Inclusion Criteria:

          1. Be ≥18 years of age.

          2. Have a pathologically confirmed diagnosis of a non-Hodgkin or Hodgkin lymphoma that
             has progressed in spite of prior treatment, and for whom additional effective
             (curative or life-prolonging) standard therapy is not available. The lymphomas
             included in this study must fall within one of the following 2017 World Health
             Organization categories:

               1. Mature B-cell neoplasms (excluding plasma cell neoplasms, heavy chain disease,
                  and primary central nervous system [CNS] lymphoma)

               2. Mature T- and NK-cell neoplasms

               3. Hodgkin lymphomas

               4. Immunodeficiency-associated lymphoproliferative disorders

          3. In the case of subjects who have lymphoma for which high-dose chemotherapy and
             autologous stem cell transplantation (HD-ASCT) is considered a standard curative
             therapy, eligibility for this study requires that the subject's disease has relapsed
             after HD-ASCT, that the subject is not eligible for HD-ASCT, or that the subject has
             refused HD-ASCT.

          4. Have disease that can be clinically evaluated for improvement or progression. In the
             dose expansion phase of the study, subjects must have disease that is measurable (as
             defined by either the Lugano criteria for lymphoma or the 2011 ISCL/USCLC/EORTC
             criteria for MF/SS).

          5. Have an Eastern Cooperative Oncology Group (ECOG) performance status ≤2.

          6. Have an absolute neutrophil count (ANC) ≥1,000/uL.

          7. Have a platelet count ≥75,000/uL.

          8. Have a serum total bilirubin level ≤1.5×ULN (upper limit of normal) in the absence of
             Gilbert syndrome. Subjects with Gilbert syndrome must have a serum total bilirubin
             level ≤1.5× their baseline value.

          9. Have alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels
             ≤3.0×ULN, unless due to underlying hematologic malignancy. If ALT/AST elevations are
             determined to be due to involvement by the underlying hematologic malignancy, subjects
             must have ALT/AST levels <5.0× the ULN.(Note: There are no specific requirements for
             alkaline phosphatase [ALP].)

         10. Have a creatinine clearance (CrCl) ≥ 30 mL/min (either measured or estimated by the
             Cockcroft-Gault formula). (Cockcroft-Gault formula for estimated creatinine clearance
             [eCrCl]: eCrCl = [140 - Age] × Weight [kg] × [0.85 if Female] / [72 × serum creatinine
             (mg/dL)]).

         11. Be fully recovered from major surgery and from the acute toxic effects of prior
             chemotherapy and radiotherapy. Residual chronic toxicities of prior therapy, eg,
             alopecia, Grade ≤2 peripheral neuropathy, are allowed.

         12. If female with reproductive potential, must have a negative serum pregnancy test prior
             to the start of study therapy. Females of reproductive potential, as well as fertile
             men and their female partners of reproductive potential, must agree to use 2 effective
             forms of contraception.

         13. Able to understand and have provided written informed consent.

        Exclusion Criteria:

          1. Have a primary central nervous system (CNS) lymphoma.

          2. Have lymphomatous involvement of the CNS that is symptomatic or requires therapy.
             However, subjects who have completed treatment for lymphoma involving the CNS and have
             no further evidence of disease in the CNS may be enrolled in this study.

          3. Have lymphoma that requires immediate cytoreductive therapy.

          4. Have low-grade lymphoma that does not meet conventional criteria for requiring
             treatment.

          5. Have impairment of gastrointestinal (GI) function or GI disease that may significantly
             alter the absorption of AG-636, including any unresolved nausea, vomiting, or diarrhea
             that is National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events
             (CTCAE) Grade >1.

          6. Are unable to abstain from food or liquids other than water for 2 hours before and 2
             hours after each dose of AG-636.

          7. Have an active infection with human immunodeficiency virus (HIV), hepatitis B, or
             hepatitis C.

          8. Have an active infection (bacterial, viral, or fungal) that cannot be controlled with
             treatment.

          9. Have had significant active cardiac disease within 6 months prior to the start of
             study treatment, including any of the following:

               1. New York Heart Association (NYHA) class III or IV congestive heart failure.

               2. Acute myocardial infarction or angina pectoris.

               3. Stroke.

               4. Uncontrolled cardiac arrhythmia (subjects with rate-controlled atrial
                  fibrillation are not excluded).

         10. Have a heart rate-corrected QT interval using Fridericia's method (QTcF) >470 msec.
             Patients with bundle branch block and a QTcF >470 msec should be discussed with the
             Medical Monitor for potential inclusion.

         11. Have any other concurrent severe and/or uncontrolled concomitant medical condition
             that could compromise participation in the study (eg, clinically significant pulmonary
             disease, clinically significant neurologic disorder).

         12. Have received any systemic anticancer treatment or radiotherapy less than 2 weeks
             before the first dose of AG-636.

         13. Have received radioimmunotherapy less than 6 weeks before the first dose of AG-636.

         14. Have received treatment with an investigational small molecule <2 weeks before the
             first dose of AG-636.

         15. Are taking medications that are sensitive substrates of CYP2C8, and that cannot be
             discontinued prior to starting treatment with AG-636.

         16. Are taking medications that are sensitive substrates of either P-glycoprotein (P-gp)
             or breast cancer resistance protein (BCRP), and that cannot be discontinued prior to
             starting treatment with AG-636.

         17. Are pregnant or breastfeeding.

         18. Have any other medical or psychological condition deemed by the Investigator to be
             likely to interfere with the subject's ability to give informed consent or participate
             in the study.

         19. Have concurrent malignancy other than lymphoma; subjects must have been free of other
             malignancies for ≥1 year before the start of study treatment. However, subjects with
             the following history/concurrent conditions are allowed:

               1. Basal or squamous cell carcinoma of the skin

               2. Carcinoma in situ of the cervix

               3. Carcinoma in situ of the breast

               4. Incidental histologic finding of prostate cancer.