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PURPOSEAs yet, no checkpoint inhibitor has been approved to treat nasopharyngeal carcinoma (NPC). This study was aimed to evaluate the antitumor activity, safety, and biomarkers of toripalimab, a new programmed death-1 (PD-1) inhibitor for recurrent or metastatic NPC (RM-NPC) refractory to standard chemotherapy.PATIENTS AND METHODSIn this single-arm, multicenter phase II study, patients with RM-NPC received 3 mg/kg toripalimab once every 2 weeks via intravenous infusion until confirmed disease progression or unacceptable toxicity. The primary end point was objective response rate (ORR). The secondary end points included safety, duration of response (DOR), progression-free survival (PFS), and overall survival (OS).RESULTSAmong all 190 patients, the ORR was 20.5% with median DOR 12.8 months, median PFS 1.9 months, and median OS 17.4 months. Among 92 patients who failed at least two lines of systemic chemotherapy, the ORR was 23.9%. The ORRs were 27.1% and 19.4% in PD-L1+ and PD-L1− patients, respectively ( P = .31). Patients with ≥ 50% decrease of plasma Epstein-Barr virus (EBV) DNA copy number on day 28 had significantly better ORR than those with < 50% decrease, 48.3% versus 5.7% ( P = .0001). Tumor mutational burden had a median value of 0.95 muts/mega-base in the cohort and had no predictive value for response. Whole-exome sequencing results from 174 patients revealed that the patients with genomic amplification in 11q13 region or ETV6 genomic alterations had poor responses to toripalimab.CONCLUSIONThe POLARIS-02 study demonstrated a manageable safety profile and durable clinical response of toripalimab in patients with chemorefractory metastatic NPC. An early decrease in plasma EBV DNA copy number correlated with favorable response.

9060 Background: Dual blockade of PD-1 and CTLA-4 has shown improved overall survival (OS) in combination with a short course of chemotherapy. KN046 is a novel bispecific antibody that blocks both PD-L1 interaction with PD-1/CD80 and CTLA-4 interaction with CD80/CD86. We hypothesized that KN046 could be combined with a full course of chemotherapy and build more durable clinical benefit. Methods: This study enrolled systemic treatment naive, stage IV NSCLC patients (pts). Eligible pts received KN046 plus platinum doublet chemotherapy until progressive disease, unacceptable toxicity, withdrawal of informed consent or death. Efficacy evaluation was performed by investigators per RECIST 1.1. Safety and tolerability were assessed per NCI-CTCAE v5.0. Results: As of the Jan. 19, 2021, 87 pts [Cohort 1 (n = 51), Cohort 2 (n = 36)] have been enrolled with 83 pts having tumor PD-L1 expression data (PD-L1 ≥1%: 55.4%; PD-L1 < 1%: 44.6%). 33.3% pts remained on the study treatment and 66.7% pts discontinued treatment due to disease progression (27.6%), TEAE (13.8%), death (9.2%) and other reasons (16%). The median treatment duration of KN046 was 21 weeks (range: 1.6̃68.7 weeks). Treatment related TEAE (TRAE) occurred in 92% pts. 25.3% pts experienced Grade≥3 TRAE [diarrhoea (5.7%), alanine aminotransferase increased (4.6%), infusion related reaction (3.4%), rash (3.4%), aspartate aminotransferase increased, dermatitis allergic and immune-mediated pneumonitis (2.3%, respectively), anaphylactoid reaction, autoimmune hepatitis, back pain, bilirubin conjugated increased, hypertension, neutrophil count decreased, platelet count decreased, pneumonitis, rash maculo-papular, septic shock and white blood cell count decreased (1.1%, respectively). In 81 efficacy evaluable pts, the overall objective response rate (ORR) was 50.6% (95% CI: 39.3%,61.9%) and disease control rate (DCR) was 87.7% (95% CI: 78.5%-93.9%). The ORR and DCR in pts with non-squamous NSCLC (n = 48) were 45.8% (95% CI: 31.4%, 60.8%) and 89.6% (95% CI: 77.3%, 96.5%). The ORR and DCR in pts with squamous NSCLC (n = 33) were 57.6% (95% CI: 39.2%, 74.5%) and 84.8% (95% CI: 68.1%, 94.9). Progression free survival (PFS) and OS events have occurred in 53% and 18% patients. Median PFS was 5.9 (95%CI: 5.3, 8.7) months. Median OS was not reached. OS rate at 12 and 15 months were both 74.9%. Similar OS curves have been observed in PD-L1 ≥1% and PD-L1 < 1% pts. In PD-L1 ≥1% patients, median PFS was 6.7 months (10.8 months for PD-L1 ≥1% squamous NSCLC pts). Conclusions: KN046 combined with platinum doublet chemotherapy is tolerated and has shown promising clinical benefit as IL treatment for stage IV NSCLC particularly in PD-L1≥1% tumors and squamous histology. Pivotal Phase III trial in advanced unresectable or metastatic squamous NSCLC is currently ongoing. Clinical trial information: NCT04054531.

