To enhance both anti-tumor efficacy and specificity, the HCCS1 expression cassette AFP-HCCS1-WPRE-SV40 was introduced into the vector Ad.SP.E1A(Δ24).ΔE1B to produce Ad.(AFP-HCCS1-WPRE)SP.E1A(Δ24).ΔE1B (also denoted Ad.SPDD-HCCS1). The gene discussed is DHTKD1; the disease is neoplasm.