A tumor cell specific Zona Pellucida glycoprotein 3 RNA transcript encodes an intracellular cancer antigen

Background

Expression of Zona Pellucida glycoprotein 3 (ZP3) in healthy tissue is restricted to the extracellular Zona Pellucida layer surrounding oocytes of ovarian follicles and to specific cells of the spermatogenic lineage. Ectopic expression of ZP3 has been observed in various types of cancer, rendering it a possible therapeutic target.

Methods

To support its validity as therapeutic target, we extended the cancer related data by investigating ZP3 expression using immunohistochemistry (IHC) of tumor biopsies. We performed a ZP3 transcript specific analysis of publicly available RNA-sequencing (RNA-seq) data of cancer cell lines (CCLs) and tumor and normal tissues, and validated expression data by independent computational analysis and real-time quantitative PCR (qPCR). A correlation between the ZP3 expression level and pathological and clinical parameters was also investigated.

Results

IHC data for several cancer types showed abundant ZP3 protein staining, which was confined to the cytoplasm, contradicting the extracellular protein localization in oocytes. We noticed that an alternative ZP3 RNA transcript, which we term 'ZP3-Cancer', was annotated in gene databases that lacks the genetic information encoding the N-terminal signal peptide that governs entry into the secretory pathway. This explains the intracellular localization of ZP3 in tumor cells. Analysis of publicly available RNA-seq data of 1339 cancer cell lines (CCLs), 10386 tumor tissues (The Cancer Genome Atlas) and 7481 healthy tissues (Genotype-Tissue Expression) indicated that ZP3-Cancer is the dominant ZP3 RNA transcript in tumor cells and is highly enriched in many cancer types, particularly in rectal, ovarian, colorectal, prostate, lung and breast cancer. Expression of ZP3-Cancer in tumor cells was confirmed by qPCR. Higher levels of the ZP3-Cancer transcript were associated with more aggressive tumors and worse survival of patients with various types of cancer.

Conclusion

The cancer-restricted expression of ZP3-Cancer renders it an attractive tumor antigen for the development of a therapeutic cancer vaccine, particularly using mRNA expression technologies.

Progesterone from ovulatory menstrual cycles is an important cause of breast cancer

Many factors, including reproductive hormones, have been linked to a woman's risk of developing breast cancer (BC). We reviewed the literature regarding the relationship between ovulatory menstrual cycles (MCs) and BC risk. Physiological variations in the frequency of MCs and interference with MCs through genetic variations, pathological conditions and or pharmaceutical interventions revealed a strong link between BC risk and the lifetime number of MCs. A substantial reduction in BC risk is observed in situations without MCs. In genetic or transgender situations with normal female breasts and estrogens, but no progesterone (P4), the incidence of BC is very low, suggesting an essential role of P4. During the MC, P4 has a strong proliferative effect on normal breast epithelium, whereas estradiol (E2) has only a minimal effect. The origin of BC has been strongly linked to proliferation associated DNA replication errors, and the repeated stimulation of the breast epithelium by P4 with each MC is likely to impact the epithelial mutational burden. Long-lived cells, such as stem cells, present in the breast epithelium, can carry mutations forward for an extended period of time, and studies show that breast tumors tend to take decades to develop before detection. We therefore postulate that P4 is an important factor in a woman's lifetime risk of developing BC, and that breast tumors arising during hormonal contraception or after menopause, with or without menopausal hormone therapy, are the consequence of the outgrowth of pre-existing neoplastic lesions, eventually stimulated by estrogens and some progestins.

