Patients
A total of 131 and 193 patients received nab-PTX plus RAM and PTX plus RAM, respectively. Eighteen and 55 patients were excluded from the nab-PTX plus RAM and PTX plus RAM groups, respectively. Finally, 113 and 138 patients in the nab-PTX plus RAM and PTX plus RAM groups, respectively, were analyzed (Fig. 1). Baseline characteristics were generally well balanced between the two groups. Although the proportion of patients with ECOG PS 0 or HER2 negative were numerically higher, there were no significant differences (Table 1). Of the patients, 94.1% and 94.2% had received platinum agents in the nab-PTX plus RAM and PTX plus RAM groups, respectively. At the time of analysis in December 2019, the median follow-up was 16.8 and 37.9 months in the nab-PTX plus RAM and PTX plus RAM groups, respectively. Of the patients, 75.2% and 58.0% in the nab-PTX plus RAM and PTX plus RAM groups, respectively, received subsequent antitumor therapy, including anti-programmed cell death 1/programmed cell death 1 ligand 1 (anti-PD-1/PD-L1) inhibitor (57.5% vs. 26.8%, respectively), irinotecan (31.9% vs. 47.1%, respectively), platinum re-challenge (7.1% vs. 18.1%, respectively), and investigational agents in clinical trials (22.1% vs. 20.3%, respectively,) (Table S1).
Efficacy
The median PFS was 3.9 months (95% CI: 3.4–4.3 months) in the nab-PTX plus RAM group and 3.9 months (95% CI: 3.1–4.7 months) in the PTX plus RAM group. PFS was comparable between the two groups (HR: 1.08; 95% CI: 0.83–1.40; P = 0.573) (Fig. 2a). The median OS was 10.9 months (95% CI: 9.3–12.7 months) in the nab-PTX plus RAM group and 10.3 months (95% CI: 8.5–12.0 months) in the PTX plus RAM group. There was no significant difference between the two groups (HR 0.82; 95% CI: 0.61–1.10; P = 0.188) (Fig. 2b). The results of the subgroup analyses for PFS and OS are shown in Fig. 3. Patients with moderate or massive ascites showed a trend toward favorable outcomes for PFS in the nab-PTX plus RAM group (P for interaction = 0.051), whereas there was no obvious trend observed for OS. Most of the other subgroups showed consistent results between PFS and OS.
Eighty-three and 106 patients had measurable lesions in the nab-PTX plus RAM and PTX plus RAM groups, respectively. Among these patients, 28 and 29 patients in the nab-PTX plus RAM and PTX plus RAM groups, respectively, achieved partial response, resulting in a 33.7% and 27.4% ORR, respectively (P = 0.385). Of note, higher DCR was observed in the nab-PTX plus RAM group compared with the PTX plus RAM group (81.9% vs. 67.0%, respectively; P = 0.016).
Safety
All patients initially received full-dose RAM. The proportion of patients with initial dose reductions of nab-PTX (54 patients, 47.8%) was significantly higher than that of patients with initial dose reduction of PTX (41 patients, 29.7%) (P = 0.003). During treatment, dose reduction or interruption of nab-PTX or PTX occurred in 93 (82.3%) and 98 (71.0%) patients in the nab-PTX plus RAM and PTX plus RAM groups, respectively. The median relative dose intensity (RDI) of nab-PTX in the nab-PTX plus RAM and PTX in the PTX plus RAM group was 57.1% and 61.3%, respectively. There was no difference in RDI of RAM between the nab-PTX plus RAM and PTX plus RAM groups (median: 98.2% vs. 97.6%, respectively).
Treatment-related adverse events (TRAE) are listed in Table 2. Overall, 67.3% (76/113) and 63.8% (88/138) of patients in the nab-PTX plus RAM and PTX plus RAM groups, respectively, experienced grade ≥3 TRAEs. The most frequent grade ≥3 TRAEs were neutropenia, leukopenia, anemia, thrombocytopenia, hypertension, and febrile neutropenia. Thirty-three (28.0%) and 47 patients (34.1%) in the nab-PTX plus RAM and PTX plus RAM groups, respectively, received granulocyte colony-stimulating factor, without use of granulocyte colony-stimulating factor prophylaxis in either of the groups. Although any grade of anemia, thrombocytopenia, sensory neuropathy, and fatigue were more frequently observed in the nab-PTX plus RAM group, there were no significant differences in grade ≥3 TRAEs between the two groups. Hypersensitivity reactions occurred in none of the 113 patients (0%) in the nab-PTX plus RAM group and two of the 138 patients (1.4%) in the PTX plus RAM group. These two patients were emergently hospitalized due to these hypersensitivity reactions.
TRAEs that led to treatment discontinuation were similar between the two groups: 22.1% (25/113) and 14.5% (20/138) of the patients in the nab-PTX plus RAM and PTX plus RAM groups, respectively. The most common TRAE leading to treatment discontinuation was sensory neuropathy: 3.5% (4/113) and 1.4% (2/138) of the patients in the nab-PTX plus RAM and PTX plus RAM groups, respectively.