Evaluating the effectiveness and safety of pembrolizumab for the treatment of patients with relapsed or refractory classical Hodgkin lymphoma before stem cell transplantation.

This study evaluated the effectiveness and safety of pembrolizumab (Keytruda) for the treatment of patients with relapsed or refractory (r/r) classical Hodgkin lymphoma (cHL) before stem cell transplantation. The data showed that pembrolizumab was effective and safe with manageable side effects in these patients.

Classical Hodgkin lymphoma (cHL) is a cancer of white blood cells. Most patients with cHL respond to first-line chemotherapy regimens. However, up to 25% of patients experience relapse (worsening of the disease) or refractory (not responsive to the treatment) disease. These patients can benefit from second-line therapies.

Pembrolizumab is an immunotherapy that helps the immune system detect and kill cancer cells. Some cancer cells have on their surface proteins, such as PD-L1 that bind to the PD-1 protein which helps them avoid detection by the immune system. Pembrolizumab blocks the PD-1 protein, and this inhibition triggers the immune system to attack tumor cells and kill them.

Studies have shown that pembrolizumab improved the survival without cancer worsening of patients with r/r cHL after autologous stem cell transplantation (auto-SCT). Auto-SCT involves transplanting healthy stem cells from the same patient. Allo-SCT involves transplanting healthy stem cells from a different patient. The effectiveness and safety of pembrolizumab for the treatment of patients with r/r cHL before SCT are still unknown.

This study involved 55 patients with r/r cHL who received pembrolizumab. All patients received an average of at least 3 previous lines of treatment. The average follow-up time was 15.3 months.

Overall, 74.5% of the patients responded to the treatment. The complete response rate (CR; complete disappearance of cancer cells) was 32.7%.

29 of the responding patients received subsequent auto-SCT and 9 patients received allo-SCT.

The average overall survival was not reached (exceeded the average follow-up period). After 12 months, 92% of the patients were alive. The average survival without cancer worsening was 12.5 months. After 12 months, 51% of the patients were alive without cancer worsening.

After 12 months, 88% of the patients who achieved CR were alive without cancer worsening. After 12 months, 60% of the patients who achieved partial response (PR; partial disappearance of cancer cells) were alive without cancer worsening.

After responding to pembrolizumab treatment, 15 patients received auto-SCT. After 12 months, all (100%) of these patients were alive and 92% were alive without cancer worsening.

47% of the patients experienced serious treatment-related side effects. 45.5% of the patients experienced serious immune-related side effects.

This study concluded that pembrolizumab was effective and safe with manageable side effects in patients with r/r cHL before SCT.

The sample size was very small. The follow-up time was too short. There was no control group. Further studies are needed.