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Anlotinib combined with TQB2450 in patients with platinum-resistant or -refractory ovarian cancer: A multi-center, single-arm, phase 1b trial

Summary This is a phase Ib study of anlotinib plus a programmed death-ligand 1 (PD-L1) inhibitor TQB2450 for platinum-resistant or -refractory ovarian cancer. Thirty-four patients are enrolled and receive treatment. The objective response rate (ORR) is 47.1%, and the disease control rate is 97.1%. The median duration of response (DOR) has not been reached, and 61.3% of patients have a DOR of at least 8 months. The median progression-free survival (PFS) is 7.8 months, and the median overall survival (OS) has not been reached. The PD-L1-positive group has an ORR of 25.0%, whereas the PD-L1-negative group has an ORR of 92.9%. Treatment-related grade 3 or 4 adverse events (AEs) occur in 70.6% of patients, with the most common being hypertension (29.4%) and palmar-plantar erythrodysesthesia syndrome (29.4%). Anlotinib plus TQB2450 show promising antitumor activity and manageable toxicities in patients with platinum-resistant or -refractory ovarian cancer. A phase 3 randomized controlled trial to further validate our findings is ongoing.


In brief
Lan et al. demonstrate the efficacy, safety, and survival of anlotinib plus a PD-L1 inhibitor TQB2450 in platinumresistant or -refractory ovarian cancer. They analyze the association between PD-L1 expression and clinical efficacy. They provide a combination regimen of anti-angiogenic agent and immune checkpoint inhibitor in the platinumresistant and -refractory setting.

INTRODUCTION
Ovarian cancer is the eighth leading cause of cancer-related death in women worldwide and is responsible for 207,252 deaths in 2020. 1 Approximately 70% of patients with ovarian cancer are diagnosed at later stages. 2 Despite response to first-line platinum-based chemotherapy, most patients relapse within the initial 2 years after diagnosis. 3 Almost all patients with recurrent disease eventually develop resistance to platinum. The sequential use of single-agent non-platinum is considered standard treatment for platinum-resistant relapse. 4 However, the objective response rate (ORR) to single-agent therapy was low (10%-20%), and the progression-free intervals were short (3-4 months). [4][5][6] Thus, there is an unmet need for innovative therapy with improved response rates and duration of response (DOR) in this setting.
Immune checkpoint inhibitor (ICI) therapy has revolutionized the treatment of several cancers. [7][8][9] Despite the reported immunogenicity of ovarian cancer, 10 response rates to programmed cell death-1 (PD-1)/programmed death-ligand 1 (PD-L1) inhibitors seem low in patients with ovarian cancer. [11][12][13] Single-agent PD-1 inhibitor nivolumab and pembrolizumab in heavily pretreated patients with advanced ovarian cancer achieved response rates of 15% and 8%, respectively, 11,12 and the PD-L1 inhibitor avelumab reported a response rate of 9.6% in refractory ovarian cancer. 13 Combined PD-1/PD-L1 inhibitor therapy is considered to enhance the efficacy of monotherapy, with one strategy of combining PD-1/PD-L1 inhibitors with anti-angiogenic therapy. 14,15 Thus far, two trials involving the PD-1/PD-L1 inhibitors combined with bevacizumab have shown promise in patients with recurrent ovarian cancer. 16,17 However, there is poor understanding of the efficacy of the combination of PD-1/PD-L1 inhibitors with tyrosine kinase inhibitors (TKIs) of vascular endothelial growth factor receptor (VEGFR) in this setting. Anlotinib is an oral, multi-targeted TKI with activity against VEGFR1/2/3, FGFR1/2/3, PDGFR-a, c-Kit, and Ret and is effective against various types of cancer. 18,19 In an ongoing phase 2 study of anlotinib monotherapy in patients with platinum-resistant or -refractory ovarian cancer, the preliminary results showed that the ORR was 14.3% and the disease control rate (DCR) was 71.4%. 20 TQB2450, a humanized immunoglobulin G1 (IgG1) monoclonal antibody against PD-L1, has demonstrated antitumor activity in mouse models of melanoma and colon cancer. 21 Backed by preclinical data, clinical trials of TQB2450 with or without anlotinib in treating patients with advanced refractory biliary tract cancer, triple-negative breast cancer, non-small cell lung cancer, and gynecologic cancer are ongoing. [22][23][24] Here, we present the efficacy and safety of anlotinib plus TQB2450 in patients with platinum-resistant or -refractory ovarian cancer.

