Abstract 1445P
Background
CS1001-101 is an open label, multi-center study to evaluate the efficacy and safety of CS1001, an anti-PD-L1 mAb, as mono or combo therapy in patients (pts) with solid tumors or lymphomas. CS1001+XELOX regimen for 1L GC/GEJ and CS1001+CF regimen for 1L ESCC pts were evaluated in this study and preliminary results are reported herein.
Methods
Pts with systemic therapy naïve GC/GEJ and ESCC were eligible. GC/GEJ pts received CS1001+XELOX (CS1001 1200 mg Q3W, Oxaliplatin: 130 mg/m2, IV, D1/cycle, up to 6 cycles, Capecitabine: 1000 mg/m2/time, bid, oral, D1-14/cycle, up to 6 cycles). ESCC pts received CS1001+CF (CS1001 1200 mg Q3W, Cisplatin: 80 mg/m2, IV, D1/cycle, up to 6 cycles, 5-fluorouracil: 800 mg/m2/day, IV, D1-5/cycle, up to 6 cycles).
Results
As of 19 Feb 2020, 29 GC/GEJ and 39 ESCC pts were treated, with a median treatment duration of 232 and 172 days, respectively. 22 (GC/GEJ) and 23 (ESCC) pts discontinued treatment. The ORR was 62% and 68%, and mDOR was 11.3 months and unreached, mPFS was 8.3 and 9.0 months for the 2 cohorts, respectively (Table). In GC/GEJ cohort, 28 (97%) pts reported CS1001-related AEs (TRAEs) and 14 (48%) pts had G≥3 TRAEs. 2 pts had TRAEs leading to CS1001 withdrawal: hypothyroidism and pneumonia. In ESCC cohort, 34 (87%) pts had TRAEs and 16 (41%) pts had G≥3 TRAEs. 2 pts had TRAEs leading to CS1001 withdrawal: hyponatraemia and pneumonitis. A CS1001-related death was reported in ESCC cohort. Table: 1445P
| Outcome, n (%) | GC/GEJ (N=29*) | ESCC (N=37*) |
| ORR | 18 (62) | 25 (68) |
| PR | 18 (62) | 25 (68) |
| SD | 6 (21) | 8 (22) |
| PD | 3 (10) | 2 (5) |
| DCR | 24 (83) | 33 (89) |
| mDoR (month, range) | 11.3 (1.0+, 14.1+) | NA (0.03+, 13.3+) |
| mPFS (month, range) | 8.3 (1.4, 16.1)# | 9.0 (2.0, 15.2)# |
| mOS (month, range) | 17.0 (1.4,18.7)# | NA (2.5,18.2)# |
* 2 ongoing pts have not reached the first post-baseline tumor assessment time and were excluded from the efficacy analysis. # for the min/max value from censored pts.
Conclusions
CS1001 in combination with SOC chemotherapy demonstrated high and durable anti-tumor activities with a tolerable safety profile. These results supported further evaluation of CS1001+XELOX in GC/GEJ and CS1001+CF in ESCC pts in 2 ongoing randomized phase III studies in China (NCT03802591 and NCT04187352).
Clinical trial identification
NCT03312842.
Editorial acknowledgement
Legal entity responsible for the study
CStone Pharmaceuticals.
Funding
CStone Pharmaceuticals.
Disclosure
H. Xia: Honoraria (self), Leadership role, Shareholder/Stockholder/Stock options, Full/Part-time employment: CStone Pharmaceuticals. J. Wang, Q. Shi: Full/Part-time employment: CStone Pharmaceuticals. H. Dai: Honoraria (self), Shareholder/Stockholder/Stock options, Full/Part-time employment: CStone Pharmaceuticals. J. Yang: Leadership role, Shareholder/Stockholder/Stock options, Full/Part-time employment: CStone Pharmaceuticals. All other authors have declared no conflicts of interest.