Inclusion Criteria:

- Age ≥ 18 years

- Patients with histologically/cytologically-confirmed HNSCC

- Patients must be resistant to platinum-based chemotherapy, or be ineligible (due to
medical comorbidities) or intolerant to platinum-based therapy per medical history

- For Phase Ib, there is no restriction on the number of prior therapies for recurrent
or metastatic disease

- For Phase II, patients may have received a maximum of 1 prior therapy for recurrent
or metastatic disease

- For Phase Ib, prior cetuximab or other EGFR-targeted antibody therapy is allowed
regardless of the prior treatment settings.

- For Phase II, prior cetuximab or other EGFR-targeted antibody therapy is allowed only
if administered in the induction setting, or concurrently with radiation in the
curative setting, with the last dose of cetuximab administered at least 12 months
prior to starting the study treatment

- Patients with swallowing dysfunction that are not using feeding tubes can participate
in the Phase Ib arm B; for the Phase II, these patients may participate if the
administration of drinkable suspension of BYL719 is allowed to be used in Phase II

- Availability of a representative tumor specimen

- At least one measurable or non-measurable lesion as per RECIST 1.1 criteria for
patients in Phase Ib; Measurable disease as determined by RECIST v1.1 for Phase II
patients

- World Health Organization (WHO) Performance Status (PS) ≤ 2

- Adequate organ function

- Negative serum pregnancy test

Exclusion Criteria:

- Prior treatment with PI3K-inhibitors

- Patients with a prior serious infusion reaction to cetuximab

- Patients with uncontrolled CNS tumor metastatic involvement

- Clinically significant cardiac disease or impaired cardiac function

- Patients with diabetes mellitus

- Impaired GI function or GI disease

- History of another malignancy within 2 years prior to starting study treatment

- Pregnant or nursing (lactating) women Other protocol-defined inclusion/exclusion
criteria may apply