Simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) combined with nimotuzumab for locally advanced esophageal squamous cell carcinoma (ESCC): A phase II clinical trial.

OBJECTIVE

To evaluate the feasibility, safety and efficacy of concurrent simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) combined with nimotuzumab in the treatment of locally advanced esophageal squamous cell cancer (ESCC).

METHODS

Eligible patients were histologically proven to have locally advanced ESCC, and were unable to tolerate or refuse concurrent chemoradiotherapy (CCRT). Enrolled patients underwent concurrent SIB-IMRT in combination with nimotuzumab.

SIB-IMRT: For the planning target volume of clinical target volume (PTV), the prescription dose was 50.4 Gy/28fractions, 1.8 Gy/fraction, 5fractions/week, concurrently, the planning target volume of gross tumor (PTV) undergone an integrated boost therapy, with a prescription dose of 63 Gy/28fractions, 2.25 Gy/fraction, 5 fractions/week. Nimotuzumab was administered concurrently with radiotherapy, 200 mg/time, on D1, 8, 15, 22, 29, and 36, with a total accumulation of 1200 mg through intravenous infusion. The primary endpoint of the study was the safety and efficacy of the combined treatment regimen, and the secondary endpoints were 1-year, 2-year, and 3-year local control and survival outcomes.

RESULTS

(1) From December 2018 to August 2021, 35 patients with stage II-IVA ESCC were enrolled and 34 patients completed the full course of radiotherapy and the intravenous infusion of full-dose nimotuzumab. The overall completion rate of the protocol was 97.1%. (2) No grade 4-5 adverse events occurred in the entire group. The most common treatment-related toxicity was acute radiation esophagitis, with a total incidence of 68.6% (24/35). The incidence of grade 2 and 3 acute esophagitis was 25.7% (9/35) and 17.1% (6/35), respectively. The incidence of acute radiation pneumonitis was 8.6% (3/35), including one case each of Grades 1, 2, and 3 pneumonitis. Adverse events in other systems included decreased blood cells, hypoalbuminemia, electrolyte disturbances, and skin rash. Among these patients, five experienced grade 3 electrolyte disturbances during the treatment period (three with grade 3 hyponatremia and two with grade 3 hypokalemia). (3) Efficacy: The overall CR rate was 22.8%, PR rate was 71.4%, ORR rate was 94.2%, and DCR rate was 97.1%.(4) Local control and survival: The 1-, 2-, and 3-year local control (LC) rate, progression-free survival(PFS) rate, and overall survival(OS) rate for the entire group were 85.5%, 75.4%, and 64.9%; 65.7%, 54.1%, and 49.6%; and 77.1%, 62.9%, and 54.5%, respectively.

CONCLUSIONS

The combination of SIB-IMRT and nimotuzumab for locally advanced esophageal cancer demonstrated good feasibility, safety and efficacy. It offered potential benefits in local control and survival. Acute radiation esophagitis was the primary treatment-related toxicity, which is clinically manageable. This comprehensive treatment approach is worthy of further clinical exploration (ChiCTR1900027936).