The effect of 2,6-bis(diethanolamino)-4-piperidinopyrimido [5,4-d]-pyrimidine (RA233) on growth,metastases and lung colony formation of B16 melanoma

The dissemination of malignant cells from a primary tumor to distant host sites appears to be influenced by blood platelets of the hemostatic system. Under conditions that did not inhibit primary tumor growth, RA233 decreased both the incidence and frequency of spontaneous lung metastases by 66% and 69%, respectively. Although RA 233 effectively inhibited the formation of spontaneous metastases, oral administration of RA233 prior to and after the intravenous inoculation of 1 × 10⁵ B16F10 murine melanoma cells failed to inhibit subsequent lung colony formation. These findings indicate that RA233 has antimetastatic activity, and that inhibition of platelet aggregation is not the sole determinant of this action.