared peak oestradiol concentrations and oocyte yield in 61 women who underwent COH with tamoxifen co-administration and 49 women who underwent COH without tamoxifen. One study compared letrozole and tamoxifen co-administration, and another study compared the co-administration of letrozole and anastrozole. The search identified 1002 records of which 15 were included in the final analysis. There was no evidence of a decline in relapse-free survival rates in the two studies of women with breast cancer who received COH with letrozole co-administration compared with women who did not undergo fertility preservation procedures. The largest of these studies reported recurrences in 6/120 (5.0%) women who received COH plus letrozole compared with 12/217 (5.5%) women who did not undergo COH (mean follow-up 5.0 versus 6.9 years; hazard ratio for recurrence 0.77, 95%CI 0.28-2.13). Conclusions regarding women with breast cancer who received tamoxifen during COH could not be made due to insufficient data. Peak oestradiol concentrations (338-829 pg/ml) were suppressed by letrozole when commenced on Days 2-3, with no decrease in oocyte yield. Tamoxifen does not suppress oestradiol concentrations, but may convey protection via its inhibitory action on the oestrogen receptor. Any statements regarding the safety of COH in women with breast cancer are based on a limited number of observational studies. High quality evidence is unlikely to become available for ethical and practical reasons. Whilst available data do not indicate a decline in disease-free survival, a small effect cannot be excluded. Breast cancers are heterogeneous in their genetic profile and receptor status, making the results of studies difficult to generalize to individual cases. The implication of alterations in other hormone levels such as androgens, progestins or vascular endothelial growth factor secondary to COH in women with breast cancer has not been quantified. The co-administration of 5 mg of letrozole daily commencing on Day 2 and continuing throughout COH is recommended as it reduces peak oestradiol concentrations without significantly decreasing oocyte yield. The use of a GnRH agonist trigger is beneficial as oestradiol concentrations rapidly decrease post-administration and rates of ovarian hyperstimulation are lower than with an hCG trigger, without a corresponding reduction in clinical pregnancy or live birth rates in cryopreservation cycles. The protective effect of tamoxifen has not been evaluated although theoretically may be of benefit due to its action on the oestrogen receptor. None. None.

Suppression of liver Apo E secretion leads to HDL/cholesterol immaturity in rats administered ethinylestradiol.

Ethinylestradiol (EE), a main component of the combined oral contraceptive pill, is associated with an increased risk of arterial diseases. However, the toxicity mechanism of EE is poorly understood. In this study, we found that the exposure to EE reduced the serum apolipoprotein E (Apo E) level and high‐density lipoprotein (HDL)/cholesterol concentration in adult female rats. Diethylstilbestrol showed the same effects and both reductions were suppressed by coadministration of tamoxifen (TAM). Liver perfusion experiments revealed that the secretion rate of Apo E from the liver was significantly reduced. It is concluded that EE damages the maturation of HDL/cholesterol by delaying Apo E secretion from the liver, and this may lead to an increased risk of arterial diseases, such as atheromas.

Modification of sphingolipid metabolism by tamoxifen and N-desmethyltamoxifen in acute myelogenous leukemia—Impact on enzyme activity and response to cytotoxics

