Inclusion Criteria: 

• Adults  18 to < 70 years of age.
• Adequate hematological function without growth factor or transfusion support for at least 7 days prior to enrollment, including:
  • Absolute neutrophil count  1000 uL
  • Platelet count  ≥ 75,000/uL
  • Hemoglobin 8 g/dL
  • Absolute Lymphocyte count  ≥ 1000/uL
• Creatinine clearance (CrCl)  50 mL/min using the Cockcroft-Gault formula.
•  Adequate liver, cardiac, and pulmonary function, including: See Protocol 
• Resolved acute effects of any prior therapy to baseline severity or Common Terminology 1 except for AEs consideredclinically nonsignificant and/or stable on supportive therapy as determined by the Investigator. 
• A highly sensitive urine pregnancy test or serum pregnancy test (for females of childbearing potential) negative at screening. 
•  Female participants of non-childbearing potential must meet at least 1 of the following criteria: 
  • Achieved postmenopausal status, defined as follows: cessation of regular menses for at least 12 consecutive months with no alternative pathological or physiological cause; status may be confirmed with a serum follicle stimulating hormone level confirming the postmenopausal state
  • Documented hysterectomy and/or bilateral oophorectomy
  • Medically confirmed ovarian failure / ovarian insufficiency

All other female participants (including those with tubal ligations) are considered to be of childbearing potential. 

• Fertile male and female participants of childbearing potential must be willing to use a highly effective method of contraception from the time of signing the informed consent form (ICF) and for at least 12 months (6 months for males) after receiving LD or ALLO329, whichever is longer. For definition and examples of highly effective methods of contraception,
• Signed and dated ICF indicating that the participant has been informed of all pertinent aspects of the study. 
• Willing and able to comply with scheduled visits, treatment plan, laboratory tests, and other procedures. 

Participants with SLE

• SLE defined by the Systemic Lupus International Collaborating Clinics (SLICC) criteria.
• Positive for at least 1 of the following autoantibodies at screening:
  • Anti-dsDNA above the upper limit of normal (ULN)
  • Anti-Sm above the ULN
  • Anti-RNP above the ULN
• Active (moderate-severe) disease as defined by:  
  • SLEDAI-2K  6 and at least 1 of the following significant SLE-related organ involvements: At least one BILAG A OR two BILAG B manifestations.
  • Active lupus nephritis (LN) as determined by a recent kidney biopsy (within 6 months) showing Class III or IV +/- Class V according to International Society of Nephrology (ISN)/Renal Pathology Society (RPS) 2003 classification (with 2018 modification). Modified NIH Activity  Exception to biopsy after medical monitor discussion with the EAC. 
• Disease activity as above despite prior treatment with standard of care therapy including at least one immunosuppressive agent for at least 3 months (in addition to HCQ). Definitions of prior therapies for assessing eligibility are provided in Table 4. Intolerance to prior therapy due to AE is acceptable. 

Participants with IIM 

•  Classification of probable or definite dermatomyositis, IMNM or anti-synthetase syndrome by 2017 EULAR/ACR classification criteria.
• Muscle, skin, OR lung involvement as defined by:
  • Recent muscle biopsy
  • Elevated creatinine phosphokinase (CPK) > 3 × ULN (or aldolase > 8)
  • Rash with Cutaneous Dermatomyositis Area Severity Index (CDASI) > 14 (not counting damage)
  • Presence of interstitial lung disease (ILD) on HRCT with progression as defined by Raghu, 2022 (for definition refer to Section 14.4.1).
• Disease activity as above despite prior treatment with standard of care therapy including at least one immunosuppressive agent for at least 3 months (in addition to HCQ). Definitions of prior therapies for assessing eligibility are provided in Table 4. Intolerance to prior therapy due to AE is acceptable.

Participants with SSc 

• SSc as defined by the 2013 EULAR/ACR classification criteria.
• Within 7 years of first non-Raynaud’s presentation (or positive skin/lung progression AND discussion with EAC). 
•  Disease activity:
  • mRSS > 10 (or early progression AND discussion with EAC)
  • Presence of ILD on HRCT with progression as defined by Raghu, 2022 (for definition refer to Section 14.4.1)
  • Myositis with CPK > 1.5 × ULN
  • CRP elevated at 1.5 × ULN (AND discussion with EAC). 
• Disease activity as above despite prior treatment with standard of care therapy including at least one immunosuppressive agent for at least 3 months (in addition to HCQ). Definitions of prior therapies for assessing eligibility are provided in Table 4. Intolerance to prior therapy due to AE is acceptable.  See Protocol 

Exclusion Criteria:

