Real-World Study of Adding Bevacizumab to Chemotherapy for Ovarian, Tubal, and Peritoneal Cancer as Front-Line or Relapse Therapy (ROBOT): 8-Year Experience

This study aimed to determine the real-world, long-term prognostic impacts, and adverse effects (AEs) of bevacizumab (BEV) in Asian patients with ovarian/tubal/peritoneal cancers. We retrospectively reviewed the medical records of consecutive patients with ovarian/tubal/peritoneal cancer on front-line chemotherapy with or without BEV (Cohort 1) and those who relapsed following chemotherapy and/or BEV (Cohort 2) between 2011 and 2018 in a tertiary medical centre. Patient characteristics, BEV dosages, clinical outcomes, and AEs were analyzed. Hazard ratios for disease progression and death were analyzed using a cox proportional regression model. Benefits of BEV used throughout triweekly, in terms of improved progression-free survival (PFS) and overall survival (OS), were observed at a dosage of 7.5–15 mg/kg among advanced-stage Cohort 1 patients. A progression-free interval of <6 months was the strongest predictor of disease progression and death in advanced-stage patients. BEV throughout and optimal cytoreduction were independent predictors of reduced disease progression. No prognostic advantage was observed between serous and clear cell histologies when BEV was added. Moreover, BEV resulted in improved OS in Cohort 2 patients, especially in the platinum-sensitive subgroup. Most patients had a front-line BEV dosage <10 mg/kg per cycle with <10 treatment cycles. Low rates and grades of BEV-related AEs were observed in both cohorts. BEV used throughout effectively extended PFS and OS in advanced-stage patients with ovarian/tubal/peritoneal cancer. Patients with platinum-sensitive carcinoma, treated with BEV, had a significant improvement in OS and extended PFS. Therefore, BEV can safely be added to chemotherapy for ovarian/tubal/peritoneal cancers.


INTRODUCTION
Epithelial ovarian cancer (EOC) is the leading cause of death among gynecological cancers in many countries (1)(2)(3). Most patients with chemotherapy-sensitive disease develop chemotherapy-resistant relapse after undergoing several lines of therapy. Maintenance therapy with targeted agents following primary cytoreductive surgery and chemotherapy to extend the progression-free interval (PFI) is promising for improving EOC prognosis (4,5). Bevacizumab (BEV) can improve overall response rates in front-line or relapse therapy settings (5,6). Front-line chemotherapy with BEV throughout improved progression-free survival (PFS) in the GOG-218 (7) and ICON7 (8) trials and prolonged overall survival (OS) in GOG-218 stage IV and ICON7-defined high-risk patients (9,10). In total, 52 and 39% reductions in the risk of progression or death by adding BEV to chemotherapy were observed in platinumsensitive recurrent EOC in the OCEANS (11) and GOG-213 (12) trials, respectively. A 52% reduction in the risk of progression or death was seen in platinum-resistant recurrent EOC in AURELIA (13). However, the secondary endpoint in extending OS was not achieved (9,(11)(12)(13).
Based on these large clinical trials, BEV is used as the standard of care in EOC patients in many countries. However, the medical cost of adding BEV to chemotherapy may make this treatment unaffordable for EOC patients if it is not covered by the national health insurance (NHI). Moreover, the disease status in realworld patients is much more complex than that in clinical trials. Some real-world investigations have focused on the impact on PFS and AEs when BEV is added to front-line treatment (15)(16)(17). More real-world data to compare BEV effects on prognosis in recurrent EOCs or AEs between patients with or without prior BEV treatment are needed to assess cost-effectiveness (18)(19)(20).
Therefore, our study focused on EOC/tubal cancer (TC)/primary peritoneal cancer (PPC) patients who underwent front-line paclitaxel-carboplatin chemotherapy ± BEV or those with recurrent/persistent disease who underwent BEV ± chemotherapy. Our primary aim was to describe the correlation between clinico-pathological factors and physician-patient shared decision-making (SDM), as well as the survival benefits of adding BEV to front-line chemotherapy. Secondarily, we aimed to determine the safety of combination regimens of BEV plus chemotherapy, with or without prior BEV use. We aimed to identify advanced-stage or high-risk patients who may have a more favorable outcome in the front-line setting and predict which subgroup has a better prognosis after adding BEV.

Participants
The clinical research protocol was approved by the National Cheng Kung University Hospital Institutional Review Board (Protocol No. A-ER-108-119). The study was performed in accordance with the Declaration of Helsinki. The requirement for informed consent was waived due to the retrospective nature of the study and the difficulties to access to patients. The study flow chart regarding patient inclusion is illustrated in  Chemotherapy regimen was referred to paclitaxel-carboplatin doublets. Data was analyzed by X 2 or Fisher's exact test. SD, standard deviation; PFI, progression-free interval.