RESULTS
Between February 27, 2020, and February 26, 2021, we screened 44 patients, of whom 34 eligible patients were enrolled and received the study treatment (full analysis set [FAS] and safety analysis set). One patient (2.9%) who discontinued the treatment before the first post-baseline tumor assessment due to adverse events (AEs) was excluded from the per-protocol set (PPS) ( Figure 1). As of the data cutoff (May 31, 2021), the median follow up was 8.6 (range: 2.3-15.3) months. Thirteen (38.2%) of the 34 patients were still on treatment. Twenty-one  Table 1.

Antitumor activity
In the first nine patients enrolled, confirmed responses were noted in five patients. The ORR threshold for the first stage of Simon's two-stage design was reached, and the trial continued to full accrual. In the FAS, 16 of 34 patients achieved partial response (PR), thus the ORR was 47.1% (95% confidence interval [CI], 29.8-64.9) ( Table 2). An additional three patients had unconfirmed PR. Similar responses were recorded in PPS (Table 2). Seventeen (50.0%) of 34 patients achieved stable disease (SD), hence the DCR was 97.1% (95% CI, 84.7-99.9; Table 2). As shown in Figure 2A, 26 (78.8%) of the 33 patients who had an evaluable tumor assessment had some degree of tumor shrinkage.
Among the 16 patients with a confirmed objective response, the median time to achieve response was 2.7 (range: 1.3-7.0) months, and the median DOR was not reached (95% CI, 5.3 to not reached; Figure 3A). A DOR of at least 8 months was observed in 61.3% (95% CI, 25.1-84.0). Figure 2B presents a swimmer plot of the time to receive treatment across all patients.
All 34 patients received at least one complete cycle of anlotinib. Anlotinib dose interruption due to AEs occurred in 22 patients (64.7%). Sixteen (47.1%) patients required anlotinib dose reduction, of whom 12 (81.3%) required only one dose reduction and three (18.8%) required two dose reductions. The most common AE leading to anlotinib dose reduction was palmar-plantar erythrodysesthesia syndrome (10/16, 62.5%). AEs leading to anlotinib dose reduction are shown in Table S2. TQB2450 dose interruption occurred in 8 (23.5%) of the 34 patients. Eight (23.5%) patients required corticosteroids: two with pneumonitis, two with arthritis, one each with a rash, myositis, and hyperthyroidism, and one with increased aspartate aminotransferase and alanine aminotransferase. In the patients who received corticosteroids, one patient had a Assessed by fluorescent multiplex polymerase chain reaction (PCR) and capillary gel electrophoresis (CGE). to not reached) in PD-L1-positive patients and was not reached (95% CI, 6.8 to not reached) in PD-L1-negative patients ( Figure 4). The difference in PFS was not statistically significant between PD-L1-positive or -negative patients (p = 0.28; Figure 4).

