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A topical gel might prove to be a safe and effective treatment for a rare type of blood cancer that affects the skin, a new study has claimed.
"To our knowledge, this is the first topical therapy that can clear untreated lesions and lead to complete remission in some patients," said first author Alain Rook, director of the Cutaneous Lymphoma Programme at University of Pennsylvania.
Results of a phase I trial show that an investigational topical drug, resiquimod gel, causes regression of both treated and untreated tumour lesions and may completely remove cancerous cells from both sites in patients with early stage cutaneous T cell lymphoma (CTCL) -- a rare type of non-Hodgkin lymphoma that affects the skin.
Currently, there is no cure for CTCL aside from a bone marrow transplant, researchers said.
However, researchers at the Harvard Medical School and Perelman School of Medicine at the University of Pennsylvania, show the topical gel can eliminate malignant T cells, leading to diminished lesions.
In the trial, 12 patients who had previously undergone an average of six treatments for early stage CTCL were treated with topical resiquimod gel at varying doses and intervals.
Patients applied specified doses (0.03 per cent or 0.06 per cent) to select skin lesions for 16 weeks. However, some patients using the 0.06 per cent dose showed a full clearing of all malignant cells after only eight weeks.
By the final evaluation, treated lesions were significantly improved in 75 per cent of patients, and 30 per cent saw full resolution in all treated lesions. Unlike other treatments, resiquimod also improved untreated lesions, resulting in a more than 50 per cent improvement in more than 90 per cent of patients.
Two participants, one of whom had been living with CTCL for more than 15 years without response to treatment, saw full eradication of the disease. "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," Rook said.
Using a method known as high throughput sequencing (HTS), the team was able to determine how many distinct malignant cells were present within a sample of healthy cells.
The technique showed it could identify a single malignant cell amongst 100,000 healthy cells.
DNA from biopsies of the same treated lesion were analysed before treatment and eight weeks after treatment began to identify the number of malignant T cells.
The percentage of malignant T cells was reduced significantly in nine of ten tested participants, three of whom had complete eradication of the malignant population, and one of whom had a 99.6 per cent reduction.
The study was published in the journal Blood.
