Second-line raltitrexed plus irinotecan (SALIRI) with bevacizumab, cetuximab, or alone for metastatic colorectal cancer: a prospective multicenter cohort-based secondary analysis of the SALLY trial

Introduction

Colorectal cancer (CRC) ranks third and second in terms of incidence and mortality among malignancies, respectively, representing a significant global health challenge (1). In China, nearly 517,100 patients were diagnosed with CRC in 2022 (2), and approximately 20% of all CRC cases are diagnosed at the metastatic stage (3). For patients with metastatic CRC (mCRC), chemotherapy remains the preferred treatment strategy. With the development of novel drugs, targeted therapies, including epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) inhibitors, have emerged as effective options (3,4). Additionally, immunotherapy, based on the molecular subtypes of CRC, is being increasingly used, showing promising effectiveness (5).

In China, FOLFOX [5-fluorouracil (5-FU) and leucovorin combined with oxaliplatin] is the most common first-line regimen for patients with mCRC (5). In the V308 study, FOLFOX and FOLFIRI (leucovorin and fluorouracil plus irinotecan) were found to be interchangeable in the first- and second-line treatment for patients with mCRC, but both the objective response rate (ORR) and progression-free survival (PFS) were significantly reduced in the second-line setting, possibly due to resistance to 5-FU cross-line use (6,7). If first-line chemotherapy fails, a change to second-line treatment is recommended as this can prevent potential resistance to the same drug.

Several recent phase II studies involving small patient cohorts have indicated that the raltitrexed plus irinotecan (SALIRI) regimen demonstrates promising efficacy and a manageable safety profile in patients with mCRC who have progressed following oxaliplatin-based first-line therapy (8,9). Subsequently, a large prospective trial, SAILIRI-based therapy as a second-line treatment for patients with metastatic colorectal cancer (SALLY), enrolled over 1,000 patients with mCRC to evaluate SALIRI as second-line treatment following the failure of first-line 5-FU with platinum. The median PFS (mPFS) and median overall survival (mOS) were 7.3 months [95% confidence interval (CI): 7.0–7.6] and 17.8 months (95% CI: 17.0–19.2), respectively (10). These findings support SALIRI as a viable second-line treatment for patients with mCRC. Moreover, other research indicated that the addition of targeted agents [i.e., bevacizumab (Bev) and cetuximab (Cet)] to second-line chemotherapy results in improved efficacy in patients with mCRC (11-13). Notably, the SALLY study demonstrated that patients administered SALIRI combined with targeted drugs (primarily Bev and Cet) experienced better outcomes than did those treated with SALIRI alone, with an mPFS of 7.6 months (vs. 5.8 months; P=0.07) and an mOS of 18.1 months (vs. 17.0 months; P=0.045) (10).

However, little is known regarding the efficacy and tolerability of SALIRI in combination with Bev or Cet, and no randomized trial has directly compared SALIRI + Bev, SALIRI + Cet, and SALIRI alone as second-line treatment. We therefore performed an exploratory secondary analysis of the prospective multicenter SALLY registry to compare response, survival, and safety outcomes among these three groups. Since treatment was not randomized, the analysis was designed to describe observed outcomes and generate hypotheses, not to determine the comparative efficacy of Bev and Cet. We present this article in accordance with the TREND reporting checklist (available at https://jgo.amegroups.com/article/view/10.21037/jgo-2026-0657/rc).

Methods

Study design and patients

The SALLY trial was a prospective, multicenter, noninterventional registry clinical trial conducted across 58 centers in China from April 2018 to March 2021. The details of the study design has been reported previously (10). A total of 1,066 patients with mCRC administered with SALIRI-based second-line therapy were included in the full analytical set (FAS) from the SALLY trial. For this secondary analysis, we included patients from the FAS who received SALIRI + Bev, SALIRI + Cet, or SALIRI alone. Because the parent study was noninterventional, treatment was chosen by physicians in routine practice according to tumor molecular profile, primary tumor location, prior therapy, comorbidities, patient preference, and drug availability. Treatment assignment was not randomized.

Eligible patients had mCRC that had progressed after first-line fluoropyrimidine- and platinum-based systemic therapy before they started second-line SALIRI-based treatment. The registry recorded age, sex, Eastern Cooperative Oncology Group (ECOG) performance status, histology, pathological grade, initial clinical stage, primary tumor location, primary tumor resection, number of metastatic organs, available RAS/BRAF/MSI status, treatment exposure, response, survival, and safety outcomes. Detailed first-line biologic exposure was not collected systematically in the source registry and was therefore not included in the comparative adjustment.

