Inclusion Criteria prior to enrollment:

* 1. Age \> 1 months (with minimum weight of 10 Kg) and \< 45 years.
* 2. Patients deemed eligible for allogeneic HSCT under the originating study, NCT 04249830
* 3. Patients with life-threatening hematological malignancies for which HSCT has been recommended:

1. High-risk ALL in 1st CR, ALL in 2nd or subsequent CR;
2. High-risk AML in 1st CR, AML in 2nd or subsequent CR;
3. Myelodysplastic syndrome;
4. JMML (Juvenile myelomonocytic leukemia);
5. Non-Hodgkin lymphomas in 2nd or subsequent CR;
6. Other hematologic malignancies eligible for stem cell transplantation per institutional standard.
* 4. All subjects ≥ 18 years of age must be able to give informed consent, or adults lacking capacity to consent must have a LAR available to provide consent. For subjects \<18 years old their LAR (i.e. parent or guardian) must give informed consent. Pediatric subjects will be included in age appropriate discussion and verbal assent will be obtained for those \> 7 years of age, when appropriate.

Inclusion criteria prior to T-allo10 infusion:

1. Patient already received αβdepleted-HSCT and has myeloid engraftment.
2. Absence of active grade II aGvHD requiring \>0.5 mg/Kg of steroids or any diagnosis of grade III/IVaGvHD.

Exclusion Criteria prior to MNC collection for Tallo-10 manufacturing.:

1. Not eligible to receive HSCT on NCT04249830
2. Received another investigational agent within 30 days of enrollment.
3. Pregnancy (positive serum or urine beta-HCG) within 7 days of MNC donation.
4. Patient or donor is not willing or able to undergo an additional non-mobilized apheresis for collection of MNC prior to donation of cells for participation in NCT04249830.