Study of 177Lu Human Monoclonal Antibody 5B1 (MVT-1075) in Combination With a Blocking Dose of MVT-5873 as Radioimmunotherapy

Inclusion Criteria:

1. Signed, informed consent
2. Age 18 or more years
3. Histologically or cytologically confirmed, previously treated, locally-advanced or metastatic pancreatic ductal adenocarcinoma (PDAC) or other CA19-9 positive malignancies
4. Prior treatment with (or intolerance to) at least one standard systemic regimen for the patient's respective tumor
5. Evidence of tumor expression of CA19-9 based on immunohistochemistry performed on tumor samples or elevated serum levels (≥1.5 x upper limits of normal \[ULN\]) of CA19-9 considered secondary to tumor
6. Evaluable or measurable disease based on RECIST 1.1
7. Recovered from any prior treatment related toxicity to at least Grade 1 with exception of Grade 2 alopecia or other Grade 2 toxicity with prior approval of the Medical Monitor
8. If previously exposed to irradiation, the combined prior and anticipated exposure for Cycle 1 is not expected to exceed organ exposure limits outlined in the study protocol
9. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, or Karnofsky performance status (KPS) of 100% to 80%
10. Adequate hematologic, renal and hepatic laboratory parameters
11. Willingness to participate in collection of pharmacokinetic samples
12. Willingness to use adequate contraception throughout study and for a period of 3 months after last dose of MVT-5873 or MVT-1075 (whichever is later)

Exclusion Criteria:

1. Brain metastases unless previously treated and well controlled for at least 3 months
2. Any tumor mass greater than 10 cm in longest diameter
3. Other known active cancer(s) likely to require treatment in the next two years
4. Active, uncontrolled bacterial, viral, or fungal infection(s) requiring systemic therapy
5. Prior radiation therapy encompassing more than 25% of the skeleton or prior treatment with 89Strontium or 153Samarium
6. Fewer than 28 days from prior anticancer therapy including chemotherapy, hormonal, investigational, and/or biological therapies and irradiation except for:

   1. Ongoing hormonal therapy administered for control of cancer (e.g., breast cancer, prostate cancer), which may be continued throughout the study
   2. MVT-5873 and MVT-2163 administered as part of a different protocol
7. Major surgery other than diagnostic surgery within 28 days of Study Day 1
8. History of anaphylactic reaction to human, or humanized, antibody
9. Pregnant or currently breast-feeding
10. Known to be positive for human immunodeficiency virus (HIV), Hepatitis B, or Hepatitis C
11. Psychiatric illness/social situations that would interfere with compliance with study requirements
12. Significant cardiovascular risk including, but not limited to, recent (within 4 weeks) coronary stenting or myocardial infarction within 6 months