Bowel cancer drug works well against KS

A drug which is usually used to treat bowel cancer is an effective treatment for the AIDS-defining cancer, Kaposi’s sarcoma (KS), Italian researchers have found. In a study published in the November 4^th edition of AIDS the investigators found that three quarters of individuals treated with irinotecan (Campto) experienced complete or partial remission of their KS.

New cases of KS have decreased dramatically since the advent of effective antiretroviral therapy, and anti-HIV treatment regimens containing both protease inhibitors and non-nucleoside reverse transcriptase inhibitors (NNRTIs) have been shown to be effective at preventing the development of KS and the treatment of KS if it is present.

Nevertheless, new cases of KS do occur in rare circumstances in patients taking antiretroviral therapy, and instances of previously controlled KS relapsing in patients taking anti-HIV drugs have been observed.

If an individual’s KS affects the skin and is rapidly progressing, or is affecting the organs or veins, then anti-KS chemotherapy is considered to be the most effective treatment. In many cases, therapy with antiretroviral drugs is also continued.

Italian investigators wished to see if the anti-cancer drug irinotecan, used to treat colorectal cancer, was an effective treatment for KS. They designed a trial involving 14 patients with advanced KS where the cancer had developed or relapsed despite the use of antiretroviral therapy. The study ran between summer 1999 and late 2004.

Individuals received an intravenous dose of 150mg/m² irinotecan on the first day of treatment, again on day ten and then every 21 days. Individuals whose earlier chemotherapy had led to granuloctyopenia – the death a special kind of white blood cells – were provided with a drug called granulocyte colony stimulating factor to try and prevent this occurring again.

All the patients were men and eight (57%) had received previous anti-KS chemotherapy. Eleven individuals (79%) continued to take a Lopinavir/ritonavir (Kaletra) -containing antiretroviral regimen.

One patient was lost to follow-up and one patient died after the first cycle of irinotecan chemotherapy due to myelotoxicity – the destruction of bone marrow. Of the remaining patients, nine (75%) experienced partial remission of their KS (median duration, over eleven months), one patient remained stable, however KS progressed in the remaining two patients.

Severe bone marrow destruction occurred in four of these twelve patients, and three patients also developed severe leucopenia – a very low white blood cell count – despite taking prophylactic treatment to prevent this. Serious anaemia – a shortage of red blood cells – occurred in two patients and two individuals developed thrombocytopenia – a persistently low platelet count.

“Our preliminary results suggest that irinotecan is active and well tolerated in epidemic KS”, conclude the investigators. They call for larger scale studies.