A new study published in the journal Blood is the first to show how a topical gel may help treat a rare type of non-Hodgkin lymphoma – cutaneous T cell lymphoma – by triggering an immune response to kill malignant cells.
Image credit: Penn Medicine
Cutaneous T cell lymphoma (CTCL) accounts for around 5% of all lymphomas, or blood cancers, in the US. CTCL begins in the skin, occurring when T cells in the skin grow out of control and cause lesions or form tumors. Symptoms include dry skin, severe itching and a red rash.
CTCL is most common among people in their 50s or 60s, and men are at greater risk of developing the condition than women.
While the majority of patients with CTCL only experience skin symptoms, around 10% of patients whose condition progresses go on to suffer severe complications.
According to study leader Dr. Rachel Clark, associate professor of dermatology at Harvard Medical School in Boston, MA, and colleagues, there is no cure for CTCL other than bone marrow transplantation, which is normally administered to patients for whom other treatments have failed.
However, the team’s findings suggest a topical drug called resiquimod could eliminate malignant cells in some patients with early-stage CTCL in a matter of weeks.
For their phase 1 trial, Dr. Clark and colleagues enrolled 12 patients with early-stage CTCL, all of whom had previously received an average of six treatments for the condition.
In the study, participants were required to apply either a 0.03%-dose or a 0.06%-dose of resiquimod gel – which stimulates immune cell response via TLR7 and TLR8 pathways – to specific skin lesions for 16 weeks.
At the end of the 16-week study period, the researchers found resiquimod significantly improved treated skin lesions for 75% of participants, and skin lesions were completely cleared for 30% of participants.
Interestingly, 92% of participants saw a minimum 50% improvement in skin lesions to which the resiquimod gel was not directly applied. What is more, CTCL was completely eradicated for two patients who had been living with the disease for over 15 years.
The team used high throughput sequencing (HTS) to analyze the number of malignant cells present within the healthy cells of 10 participants before resiquimod treatment and 8 weeks after.
The researchers found that resiquimod significantly reduced the number of malignant cells in 9 out of 10 participants. Malignant cells were completely eradicated for three participants, while a 99.6% reduction was identified in another.
Commenting on their findings, first study author Dr. Alain Rook, professor of dermatology and director of the Cutaneous Lymphoma Program at the University of Pennsylvania’s Perelman School of Medicine, says:
“The results of the trial suggest that resiquimod is safely and effectively absorbed into the skin, and beyond diminishing treated lesions, also enhances the immune response, leading to healing of even untreated lesions.
To our knowledge, this is the first topical therapy that can clear untreated lesions and lead to complete remission in some patients.”
Dr. Rook says the lesions of CTCL patients in this study responded much better to resiquimod than with other treatments, such as some strong topical steroids and topical chemotherapy, and the drug was also well tolerated.
As well as a potentially effective treatment for early-stage CTCL, the team believes resiquimod could be used in combination with other therapies to treat more advanced stages of the disease.
“Further research with larger participant populations is needed to determine the best approach and application for these patients,” adds Dr. Rook.
Last month, Medical News Today reported on a study in which researchers discovered a way to disable lymphoma’s ability to escape the body’s immune response, potentially leading to new treatments for the disease.