Phase I Study of Preoperative Chemoradiation With S-1 and Oxaliplatin in Patients With Locally Advanced Resectable Rectal Cancer

629 Background: We conducted a phase II study of preoperative chemoradiation (CRT) with S-1, a novel oral fluoropyrimidine, plus oxaliplatin in patients (pts) with locally advanced rectal cancer. Tumor ADCs were measured by DW-MRI and were evaluated as a predictive marker for pathologic responses. Methods: Radiotherapy was delivered to a total 50.4 Gy. The recommended doses were determined by a previous phase I study; oxaliplatin 50 mg/m2/week on D1, 8, 22 and 29, and S-1 80 mg/m2/day on D1-14 and D22-35. Total mesorectal excision was performed within 6 ± 2 weeks. Primary endpoint was pathologic complete response (pCR) rate. The value of tumor ADCs by DW-MRI was measured before and after CRT, and was correlated with pathologic responses after surgery. Results: A total of 38 patients were enrolled; 22 (57.9%) were men and the median age was 54 years (range, 28-67). Of 35 patients who underwent curative surgery, 28 patients underwent sphincter-saving operations. There was no grade 4 toxicity, and grade 3 toxicities included leukopenia (2.7%), neutropenia (2.7%), anorexia (2.7%), nausea (2.7%) and diarrhea (8.8%). The pCR rate was 25.7% (8/35, 95% CI [10.9-42.1]) and additional 10 patients (28.6%) showed near total regressions of tumor. Tumor ADCs by DW-MRI were calculated in 38 patients (including phase I part). The post-CRT ADC and the ADC changes (ΔADC) were significantly correlated with pCR rate (post-CRT ADC: 1.52±0.46 vs. 1.07±0.58, p=0.037, ΔADC: 44.5% vs. -7.6%, p=0.026). Conclusions: Preoperative CRT with S-1 plus oxaliplatin showed promising results in pathologic responses and favorable toxicities profiles. Tumor ADC by DW-MRI seems to be a useful method for predicting responses. No significant financial relationships to disclose.

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

Journal of Clinical Oncology ◽

10.1200/jco.2019.37.4_suppl.694 ◽

2019 ◽

Vol 37 (4_suppl) ◽

pp. 694-694

Author(s):

Jessica Frakes ◽

Rutika Mehta ◽

Sarah E. Hoffe ◽

Iman Imanirad ◽

Maria E Martinez Jimenez ◽

...

Keyword(s):

Clinical Trial ◽

Rectal Cancer ◽

Radiation Therapy ◽

Phase I ◽

Phase I Study ◽

Locally Advanced ◽

Vascular Endothelial Cell ◽

Rectal Adenocarcinoma ◽

External Beam Radiation ◽

Beam Radiation

694 Background: Despite routine use of neoadjuvant chemoradiation, patients with advanced rectal tumors experience significant rates of treatment failure and recurrence. Radiation resistance is a particular problem. Dual targeting of PDGF and VEGFR (Vascular endothelial cell growth factor receptor) in combination with radiation can enhance tumor response. Lenvatinib inhibits the kinase activities of VEGFR1-3, FGFR1-4, PDGFRα, KIT, and RET and in vivo results show that it effectively delays the growth of human colorectal xenografts. Methods: This is a phase I clinical trial of lenvatinib in combination with capecitabine administered with radiation. Patients with stage II or III rectal cancer confirmed by endoscopic ultrasound or MRI were eligible for the study. In this 3+3 phase I study with 3 cohorts, patients were treated with escalating doses of lenvatinib administered in combination with standard doses of capecitabine (850 mg/m2 PO BID D1-5 weekly for 5 ½ to 6 weeks) and external beam radiation therapy (180 cGY on D1-5 weekly for 5 ½ to 6 weeks). Patients underwent surgery 6-10 weeks after neoadjuvant therapy. Results: Nine patients have been enrolled in the 3 cohorts with the median age of 51 years. Lenvatinib dosing started at 14 mg PO daily (cohort 1) and was safely escalated to 20 mg PO daily (cohort 2) followed by 24 mg PO daily (cohort 3). There were no DLTs at the maximum tested dose of lenvantinib (24 mg). 5 patients have undergone low anterior resection and 4 have had abdominoperineal resection. The pathological complete response (pCR) rate was 33.33%, and downstaging was observed in 100% of patients. Median neoadjuvant rectal cancer score (NAR) was 8.7. Three pts had grade 3 events (2 hypertension (HTN), 1 lymphopenia) without any grade 4 events. Most common AEs were HTN and fatigue. No perioperative complications were observed. Tissues for all pts have been collected for planned correlative studies. Conclusions: This study shows that the combination of lenvatinib with capecitabine, and EBRT is well tolerated. NAR score and downstaging rates are encouraging. Currently we are enrolling 10 additional pts at the maximum tested dose of lenvatinib to further evaluate efficacy and safety. Clinical trial information: NCT02935309.

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