Inclusion Criteria:

For Patients with CLL

• Confirmed diagnosis of chronic lymphocytic leukemia (CLL).
• Must have received at least two (2) prior therapy regimens.
• Patients with Richter's transformation should have failed standard therapy.

For Patients with NHL

• Histologically confirmed diagnosis of B- or T-cell non-Hodgkins lymphoma (NHL).
• Must have a site of disease amenable to biopsy, and be suitable and willing to undergo study required biopsies at screening and during therapy.
• The histologic subtypes of NHL that are permitted in the dose escalation part were specified.
• Must have received at least two (2) prior therapy regimens.
• Patients with indolent lymphoma must have received and failed standard-of-care therapy or be intolerant or ineligibile to approved therapies and must be in need of therapeutic intervention.
• Patients with prior CART T-cell therapy will be permitted on this trial 30 days after CART infusion and meet protocol defined inclusion/exclusion criteria.

Exclusion Criteria:

Applicable to both CLL and NHL

• History of anaphylactic or other severe hypersensitivity/infusion reactions to ADCs, monoclonal antibodies (mAbs) and/or their excipients such that the patient in unable to tolerate immunoglobulin/monoclonal antibody administration.
• Any prior history of treatment with maytansine (DM1 or DM4)-based ADC.
• Known intolerance to a maytansinoid.
• Patients with any active or chronic corneal disorders.
• Patients who have any other condition that precludes monitoring of the retina or fundus.
• Patients with active CNS involvement are excluded, except if the CNS involvement has been effectively treated and provided that local treatment was > 4 weeks before enrollment. Patients that have been effectively treated for CNS disease and are stable under systemic therapy may be enrolled provided all other inclusion and exclusion criteria are met.
• Impaired cardiac function or clinically significant cardiac disease.
• Known history of Human Immunodeficiency Virus (HIV) infection, Active Hepatitis B Virus (HBV), or Hepatitis C Virus (HCV) infection.