A peptide compound having the sequence Lys-Pro-Ser-Ser-Pro-Pro-Glu-Glu [SEQ ID NO:2] or a substitution variant, addition variant or other chemical derivative thereof inhibits cell invasion, endothelial tube formation or angiogenesis in vitro. A number of substitution variants and addition variants of this peptide, preferably capped at the N- and C-termini, as well as peptidomimetic derivatives, are useful for treating diseases and conditions mediated by undesired and uncontrolled cell invasion and/or angiogenesis. Pharmaceutical compositions comprising the above peptides and derivatives are administered to subjects in need of such treatment in a dosage sufficient to inhibit invasion and/or angiogenesis. The disclosed compositions and methods are particularly useful for suppressing the growth and metastasis of tumors.