Abstract 1484P
Background
PI3K/AKT/mTOR pathway is activated in gastric cancer (1). Since, Liao et al (2) found that regular use of aspirin resulted in better survival in patients with PI3KCA mutated CRC(colorectal cancer),we randomized patients to either EOX (epirubicin, oxaliplatin, capecitabine) alone or EOX plus aspirin, and studied outcomes in patients with PI3K expressing and PI3K non-expressing gastric cancers.
Methods
All eligible patients between March-2017 to May-2019 were randomly assigned to standard EOX or standard EOX plus 150 mg of aspirin daily. Aspirin continued till progression. Tumor measurements were performed at baseline and then after 3-4 cycles, the response to treatment was assessed by a radiologist (blinded to treatment arms) according to RECIST1.1 criteria. PI3KCA expression was assessed based on standard IHC procedure.
Results
Out of the 95 patients randomized, only a subset analysis of 55 patients (whose PI3KCA expression by IHC was available), is reported here. In this subset, 24 were in EOX arm and 31 in EOX plus aspirin arm. PI3K expression was absent in 23 out of the 55 patient subset. A 38 % ORR (CR+PR) was seen in PI3K positive patients and a 16.6 % ORR was seen in PI3K negative patients irrespective of treatment arms, however the difference was not significant (p=0.124). Also the OS and PFS were numerically higher in the category with strong PI3K expression on IHC,but this too was not statistically significant.
Conclusions
Locally advanced and metastatic gastric cancer patients with PI3K expression on IHC are likely to have better response rates with 3-4 cycles of first line EOX chemotherapy irrespective of addition of aspirin. Bibliography- 1)Matsuoka T, Yashiro M. The Role of PI3K/Akt/mTOR Signaling in Gastric Carcinoma. Cancers. 2014;6:1441–63. 2)Liao X, Lochhead P, Nishihara R, Morikawa T, Kuchiba A, Yamauchi M, Imamura Y, Qian ZR, Baba Y, Shima K, Sun R, Nosho K, Meyerhardt JA, Giovannucci E, Fuchs CS, Chan AT, Ogino S. Aspirin use, tumor PIK3CA mutation, and colorectal-cancer survival. N Engl J Med. 2012 Oct 25;367(17):1596-606.
Clinical trial identification
CTRI no. CTRI/2017/11/010651.
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
JIPMER, Puducherry, India.
Disclosure
The author has declared no conflicts of interest.