Main Session
Sep 29
PQA 06 - Genitourinary Cancer, Gynecological Cancer, and Health Care Access and Engagement

3731 - Cervicovaginal Bacterial Microbiome Remodeling after Brachytherapy in Patients with Locally Advanced Cervical Cancer Patient Treated with Chemoradiation with or without Therapeutic HPV Vaccine

02:15pm - 03:30pm ET
Poster Hall - Exhibit Hall A
Screen: 23
POSTER

Presenter(s)

Tissana Prasartseree, MD - Siriraj Hospital Mahidol University, Bangkok, Bangkok

T. Prasartseree1,2, A. V. Damania3, K. Court1, N. J. Ajami3, M. Wong3, A. Day3, L. Colbert4, and A. H. Klopp4; 1Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 2Division of Radiation Oncology, Department of Radiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand, 3Department of Genomic Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, 4Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX

Purpose/Objective(s):

In cervical cancer, cervicovaginal microbiome may play an important role via radiation delivery and direct bacterial inoculation during cervical brachytherapy (BT) to modulate immunologic response, especially in the era of concurrent chemoradiation (CCRT) and immunotherapy combination. This study is aimed to investigate the cervicovaginal microbiome before and after brachytherapy.

Materials/Methods:

Patients with locally advanced cervical cancer treated with CCRT in standard of care (SOC group) and IMMUNOCERV trial (PDS group; primary =5 cm and/or imaging-positive nodes) in presence of therapeutic HPV vaccine immunotherapy PDS0101: subcutaneously administered HPV-specific vaccine containing peptide pools encoding E6/E7 antigens were prospectively undergone cervicovaginal swab for microbiome detection at pre-brachytherapy (pre-BT) and post-brachytherapy (post-BT). BacMap DNA analysis was utilized for bacterial DNA identification. Alpha diversity (inverse Simpson&Shanon), beta diversity, and differential abundance were assessed.

Results:

Among 30 patients (SOC=18, PDS=12) there were no significant difference in baseline clinical characteristics between PDS and SOC group. No significant differences in alpha or beta diversity were observed between pre- and post-BT time points.

Multivariate differential abundance modeling identified enrichment of gram-positive mucosa associated cocca, including (Anaerococcus obesiensis (Adj. p <0.001), Peptostreptococcaeceae bacterium (Adj. p <0.001) and Streptococcus agalactiae (Adj p =0.006) and Streoptococcus species, independent of brachytherapy modality and recent antibiotic exposure.

Conclusion:

Global alpha and beta diversity was stable after brachytherapy but composition remodeling including enrichment of gram-positive mucosa associated cocci including members of Peptostreptococcaceae family. Brachytherapy appears to induce restructuring and not broad depletion of microbiome. Future studies will investigate the clinical and immunologic implications of these changes.

PDS N = 12

 SOC N = 18

 P
Menopause

 7 (58%)

 10 (56%)

 0.9
Presenting symptom

Bleeding

 10 (83%)

 16 (89%)

 >0.9
Vaginal discharge

 4 (33%)

 7 (39%)

 >0.9
Race

0.5
Other

 4 (33%)

 6 (33%)

White or Caucasian

 8 (67%)

 12 (67%)

Smoking

0.3
Current

 1 (8.3%)

 2 (11%)

Former

 4 (33%)

 2 (11%)

Never

 7 (58%)

 14 (78%)

Histology

0.5
SQ

 11 (92%)

 13 (72%)

Non-SQ

 1 (8%)

 5 (28%)

FIGO2009

0.5
I-II

 8 (67%)

 16 (88%)

III-IV

 4 (33%)

 2 (12%)

FIGO2018

0.091
I-II

 3 (25%)

 2 (11%)

IIIB

 1 (8%)

 0

IIIC1

 7 (59%)

 11 (61%)

IIIC2

 0 (0%)

 4 (22%)

IVA

 1 (8%)

 1 (6%)

Antibacterial exposure within

30 days before post-BT timepoint

 9 (75%)

 9 (50%)

 0.3
Brachytherapy Modality

0.024
PDR

 4 (33%)

 14 (78%)

HDR

 8 (67%)

 4 (22%)

1st HR-CTV volume >30cm3

 4 (33%)

 4 (24%)

 0.7
Disease recurrence/progression

 3 (25%)

 3 (17%)

 0.7