A phase I and pharmacokinetic study of high dose tamoxifen and weekly cisplatin in patients with metastatic melanoma

Comprehensive understanding of multiple actions of anticancer drug tamoxifen in isolated mitochondria

Tamoxifen has been widely used in the treatment of estrogen receptor (ER)-positive breast cancer, whereas it also exhibits ER-independent anticancer effects in various cancer cell types. As one of the convincing mechanisms underlying the ER-independent effects, induction of apoptosis through mitochondrial dysfunction has been advocated. However, the mechanism of action of tamoxifen even at the isolated mitochondrial level is not fully understood and remains controversial. Here, we attempted to comprehensively understand tamoxifen's multiple actions in isolated rat liver mitochondria through not only revisiting the actions hitherto reported but also conducting originally designed experiments. Using submitochondrial particles, we found that tamoxifen has potential as an inhibitor of both respiratory complex I and ATP synthase. However, these inhibitory effects were not elicited in intact mitochondria, likely because penetration of tamoxifen across the inner mitochondrial membrane is highly restricted owing to its localized positive charge (-N⁺H(CH₃)₂). This restricted penetration may also explain why tamoxifen is unable to function as a protonophore-type uncoupler in mitochondria. Moreover, tamoxifen suppressed opening of the mitochondrial permeability transition pore induced by Ca²⁺ overload through enhancing phosphate uptake into the matrix. The photoaffinity labeling experiments using a photolabile tamoxifen derivative (pTAM1) indicated that pTAM1 specifically binds to voltage-dependent anion channels (VDACs) 1 and 3, which regulate transport of various substances into mitochondria. The binding of tamoxifen to VDAC1 and/or VDAC3 could be responsible for the enhancement of phosphate uptake. Taking all the results together, we consider the principal impairment of mitochondrial functions caused by tamoxifen.

AMPK Activation and Metabolic Reprogramming by Tamoxifen through Estrogen Receptor-Independent Mechanisms Suggests New Uses for This Therapeutic Modality in Cancer Treatment

Tamoxifen is the most widely used adjuvant chemotherapeutic for the treatment of estrogen receptor (ER)-positive breast cancer, yet a large body of clinical and preclinical data indicates that tamoxifen can modulate multiple cellular processes independently of ER status. Here, we describe the ER-independent effects of tamoxifen on tumor metabolism. Using combined pharmacologic and genetic knockout approaches, we demonstrate that tamoxifen inhibits oxygen consumption via inhibition of mitochondrial complex I, resulting in an increase in the AMP/ATP ratio and activation of the AMP-activated protein kinase (AMPK) signaling pathway in vitro and in vivo AMPK in turn promotes glycolysis and alters fatty acid metabolism. We also show that tamoxifen-induced cytotoxicity is modulated by isoform-specific effects of AMPK signaling, in which AMPKα1 promotes cell death through inhibition of the mTOR pathway and translation. By using agents that concurrently target distinct adaptive responses to tamoxifen-mediated metabolic reprogramming, we demonstrate increased cytotoxicity through synergistic therapeutic approaches. Our results demonstrate novel metabolic perturbations by tamoxifen in tumor cells, which can be exploited to expand the therapeutic potential of tamoxifen treatment beyond ER(+) breast cancer. Cancer Res; 76(11); 3295-306. ©2016 AACR.

CYP2D6 genotype- and endoxifen-guided tamoxifen dose escalation increases endoxifen serum concentrations without increasing side effects

