Study to Assess Change in Disease Activity of Oral Venetoclax in Adult Participants With Recurring Relapsed or Refractory (R/R) Waldenström Macroglobulinemia (WM)/Lymphoplasmacytic Lymphoma (LPL)

• Venetoclax (Drug): Oral

Primary outcomes

• Number of Participants with Major Response [Up to Approximately 28 Months]: Major response is defined as participants with a best overall response of complete response (CR), very good partial response (VGPR) or partial response (PR) per independent review committee (IRC) assessment according to International Workshop on Waldenstrom macroglobulinemia (WM) (IWWM)-11 criteria in participants with Immunoglobulin M (IgM) >= 500 mg/dL at screening.
• Number of Participants with Major Response in participants with IgM >= 500 mg/dL [Up to Approximately 28 Months]: Major response is defined as participants with a best overall response of CR, VGPR or PR per IRC assessment according to IWWM-11.

Secondary outcomes

• Progression-Free Survival (PFS) [Up to Approximately 28 Months]: PFS is defined as time from first study treatment to a documented disease progression (PD) according to IWWM-11 criteria, determined by investigator or death from any cause, whichever occurs first.
• Overall Survival (OS) [Up to Approximately 28 Months]: OS is defined as time from first study treatment to death due to any cause.
• Overall Response (OR) [Up to Approximately 28 Months]: For participants with IgM >= 500 mg/dL at screening, overall response is defined as participants with a best overall response of CR, VGPR, PR or minor response (MR) per investigator assessment according to IWWM-11 criteria. For participants with IgM < 500 mg/dL at screening, overall response is defined as participants with the best overall response of CR or PR per investigator assessment according to Revised Response Criteria for Malignant Lymphoma.
• Duration of Response (DOR) [Up to Approximately 28 Months]: For participants with IgM >= 500 mg/dL at screening, DOR is defined as time from the initial response of CR, VGPR or PR per investigator review according to IWWM-11 criteria to PD or death of any cause, whichever occurs first. For participants with IgM < 500 mg/dL at screening, DOR is defined as time from the initial response of CR or PR per investigator review according to Revised Response Criteria for Malignant Lymphoma to PD or death of any cause, whichever occurs first. DOR will be summarized for the participants achieving overall response.
• Time to Next Treatment (TTNT) [Up to Approximately 28 Months]: TTNT is defined as time from first study treatment to the starting date of new anti-cancer therapy.

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* Documented diagnosis of Waldenström macroglobulinemia(WM) /lymphoplasmacytic lymphoma (LPL) according to the 5th edition of the World Health Organization (WHO) classification and/or documented clinicopathological diagnosis of WM in accordance with the consensus panel of the second International Workshop on WM (IWWM).
* At least one prior standard therapy for WM/LPL.
* Measurable disease, defined as follows:

  * WM type LPL population: Immunoglobulin M (IgM) >= 500 mg/dL per central laboratory (approximately 14 participants)
  * Non-IgM type LPL population or IgM < 500 mg/dL: A measurable node having a longest diameter (LDi) greater than 1.5 cm, or a measurable extranodal disease having a LDi greater than 1.0 cm, according to contrast-enhanced computed tomography (CT) scan. (up to 2 participants)
* Requires systemic anti-cancer treatment for WM/LPL, according to the investigator.
* Eastern Cooperative Oncology Group Performance Status < = 2
* Adequate organ and bone marrow function

Exclusion Criteria:

* History of prior exposure to venetoclax or BCL-2 targeted therapy.
* Uncontrolled active systemic infection.
* Known bleeding disorders (e.g., hemophilia).

• ABBVIE INC., Study director, AbbVie