TPS255 Background: ESCC is the predominant histological subtype of esophageal cancer, particularly in Asian countries. Platinum-based chemotherapy is the first-line standard therapy for patients with unresectable, locally advanced, recurrent or metastatic ESCC. The FP regimen is recommended as the preferred treatment by guidelines. However, the survival benefit conferred by this therapy leaves considerable space for improvement, with median OS being less than 1 year. Blockade of the immune checkpoint receptors has shown clinical benefits in multiple tumor types. Recent studies combining standard treatments with checkpoint inhibitors have shown encouraging efficacy and favorable safety profile in patients with unresectable, locally advanced, recurrent or metastatic ESCC. CS1001 (sugemalimab) is the first full-length, fully human immunoglobin G4 (IgG4, s228p) anti-programmed death-ligand 1 (PD-L1) monoclonal antibody developed by the OMT transgenic rat platform. In an ongoing Phase Ib trial, CS1001 in combination with FP regimen demonstrated an ORR of 67.6% (25/37) and an mPFS of 9.0 months with a manageable safety profile in unresectable, locally advanced or distantly metastatic ESCC (19 Feb 2020 data cutoff; Shen, L., et al, ESMO 2020). Methods: CS1001-304 is a randomized, double-blind Phase III study to compare the efficacy and safety of FP regimen with CS1001 or placebo as first-line treatment in ESCC. The study enrolls patients with histologically or cytologically confirmed unresectable locally advanced, recurrent or metastatic ESCC who have ECOG PS of 0-1, patients are not eligible for curative therapy (curative surgery or definitive chemoradiotherapy), and have not received any prior systemic anti-tumor therapy for locally advanced or metastatic disease. Approximately 540 patients will be randomized at 2:1 into CS1001 + FP and placebo + FP arms respectively, stratified by PD-L1 expression status (PD-L1 expression < 1% vs ≥ 1% and < 10% vs ≥10%), ECOG PS (0 vs 1) and distant metastasis (no vs yes). Patients randomized to either arm will receive FP regimen (fluorouracil: 800 mg/m2/day, continuous intravenous infusion [IV], D1-4 of each cycle; cisplatin: 80 mg/m2, IV, D1 of each cycle), Q3W for up to 6 cycles in combination with CS1001 1200 mg or placebo (IV, D1 of each cycle), Q3W for up to 24 months. AEs will be monitored throughout the study and graded per NCI CTCAE v5.0. Tumor response will be assessed by RECIST v1.1 every 6 weeks in the first 12 months, and every 12 weeks thereafter. The primary endpoints are blinded independent central review (BICR)-assessed PFS and OS. Secondary endpoints include investigator-assessed PFS, BICR and investigator-assessed ORR and DoR, safety, PK profile, and immunogenicity. The study is actively enrolling patients in over 60 sites in China. Clinical trial information: NCT04187352.

