Inclusion Criteria:

        For patients with CLL:

        • Confirmed diagnosis of chronic lymphocytic leukemia (CLL)

        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.

        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

        Other inclusion and exclusion criteria may apply.