The common side effect of hand-foot syndrome seen in patients taking capecitabine can be prevented by a cheap and safe topical gel containing 1% diclofenac, researchers reported in a study that has been hailed by experts as 'practice changing.'
Hand-foot syndrome causes painful, bleeding blisters and ulcers on the palms and soles. It often leads to dose reductions and sometimes even discontinuations, both of which limit the effectiveness of capecitabine, a standard oral chemotherapy drug widely used for colorectal and breast cancers.
In a new study presented at the recent American Society of Clinical Oncology annual meeting, Indian researchers reported that a cheap, safe, and widely available over-the-counter nonsteroidal anti-inflammatory gel containing 1% diclofenac reduced the incidence of hand-foot syndrome by 75% among patients with cancer being treated with capecitabine.
Up until now, the oral anti-inflammatory celecoxib (Celebrex) was the only agent proven to prevent the problem, but it's rarely used because of the risk for strokes, gastric bleeding, and other issues, none of which are a concern with topical diclofenac, which osteoarthritis patients have used safely for years.
The Indian trial, dubbed D-Torch, establishes "1% topical diclofenac gel as the new standard of care to prevent capecitabine-associated hand-foot syndrome," said investigator and study presenter Atul Batra, MD, a medical oncologist at the All India Institute of Medical Sciences, New Delhi.
Batra told ASCO Daily News that there is no need for a second trial. "We don't feel there's a need to replicate these results" in a larger study "because this was adequately powered, and the results speak for themselves. There's no confusion about these results. Diclofenac is clearly effective," Batra said.
Batra also commented that his clinic now uses topical diclofenac routinely during capecitabine treatment and that he hopes oncology practices elsewhere will do the same.
Diclofenac gel is sold under the brand name Voltaren and is also available as a generic; in the United States, a 150-gram tube costs about $18 at Walmart.
"The Most Practice-Changing Study" at ASCO23
Audience members at ASCO's annual meeting immediately saw the importance of the study.
Tarah Ballinger, MD, a breast cancer specialist at Indiana University, Indianapolis, said on Twitter that "this might be the most practice changing study I heard at ASCO23." Topical diclofenac is "widely available, affordable, [and] addresses [a] major" quality of life issue.
The study discussant at the meeting, University of Pennsylvania gastrointestinal cancer specialist Pallavi Kumar, MD, concurred: "For me as a GI oncologist, topical diclofenac for prevention of HFS for patients on capecitabine is practice changing," she said.
The takeaway is "that topical diclofenac significantly reduces the incidence of grade 2 or higher HFS in patients receiving capecitabine." The results are "very impressive," Kumar said.
The idea for the new study came after Batra and his colleagues realized that celecoxib, a COX-2 enzyme inhibitor, helps prevent capecitabine hand-foot syndrome (HFS) by blocking a key process that leads to it, the upregulation of COX-2 and subsequent release of pro-inflammatory prostaglandins.
They turned to diclofenac gel hoping to get the same effect but more safely; diclofenac is also a COX-2 blocker, and its topical formulation has a strong safety record.
To test the approach, the team randomly assigned 130 patients to topical diclofenac and 133 to placebo — the gel vehicle without the medication — while they were being treated with capecitabine for 12 weeks; 56% were being treated for breast cancer and the rest for gastrointestinal cancers.
Subjects rubbed one fingertip's worth of gel — about half a gram — on each palm and the back of each hand twice a day. The dose was about 4 grams/day, which is well below maximal dosages for osteoarthritis (up to 32 g/day over all affected joints). Adherence to treatment was about 95% in both arms.
By the end of 12 weeks, the incidence of grade 2 or higher HFS was 3.8% in the diclofenac arm (5 patients) vs 15% (n = 20) with placebo (P = .003), a 75% risk reduction.
The incidence of any grade HFS was 6.1% in the treatment group vs 18.1% with placebo (P = 0.003).
Hand-foot syndrome led to dose reductions of capecitabine in 13.5% of placebo but only 3.8% of those in the diclofenac group (P = .002).
The findings held regardless of whether patients were being treated for breast or GI cancer or if they were men or women.
Other capecitabine-induced adverse events, including diarrhea, mucositis, and myelosuppression, were not significantly different between the groups.
The treatment arms were well balanced, with a median age of 47 years in both groups and women making up about 70% of each. About 40% of subjects in each group were on capecitabine monotherapy with the rest on combination treatments. The mean dose of capecitabine was just over 1880 mg/m2 in both groups.
At the meeting, Batra was asked if topical diclofenac would also work for another common problem in oncology: hand-food syndrome occurring as a side-effect with VEGF-tyrosine kinase inhibitors. He didn't think so because it probably has a different cause than capecitabine HFS, one not strongly related to COX-2 upregulation.
The study was partly funded by the Indian Supportive Care of Cancer Association. The investigators reported no relevant financial relationships.
ASCO 2023 annual meeting. Abstract 12005. Presented June 3, 2023.
M. Alexander Otto is a physician assistant with a master's degree in medical science and a journalism degree from Newhouse. He is an award-winning medical journalist who worked for several major news outlets before joining Medscape. Alex is also an MIT Knight Science Journalism fellow. Email: firstname.lastname@example.org