Study stopped due to lack of recruitment.

This study is being conducted to satisfy a post-marketing requirement (PMR) to provide evidence characterizing 1) the safety of moxetumomab pasudotox-tdfk in patients who are 65 years of age and older and/or 2) the safety of moxetumomab pasudotox-tdfk in patients who have moderate renal impairment defined as an estimated GFR of 30-59 ml/min

The pivotal Phase 3 study (Study 1053) supported full approval of moxetumomab pasudotox-tdfk from the US Food and Drug Administration (FDA) for the treatment of adult patients with relapsed or refractory hairy cell leukemia (HCL) who received at least two prior systemic therapies, including treatment with a PNA, on 13 September 2018. Since HCL is a rare disease, clinical research has limited information concerning the safety of moxetumomab pasudotox-tdfk in elderly patient populations and patients with moderate renal impairment.This study is being conducted to satisfy a post-marketing requirement (PMR) to provide evidence characterizing the safety of moxetumomab in these patients.

Inclusion Criteria:

• Provision of written informed consent, if required
• Patient received at least 1 dose of moxetumomab pasudotox-tdfk and has completed or discontinued the treatment
• Patient has a medical record available from the start of first dose of moxetumomab pasudotox tdfk

AND at least 1 of the following:

• Patient is ≥65 years old at the time of starting initial treatment with moxetumomab pasudotox-tdfk OR
• Adult (≥18 years old) patient has moderate renal impairment, at the time of starting initial treatment with moxetumomab pasudotox-tdfk

The study population will be patients who are prescribed moxetumomab-pasudotox-tdfk who are ≥65 years old at the time of starting initial treatment with moxetumomab pasudotox-tdfk or are ≥18 years old with moderate renal impairment defined as an estimated GFR of 30-59 ml/min, at the time of starting initial treatment with moxetumomab pasudotox-tdfk. These two populations may not be mutually exclusive.