e15083 Background: Platinum based chemotherapy is the standard care for 1st line treatment of metastatic gastric adenocarcinoma (GC), esophageal squamous cell carcinoma (ESSC), nasopharyngeal carcinoma (NPC) and head and neck squamous cell carcinoma (HNSCC). Combinations of PD-1 blockade with chemotherapy have shown promising but mixed results in solid tumors. Predictive biomarkers for chemo-immunotherapy combination as 1st line treatment remain undefined. Methods: Patients (n = 60) included in this analysis were four complete cohorts from a multi-center, phase Ib/II trial (NCT02915432) evaluating the safety and activity of toripalimab, a humanized PD-1 antibody in combination with standard chemotherapy for the 1st line treatment of GC, EC, NPC and HNSCC (excluding NPC). Whole exome sequencing (WES), RNA sequencing and immunohistochemistry were performed on tumor biopsy samples. PD-L1 expression and tumor mutational burden (TMB) were evaluated for correlation with clinical efficacy. Results: From Oct 2016 to Feb 2019, 33 GC, 12 ESSC, 12 NPC and 3 HNSCC patients were enrolled and treated with 240mg or 360 mg toripalimab Q3W via IV infusion in combination with Oxaliplatin/Capecitabine (XELOX), Paclitaxel/Cisplatin (PP), Gemcitabine/Cisplatin (GP) and Docetaxel/Cisplatin/5-FU(TPF) respectively. By the data cutoff date of Nov 15, 2019, all patients experienced treatment related adverse event (TRAE). There was one TRAE (heart failure) leading to death. Grade 3-4 TRAEs occurred in 67% patients, mostly attributed to chemotherapy, including 27% neutropenia, 23% thrombocytopenia, 18% leukopenia and 12% anemia. As assessed by investigators according to RECIST v1.1, the ORR/DCR were 54.5%/84.8%, 66.7%/91.7%, 75.0%/83.3% and 33.3%/100% respectively for GC, EC, NPC and HSNCC cohorts. The median duration of response was 8.3, 6.8, 7.7 and 7.1 months respectively. WES showed distinctive patterns of genomic alterations among different cohorts. The clinical response was not correlated with either PD-L1 expression or tumor mutational burden. Conclusions: Toripalimab in combination with chemotherapy as first-line treatments showed promising results for metastatic GC, EC, NPC and HNSCC patients. Two randomized Phase III trials of toripalimab in combination with Paclitaxel/Cisplatin or Gemcitabine/Cisplatin versus chemotherapy alone are ongoing to further evaluate the combination as first-line treatments in metastatic EC and NPC patients. Clinical trial information: NCT02915432 .

6542 Background: Metastatic nasopharyngeal cancer (mNPC) patients progressed after standard therapy have limited treatment options. This study is to evaluate the clinical efficacy and safety of toripalimab in mNPC patients refractory to standard chemotherapy treatment (Clinical trial ID: NCT02915432). Methods: Patients receive 3 mg/kg toripalimab Q2W via IV infusion until disease progression, unacceptable toxicity, or voluntary withdrawal. Clinical response is assessed every 8 weeks according to RECIST v1.1. Tumor PD-L1 expression, plasma EBV titer and other biomarkers will be evaluated for correlation with clinical response. Results: From Dec 2016 to Feb 2019, 190 mNPC patients were enrolled from 17 participating centers in China. The median age was 46 years with 83% male. Patients were heavily pretreated with a median of 2 lines of prior systemic treatments. By the cutoff date of Jan 17, 2020, 97% patients experienced treatment related adverse events (TRAE). Most common TRAE included anemia, hypothyroidism, AST increased, proteinuria and fever. Grade 3+ TRAE occurred in 28% patients. Among 190 patients assessed by Independent Review Committee per RECIST v1.1, 6 CR, 33 PR and 40 SD were observed for an ORR of 20.5% and a DCR of 41.6%. The median DOR was 12.9 months. The median PFS and median OS were 1.9 months and 18.6 months respectively. PD-L1+ patients (n=48) had higher ORR than PD-L1- patients (n=134), 27.1% versus 19.4%. By tumor histology, ORR was higher in keratinizing NPC (n=8) than non-keratinizing NPC (n=168), 62.5% versus 19.0%. 144 patients had valid plasma EBV titer measured every 28 days during the study. An average drop of 101-fold plasma EBV titer from baseline was observed in patients with objective responses. Patients with 2-fold+ drop in plasma EBV titer on day 28 (n=60) went on to have 48.3% ORR and 76.7% DCR, whereas patients with less than 2-fold drop (n=88) had 5.7% ORR and 25.0% DCR. 14 responding patients who later developed progressive disease had at least 2-fold+ increase of plasma EBV tier 3-months (median) before radiographic identification of disease progression. Conclusions: Toripalimab demonstrated encouraging clinical activity with a manageable safety profile in mNPC patients refractory to standard chemotherapy. Patients with 2-fold+ drops in plasma EBV titer on day 28 from baseline had favorable clinical response of 48.3% ORR, which might be used as a predictive biomarker. Clinical trial information: NCT02915432 .

