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Response-Adapted Ultralow-Dose Therapy Demonstrates Beneficial Outcomes for Patients With Indolent Orbital B-Cell Lymphoma
According to results from a prospective phase 2 non-randomized controlled trial, response-adapted ultralow-dose therapy for indolent orbital B-cell lymphoma demonstrated reduced radiation exposure, insignificant toxic effects, and superior disease outcomes.
“Radiation therapy to doses of 24 to 36 [gray] is currently used to treat indolent B-cell lymphoma of the ocular adnexa; however, ocular adverse effects are common,” explained first author Chelsea Pinnix, MD, PhD, The University of Texas MD Anderson Cancer Center, Houston, Texas, and colleagues.
This trial of a response-adapted strategy included 50 evaluable patients with stage 1 to 4 indolent B-cell lymphoma of the ocular adnexa enrolled between July 2015 and January 2021. Investigators noted the primary end point was 2-year local orbital control within the irradiated field after response-adapted therapy. Patients were treated with ultralow-dose radiation therapy to 4 grays in 2 fractions and then were assessed for response at 3-month intervals. Furthermore, patients with persistent orbital lymphoma were offered an additional 20 grays in 10 fractions to complete the response-adapted treatment.
Results demonstrated that among this patient population, 32 patients (64%) had mucosa-associated lymphoid tissue lymphoma, 12 (24%) had follicular lymphoma, and 6 (12%) had unclassifiable low-grade B-cell lymphoma. It was also noted that 31 patients (62%) had stage 1 disease, and 36 (72%) were newly diagnosed.
At a median follow-up of 37.4 (95% [confidence interval] CI, 33.7 to 52.5) months, the 2-year local control rate was 89.4% (95% CI, 81% to 98.7%), and the 2-year overall survival (OS) rate was 98% (95% CI, 94.1% to 100%). Additionally, 45 patients (90%; 95% CI, 78.2% to 96.7%) experienced a complete response (CR) to response-adapted radiation, which included 44 patients with a CR to ultralow-dose radiation and 1 patient with a CR after an additional 20 grays.
Investigators observed no local recurrences among patients with a CR to response-adapted therapy. Furthermore, no grade 3 or higher toxic effects were observed. In a planned subset analysis of 22 patients with newly diagnosed, untreated stage 1 mucosa-associated lymphoid tissue lymphoma, the 2-year local control rate was 90.7% (95% CI, 79.2% to 100%), and the 2-year freedom from distant relapse rate was 95.2% (95% CI, 86.6% to 100%).
“In this non-randomized controlled trial, response-adapted ultralow-dose therapy for indolent orbital B-cell lymphoma resulted in reduced radiation exposure, negligible toxic effects, and excellent disease outcomes,” concluded Dr Pinnix et al.
Source:
Pinnix C, Dabaja B, Gunther J, et al. Response-adapted ultralow-dose radiation therapy for orbital indolent B-cell lymphoma. JAMA Onc. Published online July 11, 2024. doi: 10.1001/jamaoncol.2024.2112
