Polymer microparticles with a cavity designed for transarterial chemo‐embolization with crystalline drug formulations

Transarterial chemo‐embolization with drug‐eluting embolic beads (DEB‐TACE) is still evolving. Recent developments include the introduction of radiopaque (X‐ray imageable) drug‐eluting particles. Here, we report on conceptually different radiopaque polymeric drug‐eluting embolic particles, which are (i), cross‐linked poly(methacrylates); (ii), radiopaque; (iii), microporous. Furthermore, the particles are not perfectly spherical: they have a large indentation in the sense that they are either a spherical/cup‐shaped or ellipsoid/mouth‐shaped. The micropores and the large indentation can confer useful features upon the particles, since they can be filled with a crystalline lipophilic chemotherapeutic drug. It is important, in this respect that (i), many potent chemotherapeutics are lipophilic and crystalline; (ii), available drug‐eluting beads (DEBs) have the limitation that they can only be used in combination with water‐soluble chemotherapeutic agents. Cup‐ and mouth‐shaped particles were obtained in a Cu(0) catalyzed free‐radical polymerization reaction. The microparticles could be charged with crystalline drug, in such a manner that the crystals reside in both the micropores and the large cavity, and in quantities that would be required for effective local chemotherapy. The antifungal drug voriconazole, lipophilic, and crystalline, was used to demonstrate this. We believe that the ability of the microporous/cavitated DEBs to carry lipophilic chemotherapeutic drugs is especially important. DEB‐TACE is likely to become a cornerstone method of interventional oncology in the years ahead, and the new embolic particles described herein hold the promise of becoming scope widening for the technique.