Maintaining bone health by estrogen therapy in patients with advanced prostate cancer: a narrative review

The purpose of androgen deprivation therapy (ADT) in prostate cancer (PCa), using luteinizing hormone-releasing hormone agonists (LHRHa) or gonadotrophin-releasing hormone antagonists, is to suppress the levels of testosterone. Since testosterone is the precursor of estradiol (E2), one of the major undesired effects of ADT is the concomitant loss of E2, causing among others an increased bone turnover and bone loss and an increased risk of osteoporosis and fractures. Therefore, the guidelines for ADT indicate to combine ADT routinely with bone-sparing agents such as bisphosphonates, denosumab or selective estrogen receptor modulators. However, these compounds may have side effects and some require inconvenient parenteral administration. Co-treatment with estrogens is an alternative approach to prevent bone loss and at the same time, to avoid other side effects caused by the loss of estrogens, which is the topic explored in the present narrative review. Estrogens investigated in PCa patients include parenteral or transdermal E2, diethylstilbestrol (DES), and ethinylestradiol (EE) as monotherapy, or high-dose estetrol (HDE4) combined with ADT. Cardiovascular adverse events have been reported with parenteral E2, DES and EE. Encouraging effects on bone parameters have been obtained with transdermal E2 (tE2) and HDE4, in the tE2 development program (PATCH study), and in the LHRHa/HDE4 co-treatment study (PCombi), respectively. Confirmation of the beneficial effects of estrogen therapy with tE2 or HDE4 on bone health in patients with advanced PCa is needed, with special emphasis on bone mass and fracture rate.

Estetrol Prevents Hot Flushes and Improves Quality of Life in Patients with Advanced Prostate Cancer Treated with Androgen Deprivation Therapy: The PCombi Study

Background

Androgen deprivation therapy (ADT) for prostate cancer (PCa) is accompanied by side effects affecting health-related quality of life (HRQL).

Objective

To assess the effects of the fetal estrogen estetrol (E4) on symptoms related to estrogen and androgen deficiency, and on HRQL measured using the validated Functional Assessment of Cancer Therapy-Prostate (FACT-P) questionnaire.

Design, setting, and participants

This was a phase 2, double-blind, randomized, placebo-controlled study in patients with advanced PCa.

Intervention

Patients receiving ADT were randomly assigned at a 2:1 ratio to daily treatment with a high dose of E4 (HDE4; n = 41) or placebo (n = 21) for 24 wk.

Outcome measurements and statistical analysis

The primary outcome was the effect of HDE4 cotreatment on hot flushes (HFs). Secondary outcomes were the Q-Man questionnaire for evaluation of the effect on estrogen and androgen deficiency symptoms, and the FACT-P questionnaire for evaluating HRQL.

Results and limitations

At 24 wk, the number of patients experiencing HFs was significantly lower in the HDE4 group than in the placebo group (14.3% vs 60.0%; p < 0.001). HDE4 treatment was associated with lower incidence of night sweats, arthralgia, and fatigue, but more nipple tenderness and gynecomastia. At 24 wk, the mean HRQL score favored HDE4 over placebo for the FACT-P total score (122.2 ± 12.3 vs 118.7 ± 19.7) and for several other FACT subscales.

Conclusions

Daily HDE4 coadministration almost completely prevented HFs in patients with advanced PCa treated with ADT. HDE4 also had positive effects on HRQL and counteracted other estrogen deficiency symptoms caused by ADT. These data support the dual efficacy concept of ADT and HDE4 to improve HRQL and increase the antitumor effect of ADT.

Patient summary

For patients on androgen deprivation therapy for advanced prostate cancer, cotreatment with a high dose of estetrol almost completely prevents the occurrence of hot flushes and improves quality of life and well-being, but nipple sensitivity and an increase in breast size may occur.

Tumor suppression, dose-limiting toxicity and wellbeing with the fetal estrogen estetrol in patients with advanced breast cancer

Purpose

The aim of this study (the ABCE4 study) was to assess dose-limiting toxicity (DLT), safety, tolerability and preliminary efficacy of high doses of the fetal estrogen estetrol (E4) in postmenopausal patients with heavily pretreated, locally advanced and/or metastatic ER+/HER2−breast cancer, resistant to anti-estrogens.

