Main

Inclusion Criteria:

- Patients 18 yrs or older with confirmed histological or cytological advanced solid
tumors, relapsed or refractory to standard treatment for which no curative therapy is
available

- Has disease activity that can be monitored by imaging or tumor biomarker measurement

- Life expectancy of at least 3 months (per investigator assessment)

- ECOG performance status of 0-2

- Adequate bone marrow, renal and liver function

- Recovered from any significant prior toxicity of previous anti-neoplastic therapy

- For patients of reproductive potential, is willing to use a medically acceptable form
of contraception throughout the study period and for at least 4 weeks after the last
dose of VX15/2503

- Expansion cohort - patients in this cohort must have one of the following
characteristics:

- A diagnosis of a pancreatic neuroendocrine tumor OR

- A diagnosis of a soft tissue sarcoma OR

- A diagnosis of a bone metastasis OR

- A diagnosis of advanced solid tumor AND a T cell count of at least 1500 cells/uL OR a
B cell count of at least 250 cells/uL at screening

Main Exclusion Criteria:

- Treatment with anti-neoplastic agents (chemotherapy, immunotherapy, radiotherapy or
endocrine therapy) within 3 weeks prior to start of study treatment

- Treatment with an investigational agent within 4 weeks prior to start of study
treatment

- Is on concurrent anti-neoplastic therapy with the exception of continuing luteinizing
hormone-releasing hormone agonist/antagonist therapy for patients with
castrate-resistant prostate cancer

- Treatment with oral or parenteral corticosteroids in excess of 10mg/day of
prednisolone or equivalent for more than 5 days within 4 weeks prior to start of
study treatment or a requirement for systemic immunosuppressive therapy for any
reason

- Untreated brain Mets or CNS tumor involvement

- Any other intercurrent illness or condition which could impact patient compliance or
ability to complete the study

- Sensitivity to VX15/2503 or the ingredients or excipients of VX15/2503

- Pregnant or breast-feeding women (women of child-bearing potential must have negative
serum pregnancy test within 3 days prior to receiving the first dose of VX15/2503)