PARP, presentations and posters



Posted December 13th, 2008 by Jane

I had a little frisson of excitement all week when I heard that a presentation on PARP inhibitors was expected at the big guns grown up cancer conference in San Antonio, Texas. PARP inhibitors are a new class of drugs and the man at the Marsden had suggested that after taxol and vinorilbine I might be eligible for a Phase 1 trial of a PARP inhibitor.

PARP, by the way, as far as I can make out, (and google searches are very technical) is an enzyme called PolyARP-ribose polymerase which is often present in breast cancers which have the hereditary BRCA1 nad BRA2 genes, and also seem to be present in many triple negative breast cancers which aren’t BRCA1 and BRCA2. PARP inhibitors block the enzyme…and either damage or undo damage caused by DNA repair (I just can’t understand the literature on this…but it looks like PARP makes some cancers grow so the idea is block the PARP with an inhibitor and cancer shrinks…)

Anyway I’d been told that a presentation was anticipated at San Antonio on a Phase 2 US trial of a PARP inhibitor targetted at triple negative breast cancer. Like the desperate cancer patient that I am, I allowed myself a couple of days of miracle cure fantasy…astounding results at San Antonio and PARP rushed over the Atlantic, approved by NICE and I’m cured.

Oh lovely dream. The ‘presentation’ yesterday, turned out to be a poster display. I spent eight very irreverent years working in HE and ‘poster diplays’ at conferences were just one of its quirky features and I confess to prejudice. Stressed lecturers, whose research wasn’t quite finished, or those with dodgy research questions or short of papers for the RAE, cobbled together strange poster collages with blu tak and prit stick like primary school friezes. More recently of course, with ‘IT’ the posters looked better, though the quality of the reserach they touted, often seemed to my cynical eyes to be of variable quality. But maybe cancer conferences are better than education conferences.

I digress. Back to the PARP inhibitor poster and all the results show this far is that the drug (BS1-201) doesn’t cause any additional side effects or ‘toxicities’ over chemotherapy: there are two arms in the trial: one group are getting chemotherapy alone and one group chemotherapy plus BS1-201, and BS1-201 isn’t turning anyone green. It’s safe. As to ‘efficacy’…well there will be another poster on that in mid 2009.

I feel hysterically disappointed. I google PARP some more and the research papers are nearly incomprehensible…but I do understand some rather dispiriting results which suggests PARP inhibitors might be useful in preventing breast cancer, but pretty useless in having an impact on real tumours. But I tell you a hell of a lot of scientists are getting really excited about PARP inhibitors, though I’m not sure they’ve prolonged the life of one mouse yet, let alone a human.