A Phase Ib/II Study of an Anti-HER3 Antibody, HMBD-001, With Cetuximab +/- Docetaxel in Advanced Squamous Cell Cancers

* Ability to understand and be willing to sign an informed consent form

* Males and females aged over 18 years (or having reached the age of majority according to local laws if the age of majority is \> 18 years of age) * Eastern Cooperative Oncology Group (ECOG) status of 0 to 1 * Arm B only: Locally advanced or metastatic squamous non-small cell lung cancer for which all available standard of care treatment options have been exhausted or refused and for which at least one lesion is measurable * Arm C only: Advanced or metastatic sqNSCLC, HNSCC, ESCC, CSCC, cervical SCC, NPC and other SCCs with at least one prior line of systemic therapy, * Have an estimated life expectancy of at least 3 months * Participants must be willing to provide a fresh tumor biopsy sample * Have adequate organ function * Females must be non-pregnant and non-lactating, willing to use a highly effective method of contraception from screening until study completion or be either surgically sterile or post-menopausal * Males must be surgically sterile, abstinent, or if engaged in sexual relations with a woman of child-bearing potential, the participant and his partner must be surgically sterile or using an acceptable, highly effective contraceptive method from screening until study completion