Study of HuMab-5B1 (MVT-5873) in Subjects With Pancreatic Cancer or Other Cancer Antigen 19-9 (CA19-9) Positive Malignancies

Inclusion Criteria \[all groups\]

* Signed, informed consent
* Age 18 or more years
* Histologically or cytologically confirmed, locally-advanced or metastatic pancreatic ductal adenocarcinoma (PDAC) or other CA19-9 positive malignancies
* Recovered from prior treatment related toxicity to at least Grade 1 with exception of Grade 2 alopecia or other Grade 2 toxicity with approval of the Medical Monitor
* Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1 or KPS of 100% to 80%
* Adequate hematologic, hepatic, and renal function
* Willingness to participate in collection of pharmacokinetic samples
* Willingness to use adequate contraception throughout study and for a period of 3 months after last dose of MVT-5873 and for up to at least 9 months after the last Oxaliplatin dose.

\[Group A, C, and Group D Dose Escalation\]

* Evaluable or measurable disease based on RECISTv1.1

\[Group A, C, and D\]

* Progression following treatment with standard of care for the subject's specific tumor type

\[Group C and D Dose Expansion and Group E Dose Escalation and Expansion\]

* Measurable disease based on RECISTv1.1

\[Group C and D Dose Expansion, non-PDAC malignancies\]

* If serum CA19-9 levels (defined as \< 1 U/mL or below the level of detection for institutional test used), subject must have confirmation of CA19-9 expression in their tumor prior to study entry (based on institutional determination of CA19-9)

\[Group E and F\]

* Candidates for mFOLFIRINOX based on accepted standard of care

\[Group F\]

* Histologically or cytologically confirmed PDAC
* Macroscopically complete resection (R0 or R1 resection) performed between ≥21 and ≤84 days prior to Cycle 1, Day 1 (C1D1)
* Baseline scans without evidence of disease (e.g., CT/MRI)
* Serum CA19-9 ≤ 180 U/mL within 21 days of C1D1
* Full recovery from surgery and able to receive chemotherapy
* Free of significant nausea and vomiting
* No prior radiotherapy or chemotherapy

Exclusion Criteria \[Groups A, B, C, D, and E\]

* Brain metastases unless previously treated and well controlled for at least 3 months prior to study day 1
* Other known active cancer(s) likely to require treatment in the next two (2) years
* Active, uncontrolled bacterial, viral, or fungal infection(s) requiring systemic therapy
* Fewer than 28 days (or 5 half-lives for systemic agents, whichever is shorter) from prior anticancer therapy including chemotherapy, hormonal, investigational, and/or biological therapies and irradiation (except for ongoing hormonal therapy for prostate cancer)
* Major surgery within 28 days of Study Day 1
* History of anaphylactic reaction to human, or humanized, antibody
* Pregnant or currently breast-feeding
* Known HIV, Hepatitis B or C-positive
* Psychiatric illness/social situations that would interfere with compliance with study requirements
* Significant cardiovascular risk (e.g., coronary stenting within 4 weeks, myocardial infarction within 6 months)

\[Group F\]

* Incomplete macroscopic tumor removal (R2 resection)
* Other known active cancer(s) likely to require treatment in the next 2 years
* Active, uncontrolled bacterial, viral, or fungal infection (s) requiring systemic therapy
* History of anaphylactic reaction to human, or humanized, antibody
* Pregnant or currently breast-feeding
* Known HIV, Hepatitis B or C-positive
* Psychiatric illness/social situations that would interfere with compliance with study requirements
* Significant cardiovascular risk (e.g., coronary stenting within 4 weeks, myocardial infarction within 6 months)
* Pre-existing neuropathy
* Known homozygous for UGT1A1\*28 mutation
* Inflammatory disease of the colon or rectum, or occlusion or sub-occlusion of the intestine or severe postoperative uncontrolled diarrhea