This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments, and was approved by the ethics committee of Peking University Cancer Hospital (No. 2018YJZ58). The SALLY trial was approved by the ethics committees of Tongji University Shanghai East Hospital (2018-Research Review No. 12) and Bayi Hospital Nanjing Chinese Medicine University (No. 81YY-ZLLL-17-32), and informed consent was obtained from all participants. The SALLY trial was registered with the Chinese Clinical Trial Registry (registration number: ChiCTR1800016185).

Treatment

The treatment regimen typically included irinotecan (150–180 mg/m²) and raltitrexed (2 mg/m²) with either Bev (5 mg/kg) or Cet (500 mg/m²) on day 1, repeated every 2 weeks. An alternative regimen included irinotecan (200–250 mg/m²) and raltitrexed (3 mg/m²) with Bev at 7.5 mg/kg on day 1, repeated every 3 weeks.

Genetic testing

Microsatellite instability (MSI) status was detected via immunohistochemistry or polymerase chain reaction (PCR). Rat sarcoma viral oncogene homolog (RAS) and v-Raf murine sarcoma viral oncogene homolog B1 (BRAF) status were assessed via Sanger sequencing, PCR testing, or next-generation sequencing.

Evaluation of efficacy and toxicity

The objective of this subgroup analysis was to compare the efficacy and safety of SALIRI alone to those of SALIRI combined with Bev or Cet, taking into account that treatment was not randomly assigned. The primary outcomes were ORR, PFS, and overall survival (OS), while secondary outcomes included the disease control rate (DCR) and treatment-related toxicities.

Tumor response was assessed using Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. Imaging was performed according to routine practice at each participating center, without a mandated central imaging schedule. Responses were assessed by investigators and were not reviewed centrally or blinded. The ORR was considered to be the proportion of patients with complete response (CR) or partial response (PR). The DCR was considered to be the proportion of patients with CR, PR, or stable disease (SD). PFS was calculated as the period from enrollment to documentation of progression or death from any cause. OS was defined as the time between enrollment and death from any cause. Patients without documented events were censored at the last available follow-up. Toxicities were recorded prospectively in the registry and graded according to National Cancer Institute Common Toxicity Criteria (NCI-CTCAE) version 4.0. Adverse events (AEs) were graded from 1 to 5.

Statistical analysis

Categorical variables were reported as the frequency and percentage and were compared via the Chi-squared test and the Fisher exact test. OS and PFS were estimated with the Kaplan-Meier method and were compared between groups via the log-rank test. AEs were evaluated by descriptive statistics. All analyses were conducted based on the FAS, and safety analyses used the safety set. Missing data were not inputed, and analyses were based on available data. A two-sided P value <0.05 was considered statistically significant, without adjustment for multiplicity. Data analysis was performed with SAS version 9.4.

Results

Patient characteristics

The SALLY trial enrolled 1,066 patients with mCRC treated with second-line SALIRI-based therapy; in our subgroup analysis, there were 678 patients in the SALIRI + Bev group, 103 in the SALIRI + Cet group, and 268 in the SALIRI-alone group (Figure 1). The baseline characteristics were similar for sex, ECOG performance status, histological type, primary tumor resection, and number of metastatic organs, but differed in age (younger in the SALIRI + Bev group; P=0.003) and primary tumor location (higher proportion of right-sided tumors in the SALIRI + Bev group and higher proportion of rectal tumors in the SALIRI + Cet and SALIRI-alone groups; P<0.001) (Table 1). Additionally, approximately one-third of the patients underwent genetic testing. Higher RAS mutation rates were found in the SALIRI + Bev and SALIRI-alone groups than in the SALIRI + Cet group (60.6% vs. 50.0% vs. 2.1%; P<0.001), whereas BRAF mutation and MSI-high rates were low across all groups (Table 1).

Figure 1 Flowchart of the subgroup analysis in the SALLY trial. Bev, bevacizumab; Cet, cetuximab; SALIRI, raltitrexed + irinotecan.

Efficacy

In the SALIRI + Bev group, the ORR and DCR were 19.8% (95% CI: 16.8–23.0%) and 85.4% (95% CI: 82.5–88.0%), respectively, while in the SALIRI + Cet group, they were 27.2% (95% CI: 18.9–36.8%) and 87.4% (95% CI: 79.4–93.1%), respectively. In the SALIRI + Bev group, the mPFS and mOS were 7.6 months (95% CI: 7.4–7.9) and 17.8 months (95% CI: 16.6–19.6), respectively, while in the SALIRI + Cet group, they were 7.4 months (95% CI: 6.6–8.1) and 19.9 months (95% CI: 17.7–26.1), respectively (Table 2 and Figure 2).

