NEW YORK – Outside of clinical trials, therapy for early stage chronic lymphocytic leukemia in patients with deletion of the short arm of chromosome 17 (del[17]p) and/or mutation of the tumor suppressor gene TP53 requires the presence of active disease, according to Neil E. Kay, MD.

“Right now, we would propose that patients with del[17]p should have additional prognostic work-up. It’s very important to know if they are unmutated or mutated for the IgVH gene,” he said, adding that stimulated karyotype is also important to perform in those with del[17]p.

In untreated patients, del[17p] and p53 mutations are found in 5%-10% of those going on first line therapy. Poor outcomes in those with 17p deletion have been consistently observed, said Dr. Kay of the Mayo Clinic in Rochester, Minn., at an international congress on hematologic malignancies.

“The median overall survivorship in many phase II and phase III trials appears to be around 2 to 3 years,” he said.

Those with a chromosome 17 (del[17]p) and/or mutation of the tumor suppressor gene TP53 who receive chemoimmunotherapy very rarely achieve a complete response, or if they do they have a short duration of response, he added.

In treated patients, 17p deletion and p53 mutation are the most common abnormalities acquired during the course of the disease.

“Unfortunately there appears to be a selection pressure, and [in treated patients] the incidence of 17p and the p53 mutation has been reported up to 23%-44%. No one understands completely the biology of this, but it may be that subclones are present and expand, or that new mutations occur due to selection pressure of [chemoimmunotherapy] and the overgrowth of these subclones,” he said.

Importantly, not all patients with del[17]p or p53 mutation have bad outcomes; there are patients with indolent disease, he noted, adding that various criteria have been shown to help identify which patients are at risk for poor outcomes and to classify them according to risk. In general, lower-risk patients have mutated immunoglobulin heavy chain variable gene status, early stage disease, younger age, good performance status, and normal serum lactate dehydrogenase. These criteria could be used to identify low-risk patients who can be followed, he said.

Fluorescence in situ hybridization (FISH) evaluation of patients is a useful tool when there is no access to sequencing and other tests, Dr. Kay said, describing a recent multinational CLL Research Consortium study of nearly 1,600 patients (Br J Haematol. 2016 Apr;173[1]:105-13).

In that study, he and his colleagues found that patients with less than 50% 17p did not have such poor outcomes, but at 50%-plus they did much worse in terms of time to first treatment.

Based on the available data, Dr. Kay said that treatment is unnecessary in asymptomatic patients, except, perhaps, in high-risk patients identified using recently published risk models, for whom clinical trial enrollment may be considered.

“We do advocate having a discussion about allogeneic stem cell transplant since this may still be the only curative approach,” he added.

In patients with del[17]p and/or p53 mutation who have progressive disease, Dr. Kay said his take on the available data is that patients should first be categorized by age, then by whether they are fit or frail, and finally by whether or not they have del[17]p. Those under age 70 years without del[17]p and who have a mutated IgVH status should be considered for a clinical trial, and are also good candidates for chemoimmunotherapy. If they do have del[17]p or p53 mutation, consider clinical trial enrollment or treatment with ibrutinib, he said.

Fit patients in a complete response can be referred for transplant evaluation, but while the other treatments can be considered in frail patients or those aged 70 years or older, transplant is not advised, he added.

For relapsed or refractory patients, FISH testing should be performed or repeated, because such patients are at high risk of progression to develop del[17]p or mutation, he noted.

Those who are asymptomatic can be observed or enrolled in a clinical trial, and those who are symptomatic can be enrolled in a clinical trial or treated with various novel agents, including ibrutinib, idelalisib/rituximab, venetoclax, or combination therapies with methylpred–anti-CD20, or alemtuzumab with or without rituximab. Referral for transplant may be warranted in these patients if they are fit.

“Progressive CLL patients with 17p deletion/p53 mutations are much less likely to do well with chemoimmunotherapy, and novel inhibitors are effective, but we still need to enhance complete response rates and minimal residual disease-negative status for these high-risk patients,” he said.

Dr. Kay reported consulting for or receiving grant/research support from Acerta, Celgene, Gilead, Infinity, MorphoSys, Pharmacyclics, and Tolero.

sworcester@frontlinemedcom.com

In active CLL with deletion 17p, consider trial enrollment