A First-In-Human Phase 1 Trial of T-Cell Membrane-Anchored Tumor Targeted Il12 (Attil12)- T-Cell Therapy in Subjects With Advanced/Metastatic Soft Tissue and Bone Sarcoma

Inclusion criteria:

1. Age .12 years old

2. Histologically-confirmed locally advanced or metastatic soft tissue or bone sarcoma

3. Osteosarcoma expansion cohort: histologically confirmed unresectablerecurrent/metastatic osteosarcoma

4. Evaluable disease.

5. Patients must have received at least 1 prior line of systemic therapy for thetreatment of sarcoma, unless no standard therapy exists for a specific sarcomasubtype

6. Prior Cancer Therapy . At least 3 weeks must have elapsed since the last cytotoxicchemotherapy or immunotherapy prior to leukapheresis/PBMC collection.

• For targeted therapies, at least 4 half-lives or 3 weeks must have elapsedprior to leukapheresis (whichever is shorter).

7. Standard of care anti-cancer therapy will be permitted following leukapheresis butprior to initiation of cyclophosphamide such that:

. At least 3 weeks must have elapsed since last cytotoxic chemotherapy orimmunotherapy prior to starting treatment with cyclophosphamide.

. For targeted therapies, at least 4 half-lives or 3 weeks must have elapsed priorto initiation of treatment with cyclophosphamide (whichever is shorter).

. At least 2 weeks must have elapsed since last radiation therapy prior tocyclophosphamide.

. Investigational anti-cancer therapy will not be permitted.

8. ECOG performance status of 0 or 1 (Performance level as measured by Karnofsky forpatients . 16 years of age or Lansky for patients < 16 years of age, see Appendix B)

9. Participants must be willing to undergo tumor biopsy

. Patients in whom biopsy is medically contraindicated or otherwise high risk willnot be excluded and may forego research tumor biopsies

10. Patients must have organ and marrow function as defined below

11. Absolute neutrophil count (ANC) . 1 K/uL, Hemoglobin . 9 g/dL, Platelets.100 K/mm3

12. Serum creatinine . 2 mg/dL OR creatinine clearance > 50 mL/min

13. Aspartic transaminase (AST) . 1.5 x upper limit of normal (ULN), Alaninetransaminase (ALT) . 1.5 x ULN, Bilirubin . 1.5 x ULN

14. Cardiac function . LVEF >50%

15. Pulmonary function

. Oxygen saturation >92% on room air

• Total lung capacity >70% of predicted

• DLCO >60% of predicted

16. Women of childbearing potential (WOCBP) must agree to use method(s) ofcontraception: at least one highly effective or two effective accepted methods ofcontraception to avoid conception throughout the study in such a manner that therisk of pregnancy is minimized. Suggested precautions should be used to minimize therisk or pregnancy for at least 1 month before start of therapy, and while women areon study for up to 3 months after T cell infusion. WOCBP include any female who hasexperienced menarche and who has not undergone successful surgical sterilization (hysterectomy, bilateral tubal ligation or bilateral oophorectomy) or is notpostmenopausal

17. Men must be willing and able to use an acceptable method of birth control such aslatex condom during the dosing period and for at least 3 months after completion ofthe study agent administration (T cell infusion) if their sexual partners are WOCBP.

18. Signed Informed Consent and if applicable, pediatric assent

Exclusion criteria:

1. Known sensitivity to cyclophosphamide and/or study agents Active or prior documentedautoimmune disease (including inflammatory bowel disease, celiac disease, Wegenersyndrome) within the past 2 years. Subjects with childhood atopy or asthma,vitiligo, alopecia, Hashimoto syndrome, Grave's disease, or psoriasis not requiringsystemic treatment (within the past 2 years) are not excluded

2. Untreated central nervous system metastatic disease, leptomeningeal disease, or cordcompression. Subjects previously treated central nervous system metastases that areradiographically and neurologically stable for at least 6 weeks and do not requirecorticosteroids (of any dose) for symptomatic management for at least 14 days priorto first dose of attIL12-T cells are permitted to enroll. 3. Presence of metastaticdisease in or near vital or critical structures that in the judgement of thetreating physician in communication with PI or their delegate may lead to concern ofimmediate risk for harm from the inflammatory response.

3. Any concurrent chemotherapy, immunotherapy, or biologic or hormonal therapy for cancer treatment at the time of leukapheresis or attIL12 T cell infusion.

4. Standard of care anti-cancer therapy will be permitted following leukapheresis andprior to initiation of cyclophosphamide as bridging therapy (per section 12.4.1).

5. Concurrent use of hormones for non-cancer-related conditions (eg, insulin fordiabetes and hormone replacement therapy) is acceptable.

6. In addition, local treatment (eg, by local surgery, radiotherapy, or ablation) ofisolated lesions for palliative intent is acceptable beyond 30 days followingattIL12 T cell administration with prior consultation and in agreement with the PI.

7. Unresolved toxicities from prior anticancer therapy, defined as having not resolvedto NCI CTCAE v5 Grade 0 or 1 with the exception of alopecia and laboratory valueslisted per the inclusion criteria. Subjects with irreversible toxicity that is notreasonably expected to be exacerbated by any of the investigational products may beincluded (eg, hearing loss) after consultation with the PI.

8. Investigational therapy for supportive care (e.g. COVID vaccine) will be permitted,as long as it is reviewed and discussed with the PI.

9. History of primary immunodeficiency, solid organ transplantation, or previousclinical diagnosis of tuberculosis.

10. Receipt of live, attenuated vaccine within 28 days prior to the first dose ofinvestigational products 7. Major surgery (as defined by the investigator) within 4weeks prior to first dose of treatment or if still recovering from prior surgery.Biopsy as per study protocol is allowed 8. Uncontrolled intercurrent illnessincluding, but not limited to, ongoing or active infection, symptomatic congestiveheart failure, uncontrolled hypertension, unstable angina pectoris, cardiacarrhythmia, active peptic ulcer disease or gastritis, or psychiatric illness/socialsituations that would limit compliance with study requirement, substantiallyincrease risk of incurring AEs from the study agents, or compromise the ability ofthe subject to give written informed consent.

11. Subjects with cognitive impairment, including adults with cognitive impairmentsuch as trisomy 21 or similar conditions are not specifically excluded fromparticipation, such that appropriate written informed consent is obtained from theparent or legal guardian and they are able to complete with the study protocolrequirements and treatment.

12. Active concurrent second malignancy 11. Pregnant or lactating women 12. Anypositive test result for hepatitis B or C virus indicating acute or chronicinfection 13. Known history of testing positive for human immunodeficiency virus orknown acquired immunodeficiency syndrome