Figure 2 Survival analysis of the different groups in the FAS population. (A) PFS and (B) OS of patients treated with SALIRI, SALIRI + Bev, or SALIRI + Cet. Bev, bevacizumab; Cet, cetuximab; CI, confidence interval; FAS, full analysis set; OS, overall survival; PFS, progression-free survival; SALIRI, raltitrexed + irinotecan.

Compared with the SALIRI-alone group, the SALIRI + Cet group had a significantly higher ORR (27.2% vs. 15.7%; P=0.02), while the SALIRI + Bev group had a numerically but not statistically higher ORR (19.8% vs. 15.7%; P=0.16). The PFS did not significantly improve with the addition of targeted agents, although, compared with the SALIRI-alone group, there was a nonsignificant improvement in PFS in both the SALIRI + Bev (7.6 vs. 5.8 months; P=0.10) and SALIRI + Cet (7.4 vs. 5.8 months; P=0.14) groups. A significant improvement in OS with SALIRI in combination with targeted therapy was observed for the total SALLY population (18.1 vs. 17.0 months; P=0.045). Notably, compared with the SALIRI-alone group, the SALIRI + Cet group had a significantly better OS (19.9 vs. 17.0 months; P=0.006), whereas the SALIRI + Bev group did not (17.8 vs. 17.0 months; P=0.13) (Table 2 and Figure 2).

In the direct unadjusted comparison between targeted combinations, the SALIRI + Cet group, had a higher ORR (27.2% vs. 19.8%; P=0.09) and OS (19.9 vs. 17.8 months; P=0.056) than the SALIRI + Bev group, but these differences did not reach statistical significance (Table 2 and Figure 2).

Safety

In general, the AEs across all groups in the study were predominantly grade 1–2. Addition of targeted therapy did not increase the incidence of grade 3–4 AEs or the rates of dose reduction or treatment discontinuation. Grade 3–4 AEs occurred in 14.9% of patients receiving SALIRI + Bev, 12.6% receiving SALIRI + Cet, and 9.7% receiving SALIRI alone (P=0.10). AEs leading to discontinuation occurred in 6.9%, 8.7%, and 5.6% of patients, respectively (P=0.54), and no AE-related deaths were reported (Table 3). Overall toxicity rates were broadly comparable, with liver function abnormalities being the most common AEs; rash was more frequent in the SALIRI + Cet group (Table 4).

Discussion

The SALLY trial previously reported that the addition of targeted therapy to SALIRI significantly improves OS in the second-line treatment of patients with mCRC (10). In this exploratory secondary analysis, we described outcomes among patients who received SALIRI + Bev, SALIRI + Cet, or SALIRI alone. Both targeted combinations showed numerically favorable response or survival outcomes compared with SALIRI alone, and statistically significant unadjusted differences were observed for ORR and OS in the SALIRI + Cet group. In addition, both targeted therapies exhibited good safety profiles. These findings are promising and support biomarker-driven and randomized studies to explore this combination in the second-line treatment of mCRC.

FOLFOX and FOLFIRI remain interchangeable options for the first- and second-line treatment for patients with mCRC; however, their effectiveness in later lines is often limited by cumulative toxicity and potential cross-resistance following previous 5-FU exposure. Raltitrexed, a thymidylate synthase inhibitor with a distinct pharmacologic profile, represents a rational alternative. Evidence from the SALLY study and other phase II trials (8-10) consistently indicates that SALIRI provides meaningful antitumor activity with manageable toxicity in patients with 5-FU- and platinum-refractory disease, highlighting its potential to overcome fluoropyrimidine resistance.

Recent data further suggest that raltitrexed-based regimens may be used beyond their traditional role and serve as substitutes for fluoropyrimidines. In the phase II BEVATOMOX trial (14), raltitrexed plus oxaliplatin combined with Bev demonstrated comparable safety—but not superiority—to standard FOLFOX-based therapy, indicating its use as an alternative rather than a replacement. Novel combinations continue to be investigated. For instance, a regimen incorporating raltitrexed, S-1, and fruquintinib achieved encouraging disease control in heavily pretreated patients, highlighting the potential of raltitrexed as a flexible chemotherapy backbone, particularly in combination with antiangiogenic agents (15).

Within this evolving framework, our results provide descriptive comparative data on different targeted agents combined with SALIRI. To our knowledge, no randomized studies have directly compared SALIRI + Bev with SALIRI + Cet as the second-line treatment for patients with mCRC. In our cohort, SALIRI +Cet was associated with significant improvements in ORR and OS as compared with SALIRI alone, whereas Bev yielded only modest, nonsignificant associations. Nevertheless, the direct comparison between the two agents did not indicate any statistical differences, and the observed pattern may be influenced by treatment selection and baseline biology rather than by the targeted agent alone.

