Phase I study of preoperative capecitabine and lenvatinib with external radiation therapy in locally advanced rectal adenocarcinoma.

Abstract

125 Background: Neoadjuvant chemo-radiation is a standard of care for locally advanced rectal cancer. Patients with pathologic complete response (pCR) have improved outcomes with less local and systemic failure. Dual targeting with platelet derived growth factor (PDGF) and vascular endothelial growth factor receptor (VEGFR) in combination with radiation can escalate tumor response with radiation. Lenvatinib is an oral multi-kinase inhibitor and had shown potent anti-tumor activity in xenograft models cultured with human colorectal cancer (CRC) lines. Methods: Patients with stage II or III rectal cancer, confirmed by endoscopic ultrasound or MRI, were recruited in 3 cohorts of 3 patients per dose level, with an expansion cohort at the MTD. Lenvatinib oral daily dose started at 14 mg (cohort 1) and was escalated to 20 mg (cohort 2) followed by 24 mg (cohort 3). In this 3+3 design, patients received dose escalation of lenvatinib with standard doses of capecitabine (850 mg/m2 PO BID) concurrent with external beam radiation on days 1-5 weekly for 28 treatments. Following completion patients underwent surgery in 6-10 weeks. Results: Twenty patients with median age of 55 were enrolled in 3 cohorts (1 patient was ineligible). There were no dose limiting toxicity at the maximum tested dose of lenvatinib (24 mg). Two patients are still awaiting surgery. 12 patients have undergone low anterior resection and 5 patients have had abdominoperineal resection. Therefore, out of 17 patients, 29.4% (5/17) showed pCR, and downstaging was observed in 71% of the patients (12/17). The mean neoadjuvant rectal cancer score (NAR) was 11.4 and median NAR was 8.43. Six patients had grade 3 adverse events (AEs) (1 rectal pain,1 transaminitis, 2 lymphopenia, 1 HTN, 1 with both leukocytosis and hyponatremia). No grade 4 AEs were noted. Most common AEs were hypertension, rectal pain, nausea, diarrhea, fatigue and dermatitis. No peri operative complications were observed. Conclusions: The study shows that the combination of lenvatinib and capecitabine with radiation is well tolerated in locally advanced rectal cancer with promising mean NAR score. The encouraging results will need to be validated in a randomized study. Clinical trial information: NCT02935309.