Breast cancer patients with absent or reduced CYP2D6 activity and consequently low endoxifen levels may benefit less from tamoxifen treatment. CYP2D6 poor and intermediate metabolizers may need a personalized increased tamoxifen dose to achieve effective endoxifen serum concentrations, without increasing toxicity. From a prospective study population of early breast cancer patients using tamoxifen (CYPTAM: NTR1509), 12 CYP2D6 poor and 12 intermediate metabolizers were selected and included in a one-step tamoxifen dose escalation study during 2 months. The escalated dose was calculated by multiplying the individual’s endoxifen level at baseline relative to the average endoxifen concentration observed in CYP2D6 extensive metabolizers by 20 mg (120 mg maximum). Endoxifen levels and tamoxifen toxicity were determined at baseline and after 2 months, just before patients returned to the standard dose of 20 mg. Tamoxifen dose escalation in CYP2D6 poor and intermediate metabolizers significantly increased endoxifen concentrations (p < 0.001; p = 0.002, respectively) without increasing side effects. In intermediate metabolizers, dose escalation increased endoxifen to levels comparable with those observed in extensive metabolizers. In poor metabolizers, the mean endoxifen level increased from 24 to 81 % of the mean concentration in extensive metabolizers. In all patients, the endoxifen threshold of 5.97 ng/ml (=16.0 nM) reported by Madlensky et al. was reached following dose escalation. CYP2D6 genotype- and endoxifen-guided tamoxifen dose escalation increased endoxifen concentrations without increasing short-term side effects. Whether such tamoxifen dose escalation is effective and safe in view of long-term toxic effects is uncertain and needs to be explored.

The combination of glutamate receptor antagonist MK-801 with tamoxifen and its active metabolites potentiates their antiproliferative activity in mouse melanoma K1735-M2 cells

Recent reports suggest that N-methyl-d-aspartate receptor (NMDAR) blockade by MK-801 decreases tumor growth. Thus, we investigated whether other ionotropic glutamate receptor (iGluR) antagonists were also able to modulate the proliferation of melanoma cells. On the other hand, the antiestrogen tamoxifen (TAM) decreases the proliferation of melanoma cells, and is included in combined therapies for melanoma. As the efficacy of TAM is limited by its metabolism, we investigated the effects of the NMDAR antagonist MK-801 in combination with TAM and its active metabolites, 4-hydroxytamoxifen (OHTAM) and endoxifen (EDX). The NMDAR blockers MK-801 and memantine decreased mouse melanoma K1735-M2 cell proliferation. In contrast, the NMDAR competitive antagonist APV and the AMPA and kainate receptor antagonist NBQX did not affect cell proliferation, suggesting that among the iGluR antagonists only the NMDAR channel blockers inhibit melanoma cell proliferation. The combination of antiestrogens with MK-801 potentiated their individual effects on cell biomass due to diminished cell proliferation, since it decreased the cell number and DNA synthesis without increasing cell death. Importantly, TAM metabolites combined with MK-801 promoted cell cycle arrest in G1. Therefore, the data obtained suggest that the activity of MK-801 and antiestrogens in K1735-M2 cells is greatly enhanced when used in combination.

Successful management of multi-focal hepatic infantile hemangioendothelioma using TACE/surgery followed by maintenance metronomic therapy

Infantile hepatic hemangioendothelioma (IHE) is a rare angiogenic tumour with diverse clinical presentations and varied course ranging from spontaneous regression to life-threatening complications. The authors report a 2-year boy who presented with respiratory distress and was identified as a case of inoperable multi-focal hepatic IHE. He showed a transient response to trans-arterial-chemo-embolisation and liver resection but had progressive disease despite chemotherapy (prednisolone/vicristine/ifosfamide/cisplatin). Thereafter, he was successfully managed with metronomic therapy using cyclophosphamide and tamoxifen.

