Hand-Foot Skin Reaction (HFSR) is a common adverse event induced by Vascular Endothelial Growth Receptor Inhibitor (VEGFRi) in cancer patients. The main purpose of this study is to evaluate the efficacy and safety of nicotinic acid in solid tumor patients with grade II/III VEGFRi-associated HFSR.

Inclusion Criteria:

• Written informed consent obtained prior to performing any protocol-related procedures, including blood serum collecting
• HFSR grade 2 or higher after treatment with VEGFR inhibitors (such as sorafenib, regorafenib, anlotinib, and apatinib), according to NCI CTCAE V5.0 - PPE
• Age from 18 to 75 years.
• Life expectancy of at least 3 months at Day 1

Exclusion Criteria:

• History of allergy to B vitamins
• Major surgery or severe traumatic injury, fracture within 4 weeks prior to first dose of nicotinic acid or ulceration and any factors that significantly affect oral drug absorption, such as inability to swallow, chronic diarrhea, and intestinal obstruction
• Patient who takes isoniazid in combination with sorafenib and other VEGFR inhibitors.
• History of psychiatric drugs substance abuse and fails to quit it or has amental disorder
• Pregnant or nursing women, fertile patient who is unwilling or unable to use effective contraception