"Researchers have taken another step in the hunt to find a treatment for an aggressive likelytorecur form of breast cancer.    In a study published in the Jan.  online edition of the New England Journal of Medicine the experimental drug iniparib not only shrank tumors and increased the time they took to progress but also surprised researchers by prolonging survival in women with whats known as triplenegative breast cancer.    This type of breast cancer lacks receptors for estrogen and progesterone and doesnt have large quantities of HERneu protein which the most successful cancer therapies target. This means that many currently available drugs simply wont affect it.    We were surprised at the results because triplenegative breast cancer is very difficult to treat said study lead author Dr. Joyce OShaughnessy.    The big big surprise was survival added OShaughnessy who nevertheless stressed that the trial was small and preliminary.    The findings were enough to generate the interest of Dr. Lisa A. Carey the coauthor of an accompanying editorial.    It is early but its really exciting because its a new class of drugs. It isnt that often that we have a completely new approach to treating cancer said Carey medical director of the University of North Carolina Breast Center in Chapel Hill. This is a new book. Weve just opened it up.    Iniparib inhibits a pathway that helps repair DNA researchers call it the polyADPribose polymerase PARP pathway. If this chain is interrupted cancer cells dont have the necessary tools to repair themselves.    PARP inhibitors work by preventing the cells from repairing damage to their DNA Carey explained.    A similar drug in fact has shown benefit in patients with BRCA  or BRCA  mutations predisposing them to breast and ovarian cancer.    In this study  patients with triplenegative breast cancer were randomized to receive a commonly used welltolerated chemotherapy regimen gemcitabine and carboplatin or to receive chemo plus iniparib.    More than onehalf of the women responded to the combination treatment meaning the tumor volume decreased versus only about onethird of those receiving chemo alone.    Women receiving iniparib plus chemo lived an average of . months compared to just . months in the chemoalone group. This may not seen like very long in either group but for this serious a cancer it is impressive the researchers noted.    This was a phase  trial. OShaughnessy who is codirector of breast cancer research at BaylorSammons Cancer Center US Oncology and Texas Oncology in Dallas said the results of a larger about  patients phase  trial should be available within one to three months.    The whole field is still preliminary and we have to be careful not to overhype the results as were waiting on the results of the phase  trial she said. Phase  was quite positive but we really dont know if this is going to end up benefiting patients until we get to phase .    In her editorial accompanying the study Carey agreed. Both excitement and caution are appropriate in interpreting the trial she wrote. Some clear drawbacks should be noted. Among them she said were the small size of the study group imbalances at baseline favoring the iniparib group and the unconventional chemotherapy regimen. But caveats notwithstanding she concluded the results may herald improved therapy for an underserved subgroup of patients with breast cancer.    OShaughnessy added that the drug was extremely well tolerated by patients. It didnt seem to add any appreciable toxicity to chemotherapy.    In the meantime she pointed out a woman walking through a clinic door who is diagnosed with triplenegative breast cancer shouldnt panic. If its only in the breast or lymph nodes we cure most triplenegative cancers. But when it recurs and becomes metastatic its very difficult to treat she explained.    The study was funded by BiPar Sciences a subsidiary of SanofiAventis which makes the drug. More information  The U.S. National Cancer Institute has more on breast cancer http  SOURCES Joyce OShaughnessy M.D. codirector breast cancer research BaylorSammons Cancer Center US Oncology and Texas Oncology Dallas Lisa A. Carey M.D. medical director University of North Carolina Breast Center Chapel Hill Jan.   New England Journal of Medicine online"