Comparative tolerability of first-generation selective estrogen receptor modulators in breast cancer treatment and prevention

Retinal toxicities of cancer therapy drugs: biologics, small molecule inhibitors, and chemotherapies

PURPOSE

To review reported retinal side effects from current cancer therapy drugs.

METHODS

Retinal toxicities from ophthalmologic or oncologic case reports, case series, and clinical trials were identified by a systematic literature search using Lexicomp and PubMed.

RESULTS

Four biologics, 8 small molecule inhibitors, and 17 traditional chemotherapy agents had reported retinal side effects. For biologics, interferon alpha 2b was associated with retinopathy, denileukin diftitiox with pigmentary retinopathy, ipilimumab with a Vogt-Koyanagi-Harada-like syndrome, and trastuzumab with retinal ischemia. For small molecule inhibitors, v-raf murine sarcoma viral oncogene homolog B (BRAF) inhibitors were associated with uveitis, mitogen-activated protein kinase/extracellular signal-regulated kinase inhibitors with pigment epithelium detachments, and tyrosine kinase inhibitors with macular edema. Steroid antagonists were associated with crystalline retinopathy and macular edema. Nitrosoureas, platinum analogs, and cytosine arabinoside were associated with retinal vascular occlusions. Antimicrotubular agents were associated with cystoid macular edema but without fluorescein leakage. Retinoic acid derivatives were associated with impaired night vision, and mitotane was associated with a pigmentary retinopathy and papilledema.

CONCLUSION

Certain agents used in the treatment of systemic cancer are associated with ocular complications. Awareness of these complications will allow early detections and maybe reversal of some of the ocular problems.

Specific targeting of insulin-like growth factor 1 receptor signaling in human estrogen dependent breast cancer cell by a novel tyrosine-based benzoxazepine derivative

The present study sought to investigate the in vitro and in vivo effects of a tyrosine-based benzoxazepine, 4-[4-(toluene-4-sulfonyl)-2,3,4,5-tetrahydro-benzo[f][1,4]oxazepin-3-ylmethyl]-phenol) [THBP] in human breast cancer cells, with a focus on determining its molecular target. THBP had growth inhibitory effect on MCF-7 and MDA-MD-231 cells. At IC(50) value (∼20 μM), THBP resulted in G1 arrest, decrease in cyclin D1 levels and induction of apoptosis of MCF-7 cells. Mechanistically, activation of caspase 8 contributes critically to the induction of apoptotic cell death as copresence of selective inhibition of caspase 8 effectively abrogates the cytotoxic effect of THBP in MCF-7 cells. Further, THBP increased pro-apoptotic protein, Bax; decreased anti-apoptotic protein, Bcl-2; and decreased mitochondrial membrane potential in MCF-7 cells, indicating involvement of an intrinsic pathway of apoptosis following caspase 8 activation. Out of the various growth factors/hormones, THBP selectively abrogated increased viability of MCF-7 cells by insulin-like growth factor 1 (IGF-1). Molecular docking studies revealed that THBP occupied the ATP binding pocket of IGF-1 receptor (IGF-1R). Accordingly THBP was found to inhibit IGF-1-induced phosphorylation of IGF-1R and insulin receptor substrate-1 (IRS-1) without inhibiting insulin signaling in MCF-7 cells. In athymic nude mice, compared with vehicle, THBP treatment significantly reduced the growth of MCF-7 xenograft tumors through inhibition of cancer cell proliferation as well as promotion of cell death that correlated with reduced phospho-IGF-1R levels. We suggest that interfering with the IGF-1R signaling by the benzoxazepine THBP offers a novel and selective therapeutic strategy for estrogen receptor-positive, postmenopausal breast cancer patients.

The haunting of medical journals: how ghostwriting sold "HRT"

Adriane Fugh-Berman examines documents unsealed in recent litigation to investigate how pharmaceutical companies promoted hormone therapy drugs, including the use of medical writing companies to produce ghostwritten manuscripts and place them into medical journals.

Advances in Endocrine Therapy for Breast Cancer: Considering Efficacy, Safety, and Quality of Life

Breast cancer is the most common cancer found in women in the United States. Endocrine therapy is the standard of care for most women with hormone receptor-positive tumors in adjuvant and metastatic settings. The selective estrogen response modifier tamoxifen has been the standard treatment for postmenopausal patients for many years. Numerous new endocrine therapy agents provide women with novel treatment options, including the nonsteroidal aromatase inhibitors anastrozole and letrozole, the steroidal aromatase inhibitor exemestane, and the estrogen receptor antagonist fulvestrant. Clinical trials have begun to define the role of these agents and their unique side-effect profiles. Nurses are vital in supporting patients in the decision-making process, managing side effects of treatment, and making observations to enhance understanding of the patient experience with new treatments. This article will assist nurses in educating patients about endocrine therapy options and their associated potential short- and long-term side effects, as well as treatment demands.