Certain limitations to this study should be acknowledged. First, it was a secondary analysis of a prospective noninterventional registry, not a randomized head-to-head trial, and the baseline clinicopathological characteristics were imbalanced. Treatment was chosen by physicians, and patients who received Cet were more likely to have RAS wild-type disease and left-sided or rectal primary tumors. In contrast, BRAF-mutant tumors were seen only in the SALIRI + Bev and SALIRI-alone groups. Previous studies have established that left-sided primary tumors and RAS wild-type status are associated with improved survival (16-18), which may partly account for the apparent advantage in the Cet subgroup. Second, molecular testing was available for only about one-third of patients, and missing molecular data may not have been balanced across groups. Third, the SALIRI + Cet subgroup was small, which limited precision and made adjusted modeling unreliable. Fourth, the registry did not systematically record detailed first-line biologic exposure, which may have affected both second-line treatment selection and outcomes. These limitations preclude definitive conclusions regarding comparative efficacy and support the need for prospective biomarker-stratified trials.

From a safety perspective, raltitrexed-based regimens demonstrated a favorable and predictable toxicity profile, and the addition of targeted therapy did not substantially increase the incidence of grade 3–4 AEs. Hepatic toxicity was the most commonly observed AE, consistent with previous reports (8,9,19). Bev has been reported to be linked to hypertension, proteinuria, and, occasionally, serious complications such as hemorrhage and intestinal perforation (20); meanwhile, Cet has been found to increase the incidence of rash, which is consistent with the findings in our study (20). No other significant differences in toxicity profiles were found between the SALIRI-alone group and the SALIRI + Bev or SALIRI + Cet groups in our study. Notably, there were no cardiotoxic AEs associated with raltitrexed, indicating that it may have a more favorable toxicity profile compared with fluoropyrimidine-based regimens. Therefore, raltitrexed could serve as an alternative for patients with mCRC who are not eligible for 5-FU-based therapies. In addition, its intermittent administration schedule, compared with the continuous 5-FU infusion, may facilitate outpatient delivery and improve treatment adherence.

Taken together, our findings, when considered in the context of the aforementioned research, support the clinical utility of raltitrexed-based regimens as both an alternative therapeutic option and a platform for novel combination strategies in the second-line treatment of mCRC. In the context of targeted therapy, SALIRI combined with Bev or Cet represents a rational and well-tolerated treatment approach in this setting.

Conclusions

SALIRI-based combination therapy with either Bev or Cet appeared feasible and tolerable in this exploratory secondary analysis of the prospective multicenter SALLY registry. The apparent benefit seen with SALIRI + Cet should be interpreted cautiously because treatment selection was not randomized, with imbalances in tumor sidedness and molecular status. Future prospective, biomarker-driven and randomized studies are warranted to define the optimal clinical positioning of SALIRI-based combinations.

Acknowledgments

We thank all individuals who participated in our study.

Footnote

Reporting Checklist: The authors have completed the TREND reporting checklist. Available at https://jgo.amegroups.com/article/view/10.21037/jgo-2026-0657/rc