6017 Background: Metastatic nasopharyngeal cancer (NPC) patients progressed afterstandardtherapy have limited treatment options. Toripalimab, also known as JS001, a humanized IgG4 antibody specific for human PD-1, has been approved for 2nd line treatment of metastatic melanoma in China. Here we report the results from a phase IIstudy in metastatic NPC patients treated with toripalimab.(Clinical trial ID: NCT02915432). Methods: This multi-center, open-label, phase II registration study is designed to evaluate the safety and efficacy of toripalimab in metastaticNPC patients who have failed systemic treatment. Toripalimabis given at 3 mg/kg IV Q2W until disease progression or intolerable toxicity.Tumor PD-L1 expression, plasma EBV DNA level and other biomarkerswill be correlatedwith clinical response. Results: Enrollment of 190chemo-refractory metastatic NPCpatients was completed by Feb 2019 from 17 participating centers. The median age was 46 years, with 89.5% patients received at least 2 lines of prior systemic therapies. Treatment related adverse events (TRAE)occurred in 92% patients, which were mostly grade 1 or 2.Common TRAE includedanemia, hypothyroidism, AST increased, proteinuria, pyrexia, cough, constipation, ALT increased, hypoalbuminemia and pruritus.Grade 3 or higherTRAEoccurred in 25% patients.By the cut-off date of Jan 7 2019, among 135 evaluable patients, 3 complete responses, 31 partial responses and 40 stable diseaseswere observed for an objective response rate (ORR) of 25.2% and a disease control rate of 54.8%. PD-L1 expression results were obtained from 125 patients and 45.6% (57/125) were PD-L1+.PD-L1+ patientsachieved slightly higherORR than PD-L1- patients, 29.8% versus 22.1%. In addition, an average drop of 47-fold plasma EBV DNA copy number was observed in responding patients, which typically proceeded the radiographic identification of clinical benefit. Conclusions: Toripalimab has demonstrated a manageable safety profileand encouraging clinical activity in the largest check-point blockade study in NPC to date. A change in plasma EBV DNA copy number might serve as a predictive marker for favorable clinical response. Patients will be continuously monitored for additional safety and survival readouts. Clinical trial information: NCT02915432.

4036 Background: Esophageal squamous cell carcinoma (ESCC) is the predominant histological subtype of esophageal cancer in South America and East Asian countries and remains an unmet medical need worldwide. Previous studies have shown the efficacy of programmed cell death 1 (PD-1) targeted therapy in a subset of patients with metastatic ESCC. However, robust predictive biomarkers to PD-1 antibody-based immunotherapy remain undefined. Methods: Patients included in this analysis were part of multi-center, phase Ib/II trial (NCT02915432) evaluating the safety and activity of toripalimab, a humanized PD-1 antibody in solid tumors. To identify molecular determinants of response, we performed whole exome sequencing (WES), messenger RNA sequencing and immunohistochemistry on patients’ samples and evaluated genomic and transcriptional biomarkers, PD-L1 expression and tumor mutational burden (TMB) for correlation with clinical efficacy. Results: Sixty advanced chemo-refractory ESCC patients were enrolled and 59 were treated with toripalimab. 94.9% (56/59) patients experienced at least one treatment related adverse event after 16 months; mostly grade 1 or grade 2. Treatment-related grade 3 or higher AEs occurred in 30.5% (18/59) of subjects. By the data cutoff date, 11 (18.6%; 95%CI 9.7 to 30.9) patients achieved an objective response, while the disease control rate was 47.5% (95%CI 34.3 to 60.9). Copy number analysis identified 24 out of 50 (48%) patients with amplifications of chromosome 11q13 region, which was consistent with elevated mRNA expression of amplified genes, including CCND1(Cyclin D1) and fibroblast growth factor family members ( FGF3/4/19). Patients without 11q13 amplification, had significantly better objective response rate (ORR 30.8% versus 4.2%, p= 0.024) and progression free survival (3.7 versus 2.0 months, HR = 0.47 [95%CI 0.24 to 0.91], p= 0.025) when compared with 11q13 amplified individuals. In contrast, patients with high TMB (≥12 Mutations/Mb; 11/47, 23.4%) or positive PD-L1 expression (TC or IC 1%; 19/57, 33.3%) showed no significant advantage in ORR or survival. Conclusions: Toripalimab has demonstrated a manageablesafety profile and promising anti-tumor activity in chemo-refractory ESSC patients. Genomic amplification of 11q13 region may serve as a negative predictive marker for advanced ESSC patients receiving anti-PD-1 based immunotherapy. Further interrogation of putative resistance genes that lie within this region is under study. Clinical trial information: NCT02915432.