Tamoxifen vs. non-tamoxifen treatment for advanced melanoma: a meta-analysis

Although tamoxifen (TAM) is routinely used in advanced melanoma, it is still uncertain whether evidence exists to support this practice. This review assesses the benefits and harms of systemic therapy with TAM vs. without TAM on response and mortality in patients with advanced melanoma. MEDLINE, The Cochrane Database of Systemic Reviews, The Cochrane Central Register of Controlled Trials, EMBASE and LILACS were searched for randomized controlled trials comparing chemotherapy using and not using TAM in any dose, in patients of any age with advanced melanoma. References lists, databases of ongoing trials and conference proceedings were hand-searched. All included trials were evaluated for quality assessment. Primary outcomes were response and mortality. Secondary outcomes were hematologic and non hematologic toxicity, treatment-related mortality and quality of life. A meta-analysis was performed and results were presented as relative risk with 95% confidence interval. Nine randomized controlled trials met the inclusion criteria. Patients treated with TAM were more likely to respond, with a relative risk 1.36 (95% CI: 1.04-1.77, P = 0.02). However, there was no improvement in 1-year mortality. The incidence of hematologic toxicity was higher in the TAM group. Subgroup analyses showed that female patients were more likely to respond. Chemotherapies with TAM improve overall and partial response, but do not improve mortality in 1 year in advanced melanoma. Further use of TAM in melanoma should be done only in the context of clinical trials.

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.

Systemic chemotherapy for the treatment of metastatic melanoma

The role of systemic chemotherapy in the treatment of patients with metastatic melanoma remains of questionable benefit. Despite encouraging phase II data from multiple institutions that suggested an improved overall response rate for patients treated with the Dartmouth regimen, recently completed phase III trials have failed to demonstrate a significant benefit in survival. Of concern is the fact that there have been relatively few new chemotherapeutic agents in the past several years that have demonstrated any activity in this disease. More recently there has been a shift away from combination chemotherapy to biochemotherapy. However, this approach has yet to be clearly defined as superior. The basis for optimism in the future in this field resides in the realm of molecular oncology. As mechanisms of resistance are identified, new molecules such as antisense oligonucleotides may provide the basis for increasing the sensitivity of melanoma to chemotherapeutic and/or immunotherapeutic treatments.

A phase II study of high dose tamoxifen and weekly cisplatin in patients with metastatic melanoma

We have previously demonstrated that the combination of tamoxifen and cisplatin has activity in patients with metastatic melanoma. In vitro studies have demonstrated that tamoxifen and cisplatin exhibit cytotoxic synergy in human melanoma cells and that this interaction is dependent on a tamoxifen effect. The mechanism of this effect is currently under investigation in in vitro studies. In an attempt to improve the complete response rate of this regimen, we initiated a phase II trial to determine the effect of the use of high dose tamoxifen and weekly cisplatin on the complete response rate, disease-free survival and overall survival. Tamoxifen was started on day 1 initially at a dose of 240 mg/day and continued until the patient was taken off treatment. This dose was subsequently lowered to 200 mg/day. Cisplatin (80 mg/m2) was begun on day 2 and repeated weekly for a total of 3 weeks. During week 4, the patient was not treated with cisplatin but was evaluated for response. If disease stabilization or regression was documented, the patient received a second 3 week cycle of cisplatin and was then re-evaluated for response. Patients with progressive disease at any evaluation were removed from the study. In 28 consecutive patients, the overall response rate was 32% (95% confidence interval 15.88-52.35%). One patient achieved a complete remission that lasted 22 months. All other responses were partial in nature. Toxicity was primarily nausea and vomiting. Two patients developed grade 2 renal toxicity. There were no episodes of deep venous thrombosis. This phase II study demonstrates that this combination has modest activity in patients with metastatic melanoma. However, this study failed to confirm our hypothesis that high dose tamoxifen would increase the complete response rate of this combination. While this combination has activity, the overall response rate is not significantly better that that observed with the original Dartmouth regimen and the toxicity is substantial. We do not recommend this dose and schedule for routine clinical use.

Tamoxifen and carboplatin for children with low-grade gliomas: a pilot study at St. Jude Children's Research Hospital

PURPOSE

The authors conducted a single-arm, prospective study using tamoxifen and carboplatin for the treatment of children with progressive or symptomatic low-grade gliomas.

