Inclusion Criteria:

* Histologic diagnosis of classical Hodgkin's lymphoma.
* Primary refractory or relapsed disease proven by excisional or core needle biopsy at enrolling institution.
* Relapse or refractory disease following 1 line of multi-agent chemotherapy.
* Be willing and able to provide written informed consent/assent for the trial.
* Be ≥ 18 years of age on day of signing informed consent.
* Have measurable disease based on Lugano 2014 criteria
* Have a performance status of 0 or 1 on the ECOG Performance Scale.
* Demonstrate adequate organ function as defined in table below.
* Absolute neutrophil count (ANC) ≥1000 /mcL
* Platelets ≥50,000 / mcL
* Hemoglobin ≥8 g/dL
* Serum creatinine OR ≤1.5 X upper limit of normal (ULN) OR
* Measured or calculateda creatinine clearance (GFR can also be used in place of creatinine or CrCl) ≥60 mL/min for subject with creatinine levels \> 1.5 X institutional ULN
* Serum total bilirubin ≤ 1.5 X ULN OR ≤ 3 X ULN for subjects with liver metastases
* AST (SGOT) and ALT (SGPT) ≤ 2.5 X ULN OR ≤ 5 X ULN for subjects with liver metastases
* Hemoglobin-adjusted diffusing capacity for carbon monoxide ≥50% (If unadjusted DLCO is \>/= 50% then there is no need to calculate adjusted)
* Ejection fraction ≥45%
* Female subject of childbearing potential should have a negative urine or serum pregnancy within 72 hours prior to receiving the first dose of study medication.
* Female subjects of childbearing potential must be willing to use an adequate method of contraception
* Male subjects of childbearing potential must agree to use an adequate method of contraception.

Exclusion Criteria:

* Received more than 1 prior treatment (combined modality therapy represents 1 treatment) for Hodgkin Lymphoma
* Known pregnancy or breast-feeding.

* Breast-feeding should be discontinued prior to treatment initiation.
* Medical illness unrelated to Hodgkin's Lymphoma, which, in the opinion of the attending physician and/or principal investigator, makes participation in this study inappropriate.
* Has received prior radiotherapy within 2 weeks of start of study treatment. Participants must have recovered from all radiation-related toxicities, not require corticosteroids, and not have had radiation pneumonitis.
* Has known active central nervous system (CNS) metastases and/or carcinomatous meningitis.
* Has active autoimmune disease that has required systemic treatment in the past 2 years (i.e. with use of disease modifying agents, corticosteroids or immunosuppressive drugs). Replacement therapy (eg., thyroxine, insulin, or physiologic corticosteroid replacement therapy for adrenal or pituitary insufficiency, etc.) is not considered a form of systemic treatment.
* Has known active HIV, Hepatitis B (e.g., Hepatitis B PCR positive) or Hepatitis C (e.g., HCV RNA \[qualitative\] is detected).
* Has received a live vaccine or live-attenuated vaccine within 30 days prior to the first dose of study drug. Administration of killed vaccines is allowed.
* Has a history of (non-infectious) pneumonitis that required steroids or has current pneumonitis.
* Has an active infection requiring systemic therapy.
* Has undergone solid organ transplant at any time, or prior allogeneic hematopoietic stem cell transplantation within the last 5 years. (Subjects who have had an allogeneic hematopoietic transplant greater than 5 years ago are eligible as long as there are no symptoms of GVHD.)