Abstract 3815: Clinical efficacy and safety of HER2 targeted therapy in patients with metastatic colorectal cancer: A systematic review and meta-analysis
Authors: Villarreal Oscar E. , Xiao Lianchun , Allam Joelle , Sorokin Alexey , Yuan Ying , Kopetz Scott , Raghav Kanwal Pratap 
Published: March 2024

Background: Therapies targeting HER2 have shown clear benefit in patients with breast or gastric cancer,; and their use in metastatic colorectal cancer (mCRC) has been increasingly explored in recent years. HER2 overexpressed or amplified (HER2-positive) mCRC is seen in 2-8% of all mCRC cases and is enriched in RAS wild-type (WT) tumors, representing a patient population that may benefit from anti-HER2 therapies. Although, several single-arm and some non-comparative randomized clinical trials have now tested the use of diverse dual anti-HER2 therapies in mCRC, no summative analysis have been performed. We conducted a systematic review and meta-analysis to evaluate the overall clinical benefit (efficacy and safety) of dual-HER2 inhibition in patients with RAS-WT HER2-positive mCRC.

Methods: A systematic review of available literature was performed for clinical trials involving patients with mCRC treated with HER2 targeting therapy. Two independent reviewers selected studies and extracted data from PubMed and abstracts published at major international oncology meetings during the past 5 years. Case reports and other studies not meeting inclusion criteria were excluded, therefore a total of 13 studies were used for analysis. Patients with RAS-mutant tumors within each trial were excluded due to known limited benefit of dual HER2 inhibition in this subset. Inverse variance method with random-effects model was used for meta-analysis to determine the overall effect of the therapy on overall response rate (ORR), disease control rate (DCR), progression free survival (PFS) and treatment-related adverse events (TRAE).

Results: Systematic review identified 9 study cohorts which were utilized in the meta-analysis, encompassing a total of 279 patients with mCRC who received Trastuzumab (T) in combination with either Pertuzumab (P), Tucatinib (Tu), Pyrotinib (Py), or Lapatinib (L). Collectively, dual HER2 inhibition showed an ORR of 35.1% (95% CI: 29.4-41.0%), a DCR of 68.3% (95% CI: 62.5-73.9%), and a PFS of 5.2 months (95% CI: 4.4-6.0 months). Pooled TRAE of grade ≥ 3 across studies was 29.9% (95% CI: 18.8-42.4%) but displayed high inter-study heterogeneity (p&lt;0.0001, I2 = 79%), mainly driven by one trial (Pyro-HER2; TRAE = 75.0%, 95% CI: 50.9-91.3%).

Conclusions: Overall, this comprehensive meta-analysis confirms that dual HER2 targeting therapies yield meaningful clinical efficacy, with favorable safety profiles, and improve outcomes in patients with RAS-WT HER2-positive mCRC.

Citation Format: Oscar E. Villarreal, Lianchun Xiao, Joelle Allam, Alexey Sorokin, Ying Yuan, Scott Kopetz, Kanwal Pratap Raghav. Clinical efficacy and safety of HER2 targeted therapy in patients with metastatic colorectal cancer: A systematic review and meta-analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3815.