• Participants with active systemic bacterial, fungal, or viral infection requiring systemic treatment or clinically significant active, opportunistic, chronic or recurrent infection confirmed by clinical evidence, imaging, or positive laboratory tests (e.g., blood cultures, polymerase chain reaction [PCR] for DNA/RNA, such as COVID-19, etc.). Uncomplicated pharyngitis or urinary tract infection responding to routine care are excepted from this exclusion. 
•  Any active malignancy within 3 years prior to enrollment, except for adequately treated localized basal cell or squamous cell skin cancer, carcinoma in situ of the breast, cervix or bladder in observation. 
• Prior treatment with CD19 or CD70 targeted therapy or any prior engineered cell therapy (e.g., CAR T therapy).
• Received live vaccine within 4 weeks prior to enrollment. 
• Inability to stop or taper protocol-defined prior therapies (Table 4) before cell dosing on Day 0: 4 weeks prior to Day 0 for B-cell depleting therapies and 2 weeks or 5 half-lives (whichever is shorter) prior to Day 0 for non-B-cell depleting agents.  
• Clinically significant or unstable or uncontrolled acute or chronic disease (e.g., hypothyroidism and diabetes) not due to SLE, or laboratory abnormality or planned surgical procedure which in the opinion of the Investigator could put the participant at undue risk or confounds the ability to interpret data from the study. 
• History of bone marrow/hematopoietic stem cell or solid organ transplantation. 
• Participants known to be refractory to platelet or red blood cell transfusions or who will refuse indicated transfusion support to manage cell counts following treatment. 
• Positive serologic testing for hepatitis B, hepatitis C, and human immunodeficiency virus (HIV). Participants with positive serologic testing for hepatitis B or C, but with negative PCR may be considered. 
•  Any form of primary, inherited immunodeficiency. 
• Even if the cardiac function requirements in Inclusion Criterion no 4 are met, meeting any of the following criteria would exclude the participant from the study:
  • Symptomatic cardiac or vascular disease requiring medical intervention (e.g. unstable angina, myocardial infarction, cerebral vascular accident/stroke, atrial or ventricular arrhythmias, or congestive heart failure [New York Heart Association Classification Class II]) within 6 months prior to screening.
  • Hemodynamically symptomatic pericardial effusion.
  • Symptomatic electrocardiogram abnormality requiring medical intervention.
•  History of progressive multifocal leukoencephalopathy (PML).
• Even if the liver function requirements in Inclusion Criterion no 4 are met, meeting the following criterion would exclude the participant from the study:
  • Child-Pugh Class B or C cirrhosis.
• Even if the pulmonary function requirements in Inclusion Criterion no 4 are met, meeting any of the following criterion would exclude the participant from the study: 
  • Symptomatic airway disease requiring medical intervention (e.g. severe chronic obstructive pulmonary disease or history of bronchospasm requiring intubation). 
  • Pleural effusion Grade 2 or higher (CTCAE v5: intervention indicated).
  • History of pulmonary embolism requiring anticoagulant therapy within 6 months of enrollment. 
  • Lung disease secondary to the autoimmune process should not lead to exclusion if forced vital capacity (FVC) and diffusing capacity of the lung for carbon monoxide (DLCO%) are greater than 40%. Borderline cases can be discussed with medical monitor and Eligibility Adjudication Committee.
• History of hypertension crisis or hypertensive encephalopathy within 6 months prior to screening. 
• Any psychiatric condition, chronic medical condition, disability, or non-medical condition that in the opinion of the Investigator would prevent safe treatment or make adherence with treatment and follow-up unlikely. 
• Pregnant or breastfeeding or planning to become pregnant or breastfeed during the first 12 months after study treatment. Male participants must not plan for partner pregnancy for 6 months after receiving LD or ALLO-329, whichever is longer.
• Unwilling to participate in an extended safety monitoring period up to a total of 15 years after administration of ALLO-329.  

Participants with SLE

• Active disease involving CNS (eg CNS lupus and its sequelae) within the last 6 months
• Lupus that is drug-induced
•  If LN: 
  • History of dialysis within 12 months prior to signing the ICF or expected need for renal replacement therapy (dialysis or renal transplant) within a 12-month period after enrollment. History of, or current kidney diseases (other than LN) that in the opinion of the Investigator could interfere with the LN assessment and confound the disease activity assessment (e.g. diabetic nephropathy). 
  • NIH chronicity index score of 3+ in any of the following domains: glomerular sclerosis, glomerular fibrous crescents, tubular atrophy, and/or interstitial fibrosis.

Participants with IIM 

• A myositis other than IIM classification. 
• Non-reversible, unrelated or weakness not amenable to assessment (damage index > 7/10).
• Dermatomyositis with presence of anti-TIF1 gamma antibody. 

Participants with SSc

• Pulmonary arterial hypertension requiring treatment.
• Rapidly progressive or severe SSc gastrointestinal involvement.
• Prior scleroderma renal crisis.

Note: Other protocol defined Inclusion/Exclusion Criteria may apply.

Eligibility last updated 3/31/2025. Questions regarding updates should be directed to the study team contact.