4021 Background: Tumor mutational burden (TMB) is correlated with enhanced objective response rate (ORR) and progression-free survival for certain cancers receiving immunotherapy. This study aimed to investigate the safety and activity of toripalimab, a humanized PD-1 antibody, in advanced gastric cancer (AGC), and the efficacy predictive value of biomarkers including TMB and PD-L1. Methods: This study was a part of phase Ib/II trial evaluating the safety and activity of toripalimab as a single agent therapy or in combination with chemotherapy in chemo-refractory or treatment-naïve AGC, esophageal squamous cell carcinoma, nasopharyngeal carcinoma and head and neck squamous cell carcinoma. This report focused on the chemo-refractory AGC cohort receiving toripalimab (3 mg/Kg d1, Q2W) as a single agent therapy. Primary endpoint was ORR. Biomarkers including tumor PD-L1 expression, TMB, microsatellite instability (MSI) and Epstein-Barr virus (EBV) infection status were evaluated for their correlation with clinical efficacy as preplanned. Tumor PD-L1 expression was assessed with the SP142 immunohistochemistry assay, and the other biomarkers were assessed with whole exome sequencing based on tumor samples. Results: There were 58 subjects included in this cohort. The ORR was 12.1% and the disease control rate was 39.7%. Only 1 subject was MSI-H and achieved partial response. One out of 4 EBV positive subjects achieved partial response. Significant higher ORR was observed in subjects with positive PD-L1 expression (ORR 37.5%, 3/8) or TMB ≥12 Mutations/Mb (ORR 33.3%, 4/8) than those with negative PD-L1 expression (ORR 8.5%) or TMB < 12 Mutations/Mb (ORR 7.0%). The TMB-high subgroup showed significant superior OS than the TMB-low subgroup (HR = 0.48 [96% CI 0.24 to 0.96], p = 0.038), while PD-L1 expression status failed to differentiate OS. Conclusions: Toripalimab demonstrated promising anti-tumor activity in chemo-refractory AGC patients. TMB might serve as a better predictive marker for OS than PD-L1 expression for chemo-refractory AGC patients receiving PD-1 blockade immunotherapy. Clinical trial information: NCT02915432.

e15560Background: Bevacizumab (BV) was approved in China seven years ago. Safety data from multicenter observational study was limited. To understand practical use of BV and confirm the correlation...

108 Background: Patients with gastric adenocarcinoma (GC) or gastroesophageal junction cancer (GEC) often present with advanced or metastatic disease, which has poor prognosis and limited treatment options and represent an important unmet medical need especially in China/Asia. JS001, a humanized recombinant IgG4 antibody against PD-1, selectively blocks the interactions of PD-1 with its ligands PD-L1 and PD-L2, and promotes antigen specific T-cell activation. A phase I study of JS001 in Chinese patients with heavily pretreated solid tumors has demonstrated an acceptable safety profile in doses up to 10 mg/kg Q2W. Here we report the safety and efficacy of JS001 in a phase Ib/II clinical study in Chinese patients with refractory/metastatic GC. (Clinical trial ID: NCT02915432) Methods: Refractory/metastatic GC Patients receive JS001 3 mg/kg Q2W until disease progression or unacceptable toxicity. All patients with measurable disease will be assessed for clinical response every 8 weeks according to the RECIST 1.1 criteria. Tumor PD-L1 expression as well as additional potential predictive biomarkers are monitored for correlation with clinical response. Results: Between Apr 19, 2017 and Sep 11, 2017, 48 GC pts (74.5% received at least 2 Lines of treatment) were enrolled into the study. Treatment related adverse events occurred were mostly grade 1 or 2. As of Sep 11, 2017, 25 GC pts have been evaluated for clinical efficacy. 5 PR (partial response) and 10 SD (stable disease) were observed (ORR 20% and DCR 60%). The PD-L1 expression positivity (defined as positive staining ³1% on Tumor Cell or on Immune Cell by SP142) in EC tumor was 14.3% (7/48). 3/5 (60%) PD-L1+ patients and 2/20 (10%) PD-L1 negative patients achieved partial responses. Conclusions: JS001 showed a promising preliminary clinical activity in heavily pre-treated metastatic GC pts with a manageable safety profile. Of the 25 evaluable GC patients by 9/11/2017, 5 PR and 10 SD were observed (ORR 20% and DCR 60%). Among PD-L1 positive patients (n=5), ORR was 60% and DCR 80%. Pts will be continuously monitored for safety and efficacy upon JS001 treatment. Clinical trial information: NCT02915432.