Characterization of new estrogen receptor destabilizing compounds: effects on estrogen-sensitive and tamoxifen-resistant breast cancer

BACKGROUND

Antiestrogens of the selective estrogen receptor modulator (SERM) type, such as tamoxifen, have two major limitations: their mixed agonist and antagonist profile and the development of tumor resistance. We characterized two new pure antiestrogens-ZK-703 and ZK-253-that belong to the class of specific estrogen receptor destabilizers (SERDs), which includes fulvestrant, and compared their activity with that of fulvestrant and tamoxifen.

METHODS

Effects of antiestrogens on the growth of estrogen-dependent breast tumors in vivo were determined using several mouse xenograft models (including the tamoxifen-sensitive tumors MCF7, T47D, and MV3366 and the tamoxifen-resistant tumors ZR75-1 and MCF7/TAM) and chemically induced (nitrosomethyl urea [NMU] and dimethylbenzanthracene [DMBA]) rat breast cancer models (groups of 10 animals). We determined the initial response and effects on hormone receptor levels and the time to relapse after treatment (i.e., time to reach a predetermined tumor size threshold). Estrogen receptor (ER) levels were determined by immunoassay.

RESULTS

ZK-703 (administered subcutaneously) and ZK-253 (administered orally) were more effective than tamoxifen or fulvestrant at inhibiting the growth of ER-positive breast cancer in all xenograft models. For example, MCF7 tumors relapsed (i.e., reached the size threshold) in 10 weeks in mice treated with tamoxifen but in 30 weeks in mice treated with ZK-703. ZK-703 and ZK-253 also prevented further tumor progression in tamoxifen-resistant breast cancer models to a similar extent (more than 30 weeks in mice with ZR75-1 and MCF7/TAM tumors). In the chemically induced rat breast cancer models, orally administered ZK-703 and ZK-253 caused a nearly complete (>80%) inhibition of tumor growth. ER levels were dramatically reduced in MCF7 tumors after 5 weeks of ZK-703 treatment compared with ER levels in vehicle-treated tumors; by contrast, ER levels in tamoxifen-treated tumors were higher than those in control tumors.

CONCLUSION

ZK-703 and ZK-253 are potent, long-term inhibitors of growth in both tamoxifen-sensitive and tamoxifen-resistant breast cancer models.

Advances in estrogen receptor biology: prospects for improvements in targeted breast cancer therapy

Estrogen receptor (ER) has a crucial role in normal breast development and is expressed in the most common breast cancer subtypes. Importantly, its expression is very highly predictive for response to endocrine therapy. Current endocrine therapies for ER-positive breast cancers target ER function at multiple levels. These include targeting the level of estrogen, blocking estrogen action at the ER, and decreasing ER levels. However, the ultimate effectiveness of therapy is limited by either intrinsic or acquired resistance. Identifying the factors and pathways responsible for sensitivity and resistance remains a challenge in improving the treatment of breast cancer. With a better understanding of coordinated action of ER, its coregulatory factors, and the influence of other intracellular signaling cascades, improvements in breast cancer therapy are emerging.

Breast cancer chemoprevention: risk-benefit effects of the antioestrogen tamoxifen

The anti-oestrogen tamoxifen, which is widely used as adjuvant therapy for breast cancer, is undergoing evaluation as a chemopreventive agent in women at increased risk of developing this disease. Recent results from the National Surgical Adjuvant Breast and Bowel Project (NSABP) P-1 prevention trial show a 49% reduction in breast cancer incidence in healthy, high-risk women. However, tamoxifen treatment has the serious side effect of increasing the incidence of endometrial cancer in women and long-term administration of tamoxifen causes hepatic tumours in rats. These liver tumours are induced via a genotoxic mechanism, but the mechanisms responsible for endometrial cancer in women are not yet known and are a focus of much debate. This review describes the findings from the chemoprevention trials and problems associated with the use of tamoxifen in this setting. The mechanism of carcinogenesis in rat liver is explained in detail and compared to the situation in humans, with a view to assessing the risks associated with tamoxifen therapy and predicting whether other anti-oestrogens might be safer alternatives.