Methods

This was a multicenter, open-label, phase IB/IIA, dose-escalation study with a 3 + 3 cohort design, whereby successive cohorts of three patients received 20 mg, 40 mg or 60 mg E4 per day for 12 weeks by oral administration. DLTs, safety and wellbeing were evaluated after 4, 8 and 12 weeks of treatment. Anti-tumor effects were investigated by computer tomography scanning and evaluated according to RECIST criteria before and after 12 weeks of treatment. Wellbeing was judged weekly by the investigator and by quality-of-life questionnaires by the patients. In view of the small number of patients, no statistical testing was performed.

Results

All 12 patients enrolled had progressive, heavily pre-treated advanced breast cancer. No treatment-related serious adverse events or DLTs occurred during the first 4 weeks of E4 treatment allowing the investigation of all three doses. Five of nine patients completing 12 weeks of E4 treatment showed objective anti-tumor effects and six of nine patients reported improved wellbeing.

Conclusion

High doses of estetrol seem to be safe and are well tolerated during 12 weeks of treatment without dose-limiting toxicity and with anti-tumor effects in five of nine heavily treated patients with progressive, anti-estrogen resistant, advanced breast cancer.

Abstract P5-11-15: Estetrol for treatment of advanced ER+/HER2- breast cancer

Introduction: A high dose of the fetal estrogen estetrol (E4) is anticipated to have anti-tumor effects in patients with advanced, anti-estrogen resistant, ER+/HER2- breast cancer (BC). It will most likely also improve patient’s quality of life by reducing symptoms of estrogen deficiency such as hot flushes, arthralgia, sleep disturbances, vaginal dryness, mood changes and depression, bone loss and fractures and cognition. The ABCE4 study is performed in Germany in this patient population. The main objectives of the study are to assess safety and tolerability of three doses of E4, to determine anti-tumor response and to evaluate estrogen deficiency symptoms. Study design: This is a multi-center, open-label, phase IB/IIA, dose-escalation study with a 3 + 3 cohort design, whereby successive cohorts of 3 patients receive 20 mg, 40 mg and 60 mg E4 per day by oral administration. Dose limiting toxicity (DLT), safety and wellbeing are evaluated after 4, 8 and 12 weeks of treatment. Occurrence of DLT at completion of phase IB after 4 weeks treatment determines escalation to the next higher dose. Objective anti-tumor effects are assessed by computer tomography scanning and evaluated according to RECIST criteria before and after 12 weeks of treatment. Thereafter treatment may continue based on an evaluation of the patient and her treating physician. In view of the small numbers required for this study design no statistical testing was performed. Results: A total of 12 postmenopausal women with progressive, heavily pre-treated advanced BC have been enrolled. Nine patients completed Phase IB. One patient in the 20 mg group discontinued the study during Phase IIA due to disease progression after 9,5 weeks of E4 treatment. She died 3 weeks later. Eight patients completed both the Phase IB and IIA part of the study. None of the patients experienced a DLT. All three E4 doses were well tolerated by all patients. In total 38 adverse events were reported. Adverse events were mainly of mild or moderate intensity. The following 8 events were considered possibly related to E4 treatment: increased endometrial thickness, spotting (2 patients), dry skin, pruritus, edema, fatigue (2 patients), alopecia and acid regurgitation. Seven events fulfilled the criteria of seriousness from which one was considered to be related to E4 treatment. This patient experienced moderate vaginal bleeding after 36 weeks treatment with 20 mg E4 and was hospitalized for hysteroscopy and endometrial ablation with full recovery thereafter. Importantly five of the eight patients who completed treatment with E4 reported subjective improvement and “felt much better” than before the start of E4 treatment. This was described by one of the patients as: ‘”feeling less down and exhausted; instead feeling much more optimistic, powerful and positive when taking E4”. Five patients completing 12 weeks E4 treatment showed objective anti-tumor effects with stable disease (n=4) and one remission. All five continued E4 treatment. Tumor assessment after 24 weeks of E4 treatment showed again stable disease in 4 patients. Conclusion: We conclude that daily doses of 20 mg, 40 mg and 60 mg E4 are well tolerated without DLTs. The majority of patients experienced favorable subjective effects and four patients treated for 24 weeks or longer showed stable disease and tumor remission respectively. Treatment with E4 meets the criteria for further investigation and development of E4 as a new drug for the treatment of anti-estrogen resistant advanced breast cancer. Final dose selection of E4 will take place in September 2019.