116 Background: Patients with Esophageal squamous cell carcinoma (EC) often present with advanced and metastatic stage disease, which has poor prognosis and limited treatment options, and represent an important unmet medical need especially in China/Asia. JS001, a humanized recombinant IgG4 antibody against PD-1, selectively blocks the interactions of PD-1 with its ligands PD-L1 and PD-L2, and promotes antigen specific T-cell activation. A phase I study of JS001 in Chinese patients with heavily pretreated solid tumors has demonstrated an acceptable safety profile in doses up to 10 mg/kg Q2W. Here we report the safety and efficacy of JS001 in a phase Ib/II clinical study in Chinese patients with refractory/metastatic EC. (Clinical trial ID: NCT02915432) Methods: Refractory/metastatic EC Patients receive JS001 3 mg/kg Q2W until disease progression or unacceptable toxicity. All patients with measurable disease will be assessed for clinical response every 8 weeks according to the RECIST 1.1 criteria. Tumor PD-L1 expression as well as additional potential predictive biomarkers are monitored for correlation with clinical response. Results: Between Apr 19 2017 and Sep 11 2017, 56 EC pts (84.9% received at least 2 Lines of treatment) were enrolled into the study. Treatment related adverse events occurred were mostly grade 1 or 2. As of Sep 11 2017, 34 EC pts have been evaluated for clinical efficacy. Among these pts, 8 PR (partial response) and 14 SD (stable disease) were observed (ORR 23.5% and DCR 64.7%). The PD-L1 expression positivity (defined as positive staining ³1% on Tumor Cell [TC] or on Immune Cell [IC] by SP142) in EC tumor tissue was 21.4% (12/56). 2/10 (20%) PD-L1+ patients and 6/24 (25%) PD-L1 negative patients achieved partial responses. Conclusions: JS001 showed a promising preliminary clinical activity in heavily pre-treated metastatic EC pts with a manageable safety profile. Clinical response was not correlated with PD-L1 expression. Pts will be continuously monitored for safety and efficacy upon JS001 treatment. Clinical trial information: NCT02915432.

327 Background: nab-P + Gem demonstrated significantly better overall survival (OS; median: 8.7 vs 6.6 mo; HR 0.72; P < 0.001) than Gem alone as first-line treatment for pts with MPC in the MPACT study. This phase II bridging study evaluated efficacy and safety of nab-P + Gem in Chinese pts with MPC. Methods: Efficacy and safety of nab-P 125 mg/m2 + Gem 1000 mg/m2 on days 1, 8, and 15 every 4 weeks was evaluated in a 3-part sequential study. In part 1, safety was examined. In part 2, efficacy was evaluated by the Simon optimal 2-stage design. If there were > 2 responses in 28 pts in stage 1 of part 2, an additional 54 pts would be treated in stage 2. The study would be completed if > 9 responses were observed. If there was an insufficient number of responses in either stage of part 2, part 3 would be triggered to compare nab-P + Gem vs Gem alone. The primary endpoint was overall response rate (ORR). Secondary endpoints included duration of response (DOR), OS, and safety. Correlation of OS and baseline neutrophil-to-lymphocyte ratio (NLR) was also analyzed. Results: Eighty-three pts were treated. Median age was 57.0 y; 19% were aged > 65 y; baseline Karnofsky performance status was 90 - 100 in 70% of pts and 70 - 80 in 30%. Combining results for stages 1 and 2, ORR was 35% by independent assessment, median DOR was 8.9 mo (95% CI, 6.01 - 8.94), median OS and PFS were 9.2 mo (95% CI, 7.60 - 11.10) and 5.5 mo (95% CI, 5.29 - 7.16), respectively (Table). Baseline NLR ≤ 5 was associated with a nonsignificant trend toward longer OS vs NLR > 5 (median, 10.0 vs 8.3 mo; HR 0.62; P= 0.148). The most common grade ≥ 3 adverse events included neutropenia (37%), leukopenia (31%), and fatigue (14%). Grade ≥ 3 peripheral neuropathy occurred in 7% of pts. Part 3 was not triggered per study design. Conclusions: nab-P + Gem demonstrated efficacy in Chinese pts with MPC. The OS and ORR were numerically better than those of the phase III MPACT trial (Table). A trend toward longer OS in pts with baseline NLR ≤ 5 vs > 5 confirmed previous findings from the MPACT study. No new safety signals were identified. Clinical trial information: NCT02135822. [Table: see text]