1585: Evaluating a Safer, Less Toxic Radiation Therapy in the Treatment of Lymphoma
Grant Status: Closed
The primary goal of this work was to explore and clinically implement involved-field radiotherapy (IFRT) technique for canine patients with advanced-staged lymphoma and test its feasibility, tolerability, and safety. This information is a necessary prerequisite to the eventual interrogation of IFRT’s (in combination with chemotherapy) potential superiority to the current standard of care (chemotherapy alone). We have accrued 19 total patients and have characterized their toxicity profiles over the course of 3.5 years. Thirteen patients completed therapy with 3 patients on Dose Level 1, 3 patients on Dose Level 2, 6 patients on Dose Level 3*, and 1 patient on Dose Level 4. Of the 6 remaining patients, 1 patient experienced a DLT in Dose Level 4 resulting in discontinuation of therapy, 2 patients have been voluntarily withdrawn by clients prior to starting Phase 2 of the study (radiation component), 2 patients have had extra nodal and/or substage progression prior to start of Phase 2, and 1 patient was euthanized due to an aspiration event unlikely related to IFRT after fraction 2 of radiation.
From an implementable strategy perspective, we have demonstrated the ability to integrate and refine this technique clinically. From a tolerability (toxicity) perspective, only three patients experienced treatment delays due to concerns of inducing a life threatening or clinically unacceptable complication. No patients have actually experienced a life threatening complication. One patient was on Dose Level 3, the reason why the level was expanded, while the other two were on Dose Level 4, the highest testable dose level in the study. The remaining toxicities experienced by the study patients have resulted in acute transient hematological depressions and gastrointestinal signs all responding to symptomatic management or resolving within a couple weeks post IFRT. Six month follow-up is below expectations primarily due to progressive disease in the patient population. Of the available data, patients living at least 6 months or longer, no long term toxicity has been specifically associated or identified as a complication of IFRT at this time within the Dose Level 1-3 in light of most being on one to several rescue chemotherapy protocols. Dose Level 4 long-term toxicity remains undefined at this time as acute toxicity for the protocol was unacceptable and would not be clinical usable in its current implementation.
* Dose Level 3 was expanded from 3 patients to 6 patients due to the occurrence of a single dose limiting toxicity within a single patient.
None at this time.
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