• Subject aged ≥ 18 years.

• Histologically confirmed relapsed or refractory Classical Hodgkin Lymphoma who have progressed on or after at least one line of prior therapy and have had prior exposure to anti-PD-1/anti-PDL-L1 therapy

• Partial response or stable disease after at least 4 cycles of anti-PD-1/ anti-PDL-1 therapy such as, but not limited to, nivolumab, pembrolizumab, atezolizumab, tislelizumab, and durvalumab or progression on anti-PD-1/ anti-PDL-1 therapy such as, but not limited to, nivolumab, pembrolizumab, atezolizumab, tislelizumab, and durvalumab. (Notes: prior combination treatment with chemotherapy and an anti-PD-1/anti-PDL-1 therapy is acceptable.)

• Subject must have at least one measurable area of disease (greater than 1.5 cm longest transverse diameter (LDi) to allow for response assessment and biopsy) by Lugano Criteria

• Subjects with prior history of allogeneic or autologous stem cell transplant must have had at least 90 days since the transplant and must be off of immunosuppressive agents for Graft vs Host disease for at least 2 months.

‣ Subjects with a prior autologous transplant are eligible

⁃ Transplant ineligible subjects are permitted on this study if they have had exposure to anti-PD(L)1 therapy as defined above.

• ECOG Performance Status ≤ 2.

• Adequate organ function, without the use of transfusions or growth factors within 7 days, as defined as:

‣ Hematologic:

• Platelet count ≥ 50,000/mm3 (unless bone marrow involved)

∙ Hemoglobin ≥ 8 g/dL (unless bone marrow involved)

∙ Absolute Neutrophil Count (ANC) ≥.5 × 10\^9/L unless bone marrow involvement from classical Hodgkin lymphoma

⁃ Hepatic:

• Total Bilirubin ≤ 1.5x institutional upper limit of normal (ULN). Exceptions include patients with underlying Gilbert Syndrome in whom ≤ 3x institutional upper limit of normal (ULN) of Total Bilirubin will be allowed.

∙ AST(SGOT)/ALT(SGPT) ≤ 3 × Institutional ULN

⁃ Subjects with liver metastases will be allowed to enroll with AST and ALT levels ≤ 5 x ULN.

⁃ Renal:

• Estimated creatinine clearance ≥ 50 mL/min by Cockcroft-Gault formula

• For female subjects: Negative pregnancy test or evidence of post-menopausal status. The post-menopausal status will be defined as having been amenorrheic for 12 months without an alternative medical cause. The following age-specific requirements apply:

‣ Women \< 50 years of age:

∙ --Amenorrheic for ≥ 12 months following cessation of exogenous hormonal treatments; and

∙ --Luteinizing hormone and follicle-stimulating hormone levels in the post-menopausal range for the institution; or

∙ --Underwent surgical sterilization (bilateral oophorectomy or hysterectomy).

⁃ Women ≥ 50 years of age:

• Amenorrheic for 12 months or more following cessation of all exogenous hormonal treatments; or

∙ Had radiation-induced menopause with last menses \>1 year ago; or

∙ Had chemotherapy-induced menopause with last menses \>1 year ago; or

∙ Underwent surgical sterilization (bilateral oophorectomy, bilateral salpingectomy, or hysterectomy).

• Female subjects of childbearing potential and male subjects with a sexual partner of childbearing potential must agree to use a highly effective method of contraception as described in Section 5.4.1.

• Recovery to baseline or ≤ Grade 1 CTCAE v5.0 from toxicities related to any prior cancer therapy, unless considered stable or clinically not significant by the treating investigator.

• Able to provide informed consent and willing to sign an approved consent form that conforms to federal and institutional guidelines.