A Study to Evaluate the Safety and Efficacy of Pembrolizumab (MK-3475) Coformulated With Berahyaluronidase Alfa (MK-3475A) in Participants With Relapsed or Refractory Classical Hodgkin Lymphoma (rrcHL) or Relapsed or Refractory Primary Mediastinal Large B-cell Lymphoma (rrPMBCL)(MK-3475A-F65)

To join this study, people generally need to have a confirmed diagnosis of classical Hodgkin lymphoma or primary mediastinal large B-cell lymphoma that has either come back or not responded well to past treatments. Your doctor would need to be able to measure your lymphoma on scans. You should also be generally well enough to take part, with a life expectancy of more than three months, and your doctor will check your overall health and how active you are, usually rated on a scale of 0 to 1.

There are also some specific health checks. For example, if you have HIV, it needs to be well-managed with your usual medication. If you've had hepatitis B or C, it needs to be under control. However, if you have certain heart conditions, active spread of another cancer, or a weakened immune system, you might not be able to join. Also, if you've recently had other antibody treatments or treatments that target similar pathways as pembrolizumab, you would likely not be eligible.

This study is for adults aged 18 and over, and it's open to both men and women.

If you join this study, you will receive the study medication, which is a combination of pembrolizumab and berahyaluronidase alfa, given as an injection under your skin. You'll have regular hospital visits for these injections, check-ups, blood tests, and scans to monitor your lymphoma and how you're responding to the treatment. These visits will help the study doctors understand how the medicine is working and check for any side effects.

The exact number and timing of visits will be explained by the study team, but typically, there will be frequent visits initially, becoming less regular over time if the treatment is working well. You'll also have follow-up appointments after your treatment period ends to continue monitoring your health. The total duration of your involvement, including treatment and follow-up, will be made clear before you agree to take part.