Abstract 4732
Background
The use of progesterone receptor (PR) ligands for adjuvant breast cancer treatment remains controversial. We propose that antiprogestins inhibit the breast tumor growth with high isoform A (PRA)/isoform B (PRB) ratio while progestins may inhibit those with opposite ratios.
Methods
We used metastatic models with different PR isoform ratios to evaluate the effect of antiprogestins [mifepristone (MFP), aglepristone (AGLE), telapristone acetate (TLP), ulipristal acetate (UPA), or progestins [medroxyprogesterone acetate (MPA) or progesterone (Pg)]. Murine BALB/c tumors with PRA>PRB (C7-2-HI) and PRB>PRA (C7-HI), human MDA-MB-231 cells transfected with PRB and the inducible MDA-MB-231-iPRAB cells were inoculated into NSG mice.
Results
All antiprogestins inhibited C7-2-HI tumor growth rate (MFP 88%, TLP 59% UPA 70%) and the onset of lymph node and lung metastasis. AGLE induced complete tumor regression. The progestin MPA, increased tumor size and metastasis in a 60% (p < 0.001) and Pg showed a similar trend (22%). MFP and AGLE also inhibited the tumor growth and number of metastatic foci of the MDA-MB-231-iPRAB expressing PRA. Onset of long-term metastasis was evaluated by tumor surgery after interruption of MFP or AGLE neoadyuvant treatment. Both antiprogestins increased the Disease Free Survival rate (p < 0.001) compared with controls. Six out of 8 and 3/5 mice receiving AGLE and MFP, respectively, are disease free one year after surgery. AGLE adjuvant treatment, also inhibited long-term metastasis (p < 0.001). With C7-HI model (PRB>PRA), AGLE, UPA or MFP increased tumor growth and/or metastasis (p < 0.001) whereas MPA showed an opposite trend in the number of metastatic foci. Experiments performed with the MDA-MB-231 cells transfected with or induced to express PRB confirmed the inhibitory effects of MPA on the metastatic development.
Conclusions
Progestins/antiprogestins stimulate or inhibit, respectively tumor growth/metastasis of mammary carcinomas with high PRA/PRB ratio, and they may exert opposite effects in tumors with low PRA/PRB ratio. These findings highlight the relevance of evaluating PR isofor.m ratio prior to PR ligand treatment on human breast cancer.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
CONICET.
Funding
CONICET; INC, ANPCYT.
Disclosure
All authors have declared no conflicts of interest.
Resources from the same session
2686 - Clinicopathological characteristics, survival and prognostic factors of breast cancer-related microangiopathic haemolytic anemia: a multicenter study
Presenter: Marion Alhenc Gelas
Session: Poster Display session 2
Resources:
Abstract
1565 - Metabolic tumor volume by 18F-FDG PET/CT is an independent prognostic factor in metastatic breast cancer
Presenter: Heekyung Ahn
Session: Poster Display session 2
Resources:
Abstract
4498 - Patient Preferences for breast cancer treatments: A Discrete Choice Experiment from four European countries
Presenter: Thomais Konstantopoulou
Session: Poster Display session 2
Resources:
Abstract
1423 - Palbociclib plus fulvestrant as second- or later-line therapy for patients with locally advanced, inoperable or metastatic HR+/HER2- breast cancer in Germany: Interim results of the INGE-B phase 2 study
Presenter: Diana Lüftner
Session: Poster Display session 2
Resources:
Abstract
2284 - Ventriculoperitoneal Shunt for CNS Metastasis in Breast Cancer: Clinical Outcomes Based on Intrinsic Subtype
Presenter: Hee Kyung Kim
Session: Poster Display session 2
Resources:
Abstract
4598 - Administration of chemotherapy for metastatic breast cancer near the end of life: a population registry study
Presenter: Luisa Edman Kessler
Session: Poster Display session 2
Resources:
Abstract
5706 - Prognostic value of histological growth pattern in patients operated for breast cancer liver metastases
Presenter: Ali Bohlok
Session: Poster Display session 2
Resources:
Abstract
1697 - Illness perceptions, quality of life and mood in metastatic breast cancer patients
Presenter: Isabel Domingues
Session: Poster Display session 2
Resources:
Abstract
1935 - Multidisciplinary Treatments Increases Overall Survival in Patients with Newly Diagnosed Stage IV Breast Cancer:An Analysis of 2010–2014 SEER Data
Presenter: Jian Zhang
Session: Poster Display session 2
Resources:
Abstract
3875 - Correlation of radiotherapy with the prognosis of elderly patients with hormone receptor-positive breast cancer according to immunohistochemical subtyping
Presenter: Jin Zhang
Session: Poster Display session 2
Resources:
Abstract