Study to Evaluate the Efficacy and Tolerability Debio 1562 in Combination With Rituximab in Patients With Relapsed and/or Refractory DLBCL and Other Forms of NHL

Inclusion Criteria:

- For Part 1 of the study, participants must have histopathologically confirmed
diagnosis of R/R, DLBCL, FL, MZL/MALT, MCL, or other Sponsor approved NHL subtypes
according to the World Health Organization (WHO) classification 2008 for which
standard measures do not exist or are no longer effective.

- For Part 2 and Part 3 of the study, participants must have histopathologically and
clinically confirmed diagnosis of relapsed DLBCL. Participants will be considered to
have a relapsed disease if they showed a duration of response of at least 24 weeks
after their first line of therapy. The following participants with relapsed DLBCL will
be enrolled:

1. Participants who received at least only one line of previous therapy and achieved
either complete response (CR) or partial response (PR) for at least 24 weeks
(from the last day of the last cycle) after their first line of therapy, but are
not eligible for high dose chemotherapy with autologous stem cell transplantation
(HD-ASCT)

2. Participants who received more than one line of previous therapy (including
HD-ASCT), and have achieved a duration of response (CR or PR) of at least 8 weeks
(from the last day of the last cycle) after their last line of therapy

- Participants must have evaluable or measurable disease in accordance with the
International Working Group Guidelines for Lymphoma.

- Participants must have received at least one but no more than six prior treatment
regimens. Prior treatment with an anti-CD20 agent, either alone or in combination, is
allowed.

- Participants must have Eastern Cooperative Oncology Group (ECOG) Performance Status 0
- 2.

- Participants who are Hepatitis B surface antigen positive (HBsAg+) (must be PCR
negative) who are taking antivirals, are allowed to enroll.

Exclusion Criteria:

- Participants with a diagnosis of chronic lymphocytic leukemia (CLL) or small
lymphocytic lymphoma (SLL).

- For Part 2 and Part 3 of the study, patients with primary refractory DLBCL (defined as
progression of disease within 24 weeks after first line of treatment).

- For Part 2 and Part 3 of the study, participants that are eligible to undergo first
time HD-ASCT.

- For Part 2 and Part 3 of the study, participants with R/R FL, MZL/MALT, MCL, or any
other NHL subtypes according to the WHO classification.

- Participants with active hepatitis A, B or C infection.

- Women who are pregnant or breast feeding.

- Participants who have received prior therapy with other anti-CD37-targeting therapy.

- Participants who have known central nervous system, meningeal, or epidural disease
including brain metastases.

- Participants with impaired cardiac function or clinically significant cardiac disease.