Study Methods
Medical records were reviewed for patients' clinical characteristics, treatment-related AEs, and treatment outcomes. Patients without postoperative front-line chemotherapy owing to any reason and those who had non-paclitaxel-platinum doublet were excluded. Cancer stage was determined according to the criteria of the International Federation of Gynecology and Obstetrics (FIGO). Residual nodules <1 cm and ≥1 cm were categorized as "optimal" and "suboptimal, " respectively. Cancer progression was defined based on the objective Response Evaluation Criteria in Solid Tumors 1.1 or the Gynecologic Cancer InterGroup (GCIG) definition. Our high-risk patients for progression was defined as FIGO stage IV, inoperable or macroscopic residuum >1 cm FIGO stage III disease, based on ICON7 definition (10). The last record was retrieved on August 31, 2019. AE severity was graded according to the Common Terminology Criteria for Adverse Events, version 4.03. OS was calculated based on the diagnosis date. PFS and PFI were determined using the date of last contact or progression after front-line chemotherapy. PFI <6 months (m) and ≥6 m were categorized as "platinum-resistant" and "platinum-sensitive, " respectively. "PFS2-PFS" was calculated based on the date of the first relapse or persistence to the next progression or death.

Statistical Analysis
Data were analyzed using SPSS (version 19.0; SPSS Inc., Chicago, IL, USA) (21). Interval variables are presented as means ± standard deviations. Differences between groups were tested using the Mann-Whitney U test. Frequency distributions between categorical variables were compared using Pearson X 2 or Fisher's exact tests. Survival was estimated using the Kaplan-Meier method and compared using log-rank tests. P < 0.05 (two-sided) was considered statistically significant. Cox proportional hazards models were used to estimate hazard ratios (HRs) and confidence intervals (CIs). Possible confounders were included in multivariate analyses. The independent effect of BEV use on survival and disease progression was analyzed in the multivariate analysis.
Relationships between PFI <6 or ≥6 m and clinicopathological factors are presented in Table 2. No statistical difference between PFI of 6 m and stage, histology, tumor grade, residual tumor size during primary surgery, or next disease progression was observed.
Advanced-stage patients treated with chemotherapy plus BEV in the subgroup of PFI <6 m had a significantly greater PFS (P = 0.001), but not OS ( Figure 3B) when compared to those treated with chemotherapy alone; no statistical difference in PFS or OS was observed in the subgroup of PFI ≥ 6 m ( Figure 3A). No statistical difference in the impacts of BEV on PFS or OS between clear cell and serous histology was observed in the early or advanced stage (Supplementary Figure 1).

Cohort 2 With Relapsed or Persistent Disease
The survival curves stratified by PFI of 6 and 12 m are illustrated in Figure 4. Patients with PFI ≥6 m after primary therapy had a significantly better OS and PFS2-PFS than those with PFI <6 m (P < 0.001 and P < 0.001, respectively) ( Figure 4A). Patients with a longer PFI had more favorable survival. Patients with PFI ≥12 m had greater OS and PFS2-PFS than those with PFI <6 m (P < 0.001 and P < 0.001, respectively) ( Figure 4B).

Univariate and Multivariate Analyses
In the univariate analysis, residual nodules ≥1 cm and PFI <6 m were significantly associated with a high risk of death and disease progression in Cohort 1 patients with advanced disease Table 3. Age ≥53 years was associated with a high risk of death due to cancer. In a multivariate-adjusted model, PFI <6 m was the strongest predictor of disease progression (HR 27.78, 95% CI 15.87-47.62) and death (HR 5.92, 95% CI 3.82-9.17) ( Table 4). BEV throughout and optimal cytoreduction in the front-line setting were independent predictors of reduced cancer progression (HR 0.43, 95% CI 0.25-0.73, and HR 0.63, 95% CI 0.44-0.90, respectively). Although BEV throughout was a predictor of cancer death, its impact was influenced by confounders in the multivariate analysis.
By cox proportional analysis in Cohort 2 patients, those with PFI of ≥6 m after primary therapy had significantly lower risks of death (HR 0.22, 95% CI 0.10-0.50) and next progression (HR 0.17, 95% CI 0.08-0.39) than those with PFI <6 m.

