Implantable delivery system for cancer treatment

A new drug delivery system for the treatment of cancer has been described in a study recently published in Experimental Biology and Medicine.

Led by Dr Horst A. von Recum (Department of Biomedical Engineering at Case Western Reserve University, Cleveland), the study reported on an implantable local delivery system that is activated by the acidic environment surrounding a tumour and found that sustained drug release was provided without healthy tissue damage.

Often, clinical care of cancer requires intravenous administration of treatments, which enables distribution of the drug throughout the patient’s body — including healthy tissues. In some instances, the quantity of drug and time the patient receives treatment must be reduced to prevent damage to normal tissues, however, this also reduces the potential for the treatment to affect cancer cells.

Moreover, the toxicity of some drugs that are highly effective in killing cancer cells means that they are unsuitable for use. An example of this type of drug is doxorubicin, which is an effective treatment for numerous tumours but is also toxic to the heart, liver, kidneys and healthy tissue. Therefore, a delivery system that enables the use of this type of drug without compromising on its effectiveness and that minimises the damage to healthy tissues would be beneficial.

Several studies have been published that suggest pH sensitive delivery systems can overcome the toxicity issues of doxorubicin, however, they do not necessarily provide the sustained level of release required to kill cancer cells. In the recent study performed by von Recum and team, a modified form of doxorubicin was used that can be activated in the slightly acidic tissue that surrounds tumours and can be preferentially released over 40 days at the tumour site.

Negligible amounts of active drug were released in the healthy tissue, according to the study, and the efficacy of the modified drug was found to be equivalent to that of the unmodified version. “We feel that this is a new lease on the life of doxorubicin, a great anti-cancer drug, since the total contained dose is far lower than that used systematically, and well below the toxicity threshold of the heart,” added von Recum.