GDC-0449 and Erlotinib Hydrochloride With or Without Gemcitabine Hydrochloride in Treating Patients With Metastatic Pancreatic Cancer or Solid Tumors That Cannot Be Removed by Surgery

Known standard therapy for the patient's disease that is potentially curative or definitely capable of extending life expectancy

Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements

Any of the following prior therapies:

* Chemotherapy =\< 4 weeks prior to registration

* Mitomycin C/nitrosoureas =\< 6 weeks prior to registration

* Immunotherapy =\< 4 weeks prior to registration

* Biologic therapy =\< 4 weeks prior to registration

* Radiation therapy =\< 4 weeks prior to registration

* Radiation to \> 25% of bone marrow

Failure to fully recover from acute, reversible effects of prior therapy regardless of interval since last treatment

New York Heart Association classification III or IV

Seizure disorder

Central nervous system (CNS) metastases if not stable for at least 2-3 months based on imaging, clinical assessment, and use of steroids, or seizure disorder

Pregnant women

Nursing women

Men or women of childbearing potential who are unwilling to employ adequate contraception until 12 months after last study drug dose

Other concurrent chemotherapy, immunotherapy, radiotherapy, or any ancillary therapy considered investigational (utilized for a non-Food and Drug Administration \[FDA\]-approved indication and in the context of a research investigation)

Current therapy with a CYP3A4 inhibitor or inducer

Immunocompromised patients (other than that related to the use of corticosteroids) including patients receiving highly active antiretroviral therapy (HAART) treatment

Receiving any other investigational agent which would be considered as a treatment for the primary neoplasm

Active other malignancy, excepting non-melanotic skin cancer or carcinoma-in-situ of the cervix; if there is a history of prior malignancy, they must not be receiving other specific treatment (other than hormonal therapy) for their cancer

History of myocardial infarction =\< 6 months, or congestive heart failure requiring use of ongoing maintenance therapy for life-threatening ventricular arrhythmias

Abnormalities of the cornea based on history (e.g., dry eye syndrome, Sjogren's syndrome), congenital abnormality (e.g., Fuch's dystrophy), abnormal slit-lamp examination using a vital dye (e.g., fluorescein, Bengal Rose), and/or an abnormal corneal sensitivity test (Schirmer test or similar tear production test)

More than 2 prior chemotherapy regimens for the current metastatic malignancy; full dose chemotherapy used in conjunction with concurrent radiation therapy will be included as prior therapy; Note: prior hormonal therapy (e.g. leuprolide, aromatase inhibitors, tamoxifen) will be allowed and not included as a prior chemotherapy

Previous therapy with a hedgehog inhibitor

What this study is about