Citation Format: Marcus Schmidt, Arnd Hönig, Yvette Zimmerman, Carole Verhoeven, Katrin Almstedt, Marco Battista, Hans Georg Lenhard, Jan Krijgh, Herjan Coelingh Bennink. Estetrol for treatment of advanced ER+/HER2- breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-11-15.

Abstract P4-13-12: Estetrol for treatment of advanced ER+ breast cancer

Introduction: Currently, a multi-center, open-label, phase I/IIA, dose-escalation study with the fetal estrogen estetrol (E4) is ongoing in Germany in postmenopausal patients with advanced breast cancer (ABCE4 study). The objective of the study is to assess safety and tolerability of different doses of E4 (range 20-60 mg per day). In addition initial anti-tumor response will be determined.

Study design: Patients are treated for 12 weeks with E4; 4 weeks in Phase I and thereafter 8 weeks in Phase IIA. Phase I of the study will follow the traditional 3 + 3 design to determine the optimal dose in patients with advanced breast cancer. Patients are treated in cohorts of three all receiving the same dose. Occurrence of dose limiting toxicity (DLT) at completion of phase I (4 weeks treatment) will determine escalation to the next higher dose in the study. After completion of Phase I, patients will continue treatment for 8 weeks to assess preliminary anti-tumor response in Phase IIA. Treatment may continue beyond 12 weeks based on evaluation of the patient and her treating physician.

Results: Phase I of the first treatment cohort with 20 mg E4 per day has been completed. A total of six postmenopausal women with advanced breast cancer has been included in the first cohort. One patient withdrew consent before treatment with E4 started. She was replaced. Two patients discontinued the study before completion of Phase I for reasons other than DLTs. These patients were unevaluable for toxicity and were also replaced. Three patients completed Phase I. One patient discontinued the study during Phase IIA due to disease progression after 9,5 weeks of E4 treatment. One patient completed both the Phase I and IIA part of the study. She had stable disease at study completion and wanted to continue E4 treatment because of improved well-being. Tumor assessment after 24 weeks of E4 treatment showed again stable disease. One patient is presently in Phase IIA of the study.

None of the patients experienced a DLT. The 20 mg E4 dose was well tolerated by all patients. In total 17 adverse events were reported. Adverse events were mainly of mild or moderate intensity. Five of 17 events fulfilled criteria of seriousness; none of these events were considered to be related to the E4 treatment. Four events were considered to be possibly related to the E4 treatment. These events were increased endometrial thickness, dry skin, pruritus and fatigue, all of mild intensity. A remarkable finding was that three of the five patients treated with E4 reported to the investigator to “feel better” than before the start of E4 treatment. This '”feeling better” was described by one of the patients as: '”feeling less down and exhausted; instead feeling much more optimistic, powerful and positive when taking E4”.

So far anti-tumor response could be estimated in one patient. This patient, who started the study with progressive disease, had stable disease as shown by tumor assessments after 12 weeks and 24 weeks of E4 treatment.

Conclusion: Based on these results, we conclude that a daily dose of 20 mg E4 is well tolerated. The majority of patients experienced favorable subjective effects on wellbeing. The data obtained with the 20 mg dose E4 allow dose escalation to the next higher dose of 40 mg E4 per day.

Citation Format: Schmidt M, Hönig A, Verhoeven C, Almstedt K, Battista M, Lenhard HG, Krijgh J, Coelingh Bennink H. Estetrol for treatment of advanced ER+ breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-13-12.