DISCUSSION
We found improved PFS as a benefit of BEV throughout triweekly in the dosage range of 7.5-15 mg/kg, which is consistent with results of independent phase 3 trials assessing front-line therapy (7,8) and real-world data (15)(16)(17). PFI <6 m independently predicted shorter PFS and OS, but BEV may reduce platinum-resistant relapse; these findings are in concordance with the prospective single-arm results in JGOG3022 (17). Moreover, to our knowledge, this is the first realworld study to provide data on improved OS as an advantage of BEV throughout, relative to chemotherapy alone, in frontline therapy in advanced-stage EOC patients and the highrisk subgroup.  The GCIG considered PFS as the primary endpoint in front-line therapy for ovarian cancer, and not OS, because of the confounding effects of post-progression therapy on OS (7,22). Advances in various post-progression therapies, such as BEV (11)(12)(13)(14)18), trientine (23), and poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) inhibitor (4,(24)(25)(26), may help extend patients' lives. We provided evidence while we observed a longer median OS in the BEV throughout group compared to that in GOG-218 and ICON7, even in patients who received only chemotherapy. When adjusted by multivariate analysis, our real-world findings corresponded to the GCIG consensus and emphasized the role of BEV throughout in PFS prolongation. This phenomenon is observed in the improved OS after using BEV in relapsed EOC, specifically in the platinum-sensitive subgroup.
A significantly improved PFS when adding olaparib after a response to chemotherapy plus BEV has occurred and a higher incidence of reversible grade ≥ 3 haematologic AEs were reported in the PAOLA-1 trial (27). Tewari et al. reported the reductions in risk of death for BRCA1/2mutated or non-BRCA1/2 homologous recombination deficient (HRD) carcinomas when compared to the wild type (9). However, BRCA/HRD testing was not predictive of BEV activity. Our patients had a shorter median PFS than that of the non-Olaparib arm in PAOLA-1 trial (27) or those in real-world studies (15)(16)(17). The reason for these discrepancies may be multifactorial, including different study designs, shorter maintenance duration or lower dosage of BEV, more complex disease, or reimbursement issues in the real-world setting.
Platinum resistance is an indicator of poor prognosis, and its involved mechanism is complex (28-30). Lee et al. reported that the effectiveness of BEV-included chemotherapy was feasible but varied according to the chemotherapy partner in platinumresistant EOC (20). A real-world small study showed PFS benefits of early BEV-added chemotherapy, but insignificant survival differences between platinum-resistant and -sensitive recurrent EOC (31). However, we provided more favorable oncologic outcomes of BEV-added relapse therapy in platinumsensitive patients. Furthermore, CCC has been thought of as a platinum-resistant malignancy. The histological distribution of EOC in Asia is quite different from that in the West. Serous, endometrioid, and CCC histology constituted 40-50, 15-20, and 15-20%, respectively, of EOC in Taiwan from 2000-2008 (32). Early-stage patients with CCC or grade 3 tumor were included in ICON7 trial as a subgroup of particular interest (8). Our early-stage patients used BEV following ICON7 inclusion criteria. Komiyama et al. reported that BEV-added front-line therapy was effective for advanced-stage clear cell carcinoma (17). However, the lack of benefits of BEV on clinical outcomes across different histologies in our study is similar to findings recorded in the ICON7 final results (10). Therefore, BEV could be applied regardless of histology in either an early or advanced stage.
Haematologic AEs were the most common in BEV-included trials in EOC (7,8,(11)(12)(13)(14), while similar results were observed in our study. Its safety was also promising in our relapse therapy. The cumulative incidences of hypertension and proteinuria were associated with median cumulative BEV dosages (33) or the treatment durations (17) in Asian women. However, our patients had less BEV-specific incidences and lower grades of AEs. This may be related to lower dosages, or fewer treatment cycles in most patients, which were in concordance with lower incidence rates of hypertension, proteinuria, GI, or non-CNS bleeding events in the BEV throughout arm in ICON7 than that in GOG-218 (7,8).
A study carried out in Belgium reported the relatively high cost-effectiveness of BEV with the most promising results in front-line treatment of stage IV EOC patients (34). The prognostic factors, e.g., advanced stage, histology, pre-and post-operative chemotherapy, and residual tumor size, were adjusted for during multivariate analysis, but expert-patient SDM regarding BEV utilization may possibly be influenced by choices of post-progression therapy or socio-economic factors which were not included in our analysis.
There are some other limitations to our study. BEV and BRCA/HRD testing has not yet been covered by our NHI. Hence, we are unable to provide real-world data regarding BEV in patients with BRCA mutation/HRD. Although most AEs were mild and treatable, the number of patients treated with BEV after prior BEV is too small to draw a conclusion in our relapsed cohort. Further research should be conducted to clarify these questions.
In conclusion, adding BEV to traditional front-line or relapse therapy was safe in EOC. This strategy as maintenance therapy was effective in extending PFS and OS in advancedstage patients. Platinum-sensitivity was the strongest prognostic factor. Platinum-sensitive relapsed EOC patients treated with BEV-added chemotherapy had a significant improvement in OS and had a longer duration in progressing to the next progression.

DATA AVAILABILITY STATEMENT
The datasets analyzed in this article are not publicly available because they contain information that could compromise research participant privacy. Requests to access the datasets should be directed to Yu-Fang Huang, yufangh@mail.ncku.edu.tw.

ETHICS STATEMENT
The clinical research protocol was approved by the National Cheng Kung University Hospital Institutional Review Board (Protocol No. A-ER-108-119). The study was performed in accordance with the Declaration of Helsinki. The requirement for informed consent was waived due to the retrospective nature of the study and the difficulties to access to patients.

AUTHOR CONTRIBUTIONS
All authors participated in the conception or design of the present study. P-YW, Y-MC, M-RS, Y-FH, and C-YC conducted research. P-YW and Y-MC acquired data. Y-CC and Y-FH performed the statistical analysis and P-YW, Y-FH, and C-YC interpreted the results. M-RS and C-YC provided administrative support. All authors drafted and revised the article for important intellectual content and have approved the final submitted version of the manuscript.

FUNDING
This clinical research received funding from the headquarters of the University Advancement at the National Cheng Kung University, which is sponsored by the Ministry of Education, Taiwan.