MOESM1 of Elacestrant (RAD1901) exhibits anti-tumor activity in multiple ER+ breast cancer models resistant to CDK4/6 inhibitors
Creators: name: Hitisha Patel
name: Nianjun Tao
name: Lee, Kyung-Min
name: Huerta, Mariela
name: Arlt, Heike
name: Mullarkey, Tara
name: Troy, Steven
name: Arteaga, Carlos
name: Teeru Bihani
Publisher: name: figshare
Year: 2019
Subjects: subject: Biochemistry
subject: Microbiology
subject: FOS: Biological sciences
subject: FOS: Biological sciences
subject: Cell Biology
subject: Genetics
subject: Molecular Biology
subject: Pharmacology
subject: Biotechnology
subject: 39999 Chemical Sciences not elsewhere classified
subject: FOS: Chemical sciences
subject: FOS: Chemical sciences
subject: Immunology
subject: FOS: Clinical medicine
subject: FOS: Clinical medicine
subject: Cancer
subject: Hematology
subject: 110309 Infectious Diseases
subject: FOS: Health sciences
subject: FOS: Health sciences
subject: Plant Biology

description: Additional file 1: Figure S1. Characterization of CDK4/6i (Ribociclib and Abemaciclib) resistance models developed in ESR1wt and ESR1mut: D538G/Y537S backgrounds. CellTiter-Glo assay, colony formation assay and western-blot analysis of (A) ESR1wt/ESR1mut: D538G/ESR1mut: Y537S-RiboS and ESR1wt/ESR1mut: D538G/ESR1mut: Y537S-RiboR cells and (B) ESR1wt/ESR1mut: D538G/ESR1mut: Y537S-AbemaS and ESR1wt/ESR1mut: D538G/ESR1mut: Y537S-AbemaR cells; treated with controls and the pertinent CDK4/6i at the indicated doses. Figure S2. Elacestrant downregulates upregulated ER pathway genes in palbociclib-resistant cells. A. Log2FC for genes modulated in the ER signaling pathway in ESR1wt-PalboR cell line vs ESR1wt-PalboS cell line. B. Log2FC for genes modulated by elacestrant (300 nM) treatment of ESR1wt-PalboR cells. Figure S3. Comparative expression of cell cycle proteins in palbociclib-sensitive and palbociclib-resistant in vitro and in vivo models. A. Western blot analysis of indicated proteins from baseline/vehicle-treated samples of the denoted palbociclib-sensitive and palbociclib-resistant models. B. Summarized treatment histories and palbociclib responses for the PDX models shown in this paper. Figure S4. Single-dose pharmacokinetic profile for palbociclib in non-tumor bearing mice. Mice were treated with the indicated doses of palbociclib and plasma collected at the indicated timepoints after single dose. Mean concentration Â± SD of palbociclib is depicted (n=4/timepoint/dose). Area under the curve (AUC0-inf) was calculated and divided by the AUC0-inf for the clinical regimen of palbociclib (Ibrance-125 mg). Figure S5. ER-independent growth of PDX model previously treated with AI + palbociclib. A. Mean tumor volume of CTG-2308 PDX model, asterisks represent differences between the indicated groups at the end-of-study; p-values *, p&lt;0.05, **, p&lt;0.01, ***, p&lt;0.001, ****, p&lt;0.0001. B. Western blot analysis of phospho-RB and RB from tumors harvested 4h post-last dose. C. Western-blot analysis of indicated proteins from tumors harvested 4h post-last dose for the indicated treatment arms. D. qRT-PCR analysis of PGR, TFF1, and GREB1 in end-of-study tumors treated with the elacestrant and fulvestrant. Table S1. Commonly observed mechanisms upregulated in CDK4/6i-resistance models include CCNE1 and E2F1 overexpression. Summarized results from Fig. 2 demonstrating modulation of cell cycle proteins in our in vitro models resistant to palbociclib, ribociclib, and abemaciclib.