Journal: ESMO Open
Article Title: TBCRC 035: randomized phase II pharmacodynamic study of standard and reduced-dose palbociclib with endocrine therapy in hormone receptor (HR)-positive previously treated metastatic breast cancer
doi: 10.1016/j.esmoop.2026.106063
Figure Lengend Snippet: Changes in Ki-67 and phosphorylated Rb in tumor tissue and skin. (A) Analysis of pharmacodynamic markers show marked reduction in on-treatment biopsy. Representative tumor biopsy specimens (patient 214-0143) obtained pre-treatment and on-treatment (C1D17) were stained using antibodies to phospho-retinoblastoma protein [pRb (S780)], total Rb, and Ki-67. (B) The box plot depicts the expression of Ki-67, total-Rb, and pRb in 27 paired tumor tissue samples, as determined by percentage of cells staining positive. Data are presented before and after treatment, regardless of palbociclib dose level or endocrine therapy partner. (C) The box plot depicts the change in the percent of cells staining positive for expression of Ki-67, total Rb, and pRb in tumor tissue samples between baseline and on-treatment for patients receiving both 100 mg and 125 mg of palbociclib. (D) The box plot depicts pRb and Ki-67 expression, as determined by the percentage of cells staining positive in 66 paired skin biopsies taken at baseline and between day 14 and 21 of the first cycle of palbociclib. Expression is shown pre-treatment and on-treatment at both dose levels of palbociclib. pRb, phosphorylated retinoblastoma protein; total-Rb, total retinoblastoma protein; Pre, pre-treatment; On-Tx, on-treatment
Article Snippet: Baseline and on-treatment skin punch and tumor core biopsies were formalin-fixed, paraffin-embedded, sectioned (5 μM), and stained for pRb (S780) (Cell Signaling Technology #9308, Danvers, MA), total Rb (clone 3C8, LS-3414, Abnova, Taipei City, Taiwan), and Ki-67 (clone MIB-1, #M7240, Agilent Dako, Santa Clara, CA) on the Leica BOND IHC platform using 3, 3-diaminobenzidine or polymer red detection (to reduce melanin background).
Techniques: Staining, Expressing
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![Changes in Ki-67 and phosphorylated Rb in tumor tissue and skin. (A) Analysis of pharmacodynamic markers show marked reduction in on-treatment biopsy. Representative tumor biopsy specimens (patient 214-0143) obtained pre-treatment and on-treatment (C1D17) were stained using antibodies to phospho-retinoblastoma protein [pRb <t>(S780)],</t> total Rb, and Ki-67. (B) The box plot depicts the expression of Ki-67, total-Rb, and pRb in 27 paired tumor tissue samples, as determined by percentage of cells staining positive. Data are presented before and after treatment, regardless of palbociclib dose level or endocrine therapy partner. (C) The box plot depicts the change in the percent of cells staining positive for expression of Ki-67, total Rb, and pRb in tumor tissue samples between baseline and on-treatment for patients receiving both 100 mg and 125 mg of palbociclib. (D) The box plot depicts pRb and Ki-67 expression, as determined by the percentage of cells staining positive in 66 paired skin biopsies taken at baseline and between day 14 and 21 of the first cycle of palbociclib. Expression is shown pre-treatment and on-treatment at both dose levels of palbociclib. pRb, phosphorylated retinoblastoma protein; total-Rb, total retinoblastoma protein; Pre, pre-treatment; On-Tx, on-treatment](https://pub-med-central-images-cdn.bioz.com/pub_med_central_ids_ending_with_5829/pmc12995829/pmc12995829__gr2.jpg)