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RecruitingNCT06113809Updated May 22, 2026

Palbociclib and Pembrolizumab in Sarcoma

A Phase 1 interventional study of Palbociclib and Pembrolizumab in Sarcoma, sponsored by John Rieth. Recruiting at 1 site in United States. Open to participants aged 12 Years and older. Per ClinicalTrials.gov, last updated 2026-05-22.

Sponsored by John Rieth · Phase 1, Interventional, and Treatment

From the registry’s dates

  • Started Feb 2024; still recruiting 2 years 8 months later.
Phase
Phase 1
Study type
Interventional
Enrollment
8
Allocation
Not applicable
Ages
12 Years and older
Sex
All
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Study summary

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).

Read the 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.

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Conditions studied

  • Sarcoma

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03

In context

Sarcoma

1,667 studies on the registry are indexed under Sarcoma; 393 are open to participants now.

This study's planned enrollment of 8 is below the median of 40 across 1,283 interventional studies indexed under Sarcoma.

Browse Sarcoma studies →

Lead sponsor

John Rieth is the lead sponsor of 4 studies on the registry; 1 is open to participants now.

Counted across the registry records on this site, refreshed daily.

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Who can participate

Ages eligible
12 Years and older
Sexes eligible
All
Accepts healthy volunteers
No

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

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
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Study design

Phase
Phase 1
Primary purpose
Treatment
Allocation
Not applicable
Intervention model
Single group
Masking
None (open label)
Enrollment
8 participants (estimated)

Study arms

  • 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 · Drug: Pembrolizumab

Interventions

  • DrugPalbociclib

    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

  • DrugPembrolizumab

    Pembrolizumab is a PD-1 blocking antibody. Given 14 days following Palbociclib: Pembrolizumab, 200 mg, once every three weeks, intravenously (IV)

06

What researchers measure

Primary outcomes

  1. 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

    Time frame: The dose limiting toxicity period is 4 weeks after starting the first dose of pembrolizumab

Secondary outcomes

  1. 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

    Time frame: 8 weeks following treatment intiation

Other outcomes

  1. 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

    Time frame: Up to two years following completion of treatment

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Study locations

1 of 1 sites recruiting
  • University of Iowa Hospitals & Clinics
    Iowa City, Iowa 52242, United States
    Recruiting
08

References and documents

Individual participant data

Plan to share: No

No publications or documents are linked to this record.

09

Updates

Tracking since Sep 25, 2026
No changes since tracking began. The registry record was last updated on May 22, 2026, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
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Registry details

Key details

Study ID
NCT06113809
Lead sponsor
John Rieth
Responsible party
John Rieth (Clinical Professor, University of Iowa) — Sponsor-investigator
First posted
Nov 2, 2023
Start date
Feb 1, 2024
Primary completion
Jul 2028 (estimated)
Completion
Jul 2028 (estimated)
Last update
May 22, 2026

Study contacts

John Rieth, MD
Contact
john-rieth@uiowa.edu
3193561616
John Rieth, MD
principal investigator · University of Iowa Hospitals & Clinics

Oversight

Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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