Inclusion Criteria:

          -  Written informed consent obtained to participate in the study and HIPAA authorization
             for release of personal health information.

          -  Age ≥18 years at the time of consent.

          -  Subject is planned to start on standard of care anti-PD-1 therapy per community
             standards of medical care by their treating oncologist.

          -  Subject has a diagnosis of relapsed/refractory classical Hodgkin lymphoma after at
             least three lines of prior therapy with clinical progression after either ATLCAR.CD30
             and/or ATLCAR.CD30.CCR4.

          -  Subjects with prior allogeneic stem cell transplant will be eligible, but will be
             counseled during consent regarding possible increased risk of graft versus host
             disease with anti-PD-1 therapy after allogeneic stem cell transplant.

          -  Subjects must have previously been treated with anti-PD-1 therapy prior to receiving
             autologous CAR-T-cell therapy.

          -  Subject is willing to provide blood samples that are clinically necessary during
             anti-PD-1 therapy administered per community standards of medical care.

          -  Female subject of childbearing potential must agree to use adequate contraception
             during the study. Adequate contraception is defined by the concomitant use of two
             effective methods of contraception from the time of informed consent until 150 days
             after treatment discontinuation. The two contraception methods can be comprised of two
             barrier methods, or a barrier method plus a hormonal method or an intrauterine device
             that meets <1% failure rate for protection from pregnancy in the product label. Female
             subjects of non-childbearing potential are those who are postmenopausal greater than 1
             year or who have had a bilateral tubal ligation or hysterectomy or bilateral
             oophorectomy. Female subjects must refrain from egg cell donation while on study
             treatment and for at least 150 days after the last dose of investigational product.

          -  Male subjects with female partners must have had a prior vasectomy or agree to use an
             adequate method of contraception (i.e., double barrier method: condom plus spermicidal
             agent) starting with the first dose of study therapy through 150 days after the last
             dose of study therapy. Male subjects should agree to refrain from sperm donation while
             receiving study treatment and for at least 150 days after the last dose of study
             treatment.

          -  Subject is willing and able to comply with study procedures based on the judgment of
             the investigator or protocol designee.

          -  Subject is willing to consent to study-required blood draws.

        Exclusion Criteria:

          -  Subject has history of hypersensitivity reactions to anti-PD-1 therapy.

          -  Subject has any contraindication to anti-PD-1 therapy at time of enrollment or
             inability to be treated with anti-PD-1 therapy for any other reason.

          -  Subject 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 (e.g., thyroxine, insulin, or
             physiologic corticosteroids replacement therapy for adrenal or pituitary
             insufficiency, etc.) is not considered a form of systemic replacement.

          -  Subject has evidence of interstitial lung disease or a history of (non-infectious)
             pneumonitis resulting from previous anti-PD-1 treatment that required steroids or
             current pneumonitis. History of radiation pneumonitis is not considered a form of
             non-infectious pneumonitis of concern.

          -  Subject has received anti-CD30 CAR-T therapy within the previous 6 weeks.

          -  Subject is pregnant or breastfeeding (Note: breast milk cannot be stored for future
             use while the mother is being treated on the study. Subject must abstain from
             breastfeeding for 150 days after end of treatment).

          -  Subject has known active infection with HIV, HTLV, HBV, HCV or any active,
             uncontrolled infection or sepsis.

          -  Subject has received chemotherapy or anti-PD-1 therapy following CD30 CAR-T cell
             product administration.

          -  Subject has a known additional malignancy that is active and/or progressive requiring
             treatment; exceptions include basal cell or squamous cell skin cancer, in situ
             cervical or bladder cancer, or other cancer for which the subject has been
             disease-free for at least five years.

          -  Subject is currently using systemic corticosteroids at doses ≥10 mg prednisone daily
             or its equivalent, or other immunosuppressive medications.

          -  Subject has received a live attenuated vaccine within 30 days of initiating study
             treatment (i.e., 30 days prior to the first dose, during treatment, and for 30 days
             after study treatment discontinuation). Inactivated vaccines, such as the injectable
             influenza vaccine, are permitted.

          -  Subject has received radiation therapy less than 7 days prior to anti-PD-1 therapy
             initiation

          -  Subject has had a major surgery within 28 days prior to anti-PD-1 therapy.

          -  Subject is not considered to be an acceptable candidate for anti-PD-1 therapy per the
             treating oncologist's discretion.