The triphenylethylene antiestrogen, tamoxifen, can be an effective inhibitor of sphingolipid metabolism. This off-target activity makes tamoxifen an interesting ancillary for boosting the apoptosis-inducing properties of ceramide, a sphingolipid with valuable tumor censoring activity. Here we show for the first time that tamoxifen and metabolite, N-desmethyltamoxifen (DMT), block ceramide glycosylation and inhibit ceramide hydrolysis (by acid ceramidase, AC) in human acute myelogenous leukemia (AML) cell lines and in AML cells derived from patients. Tamoxifen (1–10μM) inhibition of AC in AML cells was accompanied by decreases in AC protein expression. Tamoxifen also depressed expression and activity of sphingosine kinase 1 (SphK1), the enzyme-catalyzing production of mitogenic sphingosine 1-phosphate (S1-P). Results from mass spectroscopy showed that tamoxifen and DMT (i) increased the levels of endogenous C16:0 and C24:1 ceramide molecular species, (ii) nearly totally halted production of respective glucosylceramide (GC) molecular species, (iii) drastically reduced levels of sphingosine (to 9% of control), and (iv) reduced levels of S1-P by 85%, in vincristine-resistant HL-60/VCR cells. The co-administration of tamoxifen with either N-(4-hydroxyphenyl)retinamide (4-HPR), a ceramide-generating retinoid, or a cell-deliverable form of ceramide, C6-ceramide, resulted in marked decreases in HL-60/VCR cell viability that far exceeded single agent potency. Combination treatments resulted in synergistic apoptotic cell death as gauged by increased Annexin V binding and DNA fragmentation and activation of caspase-3. These results show the versatility of adjuvant triphenylethylene with ceramide-centric therapies for magnifying therapeutic potential in AML. Such drug regimens could serve as effective strategies, even in the multidrug-resistant setting.

Abstract LB-229: A phase 1 open-label fixed-sequence two-period crossover study of the effect of multiple doses of tamoxifen on palbociclib (PD-0332991) pharmacokinetics in healthy male volunteers

Abstract Introduction: Tamoxifen and one of its primary active metabolites, 4‑hydroxy‑tamoxifen, are known to induce CYP3A4 in vitro, and in vivo coadministration of tamoxifen with letrozole and anastrozole (both CYP3A4 substrates) has resulted in decreased exposures (AUC) of each by 37% and 27%, respectively. The primary route of oxidative metabolism of palbociclib (PD‑0332991) is through CYP3A4, thus coadministration of tamoxifen and palbociclib could result in decreased exposure of palbociclib. The primary objective of this study is to estimate the relative exposure of single 125 mg palbociclib oral doses alone and in the presence of steady‑state concentrations of tamoxifen and its active metabolites (4‑hydroxy‑tamoxifen, N‑desmethyl‑tamoxifen, and endoxifen (N‑desmethyl‑4-hydroxytamoxifen)) in healthy male subjects in order to inform appropriate palbociclib dosing when administered in combination with tamoxifen in the upcoming Phase 3 PENELOPEB study. Methods: This was an open label, 2‑period fixed‑sequence study of the effect of multiple oral doses of tamoxifen on palbociclib pharmacokinetics in 25 healthy male volunteers. Each subject received a single 125 mg oral dose of palbociclib alone, followed by a single 125 mg dose of palbociclib on Day 22 of a 27-day tamoxifen loading dose regimen (60mg QD for 4 days, followed by 20mg QD for 23 days). Serial blood sampling for palbociclib pharmacokinetics was performed up to 144 hours post-palbociclib dose in both periods. Tamoxifen pre-dose blood sampling was performed on specified visits to document achievement of steady-state tamoxifen and metabolite concentrations. Plasma concentrations of palbociclib, tamoxifen, 4‑hydroxy‑tamoxifen, N‑desmethyl‑tamoxifen, and endoxifen were each measured using validated LC/MS/MS (liquid chromatography coupled with mass spectrometry) methods. Palbociclib plasma pharmacokinetic (PK) parameters were estimated using standard non-compartmental methods. Discussion: There were no significant changes in the palbociclib plasma PK parameters AUCinf (area under the curve from time zero to infinity) and Cmax (maximal plasma concentration) in the presence of steady-state tamoxifen when compared to palbociclib alone. Tamoxifen, 4‑hydroxy‑tamoxifen, N‑desmethyl‑tamoxifen, and endoxifen all achieved steady-state prior to administration of palbociclib in period 2. In general, palbociclib and the combination of palbociclib and tamoxifen were well tolerated with no reported serious adverse events; 1 subject discontinued due to generalized itchiness which resolved with a single dose of fexofenadine. Citation Format: Justin T. Hoffman, Melissa O'Gorman, Cho-Ming Loi, Anna Plotka, Tanya Boutros, Leonid Kirkovsky, Corrado Gallo Stampino, Diane Wang. A phase 1 open-label fixed-sequence two-period crossover study of the effect of multiple doses of tamoxifen on palbociclib (PD-0332991) pharmacokinetics in healthy male volunteers. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-229. doi:10.1158/1538-7445.AM2014-LB-229

Cholesterol depletion by methyl-β-cyclodextrin augments tamoxifen induced cell death by enhancing its uptake in melanoma.

