Fixed Duration Pirtobrutinib and Obinutuzumab in Chronic Lymphocytic Leukemia

Official title

A Phase 2 Study of Fixed Duration Therapy With Pirtobrutinib and Obinutuzumab in Previously Untreated Chronic Lymphocytic Leukemia (POP)

Overview

This study will evaluate fixed-duration therapy with pirtobrutinib and obinutuzumab given over 12 cycles (approximately 1 year) as first-line treatment of chronic lymphocytic leukemia or small lymphocytic lymphoma (CLL or SLL).

Detailed description

This is an open-label, multicenter, single-arm phase 2 study of pirtobrutinib with obinutuzumab for participants with CLL or SLL. Eligible participants will receive 6 cycles of pirtobrutinib alone followed by an additional 6 cycles of pirtobrutinib-obinutuzumab combination therapy. All participants will stop treatment after 12 cycles in total (approximately 1 year).

If CLL progresses and requires treatment after 1-year of therapy, participants will receive retreatment with pirtobrutinib only. Participants will be followed for up to a total of 10 years. Up to 60 participants will take part in this study.

The U.S. Food and Drug Administration (FDA) has approved pirtobrutinib for continuous treatment of CLL that has relapsed or become refractory to other treatments. Pirtobrutinib is not approved for the first-line treatment of CLL/SLL nor for fixed-duration therapy. The FDA has approved obinutuzumab for the treatment of CLL.

The research study procedures include screening for eligibility, study treatment visits, electrocardiograms, imaging (e.g. computerized tomography or CT scans), blood tests, saliva tests, bone marrow biopsies, and/or lymph node biopsies (if feasible).

Loxo Oncology at Eli Lilly and Company is supporting this study by providing pirtobrutinib and research funding.

Interventions

• Drug Pirtobrutinib
  Initial treatment: \- Pirtobrutinib 200 mg by mouth (PO) daily from Cycle 1 Day 1 until the end of Cycle 12. Each cycle is 28 days. Re-treatment: -Pirtobrutinib 200 mg PO daily continuously
• Drug Obinutuzumab
  Obinutuzumab is given intravenously from Cycle 7 to Cycle 12, for total 6 cycles during initial treatment only. Initial treatment: \- Obinutuzumab intravenous (IV) following the standard schedule from Cycle 6 through Cycle 12 (total 6 cycles: 100 mg on Cycle 6 Day 1, 900 mg on Cycle 6 Day 2, 1000 mg on Cycle 6 Day 8 and Cycle 6 Day 15, 1000 mg on Day 1 of Cycle 7 through Cycle 12).

Primary outcome measures

• Rate of complete response after initial therapy [Time frame: 1 year since treatment initiation]

Secondary outcome measures (7)

• Overall response rate [Time frame: 1 year since treatment initiation]
• Rate of partial response [Time frame: 1 year since treatment initiation]
• Time to next line of therapy [Time frame: 5 years after the last enrollment]
• Event-free survival [Time frame: 5 years after the last enrollment]
• Progression-free survival [Time frame: 5 years after the last enrollment]
• Overall survival [Time frame: 5 years after the last enrollment]
• Rate of re-treatment with pirtobrutinib [Time frame: 5 years after the last enrollment]

Eligibility criteria

Inclusion criteria

• Meet 2018 International Workshop on Chronic Lymphocytic Leukemia (IWCLL) guidelines for the diagnosis of chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL).
• Presence of measurable disease (absolute lymphocyte count > 5,000/µL, palpable or measurable lymph nodes ≥1.5cm on imaging, or bone marrow involvement of CLL ≥ 30%).
• No prior systemic therapy for CLL or SLL.
• Currently have an indication for treatment as defined by the following 2018 IWCLL guidelines
• Age ≥ 18 years
• Eastern Cooperative Oncology Group performance status ≤ 2
• Adequate organ and bone marrow function as defined by the study protocol
• Ability to take oral medications.
• Ability to understand and the willingness to sign a written informed consent document.

Exclusion criteria

• Known or suspected Richter's transformation or known central nervous system involvement.
• History of bleeding disorders
• History of stroke or intracranial hemorrhage within 6 months of starting study therapy.
• Significant cardiovascular disease such as uncontrolled arrhythmia, Class 3 or 4 congestive heart failure as defined by the New York Heart Association Functional Classification, or left ventricular ejection fraction < 40% by any methods in the 12 months prior to study therapy.
• History of other malignancies with life expectancy of < 2 years.
• Receiving any other investigational agents.
• Concurrent systemic immunosuppression < 28 days of study therapy or administration of > 20 mg of prednisone or equivalent daily < 7 days of study therapy.
• Vaccinated with live vaccine within 4 weeks of starting study therapy.
• Major surgery within 4 weeks of starting study therapy.
• Ongoing or recent infection requiring intravenous antimicrobials at time of screening. Prophylactic antibiotics are allowed if there is no evidence of active infection and the antibiotics is not included on the list of the prohibited medications.
• Patients who have tested positive for HIV are excluded due to potential drug-drug interactions between anti-retroviral medications and pirtobrutinib and risk of opportunistic infections with both HIV and irreversible BTK inhibitors. For patients with unknown HIV status, HIV testing will be performed at Screening and result should be negative for enrollment.
• Active human T cell leukemia virus infection or active hepatitis B or C virus infection
• Known active cytomegalovirus infection
• Pregnancy, lactation or plan to breastfeed during the study or within 6 months of the last dose of study treatment.
• Clinically significant active malabsorption syndrome or other condition likely to affect gastrointestinal absorption of the study drug
• Active uncontrolled auto-immune cytopenia.
• Significant co-morbid condition or disease.

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

N/A

Model

Sequential

Masking

Open label

Primary purpose

Treatment

Study locations

United States · 4 centers

• New England Cancer Specialists — Scarborough
• Beth Israel Deaconess Medical Center — Boston
• Brigham & Women's Hospital — Boston
• Dana-Farber Cancer Institute — Boston

Publications

• Davids MS. BRUIN 313 and 314 Trials Open the Door for Noncovalent Bruton Tyrosine Kinase Inhibition as Initial Therapy for Chronic Lymphocytic Leukemia. J Clin Oncol. 2026 Feb 20;44(6):435-439. doi: 10.1200/JCO-25-02691. Epub 2025 Dec 9. PMID 41363770

Identifiers

NCT: NCT06333262 · 24-017

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