Although the majority of patients with classical Hodgkin lymphoma are considered “cured” with frontline chemotherapy, some patients relapse. The current standard of treatment for these patients is salvage chemotherapy followed by autologous stem cell transplantation (ASCT).1 But up to half of all people with relapsed or refractory Hodgkin lymphoma who underwent ASCT will still relapse.2 Administering PD-1 blockade with pembrolizumab may improve progression-free survival (PFS) in patients with Hodgkin lymphoma after ASCT, according to a phase 2 study published in the journal Blood.3 However, the findings need to be confirmed in a randomized controlled trial.

“What we found is that among the patients that were in this study, the [progression-free survival] at 18 months was around 80%,” said lead study author Philippe Armand, MD, PhD, a senior physician at Dana-Farber Cancer Institute and an associate professor of medicine at Harvard Medical School in Boston, Massachusetts. Dr Armand noted that while the study did not include a control group, historical data suggest that the progression-free survival (PFS) in this patient population is typically around 60%. “We consider the 80% to be an encouraging result,” he added.

For the study, the researchers recruited 30 people with classical Hodgkin lymphoma who either had relapsed after or were refractory to frontline therapy. All the participants had also received ASCT. The patients were aged at least 18 years; the median patient age was 33 years.

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The patients began study treatment no later than 21 days following discharge after ASCT. The researchers administered up to 8 cycles of intravenous pembrolizumab to the patients, at a flat dose of 200 mg, every 3 weeks.

The researchers assessed the participants’ tumors using positron emission tomographic (PET) and computed tomography (CT) scans several times: first after ASCT and within 21 days before study treatment began; then at weeks 10 and 22 of study treatment; and at 12 months and 18 months after the patients underwent ASCT.

The researchers’ main goal was to assess the PFS at 18 months after ASCT. Some of the other factors the investigators looked at were overall survival and treatment safety. The authors assessed safety using the Common Terminology Criteria for Adverse Events (CTCAE) version 4.4

Of all the patients, 24 (80%) experienced at least one grade 2 or higher adverse event, and 9 (30%) participants experienced at least one grade 3/4 adverse event. No grade 5 adverse events were observed.

When the researchers considered solely those adverse events that were “at least possibly” linked to the pembrolizumab treatment, 15 patients (50%) experienced at least 1 grade 2 or higher adverse event related to the treatment, and 8 patients (27%) experienced at least 1 grade 3 /4 adverse event related to the treatment. Overall, the investigators identified 14 grade 3 adverse events linked to treatment and 6 grade 4 treatment-related adverse events.

The researchers also found that 13 patients (43%) experienced 39 immune-related adverse events, such as was pneumonitis, cough or dyspnea. Of these, there were 4 grade 2 events and one grade 3 event; no grade 4 or higher events were identified.

Five instances of adverse events identified in the study led to discontinuation of the treatment, the researchers found. These included 1 case of grade 2 pneumonitis, 1 case of grade 2 diplopia, 1 case of grade 3 pneumonitis, and 2 cases of grade 3 transaminitis.

The researchers found that, by 18 months post-ASCT, 5 patients (17%) had relapsed, but the other patients (83%) remained in complete remission. The overall survival for the entire study population at 18 months was 100%.