Patient Characteristics
A total of 246 patients with unresectable HCC treated with lenvatinib were retrospectively reviewed, of them 132 patients did not meet the inclusion criteria. Of the remaining 114 patients, 37 patients received a combination of SBRT and Lenvatinib (SBRT + LEN group) and 77 received lenvatinib alone (LEN group) (Fig. 1). The baseline characteristics of two groups are summarized in Table 1, and the all of the baseline characteristics were well-balanced between the two groups. According to the degree of PVTT, the whole cohort of 114 patients were divided into two subgroups (Vp1-2 group and Vp3-4 group). The baseline characteristics of Vp1-2 group and Vp3-4 group were also well-balanced (Additional fle 1: Table S1). It is noteworthy that approximately 90% of patients did not receive any previous treatment, and 44.7% (51/114) of the population in our study were out of the REFLECT criteria, with extensive tumor burden and poor liver function and performance status.
Treatment Efficacy in The Whole Cohort
The median follow-up durations for the SBRT plus lenvatinib and lenvatinib groups were 39.6 [95% CI: 18.7, 60.6] and 33.2 [95% CI: 22.3, 44.1] months, respectively. The patients in the SBRT plus lenvatinib group had longer OS (median, 19.3 [ 95% CI: 16.0, 22.6] months) than those in the lenvatinib group (median, 11.2 [95% CI: 8.8, 13.6] months; [HR] = 0.45, [95% CI: 0.30, 0.67], P < 0.001; Fig. 2A). The median PFS in the SBRT plus lenvatinib group (10.3 [95% CI: 9.0, 11.6] months) was longer than in the lenvatinib group (5.3 [95% CI: 4.2, 6.4] months) (HR = 0.45, [95% CI: 0.31, 0.65], p < 0.001; Fig. 2B). A longer median IHPFS (10.7 [95% CI, 9.0, 12.4] vs. 5.3 [95% CI, 4.2, 4.7] months) was also observed in patients treated with the combined therapy compared with the monotherapy (HR = 0.41, [95% CI: 0.28, 0.60], p < 0.001; Fig. 2C).
The best tumor response evaluated by mRECIST criteria are shown in Table 2. The ORR in the SBRT plus lenvatinib group was 56.8%, significantly higher than the 20.8% ORR observed in the lenvatinib group (p < 0.001). In addition, 34 cases in the SBRT plus lenvatinib group vs. 50 cases in the lenvatinib group achieved disease control (DCR: 91.9% vs. 64.9%, p = 0.005). Furthermore, patients who showed treatment response in the SBRT plus lenvatinib group had significantly higher OS than those who did not respond to treatment (p < 0.001). (Fig.3).
Treatment Efficacy in The Subgroup
Forest plot analysis of OS related factors showed that the benefit of SBRT combined with lenvatinib exceeded that of lenvatinib monotherapy in the patients of male, age ≥55 or <55, HBV infection, Child-Pugh class A, ECOG score 0 or 1, number of tumors >3, tumor size ≥5 cm and <10 cm, PVTT Vp1-2 or Vp3-4, ALBI grade 2, and AFP ≤200.
In the subgroup analysis of Vp1-2 group, the median OS (25.2 [95% CI, 17.6, 32.8] vs. 15.7 [95% CI, 10.6, 20.8] months; [HR] = 0.41, [95% CI: 0.21, 0.81], P = 0.019; Fig. 5A), PFS (12.3 [95% CI, 19.3, 15.3] vs. 7.1 [95% CI, 6.3, 7.8] months,; [HR] = 0.39, [95% CI: 0.22, 0.69], P = 0.001; Fig. 5B) and IHPFS (12.5 [95% CI, 11.0, 14.0] vs. 7.1 [95% CI, 6.3, 7.8] months; [HR] = 0.36, [95% CI: 0.21, 0.64], P < 0.001; Fig. 5C) in SBRT plus lenvatinib group was significantly longer than in lenvatinib group. In the Vp3-4 group, a longer median OS (16.6 [95% CI, 9.1, 24.1] vs. 9.1 [95% CI, 7.4, 10.8] months; [HR] = 0.46, [95% CI: 0.27, 0.76], P = 0.004; Fig. 5D), PFS (8.7 [95% CI, 5.9, 11.5] vs. 4.8 [95% CI, 2.9, 6.8] months; [HR] = 0.48, [95% CI: 0.29, 0.79], P = 0.005; Fig. 5E) and IHPFS (8.8 [95% CI, 4.6, 13.0] vs. 4.8 [95% CI, 3.4, 6.2] months; [HR] = 0.44, [95% CI: 0.27, 0.72], P = 0.001; Fig. 5F) were also observed in the combined therapy group.
Prognostic factors for OS, PFS and IHPFS in the Whole Cohort
The independent prognostic factors associated with OS, PFS and IHPFS were performed Univariate and multifactorial analyses based on Cox regression models (Table 3). Multivariate Cox proportional risk analysis showed that SBRT plus lenvatinib significantly improved OS ([HR] = 0.37; [95% CI, 0.26, 0.60]; P = 0.001), PFS ([HR] = 0.33; [95% CI, 0.21- 0.51]; P < 0.001), and IHPFS ([HR] = 0.29; [95% CI, 0.18- 0.45]; P < 0.001). Besides, the number of tumors and the degree of PVTT were also independent risk factors for OS, PFS and IHPFS.
Treatment-Related Adverse Events
The incidence of AEs at any grade in both groups was shown in Table 4. The overall incidence of at least 1 AE of any grade was similar in the SBRT plus lenvatinib and lenvatinib group (34 [91.9%] vs. 69 [89.6%], P = 0.962). In the SBRT plus lenvatinib and lenvatinib groups, dose reduction, dose interruption or discontinuation of lenvatinib treatment due to grade ≥ 3 AEs could be observed in 7 (18.9%) and 12 (15.6%) patients, respectively. The most common AEs in the combined therapy group were hypertension (10 [27.0%]) and diarrhea (10 [27.0%]), while in the monotherapy group the most common AEs were hypertension (24 [31.2%]) and fatigue (23 [29.9%]). Overall, AEs in the combined therapy group were mostly manageable and the incidence was not statistically significant compared to the monotherapy group.
Subsequent Therapy
During the follow-up period, all patients in lenvatinib group showed tumor progres-sion compared to 33 (89.2%) patients in the combination therapy group. 20 (60.6%) of 33 progressed patients in the SBRT plus lenvatinib group received subsequent therapy, compared with 45 (58.4%) of 77 progressed patients in the lenvatinib group. Among the patients who received subsequent treatment in the combined therapy group, 12 (36.4%) patients received single treatment and 8 (24.2%) patients received multiple treatments. Among the patients who received subsequent treatment in the monotherapy group, 27 (35.1%) patients received single treatment and 26 (33.8%) patients received multiple treatments (Additional fle 1: Table S2). In general, there was no significant difference in the subsequent treatment received by patients between the two groups.