A Study of RO6927005 Either As Monotherapy (Part A) or in Combination With Gemcitabine and Nab-Paclitaxel (Part B) to Evaluate the Safety, Tolerability, Pharmacokinetics, and Preliminary Clinical Activity in Patients With Mesothelin-positive Metastatic and/or Locally Advanced Malignant Solid Tumors

Inclusion Criteria:

* Written informed consent
* Age \>/= 18 years
* Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0-2
* Patients for whom no standard curable therapy exists
* Life expectancy of \>/= 12 weeks
* Last dose of systemic anti-neoplastic therapy \> 21 days prior to first RO6927005 infusion
* Palliative radiotherapy is allowed up to 2 weeks before the first RO6927005 infusion; palliative 8 Gy radiotherapy is allowed during therapy.
* All acute toxic effects of any prior radiotherapy, chemotherapy, or surgical procedure must have resolved to Grade \</= 1, except alopecia (any grade) and Grade 2 peripheral neuropathy
* Adequate hematological, liver, and renal function
* Negative serum or urine pregnancy test within 7 days prior to study treatment in premenopausal women and women \</= 2 years after menopause (menopause is defined as amenorrhea for \>/= 2 years)
* Agreement to use adequate contraceptive methods per protocol
* Measurable and/or evaluable disease as per the Response Evaluation Criteria In Solid Tumors (RECIST) version 1.1) \[Groups 1, 2 of Part A and Group 3 of Part B\]

Inclusion Criteria Part A: MAD

* Metastatic and/or locally advanced malignant solid tumors enriched in tumor types known to be mesothelin expressing
* Archival sample or fresh biopsy or tumor effusion must be available for retrospective mesothelin analysis

Inclusion Criteria Part A: MAD and Extension Phase (Group 1 and Group 2)

* Histologically confirmed metastatic and/or advanced malignant mesothelin-positive solid tumors as determined by central pathology lab review
* Patients must be willing to provide a screening and post-dose biopsy for biomarker analysis (extension phase only)
* Mesothelin-positive refractory/recurrent solid tumors, other than malignant pleural mesothelioma (MPM) and pancreatic ductal adenocarcinoma (PDA) (Group 1 only)
* Mesothelin-positive refractory/recurrent MPM (Group 2 only)

Inclusion Criteria Part B

* Histologically confirmed metastatic and/or advanced mesothelin-positive PDA as determined by central pathology lab review
* In the extension phase, patients must be willing to provide a screening and post-dose biopsy for biomarker analysis

Exclusion Criteria:

* Known or clinically suspected central nervous system (CNS) primary tumors or metastases including leptomeningeal metastases; history or clinical evidence of CNS metastases unless they have been previously treated, are asymptomatic, and have had no requirement for steroids or enzyme-inducing anticonvulsants in the last 14 days
* Evidence of significant, uncontrolled concomitant diseases which could affect compliance with the protocol or interpretation of results, including significant pulmonary disease other than primary cancer, uncontrolled diabetes mellitus, and/or significant cardiovascular disease (such as New York Heart Association Class III or IV cardiac disease, myocardial infarction within the last 6 months, unstable arrhythmias, unstable angina, or clinically significant pericardial effusion)
* Active or uncontrolled infections
* Known HIV or known active HBV or HCV infection
* Patients with extrapleural pneumonectomy (EPP)
* Any other diseases, metabolic dysfunction, physical examination finding, or clinical laboratory finding giving reasonable suspicion of a disease or condition that would contraindicate the use of an investigational drug
* Major surgery or significant traumatic injury \< 28 days prior to the first RO6927005 infusion (excluding biopsies) or anticipation of the need for major surgery during study treatment
* Dementia or altered mental status that would prohibit informed consent
* Live attenuated vaccinations 14 days prior to treatment
* Pregnant or breast-feeding women
* Known hypersensitivity to any of the components of RO6927005
* High doses of systemic corticosteroids within 7 days prior to first dosing. High dose is considered as \> 20 mg of dexamethasone a day (or equivalent) for \> 7 consecutive days

Exclusion Criteria (Part B):

* Patients with contra-indication and/or history of severe hypersensitivity reactions to gemcitabine and/or nab-paclitaxel as mentioned in the locally approved label