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ABSTRACT: Purpose
Cyclin D/CDK4/6 is critical in controlling the G1 to S checkpoint. CCND, the gene encoding cyclin D, is known to be amplified in a variety of solid tumors. Palbociclib is an oral CDK4/6 inhibitor, approved in advanced breast cancer in combination with endocrine therapy. We explored the efficacy of palbociclib in patients with nonbreast solid tumors containing an amplification in CCND1, 2, or 3.Patients and methods
Patients with tumors containing a CCND1, 2, or 3 amplification and expression of the retinoblastoma protein were assigned to subprotocol Z1B and received palbociclib 125 mg once daily for 21 days of a 28-day cycle. Tumor response was assessed every two cycles.Results
Forty patients were assigned to subprotocol Z1B; 4 patients had outside assays identifying the CCND1, 2, or 3 amplification and were not confirmed centrally; 3 were ineligible and 2 were not treated (1 untreated patient was also ineligible), leaving 32 evaluable patients for this analysis. There were no partial responses; 12 patients (37.5%) had stable disease as best response. There were seven deaths on study, all during cycle 1 and attributable to disease progression. Median progression-free survival was 1.8 months. The most common toxicities were leukopenia (n = 21, 55%) and neutropenia (n = 19, 50%); neutropenia was the most common grade 3/4 event (n = 12, 32%).Conclusions
Palbociclib was not effective at treating nonbreast solid tumors with a CCND1, 2, or 3 amplification in this cohort. These data do not support further investigation of single-agent palbociclib in tumors with CCND1, 2, or 3 amplification.
SUBMITTER: Clark AS
PROVIDER: S-EPMC10102836 | biostudies-literature | 2023 Apr
REPOSITORIES: biostudies-literature

Clark Amy S AS Hong Fangxin F Finn Richard S RS DeMichele Angela M AM Mitchell Edith P EP Zwiebel James J Arnaldez Fernanda I FI Gray Robert J RJ Wang Victoria V McShane Lisa M LM Rubinstein Larry V LV Patton David D Williams P Mickey PM Hamilton Stanley R SR Copur Mehmet S MS Kasbari Samer S SS Thind Ravneet R Conley Barbara A BA Arteaga Carlos L CL O'Dwyer Peter J PJ Harris Lyndsay N LN Chen Alice P AP Flaherty Keith T KT
Clinical cancer research : an official journal of the American Association for Cancer Research 20230401 8
<h4>Purpose</h4>Cyclin D/CDK4/6 is critical in controlling the G1 to S checkpoint. CCND, the gene encoding cyclin D, is known to be amplified in a variety of solid tumors. Palbociclib is an oral CDK4/6 inhibitor, approved in advanced breast cancer in combination with endocrine therapy. We explored the efficacy of palbociclib in patients with nonbreast solid tumors containing an amplification in CCND1, 2, or 3.<h4>Patients and methods</h4>Patients with tumors containing a CCND1, 2, or 3 amplifica ...[more]