Peer Review File: Available at https://jgo.amegroups.com/article/view/10.21037/jgo-2026-0657/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jgo.amegroups.com/article/view/10.21037/jgo-2026-0657/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments, and was approved by the ethics committee of Peking University Cancer Hospital (No. 2018YJZ58). The SALLY trial was approved by the ethics committees of Tongji University Shanghai East Hospital (2018-Research Review No. 12) and Bayi Hospital Nanjing Chinese Medicine University (No. 81YY-ZLLL-17-32), and informed consent was obtained from all participants.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Siegel RL, Miller KD, Wagle NS, et al. Cancer statistics, 2023. CA Cancer J Clin 2023;73:17-48. [Crossref] [PubMed]
2. Xia C, Dong X, Li H, et al. Cancer statistics in China and United States, 2022: profiles, trends, and determinants. Chin Med J (Engl) 2022;135:584-90. [Crossref] [PubMed]
3. Aparicio J, Esposito F, Serrano S, et al. Metastatic Colorectal Cancer. First Line Therapy for Unresectable Disease. J Clin Med 2020;9:3889.
4. Benson AB, Venook AP, Al-Hawary MM, et al. Colon Cancer, Version 2.2021, NCCN Clinical Practice Guidelines in Oncology. J Natl Compr Canc Netw 2021;19:329-59. [Crossref] [PubMed]
5. André T, Shiu KK, Kim TW, et al. Pembrolizumab in Microsatellite-Instability-High Advanced Colorectal Cancer. N Engl J Med 2020;383:2207-18. [Crossref] [PubMed]
6. Tournigand C, André T, Achille E, et al. FOLFIRI followed by FOLFOX6 or the reverse sequence in advanced colorectal cancer: a randomized GERCOR study. J Clin Oncol 2004;22:229-37. [Crossref] [PubMed]
7. Seymour MT, Maughan TS, Ledermann JA, et al. Different strategies of sequential and combination chemotherapy for patients with poor prognosis advanced colorectal cancer (MRC FOCUS): a randomised controlled trial. Lancet 2007;370:143-52. [Crossref] [PubMed]
8. Cheng K, Zhou YW, Chen Y, et al. Biweekly Raltitrexed Combined With Irinotecan as Second-Line Therapy for Patients With Metastatic Colorectal Cancer: A Phase II Trial. Cancer Control 2022;29:10732748221080332. [Crossref] [PubMed]
9. Cheng Y, Teng Z, Zhang Y, et al. Irinotecan plus raltitrexed as second-line treatment in locally advanced or metastatic colorectal cancer patients: a prospective open-label, single-arm, multi-center, phase II study. BMC Cancer 2024;24:1082. [Crossref] [PubMed]
10. Qin S, Li J, Zhou A, et al. SALIRI-based (raltitrexed plus irinotecan) therapy as a second-line treatment for patients with metastatic colorectal cancer (SALLY): A prospective, multicenter, non-interventional, registry study. Cancer Commun (Lond) 2024;44:910-4. [Crossref] [PubMed]
11. Cunningham D, Humblet Y, Siena S, et al. Cetuximab monotherapy and cetuximab plus irinotecan in irinotecan-refractory metastatic colorectal cancer. N Engl J Med 2004;351:337-45. [Crossref] [PubMed]
12. Sobrero AF, Maurel J, Fehrenbacher L, et al. EPIC: phase III trial of cetuximab plus irinotecan after fluoropyrimidine and oxaliplatin failure in patients with metastatic colorectal cancer. J Clin Oncol 2008;26:2311-9. [Crossref] [PubMed]
13. Giantonio BJ, Catalano PJ, Meropol NJ, et al. Bevacizumab in combination with oxaliplatin, fluorouracil, and leucovorin (FOLFOX4) for previously treated metastatic colorectal cancer: results from the Eastern Cooperative Oncology Group Study E3200. J Clin Oncol 2007;25:1539-44. [Crossref] [PubMed]
14. Samalin E, Senellart H, Thezenas S, et al. The BEVATOMOX phase II trial: raltitrexed/oxaliplatin/bevacizumab vs mFOLFOX6/bevacizumab in 2nd-line metastatic colorectal cancer. Oncologist 2026;31:oyag006. [Crossref] [PubMed]
15. Leng W, Wen Z, Wang H, et al. Raltitrexed, S-1 and fruquintinib (RSF) in the treatment of refractory metastatic colorectal cancer: study protocol for a multicenter, prospective, single-arm, phase II trial. BMC Cancer 2025;25:376. [Crossref] [PubMed]
16. Petrelli F, Tomasello G, Borgonovo K, et al. Prognostic Survival Associated With Left-Sided vs Right-Sided Colon Cancer: A Systematic Review and Meta-analysis. JAMA Oncol 2017;3:211-9. [Crossref] [PubMed]
17. Arnold D, Lueza B, Douillard JY, et al. Prognostic and predictive value of primary tumour side in patients with RAS wild-type metastatic colorectal cancer treated with chemotherapy and EGFR directed antibodies in six randomized trials. Ann Oncol 2017;28:1713-29. [Crossref] [PubMed]
18. Li ZN, Zhao L, Yu LF, et al. BRAF and KRAS mutations in metastatic colorectal cancer: future perspectives for personalized therapy. Gastroenterol Rep (Oxf) 2020;8:192-205. [Crossref] [PubMed]
19. Cocconi G, Cunningham D, Van Cutsem E, et al. Open, randomized, multicenter trial of raltitrexed versus fluorouracil plus high-dose leucovorin in patients with advanced colorectal cancer. Tomudex Colorectal Cancer Study Group. J Clin Oncol 1998;16:2943-52.
20. Cui Y, Guo Y. The effectiveness and safety of bevacizumab versus cetuximab in the treatment of colorectal cancer: a systematic review and meta-analysis. Int J Clin Pharm 2022;44:843-51. [Crossref] [PubMed]

(English Language Editor: J. Gray)