Okazawa-Sakai M, Sakai SA, Hyodo I, Horasawa S, Sawada K, Fujisawa T, Yamamoto Y, Boku S, Hayasaki Y, Isobe M, Shintani D, Hasegawa K, Egawa-Takata T, Ito K, Ihira K, Watari H, Takehara K, Yagi H, Kato K, Chiyoda T, Harano K, Nakamura Y, Yamashita R, Yoshino T, and Aoki D
Objective: To investigate an association between the gut microbiome and efficacy of poly(ADP-ribose) polymerase inhibitors (PARPi) in ovarian cancer., Methods: This study conducted fecal microbiome analysis (16S rRNA gene sequencing) and circulating tumor DNA (ctDNA) profiling for ovarian cancer patients who underwent PARPi maintenance therapy. Fecal and blood samples were collected at the baseline and the progressive disease (PD) or last follow-up. The relative abundance of gut microbes and progression-free survival (PFS) were analyzed using linear discriminant analysis of effect size and the Cox proportional hazard model according to BRCA1 / 2 mutation ( BRCA1 / 2 mut) status detected by ctDNA sequencing., Results: Baseline samples were available from 23 BRCA1 / 2 mut-positive patients and 33 BRCA1/2 mut-negative patients. The microbes enriched in the baseline samples with long PFS were Bifidobacterium , Roseburia , Dialister , Butyricicoccus , and Bilophila for BRCA1/2 mut-positive patients and Phascolarctobacterium for BRCA1/2 mut-negative patients. In multivariate analyses dividing patients by the median values of relative abundances, no bacteria were associated with PFS in BRCA1/2 mut-positive patients, whereas high Phascolarctobacterium abundances (≥1.11%) was significantly associated with longer PFS in BRCA1/2 mut-negative patients (median 14.0 vs. 5.9 months, hazard ratio=0.28; 95% confidence interval=0.11-0.69; p=0.014). In the last samples, the relative abundances of Phascolarctobacterium were significantly higher in patients without PD (n=5) than those with PD (n=15) (median 1.25% vs. 0.06%; p=0.016)., Conclusion: High fecal composition of Phascolarctobacterium was associated with prolonged PFS in patients with BRCA1/2 mut-negative ovarian cancer receiving PARPi therapy. Our results would provide new insights for future research., Competing Interests: Mika Okazawa-Sakai declares no competing interests. Shunsuke A. Sakai declares no competing interests. Ichinosuke Hyodo reports advisory roles for Asahi-Kasei, Ono, Taiho, Chugai, and Eisai Pharmaceutical Companies. Satoshi Horasawa declares no competing interests. Kentaro Sawada declares no competing interests. Takao Fujisawa reports honoraria from Amelieff Co. Ltd. Yasuko Yamamoto declares no competing interests. Shogen Boku reports honoraria from Nippon Kayaku Co., Ltd., Chugai Pharmaceutical Co., Ltd., Taiho Pharmaceutical Co., Ltd., Bristol-Myers Squibb Japan, and MSD. Yoh Hayasaki declares no competing interests. Masanori Isobe declares no competing interests. Daisuke Shintani declares no competing interests. Kosei Hasegawa reports honoraria from AstraZeneca, GSK, MSD, and Takeda; advisory role for GSK, MSD, and Takeda; research grants from MSD. Tomomi Egawa-Takata declares no competing interests. Kimihiko Ito reports honoraria from AstraZeneca. Kei Ihira declares no competing interests. Hidemichi Watari reports honoraria from AstraZeneca, Takeda, MSD, and Chugai. Kazuhiro Takehara reports honoraria from AstraZeneca, Takeda, MSD, Chugai, Eisai, and Sanofi. Hiroshi Yagi declares no competing interests. Kiyoko Kato declares no competing interests. Tatsuyuki Chiyoda reports research grants from Takeda Pharmaceutical Company. Kenichi Harano reports honoraria from AstraZeneca, Chugai, Eizai, MSD, Taiho and Takeda, and advisory roles for AstraZeneca, Chugai, Eizai, Taiho and Takeda. Yoshiaki Nakamura declares advisory role from Guardant Health Pte Ltd., Natera, Inc., Roche Ltd., Seagen, Inc., Premo Partners, Inc., Daiichi Sankyo Co., Ltd., Takeda Pharmaceutical Co., Ltd., Exact Sciences Corporation, Gilead Sciences, Inc.; speakers' bureau from Guardant Health Pte Ltd., MSD K.K., Eisai Co., Ltd., Zeria Pharmaceutical Co., Ltd., Miyarisan Pharmaceutical Co., Ltd., Merck Biopharma Co., Ltd., CareNet, Inc., Hisamitsu Pharmaceutical Co., Inc., Taiho Pharmaceutical Co., Ltd., Daiichi Sankyo Co., Ltd., Chugai Pharmaceutical Co., Ltd., Becton, Dickinson and Company, Guardant Health Japan Corp; research funding from Seagen, Inc., Genomedia Inc., Guardant Health AMEA, Inc., Guardant Health, Inc., Tempus Labs, Inc., Roche Diagnostics K.K., Daiichi Sankyo Co., Ltd., Chugai Pharmaceutical Co., Ltd. Riu Yamashita declares no competing interests. Takayuki Yoshino reports honoraria from Chugai Pharma, Takeda Pharma, Merck, Bayer Yakuhin, Ono Pharmaceutical and MSD K. K.; consulting fees from Sumitomo Corp.; and research grants from Amgen, Bristol-Myers Squibb, Chugai, Daiichi Sankyo, Eisai, FALCO Biosystems, Genomedia Inc., Medical & Biological Laboratories, Merus N.V., Molecular Health, MSD, Nippon Boehringer Ingelheim, Ono, Pfizer, Roche Diagnostics, Sanofi, Sysmex, Taiho and Takeda. Daisuke Aoki reports honoraria from AstraZeneca, Takeda, MSD, Chugai, and Myriad Genetics., (© 2025. Asian Society of Gynecologic Oncology, Korean Society of Gynecologic Oncology, and Japan Society of Gynecologic Oncology.)