Meeting Abstract | 2009 ASCO Annual Meeting I


Background: Independent of other factors, p53 status may influence sensitivity to anthracycline (A)- and taxane (T)-based chemotherapy. We investigated p53 as a predictive marker of differential neoadjuvant chemoresponse by examining change in MRI longest diameter (LD) during sequential A- then T-based chemotherapy in a prospective clinical trial. Methods: 171 patients (pts) with newly diagnosed locally advanced breast cancer received neoadjuvant A- then T-based chemotherapy. LD were obtained pretherapy, between regimens, and posttherapy but prior to surgery. P53 mutation analysis was performed on pretherapy tissue using gene chip technology, SSCP, and sequencing. Subtypes were by IHC: LumA (ER/PR+/HER2-), LumB (ER/PR+/HER2+), Basal (triple negative), HER2 (HER2+/ER/PR-). Results: 99 pts had p53 mutant (M) tumors and 72 were wildtype (WT). M and WT did not differ by age, menopausal status, or HER2. M were significantly more common among basal (71%) and HER2 (59%) than Lum A (24%). Anthracycline response did not differ between WT and M within subtypes. Within HER2, Basal, and LumB, WT had higher taxane- and overall responses than M; within LumB these were statistically significant (p=0.03 and 0.05 respectively). Conclusions: P53 mutation status may affect chemosensitivity even within hormone receptor/HER2 subsets. In this dataset response to anthracycline appeared independent of p53 status within subtypes, while WT tumors responded better to taxanes and overall in LumB, with a similar trend among basal and HER2. Mutational subset and correlative analyses with gene expression, molecular subtyping, and IHC data are ongoing and will be presented.



MRI response % change in longest diameter (LD)Luminal A P53 mutantLuminal A P53 wildtypeLuminal B P53 mutantLuminal B P53 wildtypeBasal P53 mutantBasal P53 wildtypeHER2+/ER- P53 mutantHER2+/ER- P53 wildtype
T1-T3 (anthracycline response)
No. of patients14485142010128
Median (%)-29-28-43-41-27-29-36-34
T3-T4 (taxane response)
No. patients1346514209128
Median (%)-26-28-6*-35*-29-81-42-99
T1-T4 (overall response)
No. of patients15485142510139
Median (%)-39-51-48**-66**-53-76-85-100



No significant financial relationships to disclose.

American Society of Clinical Oncology


No companion articles


DOI: 10.1200/jco.2009.27.15_suppl.11099 Journal of Clinical Oncology 27, no. 15_suppl (May 20, 2009) 11099-11099.

Published online May 20, 2009.

ASCO Career Center