BackgroundDespite modern advances in treatment, skin cancer is still one of the most common causes of death in the western countries. Chemotherapy plays an important role in melanoma management. Tamoxifen has been used either alone or in- combination with other chemotherapeutic agents to treat melanoma. However, response rate of tamoxifen as a single agent has been comparatively low. In the present study, we investigated whether treatment with methyl-β-cyclodextrin (MCD), a cholesterol depleting agent, increases the efficacy of tamoxifen in melanoma cells.MethodsThis was a two-part study that incorporated in vitro effects of tamoxifen and MCD combination by analyzing cell survival, apoptosis and cell cycle analysis and in vivo antitumor efficacy on tumor isografts in C57BL/6J mice.ResultsMCD potentiated tamoxifen induced anticancer effects by causing cell cycle arrest and induction of apoptosis. Sensitization to tamoxifen was associated with down regulation of antiapoptotic protein Bcl-2, up-regulation of proapoptotic protein Bax, reduced caveolin-1 (Cav-1) and decreased pAkt/pERK levels. Co-administration of tamoxifen and MCD caused significant reduction in tumor volume and tumor weight in mice due to enhancement of drug uptake in the tumor. Supplementation with cholesterol abrogated combined effect of tamoxifen and MCD.ConclusionOur results emphasize a potential synergistic effect of tamoxifen with MCD, and therefore, may provide a unique therapeutic window for improvement in melanoma treatment.Electronic supplementary materialThe online version of this article (doi:10.1186/1476-4598-13-204) contains supplementary material, which is available to authorized users.

Tamoxifen co-administration during controlled ovarian hyperstimulation for in vitro fertilization in breast cancer patients increases the safety of fertility-preservation treatment strategies

To evaluate the safety and efficacy of tamoxifen co-administration during conventional controlled ovarian hyperstimulation (COH) protocols for a fertility-preservation IVF cycle in breast cancer patients. Two groups: retrospective descriptive cohort study and prospective study. Breast cancer oncology and fertility-preservation centers in a tertiary hospital. Two groups of breast cancer patients: premenopausal patients treated with adjuvant tamoxifen; and patients undergoing invitro fertilization (IVF) for fertility preservation. Fertility-preservation cycles, tamoxifen co-administration during conventional IVF. Endocrine records, and IVF results. Estradiol (E2) levels were chronically high (mean 2663 pmol/L, maximum: 10,000 pmol/L) in 38 of 46 breast cancer patients treated with adjuvant tamoxifen. Co-administration of tamoxifen (48 cycles) during conventional IVF or without tamoxifen (26 cycles), using either the long gonadotropin-releasing hormone-agonist or-antagonist protocols, resulted, respectively, in a mean of 12.65 and 10.2 oocytes retrieved, and 8.5 and 6.4 embryos cryopreserved. Average peak E2 levels were 6,924 pmol/L and 5,093 pmol/L, respectively, but long-term recurrence risk (up to 10years) was not increased. In breast cancer patients, co-administration of tamoxifen during conventional COH for fertility preservation does not interfere with IVF results. The high serum E2 levels during COH should be considered safe, as it simulates the high prevalence of persistently high serum E2 levels in premenopausal breast cancer patients safely treated with adjuvant tamoxifen.

