Phase 1b Randomized, Double-Blind, Placebo-Controlled Study Of The Safety Of Therapeutic Treatment With Immunomodulatory Mesenchymal Stem Cells In Adults With COVID-19 Infection Requiring Mechanical Ventilation
Phase: PHASE1
Conditions: COVID
Sponsor: ImmunityBio, Inc.

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC 
Confidential and Proprietary 
1 
TITLE PAGE
PHASE 1b RANDOMIZED, OPEN-LABEL STUDY OF 
THE SAFETY OF THERAPEUTIC TREATMENT WITH 
IMMUNOMODULATORY MESENCHYMAL STEM 
CELLS IN ADULTS WITH COVID-19 INFECTION 
REQUIRING MECHANICAL VENTILATION 
Study Number: 
QUILT-COVID-19-MSC 
IND Sponsor: 
NantKwest, Inc. 
9920 Jefferson Blvd 
Culver City, CA 90232 
Sponsor Contact:  
(For medical questions/emergencies) 
John H. Lee, MD 
Senior Vice President Adult Medical Affairs 
NantKwest, Inc. 
9920 Jefferson Blvd 
Culver City, CA 90232 
Cell Phone: +1-605-610-6391 
Email: John.Lee@NantKwest.com 
Protocol Version 
Date 
Version 1 
08 Apr 2020 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC 
 
Confidential and Proprietary 
2 
STATEMENT OF COMPLIANCE 
This trial will be conducted in accordance with Good Clinical Practice (GCP) as described in the 
International Conference on Harmonization (ICH) Guideline for GCP (E6 [R2]) and in 
accordance with United States (US) Code of Federal Regulations (CFR) applicable to clinical 
studies (45 CFR Part 46, 21 CFR Part 50, 21 CFR Part 56, and 21 CFR Part 312) and the general 
ethical principles outlined in the Declaration of Helsinki. The study will receive approval from 
an Institutional Review Board (IRB) prior to commencement. The Principal Investigator will 
assure that no deviation from, or changes to the protocol will take place without prior agreement 
from the sponsor and documented approval from the IRB, except where necessary to eliminate 
an immediate hazard(s) to the trial participants.  
I agree to ensure that all staff members involved in the conduct of this study are informed about 
their obligations in meeting the above commitments.  
 
 
Signed: _____________________________________ Date: ______________ 
 
 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC 
 
Confidential and Proprietary 
3 
PROTOCOL SYNOPSIS 
Name of Sponsor/Company: 
NantKwest, Inc.  
Name of Investigational Product: 
BM-Allo.MSC 
Name of Active Ingredient: 
BM-Allo.MSC 
Title of Study:  
Phase 1b Randomized, Open-Label Study of the Safety of Therapeutic Treatment with 
Immunomodulatory Mesenchymal Stem Cells in Adults with COVID-19 Infection Requiring 
Mechanical Ventilation 
Study Number: 
QUILT-COVID-19-MSC 
Study Phase: 
Phase 1b 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC 
 
Confidential and Proprietary 
4 
Study Objectives: 
Primary Objectives: 
• 
To evaluate preliminary safety and efficacy of BM-Allo.MSC vs best supportive care 
in subjects who have tested positive for SARS-CoV-2 (COVID-19) and require 
ventilator support, as assessed by: 
o Mortality within 30 days of randomization. 
o Number of ventilator-free days within 60 days. 
Secondary Objectives: 
• 
To further evaluate efficacy of BM-Allo.MSC vs best supportive care in subjects who 
have tested positive for SARS-CoV-2 (COVID-19), as assessed by: 
o Days alive off mechanical ventilator support within 60 days of randomization 
o Incidence of SAEs within 30 days 
o Time to an improvement of one category from admission using the ordinal 
scale. 
o Mean change in the ordinal scale from baseline. 
o Change in NEWS from baseline. 
o Time to discharge or to a NEWS of ≤ 2 maintained for 24 hours, whichever 
occurs first. 
o Change from baseline in Sequential Organ Failure Assessment (SOFA) score 
on days 8, 15, 22, and 29. 
o Number of days requiring oxygen. 
o Duration of hospitalization. 
o Subject mortality, including date and cause of death (if applicable). 
• 
To further evaluate the safety of BM-Allo.MSC in subjects who have tested positive 
for SARS-CoV-2 (COVID-19), as assessed by: 
o Change from baseline in hemoglobin. 
o Change from baseline in platelets. 
o Change from baseline in white blood cell count. 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC 
 