PATIENTS AND METHODS

Fourteen children with consecutively diagnosed cases of low-grade glioma were enrolled in this Study; all patients were younger than 14 years. One patient was excluded after induction chemotherapy because of the diagnosis of a nonmalignant condition. Patients were treated with daily tamoxifen (20 mg/m2 administered twice per day) in addition to targeted, monthly intravenous carboplatin at an area under the curve (AUC) exposure of 6.5 mg/mL x minute for 1 year or until they had clinical or radiologic evidence of disease progression.

RESULTS

The median age at diagnosis was 5.3 years, the median age at initiation of chemotherapy was 8.3 years. Eight patients had tumors of the hypothalamus/optic pathway, two patients had thalamic tumors, and one patient each had tumors in the temporal lobe, tectum, and brain stem. Tumor histologic findings included fibrillary astrocytoma (n = 2), juvenile pilocytic astrocytoma (n = 6), and oligodendroglioma (n = 1). The best response to therapy was a partial response in two patients, stable disease in nine patients, and progressive disease in two patients. The overall survival at 3 years is 69%. The 3-year progression-free survival is 47%. Tamoxifen and carboplatin chemotherapy did not result in a significant number of objective responses in children with low-grade gliomas. The progression-free survival is similar to that of other published series. Nonmyelosuppressive agents such as tamoxifen deserve additional evaluation in the treatment of children with low-grade gliomas.

A phase II study of two cycles of high-dose chemotherapy with autologous stem cell support in patients with metastatic breast cancer who meet eligibility criteria for a single cycle

Multi-cycle high-dose chemotherapy with autologous stem cell support (HDC-ASCS) may improve the results obtained with single-cycle HDC-ASCS in metastatic breast cancer (MBC). However, the tolerability and efficacy of additional cycles of HDC-ASCS in patients selected using standard eligibility criteria for single cycle HDC-ASCS is uncertain. Twenty-nine patients with MBC and a CR or PR to induction chemotherapy were selected by standard institutional eligibility criteria for single-cycle HDC-ASCS. Cycle 1 HDC-ASCS (cyclophosphamide 6 g/m2; mitoxantrone 70 mg/m2; carboplatin 800 mg/m2) was followed by a planned second cycle (etoposide 1.6 g/m2; thiotepa 800 mg/m2; carboplatin 800 mg/m2 modulated by tamoxifen 120 mg/m2/day x 5 days) with a median interval of 3.2 months. CR rate was 20% after induction chemotherapy and 33% and 54% after HDC cycles I and II, respectively. Sixteen patients (55%) failed to complete HDC cycle II within 200 days because of disease progression, toxicity, inadequate stem cell collection, insurance denials or patient choice. Median progression-free survival (PFS) for all 29 patients entered is 301 days from date of HDC cycle I and actuarial PFS at 2 years is 35%. For the 13 patients who received the two cycles of HDC-ASCS, actuarial PFS at 2 years was 54% (P = NS compared to those receiving only one cycle). These data show that a second cycle of full-dose intensity HDC-ASCS may increase the proportion of patients with MBC that achieve CR and may increase PFS. However, a large proportion of patients that complete HDC-ASCS cycle I may fail to proceed to cycle II in a timely fashion. Bone Marrow Transplantation (2000) 25, 519-524.

High dose tamoxifen plus cisplatin and etoposide in the treatment of patients with advanced, inoperable nonsmall cell lung carcinoma

BACKGROUND

Tamoxifen sensitizes cancer cells to chemotherapeutic agents. High dose tamoxifen has been tested in the treatment of patients with melanoma and other cancers. The authors conducted a Phase II study of high dose tamoxifen plus cisplatin and etoposide for patients with advanced, inoperable nonsmall cell lung carcinoma.

METHODS

Patients with Stage IIIB, Stage IV, or recurrent disease; good performance status; measurable lesions; and good organ function were eligible. Tamoxifen 150 mg/m2/day, divided into 4 doses, was given for 8 days. Cisplatin 60 mg/m2 was given on Day 4. Etoposide 60 mg/m2/day was given on Days 4-8. Patients were allowed to remain in the study until either intolerable toxicity was observed or disease progression occurred.

