Study of KTE-X19 in Adult Japanese Participants With Relapsed/Refractory Mantle Cell Lymphoma or Relapsed/Refractory B-precursor Acute Lymphoblastic Leukemia

The goal of this clinical study is to learn more about KTE-X19, and how safe and effective it is in adult Japanese participants with relapsed/refractory (r/r) Mantle Cell Lymphoma (MCL) or r/r B-precursor Acute Lymphoblastic Leukemia (B-ALL).

The primary objectives of this study are to evaluate the efficacy of KTE-X19, as measured by:

* Objective response rate (ORR) per investigator assessment, in adult Japanese participants with r/r MCL
* Overall complete remission (OCR) defined as complete remission (CR) and complete remission with incomplete hematologic recovery (CRi) per investigator assessment, in adult Japanese participants with r/r ALL

After completing at least 24 months in the study, all participants who received an infusion of KTE-X19 will be transitioned to a separate long-term follow-up (LTFU) study (KT-US-982-5968) to complete the remainder of the 15-year follow-up assessments.

Eligibility Criteria:
Key Inclusion Criteria:

MCL Cohort:

* Pathologically confirmed MCL, with documentation of either overexpression of cyclin D1 or presence of t(11;14)
* Up to 5 prior regimens for MCL. Prior therapy must have included:

  * Anthracycline-, bendamustine-, or high-dose cytarabine- containing chemotherapy, and
  * Anti-CD20 monoclonal antibody therapy, and
  * Bruton's tyrosine kinase inhibitor (BTKi)
* Relapsed or refractory disease, defined by the following:

  * Disease progression after last regimen, or
  * Refractory disease is defined failure to achieve partial response (PR) or complete remission (CR) to the last regimen
* At least 1 measurable lesion. Lesions that have been previously irradiated will be considered measurable only if progression has been documented following completion of radiation therapy

  * If the only measurable disease is lymph node disease, at least 1 lymph node should be ≥ 2 cm

ALL Cohort:

* Relapsed or refractory B-ALL defined as one of the following:

  * Relapsed or refractory disease after one line of systemic therapy;

    * Primary refractory, or
    * First relapse if first remission ≤ 12 months
  * Relapsed or refractory disease after two or more lines of systemic therapy
  * Relapsed or refractory disease after allogeneic transplant provided individuals is at least 100 days from SCT at the time of enrollment and off of immunosuppressive medications for at least 4 weeks prior to enrollment
* Morphological disease in the bone marrow (\> 5% blasts)
* Individuals with Philadelphia-positive (Ph+) disease are eligible if they are intolerant to tyrosine kinase inhibitor (TKI) therapy, or if they have relapsed/refractory disease despite treatment with at least 2 different TKIs

Key Exclusion Criteria:

MCL Cohort:

* History of malignancy other than nonmelanomatous skin cancer or carcinoma in situ (eg, cervix, bladder, breast) unless disease-free for at least 3 years
* Autologous SCT (autoSCT) within 6 weeks of planned KTE-X19 infusion
* History of alloSCT with the exception of individuals with no donor cells detected on chimerism \> 100 days after alloSCT
* Prior CD19 targeted therapy
* Prior CAR therapy or other genetically modified T-cell therapy
* History of hypersensitivity to any of the ingredients of KTE-X19 or to any of the animal-derived ingredients (bovine and rodent) used in the manufacturing process of KTE-X19

ALL Cohort:

* Diagnosis of Burkitt's leukemia/lymphoma according to World Health Organization (WHO) classification or chronic myelogenous leukemia lymphoid blast crisis
* History of malignancy other than non-melanoma skin cancer or carcinoma in situ (eg, cervix, bladder, breast) unless disease free for at least 3 years
* History of hypersensitivity to any of the ingredients of KTE-X19 or to any of the animal-derived ingredients (bovine and rodent) used in the manufacturing process of KTE-X19

Note: Other protocols defined Inclusion/Exclusion criteria may apply.