Clinical Trial: Cladribine With Simultaneous or Delayed Rituximab to Treat Hairy Cell Leukemia

Study Status: Recruiting
Recruit Status: Recruiting
Study Type: Interventional

Official Title: Randomized Trial of Cladribine (CdA) With Simultaneous or Delayed Rituximab to Eliminate Hairy Cell Leukemia Minimal Residual Disease

Brief Summary:

Background:

Hairy cell leukemia (HCL) is highly responsive to but not curable by cladribine (CdA). HCL responds to rituximab, which is not yet standard therapy for HCL.

Patients with the CD25-negative variant (HCLv) respond poorly to initial cladribine but do respond to rituximab in anecdotal reports.

Deoxycytidine kinase phosphorylates cladribine to CdATP, which incorporates into DNA, leading to DNA strand breaks and inhibition of DNA synthesis. Rituximab is an anti-CD20 monoclonal antibody which induces apoptosis and either complement or antibody dependent cytotoxicity (ADCC or CDC).

Patients in complete remission (CR) to cladribine have minimal residual disease (MRD) by immunohistochemistry of the bone marrow biopsy (BMBx IHC), a risk for early relapse. Tests for HCL MRD in blood or marrow include flow cytometry (FACS) or PCR using consensus primers. The most sensitive HCL MRD test is real-time quantitative PCR using sequence-specific primers (RQ-PCR).

In studies with limited follow-up, MRD detected by tests other than RQ-PCR can be eliminated by rituximab after cladribine in greater than 90 percent of patients, but MRD rates after cladribine alone are unknown. Simultaneous cladribine and rituximab might be superior or inferior to delaying rituximab until detection of MRD.

Only 4 HCL-specific trials are listed on Cancer.gov: a phase II trial of cladribine followed 4 weeks later by 8 weekly doses of rituximab, and phase I-II trials of recombinant immunotoxins targeting CD22 (BL22, HA22) and CD25 (LMB-2).

Objectives:

Primary:

Detailed Summary:

Background:

Hairy cell leukemia (HCL) is highly responsive to but not curable by cladribine (CdA). HCL responds to rituximab, which is not yet standard therapy for HCL.

Patients with the CD25-negative variant (HCLv) respond poorly to initial cladribine but do respond to rituximab in anecdotal reports.

Purine analogs cladribine and pentostatin have similar efficacy for HCL, both inhibiting DNA synthesis selectively in HCL cells. Cladribine is effective after just 1 cycle. Rituximab is an anti-CD20 monoclonal antibody which induces apoptosis and either complement or antibody dependent cytotoxicity (ADCC or CDC).

Patients in complete remission (CR) to cladribine have minimal residual disease (MRD) by immunohistochemistry of the bone marrow biopsy (BMBx IHC), a risk for early relapse. Tests for HCL MRD in blood or marrow include flow cytometry (FACS) or PCR using consensus primers. The most sensitive HCL MRD test is real-time quantitative PCR using sequence-specific primers (RQ-PCR).

In studies with limited follow-up, MRD detected by tests other than RQ-PCR can be eliminated by rituximab after cladribine in > 90% of patients, but MRD rates after purine analog alone are unknown. Simultaneous cladribine and rituximab might be superior or inferior to delaying rituximab until detection of MRD.

Only 4 HCL-specific trials are listed on Cancer.gov: a phase II trial of cladribine followed 4 weeks later by 8 weekly doses of rituximab, and phase I-II trials of recombinant immunotoxins targeting CD22 (BL22, HA22) and CD25 (LMB-2).

Objectives: