PD-1 blockade with pembrolizumab was active and induced durable responses in patients with natural killer (NK)/T-cell lymphoma failing L-asparaginase, a study published in the journal Blood has shown.1

Patients with NK/T-cell lymphoma failing L-asparaginase-based regimens have limited options as there are no known salvage regimens. Therefore, researchers sought to evaluate the activity and tolerability of PD-1 inhibition with pembrolizumab in patients refractory to L-asparaginase.

For the study, investigators enrolled 7 males with NK/T-cell lymphoma who had failed 2 regimens, including L-asparaginase-based regimens. Two patients had also failed allogeneic hematopoietic cell transplantation.

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All participants received pembrolizumab and all responded to therapy. Two patients achieved a complete response with respect to all parameters and 3 patients achieved clinical and radiologic complete responses. Two patients had partial responses.

Two of the 3 patients who had clinical and radiologic complete responses achieved molecular remission, determined by having undetectable circulating Epstein-Barr virus (EBV) DNA, but had minimal EBV-encoded-RNA-positive cells in lesions comprising predominantly CD3+CD4+ and CD3+CD8+ T-cells. These cells ultimately disappeared, suggesting pseudo-progression. The third patient had detectable EBV DNA despite morphologic complete response.

All 5 patients in complete response were still in remission after 7 cycles of pembrolizumab and a median follow-up of 6 months.

One patient who had previously underwent allogeneic hematopoietic cell transplantation developed grade 2 skin graft-versus-host disease.

The findings suggest that pembrolizumab is a potentially effective treatment option for patients with NK/T-cell lymphoma failing L-asparaginase. Additional studies with larger sample sizes are needed to confirm these results.


1. Kwong Y-L, Chan TSY, Tan D, et al. PD1 blockade with pembrolizumab is highly effective in relapsed or refractory NK/T-cell lymphoma failing L-asparaginase. Blood. 2017 Feb 10. doi: 10.1182/blood-2016-12-756841 [Epub ahead of print]