76P - A Phase 1 Open-Label Fixed-Sequence Two-Period Crossover Study of the Effect of Multiple Doses of Tamoxifen on Palbociclib (PD-0332991) Pharmacokinetics in Healthy Male Volunteers

Introduction: Tamoxifen and one of its primary metabolites, 4-hydroxy-tamoxifen, are known to induce CYP3A4 in vitro, and in vivo coadministration of tamoxifen with letrozole and anastrozole (both CYP3A4 substrates) has resulted in decreased exposures (AUC) of each. The primary route of oxidative metabolism of palbociclib (PD-0332991) is through CYP3A4, thus coadministration of tamoxifen and palbociclib could result in decreased exposure of palbociclib. The primary objective of this study is to estimate the relative exposure of single 125 mg palbociclib doses with and without steady-state concentrations of tamoxifen and its active metabolites (4-hydroxy-tamoxifen, N-desmethyl-tamoxifen, and endoxifen) in healthy male subjects.

Modulation of Drug Resistance in Ovarian Adenocarcinoma by Enhancing Intracellular Ceramide Using Tamoxifen-Loaded Biodegradable Polymeric Nanoparticles

To modulate intracellular ceramide levels and lower the apoptotic threshold in multidrug-resistant ovarian adenocarcinoma, we have examined the efficacy and preliminary safety of tamoxifen coadministration with paclitaxel in biodegradable poly(ethylene oxide)-modified poly(epsilon-caprolactone) (PEO-PCL) nanoparticles. In vitro cytotoxicity and proapoptotic activity of paclitaxel and tamoxifen, either as single agent or in combination, was examined in wild-type (SKOV3) and MDR-1-positive (SKOV3TR) human ovarian adenocarcinoma cells. Subcutaneous SKOV3 and SKOV3TR xenografts were established in female nu/nu mice, and this model was used to evaluate the antitumor efficacy and preliminary safety. Paclitaxel (20 mg/kg) and tamoxifen (70 mg/kg) were administered i.v. either as a single agent or in combination in aqueous solution and in PEO-PCL nanoparticles. In vitro cytotoxicity results showed that administration of paclitaxel and tamoxifen in combination lowered the IC50 of paclitaxel by 10-fold in SKOV3 cells and by >3-fold in SKOV3TR cells. The combination paclitaxel/tamoxifen co-therapy showed even more pronounced effect when administered in nanoparticle formulations. Upon i.v. administration of paclitaxel/tamoxifen combination in PEO-PCL nanoparticle formulations, significant enhancement in antitumor efficacy was observed. Furthermore, the combination paclitaxel/tamoxifen therapy did not induce any acute toxicity as measured by body weight changes, blood cell counts, and hepatotoxicity. The results of this study show that combination of paclitaxel and tamoxifen in biodegradable PEO-PCL nanoparticles can serve as an effective clinically translatable strategy to overcome multidrug resistance in ovarian cancer.

Effect of Coenzyme Q10, Riboflavin and Niacin on Tamoxifen treated postmenopausal breast cancer women with special reference to blood chemistry profiles

Tamoxifen (TAM) a non-steroidal antiestrogen, is widely used in adjuvant therapy for all stages of breast carcinomas and in chemoprevention of high-risk group. TAM also has estrogenic activity on liver and endometrium causing severe oxidative stress with various biochemical derangements. Coenzyme Q(10), Riboflavin and Niacin (CoRN) are well-known potent antioxidants and protective agents against many diseases including cancer. In this context, this study was undertaken to find if co-administration of TAM along with CoRN could alleviate the sole TAM-induced biochemical derangements in postmenopausal women with breast cancer. The vitamin supplementation with TAM was given for a period of 90 days. Blood samples were collected at the base line, 45th and 90th day during the course of treatment. Various blood chemistry profiles were assessed in 78 untreated, sole TAM treated and combinatorial treated group along with 46 age- and sex-matched controls. A statistically significant alteration in various blood chemistry parameters, such as serum total bilirubin (S. BIL), serum glutamate oxaloacetate transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT), gamma glutamyl transpeptidase (gamma-GT), uric acid (UA), lipoprotein lipase (LPL), lecithin: cholesterol acyl transferases (LCAT), potassium, calcium and Na(+), K(+)-ATPase in sole TAM-treated group, was favorably reverted back to near normal levels on combinatorial therapy with CoRN. TAM on co-administration with CoRN has a favorable impact on various blood chemistry profiles. However, large scale randomized studies over a longer time span are required to ascertain the safety and efficacy of co-administrating antioxidants with conventional chemotherapy.

