A Phase Ib/II Study Investigating the Safety, Tolerability, Pharmacokinetics, and Efficacy of Mosunetuzumab (BTCT4465A) in Combination With CHOP or CHP-Polatuzumab Vedotin in Participants With B-Cell Non-Hodgkin Lymphoma

CR Rate at PRA Based on CT Only as Determined by the Investigator (Phase II)

Time frame: 6-8 weeks after C6D1 or last dose of study treatment

Overall Response Rate (ORR) at PRA Based on PET-CT as Determined by the Investigator (Phase II)

ORR is defined as a CR or PR at the time of primary assessment based on PET-CT, as determined by the investigator.

Time frame: 6-8 weeks after C6D1 or last dose of study treatment

ORR at PRA Based on CT Only as Determined by the Investigator (Phase II)

ORR is defined as a CR or PR at the time of primary assessment based on CT only, as determined by the investigator.

Time frame: 6-8 weeks after C6D1 or last dose of study treatment

Best ORR Based on PET-CT and/or CT Scan as Determined by the Investigator (Phase II)

Best ORR was defined as CR or PR at any time on study and based on PET-CT or CT only as determined by the investigator.

Time frame: Up to approximately 50 months

Duration of Response (DOR) as Determined by the Investigator (Phase II)

DOR is defined as the time from the first occurrence of a documented objective response to disease progression or relapse as determined by the investigator, or death from any cause, whichever occurs first. The range values (min-max) are based on censored observations (if a participant did not experience disease progression or death prior to the end of the trial DOR was censored on the date of the last tumor assessment).

Time frame: Up to approximately 50 months

Progression-free Survival (PFS) as Determined by the Investigator (Phase II)

PFS is defined as the time from randomization to the first occurrence of disease progression or relapse as determined by the investigator, or death from any cause, whichever occurs first. The earliest contributing event to PFS is reported. The range (min-max) values are based on censored observations (participants without a baseline-evaluable tumor assessment were censored at the date of randomization or first study treatment, plus 1 day).

Time frame: Up to approximately 50 months

PFS at 1 Year as Determined by the Investigator (Phase II)

PFS at 1 year is defined as the proportion of participants with disease progression or relapse as determined by the investigator, or death from any cause within 1 year of randomization.

Time frame: 1 year

Event-free Survival (EFS) as Determined by the Investigator (Phase II)

EFS is defined as the time from randomization to the first occurrence of disease progression or relapse, as determined by the investigator, initiation of new anti-lymphoma therapy (NALT), or death from any cause, whichever occurs first. The range values (min-max) are based on censored observations (if a participant did not experience disease progression or death prior to the end of the trial DOR was censored on the date of the last tumor assessment).

Time frame: Up to 50 months

Time to Deterioration in Lymphoma Symptoms as Measured by the Functional Assessment of Cancer Therapy - Lymphoma (FACT-Lym) Subscale

Time frame: C1D1 through follow-up period (to begin 2 years after PRA or at the time of study drug discontinuation)

Time to Deterioration in Physical Functioning and Fatigue as Measured by the European Organization for Research and Treatment of Cancer Quality of Life - Core 30 Questionnaire (EORTC QLQ-C30)

Time frame: C1D1 through follow-up period (to begin 2 years after PRA or at the time of study drug discontinuation)

Polatuzumab Vedotin Serum Concentrations

Time frame: C2D1, C6D1

Polatuzumab Vedotin Antibody-conjugated Monomethyl Auristatin E (acMMAE) Serum Concentrations

Time frame: C1D1-C6D1

Polatuzumab Vedotin Unconjugated Mono-methyl Auristatin E (MMAE) Serum Concentrations

Time frame: C1D1-C6D1

Mosunetuzumab Serum Concentrations

Time frame: C1D1-C5D1

Baseline Prevalence and Incidence of Treatment Emergent Anti-drug Antibodies (ADA) to Mosunetuzumab

Participants are considered to have treatment-induced ADA responses if they are ADA negative or missing data at baseline and then develop an ADA response following study drug administration. Participants are considered to have treatment-enhanced ADA responses if they are ADA positive at baseline and the titer of one or more post baseline samples is at least 4-fold greater than the titer of the baseline sample. Patients are considered to be negative for ADAs if they are ADA negative at all timepoints or if they are ADA positive at baseline but do not have any post-baseline samples with a titer that is at least 4-fold greater than the titer of the baseline sample (treatment unaffected).

Time frame: Cycles 1, 2, 6, 16, and at early discontinuation visit or at PRA (6-8 weeks after either C6D1 or last dose of study treatment)

Baseline Prevalence and Incidence of Treatment Emergent ADA to Polatuzumab Vedotin

Participants are considered to have treatment-induced ADA responses if they are ADA negative or missing data at baseline and then develop an ADA response following study drug administration. Participants are considered to have treatment-enhanced ADA responses if they are ADA positive at baseline and the titer of one or more post baseline samples is at least 4-fold greater than the titer of the baseline sample. Patients are considered to be negative for ADAs if they are ADA negative at all timepoints or if they are ADA positive at baseline but do not have any post-baseline samples with a titer that is at least 4-fold greater than the titer of the baseline sample (treatment unaffected).

Time frame: Cycles 1, 2, 6, and at early discontinuation visit or at PRA (6-8 weeks after either C6D1 or last dose of study treatment)