A total of 30 EPP patients are expected to be enrolled, along with 10 individuals without the condition, who will serve as a control group. The study will be completed by the end of the summer. Notably, it will be performed completely remotely, in line with social distancing recommendations, due to the COVID-19 pandemic.
“I hope that this study will help us better understand light sensitivity in EPP,” Dickey told PorphyriaNews in an email response. She said her overriding goal is to “improve quality of life in EPP by enabling patients to monitor their own disease, both predicting and preventing EPP-related symptoms.”
EPP is a form of porphyria caused by the lack of an enzyme called ferrochelatase. This enzyme is required for the production of heme, a molecule essential for the transport of oxygen in red blood cells and the breakdown of compounds in the liver.
One of the main symptoms of EPP is extreme sunlight sensitivity brought on by the accumulation of light-sensitive protoporphyrins (heme precursors) in the skin. Specifically, Dickey’s study aims to test the utility of a light measuring device, called a light dosimeter, as a new digital biomarker of disease activity.
The study will determine if the device — called SunSense Pro — can help those with EPP better monitor and manage their symptoms. The SunSense Pro device measures the ultraviolet index, known as the UV index, every two minutes.
“In EPP, patients are sensitive to visible light and not UV light. However, UV intensity correlates closely with visible light intensity when outdoors,” Dickey said. “In the future, I hope to be able to test a device that measures visible light, but that is not available currently.”
The scientist’s main goal is to determine how well the amount of light exposure measured by the light dosimeter correlates with patients’ symptoms, as compared with the levels of sunlight exposure the participants report.
“This comparison was chosen because for prior clinical trials in EPP, participants have been asked to self-report the amount of time they spend outdoors, without any information about light intensity,” Dickey said.
Secondary goals include investigating possible correlations between light sensitivity in EPP and other clinical, biochemical, and epidemiologic patient characteristics. The study also will evaluate differences in light sensitivity among participants, as well as between patients and controls, as its secondary goals.
“I plan to correlate light exposure/dose measured by the light dosimeter with symptoms in EPP. I hope that this analysis will reveal a method of predicting symptoms based on the accumulated dose,” Dickey added.
However, she said that additional clinical studies may be required “to reliably develop a method to predict symptoms.” That is because the relationship between cumulative light exposure and EPP symptoms has never been properly quantified, she said.
Part of the problem in treating EPP is that patients’ reactions are “very painful yet difficult to predict and hard to describe,” Kristen Wheeden, executive director of the APF, said in a separate email response.
“This study may help validate a patient report with a measurement device,” Wheeden said. “It is a critical first step to measure accuracy of such an instrument compared to self-reporting.”
Following screening, study candidates will be asked to complete a survey through RedCap to assess their levels of light sensitivity, light exposure, and other clinical features. Only those experiencing typical EPP light sensitivity symptoms at least four times monthly will be included in the study.
After enrollment, some participants will be instructed to wear the light dosimeter — which will be connected to their smartphones through a mobile application — both indoors and outdoors for a month.
During this period, they will receive text messages once daily asking if they experienced any light sensitivity symptoms, if they wore the device as instructed, and if they wore any light-protective clothing. If any answers are “yes,” they then will be prompted to complete a more detailed survey.
Participants will then complete symptom surveys and document sunlight exposure for another month. A final brief survey will follow.
The remaining patients will start by self-reporting their sunlight exposure, and then wear the light dosimeter.
“At some point after the study, each participant will receive a summary of their individual-level data,” Dickey said. “I also hope to be able to publish the data by the end of the year.”
Following publication, the information may be shared on the APF’s website at the foundation’s discretion.
Those interested in learning more about the study, or wishing to volunteer to participate may reach out to the APF at 866-APF-3635, or [email protected].
Dickey and the APF started collaborating early in the scientist’s career.
“The guidance and the support that I have received from the APF has been and continues to be incredibly important for me in my career path,” Dickey said.
She noted that the APF helped her connect with the project’s clinical coordinator, Lina Rebeiz, who has acute intermittent porphyria.
“We’re a team of porphyria patients trying to help others with porphyria,” Dickey said.
Added Wheeden: “Dr. Dickey is important to the APF as both a member and a physician/investigator. We are thrilled that she has chosen to focus her talent on advancing porphyria research.”
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