Estrogens and genomic instability in human breast cancer cells--involvement of Src/Raf/Erk signaling in micronucleus formation by estrogenic chemicals

Reports of the ability of estrogenic agents such as 17beta-estradiol (E2), estriol (E3) and bisphenol A (BPA) to induce micronuclei (MN) in MCF-7 breast cancer cells have prompted us to investigate whether these effects are linked to activation of the estrogen receptor (ER) alpha. Coadministration of tamoxifen and the pure ER antagonist ICI 182 780 to cells treated with E2 and E3 did not lead to significant reductions in micronucleus frequencies. Since these antiestrogens interfere with the transcriptional activity of the ER and block promotion of ER-dependent gene expression, it appears that this process is not involved in micronucleus formation. However, ER activation also triggers rapid signaling via the Src/Raf/extracellular signal-regulated kinase (Erk) pathway. When MCF-7 cells were exposed to E2 and BPA in combination with the specific kinase inhibitors pyrazolopyrimidine and 2'-amino-3'-methoxyflavone, reductions in micronucleus frequencies occurred. These findings suggest that the Src/Raf/Erk pathway plays a role in micronucleus formation by estrogenic agents. Enhanced activation of the Src/Raf/Erk cascade disturbs the localization of Aurora B kinase to kinetochores, leading to a defective spindle checkpoint with chromosome malsegregation. Using antikinetochore CREST antibody staining, a high proportion of micronucleus containing kinetochores was observed, indicating that such processes are relevant to the induction of MN by estrogens. Our results suggest that estrogens induce MN by causing improper chromosome segregation, possibly by interfering with kinase signaling that controls the spindle checkpoint, or by inducing centrosome amplification. Our findings may have some relevance in explaining the effects of estrogens in the later stages of breast carcinogenesis.

Preclinical studies of molecular-targeting diagnostic and therapeutic strategies against breast cancer

We have investigated protein kinase C (PKC) signaling, a putative differentiation-related and metastasis suppressor gene Cap43/NDRG1/Drg-1, and Y-box binding protein-1 (YB-1) to identify new molecular targeting for breast cancer. PKC is a family of serine/threonine kinases that is involved in the regulation of cell growth. We have demonstrated that PKC caused G(1) arrest in a breast cancer cell line through a mechanism involving a PKC-ERK MAPK-JNK-Rb protein signaling pathway. We have also characterized a novel mechanism through which all-trans retinoic acid (ATRA) and antineoplaston, anticancer drug, caused cell growth inhibition in breast cancer cells through effects on intracellular pathways. ATRA decreased the expression of PKCalpha, as well as reduced ERK MAPK phosphorylation, and consequently caused G(1) arrest. Antineoplaston caused the down-regulation of PKCalpha protein expression, resulting in inhibition of ERK MAPK phosphorylation, with resultant inhibition of Rb phosphorylation leading to G(1) arrest. PKC signaling represents a promising target for development of novel therapeutic agents. Cap43 is known as N-myc downstream-regulated gene 1 (NDRG1). Treatment with estradiol (E(2)) significantly decreased the expression of Cap43 in ER-alpha-positive breast cancer cell lines. Co-administration of tamoxifen abrogated the E(2)-induced downregulation of Cap43 in ER-alpha-positive cell lines. These results suggested that Cap43 may hold the potential of being a molecular marker to determine the therapeutic efficacy of anti-estrogenic anticancer agents in breast cancer. YB-1 is a member of the cold shock domain protein family. The expression of nuclear YB-1 was correlated with HER2 positively in clinical specimens of human breast cancer. Immunostaining studies showed that nuclear YB-1 expression was an independent prognostic factor of overall survival. Expression of nuclear YB-1 played an essential role in acquirement of malignant characteristics through HER2-dependent pathways in breast cancer patients. PKC, Cap43 and YB-1 may be useful in new molecular-targeting diagnosis and therapeutics in breast cancer.