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Study Design: 
This is a phase 1b randomized, open-label study in adult subjects with Coronavirus Disease 2019 
(COVID-19). This clinical trial will evaluate the safety and efficacy of BM-Allo.MSC vs best 
supporting care in treating patients with severe disease requiring ventilator support during COVID-19 
infection. Only subjects with moderate or severe ARDS (per Berlin criteria; see Appendix 1) will be 
enrolled in this study. 
COVID-19 infection causes progressive severe lung infection that can lead to death in a significant 
number of infected patients.  Prior work using allogeneic mesenchymal stem cells (MSCs) in severely 
infected individuals has shown promise in reversing the severe consequences of infection in critically 
ill patients. Thus, the potential exists for allogeneic MSCs to slow or halt disease progression and 
reduce time on ventilators in critically ill patients infected with COVID-19, and thus improve disease 
outcomes.  
A total of 45 subjects receiving care in the critical care or ICU setting with mechanical ventilation for 
COVID-19 will be enrolled in this study. Subjects will be randomized 2:1 to the experimental arm 
(30 subjects) and control arm (15 subjects).  
Subjects in the experimental arm will be administered BM-Allo.MSC (1×106 cells/kg IV) on day 1 and 
day 5 (day 5 only if the subject still requires ventilation on day 5). Subjects will be followed through 
day 60. Subjects in the control arm will be treated with best supportive care and followed through 
day 60. 
All subjects will be assessed using an ordinal scale that evaluates clinical status at the first assessment 
of each study day. The scale is as follows: 1) death; 2) hospitalized, on invasive mechanical ventilation 
or extracorporeal membrane oxygenation (ECMO); 3) hospitalized, on non-invasive ventilation or 
high-flow oxygen devices; 4) hospitalized, requiring supplemental oxygen; 5) hospitalized, not 
requiring supplemental oxygen; 6) not hospitalized, limitation on activities; 7) not hospitalized, no 
limitations on activities. 
In addition, all subjects will be assessed using the standard National Early Warning Score (NEWS) 
score (Royal College of Physicians 2012). The NEWS score has demonstrated an ability to identify 
patients at risk of poor outcomes and will be used as a measure of efficacy. This score is based on 
7 clinical parameters (respiration rate, oxygen saturation, any supplemental oxygen, temperature, 
systolic blood pressure, heart rate, level of consciousness).  
The primary objectives are to evaluate the percentage of subjects reporting each severity rating on the 
7-point ordinal scale in adults with COVID-19.  
Safety will be assessed for all subjects and will include monitoring of vital signs and incidence and 
severity of adverse events. Blood samples will be collected for hematology and chemistry analyses. 
Safety will be monitored throughout the study. After the first 3 subjects in the experimental arm have 
each completed the first 14 days of treatment, enrollment will be paused and the NantKwest Safety 
Review Committee (SRC) will perform an evaluation of safety. Enrollment will continue if the safety 
evaluation from the initial 3 subjects suggests that the therapy is safe. 

BM-Allo.MSC 
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Clinical Trial Protocol: QUILT-COVID-19-MSC 
 