RESULTS

Forty patients were accrued and received a total of 191 cycles of treatment. All patients were evaluable for response and toxicity. One patient had a complete remission and 14 had a partial remission (overall response rate, 37.5%). The median survival was 47 weeks. One-year survival was 44%. Increased thrombotic episodes were noted; all were clinically manageable.

CONCLUSIONS

High dose tamoxifen can be administered safely in combination with cisplatin and etoposide to patients with advanced nonsmall cell lung carcinoma. Favorable response rates and survival times were obtained. The value of high dose tamoxifen in the treatment of patients with nonsmall cell lung carcinoma can be evaluated further in randomized Phase III studies.

Tamoxifen induces p21WAF1 and p27KIP1 expression in estrogen receptor-negative lung cancer cells

Tamoxifen (Tam), besides its action as an anti-estrogen, also inhibits cell proliferation of estrogen receptor (ER)-negative cancer cells by an unknown mechanism. In this study, we used ER-negative lung cancer cells to clarify such ER-independent inhibitory effect of Tam. We found that Tam induced G1 growth arrest in these cells. However, our results indicated that the expression of G1 cyclins (including D1, 2, 3 and E) was not regulated by Tam in these lung cancer cells. Additionally, the protein levels of G1 acting cyclin-dependent kinases (CDKs), CDK2, 4 and 6, was unaltered in Tam-treated lung cancer cells with the exception of CDK2 expression in H322 cells which was attenuated by Tam in a cell line-specific manner. We next examined the effect of Tam on the expression of cyclin-dependent kinase inhibitors (CDKIs) and our results demonstrated that the expression of p21WAF1 and p27KIP1, but not p57KIP2, was strongly activated by Tam in these cells. The amounts of p21WAF1 and p27KIP1 co-immunoprecipitated with cyclin E were obviously increased after Tam treatment and reduced activity of cyclin E-associated kinases and accumulation of hypo-phosphorylated retinoblastoma (Rb) protein were clearly detected in Tam-incubated cells. No consentaneous induction of CDKIs was found when ER-negative lung cancer cells were incubated with cytotoxic drugs, cisplatin and etoposide, this indicates that enhancement of CDKI expression is not a non-specific effect of Tam. We also found that Tam may up-regulate p21WAF1 expression via transcription activation. Considered together, these results suggest that Tam-induced growth inhibition in ER-negative lung cancer cells is associated with induction of p21WAF1 and p27KIP1.

Cell cycle regulation of human pancreatic cancer by tamoxifen

BACKGROUND

Clinical trials have suggested a survival advantage for selected patients with metastatic pancreatic cancer treated with tamoxifen. We sought to identify the molecular mechanism by which tamoxifen inhibits human pancreatic cancer cell (HPCC) growth.

METHODS

HPCCs were grown in tamoxifen and growth inhibition was determined by 3H-thymidine uptake and by the MTT assay; changes in cell viability were determined by cell counts. Cell cycle alterations were evaluated by FACS, and the induction of apoptosis was evaluated using the TUNEL assay. Total cellular RNA was isolated after tamoxifen treatment, and Northern blot analysis was performed for p21waf1.

RESULTS

Tamoxifen inhibited HPCC growth as measured by inhibition of 3H-thymidine incorporation and by the MTT assay. However, there was no decrease in the total number of viable cells after 6 days of treatment with 10 microM of tamoxifen and no evident apoptosis, confirming the absence of a cytotoxic effect. Cell cycle analysis revealed cellular arrest in the G0/G1 phase, which correlated with p21waf1 mRNA upregulation in response to tamoxifen treatment.

CONCLUSIONS

Tamoxifen inhibits HPCC growth by inducing G0/G1 arrest with an associated increase in p21waf1 mRNA expression. Tamoxifen is an effective inhibitor of HPCC growth in vitro and warrants further in vivo study.