DISCUSSION
In this study, anlotinib plus TQB2450 demonstrated promising antitumor activity with favorable response rate, durable response, and tolerable toxicity profile in patients with platinum-resistant or -refractory ovarian cancer. To our knowledge, this is the largest cohort of patients in this setting treated with a multi-targeted TKI plus a PD-L1 inhibitor. Despite the immunogenic profile in ovarian cancer revealed by preclinical data, PD-1/PD-L1 inhibitor monotherapy showed only low to moderate activity in patients with recurrent ovarian cancer. [11][12][13] There is growing interest in combination studies of PD-1/PD-L1 and VEGF inhibitors to improve the treatment of ovarian cancer. A phase 2 trial combining the PD-1 inhibitor nivolumab and bevacizumab reported increased benefit in patients with platinum-sensitive ovarian cancer with a response rate of 40%. 16 However, this treatment combination seemed to have less activity in the platinum-resistant setting (response rate 16.7%). Limited data have reported the clinical effect of PD-1/ PD-L1 inhibitor combined with VEGFR TKI in advanced ovarian cancer. Remarkably, the efficacy observed in our study is encouraging, with 16 (47.1%) confirmed responses and three unconfirmed responses and 78.8% of the patients showing some degree of tumor shrinkage. Our data suggest that anlotinib plus TQB2450 has enhanced antitumor activity in platinumresistant ovarian cancer, given the efficacy previously reported in anlotinib monotherapy and PD-1/PD-L1 inhibitors monotherapy in this setting. [11][12][13]20 Yang et al. identified that PD-L1 directly interacted with VEGFR2 and that it promoted the angiogenesis and metastasis of ovarian cancer by participating in the c-JUN/VEGFR2 signaling axis. 25 Furthermore, they demonstrated the PD-L1 inhibitor durvalumab combined with the VEGFR TKI apatinib enhanced the effect of anti-angiogenesis and the inhibition of cell migration and invasion. These findings may be one of the plausible explanations for the encouraging results observed in our study, where a multi-targeted TKI anlotinib was used as a partner combined with the PD-L1 inhibitor TQB2450.
In addition, 41.2% of the patients in our study had multiple lines of single-agent therapy with a non-platinum compound after being considered resistant to the last platinum therapy, which made the platinum-free interval (PFI) R6 months. There is a concern that the prolonged PFI may, to some extent, better our efficacy. However, there is no evidence that the predictive and prognostic roles of PFI apply for more than two relapses, and PFI may not be a valuable criteria for molecular targeted  therapy. 4,26 In our study, 88.3% of patients had a treatment-free interval (TFI) <2 months, which represented a patient population with poor prognosis. 4 Of note, the findings of our study and other trials of combination PD-1/PD-L1 inhibitor therapy demonstrated a durable clinical benefit in patients with platinum-resistant ovarian cancer. In a phase 1b study of 20 patients with platinum-resistant ovarian cancer who were treated with atezolizumab and bevacizumab, despite having a modest ORR of 15%, all three patients with PR had durable responses (11.3-18.9 months) and are still ongoing at the data cutoff, with four of eight patients with SD for >8 months. 17 In a phase 2 study combining nivolumab and bevacizumab in patients with recurrent ovarian cancer, only 3 of 18 patients (16.7%) with platinum-resistant disease achieved PR. However, two of them had a prolonged response of 16-18 months, with 16.7% of patients with SD lasting at least 24 weeks. 16 Similarly, in our study, the median PFS was 7.8 months, and the median DOR was not reached, with 61.3% of the patients showing a DOR of at least 8 months.
The safety profile of anlotinib plus TQB2450 was consistent with that reported in previous studies of other selective VEGFR TKIs combined with PD-1/PD-L1 inhibitors, [27][28][29] with no unexpected AEs. Although the frequency of the overall grade 3-4 AEs was as high as 70.6% in our study, the prevalence of specific grade 3-4 AEs was not so high, with hypertension and palmar-plantar erythrodysesthesia syndrome being the highest ranked with 29.4% each. These toxicities were associated with anlotinib and were manageable. Despite the grade 3-4 hypertriglyceridemia and grade 3 increased amylase observed in 14.7% and 2.9% of the patients in our study, respectively, all these patients did not have any symptoms. In the eight patients who required corticosteroids, most of them did not need TQB2450 dose interruption. In addition, the discontinuation rate due to treatment-related AEs was only 5.9% in our study. Our findings suggested that anlotinib plus TQB2450 had a manageable safety profile. See also Table S3. PD-L1 is the most widely investigated biomarker for predicting response to PD-1/PD-L1 inhibitor therapy; however, the predictive value of PD-L1 in ovarian cancer remains highly controversial. 11,12,16 In our study, patients with PD-L1-negative tumors had higher response rates than those with PD-L1positive tumors (92.9% versus 25.0%). Several factors may explain the inconsistency between the efficacy and PD-L1 expression in our study, such as the spatial and temporal heterogeneity in PD-L1 expression, the variability between primary and metastatic tumor sites, and the influence by prior chemotherapy. [30][31][32] It should be noted that only 22 (64.7%) patients in our study had archival tumor samples for PD-L1 staining, and the small number of patients precluded definitive conclusions. Efforts are ongoing to identify more reliable biomarkers for PD-1/PD-L1 inhibitor therapy.
Anlotinib plus TQB2450 has promising antitumor activity and manageable toxicities in patients with platinum-resistant or -refractory ovarian cancer. Accordingly, a phase 3 multicenter randomized trial (ClinicalTrials.gov: NCT05145218) to investigate anlotinib plus TQB2450 as treatment for patients with platinum-resistant or -refractory ovarian cancer is ongoing.

Limitations of study
This study has limitations. This is a single-arm study lacking a comparator treatment arm; thus, selection bias could not be ruled out. Further, the small sample size reduced the certainty of effectiveness observed.

STAR+METHODS
Detailed methods are provided in the online version of this paper and include the following:

ACKNOWLEDGMENTS
We thank all of the patients and their families who participated in this study. We thank Xu Li, Ying-Ying Li, and Ming-Xun Cao for collection of the data and provision of study materials and Ding Yu for supervision of research. This study was funded by the Chia Tai Tianqing Pharmaceutical Group Co., Ltd. The funder provided the study drug and designed the studies in collaboration with the investigators, participating in data collection. The funder sources had no role in data analysis and interpretation, preparation, review, or approval of the manuscript and decision to submit the manuscript for publication. This study was also supported, in part, by the Guangdong Basic and Applied Basic Research Fund Provincial Enterprise Joint Fund (2021A1515220166).