Study of the CDK4/6 Inhibitor Palbociclib (PD-0332991) in Combination With the PI3K/mTOR Inhibitor Gedatolisib (PF-05212384) for Patients With Advanced Squamous Cell Lung, Pancreatic, Head & Neck and Other Solid Tumors

Inclusion Criteria: * For Part I, participants must have histologically confirmed malignancy that is metastatic or unresectable and resistant to standard therapy or for which no standard therapy is available. For Part II, participants must have histologically confirmed advanced squamous cell lung cancer, advanced pancreatic cancer, advanced head \& neck cancer (specifically non-oropharynx squamous cell carcinoma or HPV-negative oropharynx squamous cell carcinoma), or any tumor with suspected PI3K-pathway dependence (either by mutation or by known biologic rationale, such as endometrial cancer. PI3K dependence includes the presence of a PIK3CA-mutant hotspot mutation, PIK3CA copy number gain, or PTEN loss in the archival or fresh tumor tissue specimen identified in a CLIA-certified laboratory. All genetic findings must be reviewed by the study PI, prior to study entry.) * For Part I, participants are required to have only evaluable disease (disease that is visible on imaging studies but does not meet RECIST criteria for measurable disease). For Part II, participants must have measurable disease, defined as at least one lesion that can be accurately measured in at least one dimension (longest diameter to be recorded) as \> 20 mm with conventional techniques or as \> 10 mm with spiral CT scan. See section 10 for the evaluation of measureable disease. * Participants are permitted to have any number of prior therapies prior to enrollment * Age ≥ 18 years. . * ECOG performance sta…