Palbociclib and Pembrolizumab in Sarcoma

Phase Ib Trial Evaluating the Combination of CDK4 Inhibitor With Immunotherapy in Patients With Sarcoma

This is a single-arm open-label window of opportunity clinical study assessing the impact of pre-treatment with palbociclib in patients with soft tissue sarcomas for which PD-1 inhibitors are approved (includes undifferentiated pleomorphic sarcoma, myxofibrosarcoma, angiosarcoma, pleomorphic rhabdomyosarcoma, pleomorphic liposarcoma, or alveolar soft part sarcoma).

Study Overview

• Status: Recruiting
• Conditions: Sarcoma
• Intervention / Treatment: Drug: Palbociclib; Drug: Pembrolizumab

Detailed Description

Patients will be given palbociclib for 2 weeks following a pre-treatment ultrasound guided biopsy used to establish immunological baseline of the tumor microenvironment. After 2 weeks of palbociclib therapy, a second biopsy will be performed to assess the impact of palbociclib on the tumor microenvironment. Pembrolizumab will be started the same day as the second biopsy. After 2 doses of pembrolizumab, a third (optional) biopsy may be performed if the subject consents. At 8 weeks of therapy disease response will be assessed as per standard of care.

• Study Type: Interventional
• Enrollment (Estimated): 8
• Phase: Phase 1

Contacts and Locations

• Study Contact: Name: John Rieth, MD; Phone Number: 3193561616; Email: john-rieth@uiowa.edu

Study Locations

• United States
  • Iowa
    • Iowa City, Iowa, United States, 52242
      • Recruiting
      • University of Iowa Hospitals & Clinics
      • Contact: John Rieth, MD; Phone Number: (319) 356-1616; Email: john-rieth@uiowa.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria

A potential subject must meet all the following inclusion criteria to be eligible to participate in the study:

• Male or female patients aged > or = 12 years old
• ECOG Performance Status of < or = 2
• Any patient with the diagnosis of locally advanced, unresectable or metastatic sarcoma for which PD-1 inhibitors are approved (undifferentiated pleomorphic sarcoma, myxofibrosarcoma, angiosarcoma, pleomorphic rhabdomyosarcoma, pleomorphic liposarcoma, alveolar soft part sarcoma) who have progressed on at least 1 prior line of therapy. Prior immunotherapy treatment is allowed, including prior treatment with a PD-1 inhibitor.
• Patients with no known CNS disease, except for treated brain metastasis. Treated brain metastases are defined as having no evidence of progression or hemorrhage after treatment and no ongoing treatment for dexamethasone (as ascertained by clinical examination and brain imaging) during the screening period. Stable dose of anticonvulsants is allowed. Treatment for brain metastases may include whole brain radiotherapy, radiosurgery, or a combination as deemed appropriate by the treating physician. Patients with CNS metastases treated by neurosurgical resection or brain biopsy performed within 3 months prior to Day 1 will be excluded.
• Ability to understand and the willingness to sign a written informed consent or assent in case of patients < 18 years old.

Exclusion Criteria

A potential subject who meets any of the following exclusion criteria is ineligible to participate in the study:

• Lab values in the below ranges:
• Neutrophil count < 1000/mm3
• Platelet count < 100,000/mm3L
• Hemoglobin < 9 g/dL (transfusion to meet eligibility allowed)
• AST/SGOT and ALT/SGPT > 3.0x upper limit of normal (ULN) without disease involvement or > 5.0x ULN if the transaminase elevation is due to disease involvement
• Alkaline phosphatase > 5.0x ULN without known bony metastases
• Serum bilirubin > 1.5x ULN
• Serum creatinine > 1.5x ULN or 24-hour creatinine clearance < 30 mL/min per Cockroft- Gault equation
• Total serum calcium < lower limit of normal (LLN) or if calcium is below LLN the corrected calcium for serum albumin is > LLN
• Serum potassium < 3.0
• Serum sodium < 130
• Serum albumin < 2.5 g/dL
• History of myocardial infarction. unstable angina, stroke or transient ischemic attack within 6 months prior to Day 1
• History or drug induced pneumonitis (both pembrolizumab and palbociclib can cause pneumonitis)
• Subjects requiring hemodialysis
• Patients with severe hepatic impairment (Childs-Pugh Class C).
• Other concurrent severe and/or uncontrolled medical conditions in the opinion of the investigator which will preclude participation
• Pregnancy (positive pregnancy test) or lactation
• Concomitant use of any other anti-cancer therapy or radiation therapy of the target lesion. Palliative radiation therapy is permitted to non-target lesions.
• Patients with any significant history of non-compliance to medical regimens or with inability to grant a reliable informed consent

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Combination of Palbociclib with Pembrolizumab; Palbociclib given for 2 weeks following a pre-treatment ultrasound guided biopsy used to establish an immunological baseline of the tumor microenvironment. After the conclusion of palbociclib therapy, a post-treatment biopsy will be performed to assess the impact of palbociclib on the tumor microenvironment; pembrolizumab will be started the same day as the second biopsy. After 2 doses of pembrolizumab, a third (optional) biopsy could be performed.

Drug: Palbociclib; Palbociclib is a CDK4/6 inhibitor. Palbociclib, 125 mg, (pediatric dose 75mg/m2 up to 125mg) daily for 21 days out of every 28 days, PO (orally) starting 14 days prior to Pembrolizumab; Drug: Pembrolizumab; Pembrolizumab is a PD-1 blocking antibody. Given 14 days following Palbociclib: Pembrolizumab, 200 mg, once every three weeks, intravenously (IV)

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Dose limiting toxicities (DLTs) and adverse events (AEs) per CTCAE v5	Confirm the safety of the combination of Palbociclib and pembrolizumab in sarcomas for which PD-1 inhibitors are approved as defined by the incidence of DLTs	The dose limiting toxicity period is 4 weeks after starting the first dose of pembrolizumab

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Response rate per RECIST 1.1 criteria	To assess the response (per RECIST 1.1 criteria) of patients with advanced UPS with the combination of CDK4/6 inhibitor and anti-PD-1 immunotherapy	8 weeks following treatment intiation

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Progression free survival	To assess progression free survival as calculated by the time from start of treatment until the time of progression of disease or death due to any cause	Up to two years following completion of treatment

Collaborators and Investigators

• Sponsor: John Rieth
• Investigators: Principal Investigator: John Rieth, MD, University of Iowa Hospitals & Clinics

Study record dates

Study Major Dates

• Study Start (Actual): February 1, 2024
• Primary Completion (Estimated): July 1, 2028
• Study Completion (Estimated): July 1, 2028

Study Registration Dates

• First Submitted: October 16, 2023
• First Submitted That Met QC Criteria: November 1, 2023
• First Posted (Actual): November 2, 2023

Study Record Updates

• Last Update Posted (Actual): May 22, 2026
• Last Update Submitted That Met QC Criteria: May 20, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Neoplasms; Neoplasms by Histologic Type; Neoplasms, Connective and Soft Tissue; Sarcoma; Antineoplastic Agents, Immunological; Immune Checkpoint Inhibitors; Antineoplastic Agents; Molecular Mechanisms of Pharmacological Action; Enzyme Inhibitors; Protein Kinase Inhibitors; pembrolizumab; palbociclib
• Other Study ID Numbers: 202305133

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No