Purpose@#PIK3CA, encoding for subunit p110a of
phosphatidylinositol 3 kinase , is frequently mutated in
breast cancer . PIK3CAmutation was predictive for pathological complete response (
pCR ) in
human epidermal growth factor 2 positive
breast cancer . This study explores the
association of PIK3CA
mutation and
pCR in
triple-negative breast cancer (TNBC) treated with
neoadjuvant chemotherapy . @*Materials and
Methods @#A total of 92
patients with TNBC derived from a prospectively randomized phase II trial GeparSixto study (NCT01426880).
Exon 9 and
exon 20 of PIK3CA
mutations were evaluated by using classical Sanger
method with
formalin -fixed
paraffin -embedded
tumor tissues . @*Results@#Seven of 90
tumors (7.8%) were detectable with a PIK3CA H1047R
mutation . Overall, PIK3CA H1047R
mutation was significantly associated with a lower
pCR rate (14.3% vs. 56.6%;
odds ratio , 0.128; 95%
confidence interval [CI], 0.015 to 1.108; p=0.047). In
carboplatin - containing
treatment patients , H1047R
mutation trended to predict a lower
pCR rate (20% vs. 62.5%; p=0.146). In a multivariable
analysis , H1047R
mutation trended to predict a lower
pCR rate (
hazard ratio, 0.1; 95% CI, 0.01 to 1; p=0.056). @*Conclusion@#TNBC with a PIK3CA H1047R
mutation was less likely to achieve
pCR after anthracyclinebased
neoadjuvant chemotherapy . Development of H1047R mutant selective inhibitors might be helpful to conquer this subtype of
breast cancer .