Sym013 (Pan-HER) in Patients With Advanced Epithelial Malignancies

This is an open-label, multicenter trial composed of 2 parts in which Sym013 will be
evaluated when administered by intravenous infusion in patients with advanced epithelial
malignancies without available therapeutic options.

Part 1 is a Phase 1a dose-escalation evaluating weekly (Q1W) and every second week (Q2W)
schedules of administration in separate dose-escalation cohorts to determine the recommended
phase 2 dose (RP2D) and regimen of Sym013.

Part 2 is a Phase 2a dose-expansion at the RP2D and regimen. Four (4) dose-expansion cohorts
will be evaluated in this part of the trial and will be selected based upon findings from
Part 1, additional preclinical data, and additional clinical data available at that time from
other agents inhibiting these targets. Patients will be entered, depending upon either a
defined molecular profile or profiles, or their underlying malignancy, to 1 of 4
corresponding expansion cohorts: Cohort A, Cohort B, Cohort C, or Cohort D.

Inclusion Criteria:

Main inclusion criteria all patients, Part 1 and Part 2:

- Male or female, at least 18 years of age at the time of informed consent

- Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0 or 1

- Life expectancy >3 months assessed during Screening

- Documented (histologically- or cytologically-proven) epithelial malignancy that is
locally advanced or metastatic, having received all therapy known to confer clinical
benefit

Additional inclusion criteria applicable to Part 2 ONLY:

- Epithelial malignancy (tumor types to be determined), measurable according to RECIST
v1.1 that has been confirmed by computed tomography (CT) or magnetic resonance imaging
(MRI) within 4 weeks prior to C1/D1

- Willingness to undergo a pre-and post-dosing biopsy (total of 2 biopsies) from primary
or metastatic tumor site(s) considered safe for biopsy

Exclusion Criteria:

- Any antineoplastic agent for the primary malignancy (standard or investigational)
without delayed toxicity within 4 weeks or 5 plasma half-lives (whichever is shortest)
prior to C1/D1, except nitrosoureas and mitomycin C within 6 weeks prior to C1/D1.

- Part 2 ONLY: Radiotherapy against target lesions within 4 weeks prior to C1/D1, unless
there is documented progression of the lesion following radiotherapy

- Immunosuppressive or systemic hormonal therapy (>10 mg daily prednisone equivalent)
within 2 weeks prior to C1/D1 with exceptions

- Use of hematopoietic growth factors within 2 weeks prior to C1/D1

- Active second malignancy or history of another malignancy within the last 3 years,
with allowed exceptions

- Central nervous system (CNS) malignancies including:

1. Primary malignancies of the CNS

2. Known, untreated CNS or leptomeningeal metastases, or spinal cord compression;
patients with any of these not controlled by prior surgery or radiotherapy, or
symptoms suggesting CNS metastatic involvement for which treatment is required

- Inadequate recovery from an acute toxicity associated with any prior antineoplastic
therapy

- Major surgical procedure within 4 weeks prior to C1/D1 or inadequate recovery from any
prior surgical procedure

- Non-healing wounds on any part of the body

- Active thrombosis, or a history of deep vein thrombosis or pulmonary embolism, within
4 weeks prior to C1/D1, unless adequately treated and stable

- Active uncontrolled bleeding or a known bleeding diathesis

- Significant gastrointestinal abnormalities

- Significant cardiovascular disease or condition

- Abnormal hematologic, renal or hepatic function