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Primary Endpoints: 
• Mortality within 30 days of randomization 
• Number of ventilator-free days within 60 days 
Secondary Endpoints: 
• Days alive off mechanical ventilator support within 60 days of randomization 
• Incidence of SAEs within 30 days 
• Time to an improvement of one category from admission using the ordinal scale. 
• Mean change in the ordinal scale from baseline. 
• Change in NEWS from baseline. 
• Time to discharge or to a NEWS of ≤ 2 maintained for 24 hours, whichever occurs 
first. 
• Change from baseline in Sequential Organ Failure Assessment (SOFA) score on 
days 8, 15, 22, and 29. 
• Number of days requiring oxygen. 
• Duration of hospitalization. 
• Subject mortality, including date and cause of death (if applicable). 
• Change from baseline in hemoglobin, platelets, and white blood cell (WBC) count. 
Enrollment (planned):   
A total of 45 subjects receiving care in the critical care or ICU setting with mechanical ventilation for 
COVID-19 will be randomized 2:1 to the experimental arm (30 subjects) and control arm (15 subjects) 
in this study.  
Eligibility Criteria:  
Inclusion Criteria: 
1. Age ≥ 18 years old. 
2. Able to understand and provide a signed informed consent that fulfills the relevant Institutional 
Review Board (IRB) or Independent Ethics Committee (IEC) guidelines. For patients that are 
intubated and/or sedated, or otherwise unable to provide consent, prospective consent from a 
legally-authorized representative is required. The patient or his/her legally authorized 
representative mush be able to provide consent. 
3. Has laboratory-confirmed positive novel coronavirus (SARS-CoV-2) test, as determined by 
polymerase chain reaction (PCR), or other commercial or public health assay in any specimen 
< 72 hours prior to enrollment, or meets the criteria to guide the evaluation and testing of 
patients under investigation (PUI) for COVID-19 
(https://emergency.cdc.gov/han/2020/HAN00428.asp). 

BM-Allo.MSC 
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Clinical Trial Protocol: QUILT-COVID-19-MSC 
 
Confidential and Proprietary 
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4. Requiring mechanical ventilatory support with moderate to severe Acute Respiratory Distress 
Syndrome (ARDS) as determined by the Berlin criteria: 
a. Bilateral opacities present on a chest radiograph or computed tomographic (CT) scan. 
These opacities are not fully explained by pleural effusions, lobar collapse, lung collapse, 
or pulmonary nodules. 
b. Origin of Edema: Respiratory failure not fully explained by cardiac failure or fluid 
overload. 
c. Oxygenation: Moderate to severe impairment of oxygenation must be present, as defined 
by the ratio of arterial oxygen tension to fraction of inspired oxygen (PaO2/FiO2). The 
severity of the hypoxemia defines the severity of the ARDS: 
 
Moderate: PaO2/FiO2 >100 mmHg and ≤ 200 mmHg, on ventilator settings 
that include PEEP ≥ 5 cm H2O 
 
Severe: PaO2/FiO2 ≤100 mmHg on ventilator settings that include PEEP ≥5 cm 
H2O 
Subjects receiving extracorporeal membrane oxygenation (ECMO) will not be enrolled in this 
study. 
5. High-sensitivity C-reactive Protein (hs-CRP) serum level > 4.0 mg/dL 
6. Acute Physiology and Chronic Health Evaluation (APACHE IV) score > 5 
7.  Agrees to the collection of nasopharyngeal (OP) swabs and venous blood per protocol. 
8. Ability to attend required study visits and return for adequate follow-up, as required by this 
protocol. 
9. Agreement to practice effective contraception for female subjects of child-bearing potential 
and non-sterile males. Female subjects of child-bearing potential must agree to use effective 
contraception while on study and for at least 1 month after the last dose of BM-Allo.MSC. 
Non-sterile male subjects must agree to use a condom while on study and for up to 1 month 
after the dose of BM-Allo.MSC. Effective contraception includes surgical sterilization (eg, 
vasectomy, tubal ligation), two forms of barrier methods (eg, condom, diaphragm) used with 
spermicide, intrauterine devices (IUDs), oral contraceptives, and abstinence. 
Exclusion Criteria: 
1. Known hypersensitivity to any component of the study medication(s). 
2. Signs of multisystem organ failure. Liver function tests (LFTs) > 5x normal. 
3. Patients intubated > 72 hours. 
4. Assessed by the Investigator to be unable or unwilling to comply with the requirements of the 
protocol. 
5. Pregnant and nursing women. A negative serum pregnancy test during screening (within 
72 hours prior to the first dose) must be documented before MSCs are administered to a female 
subject of child-bearing potential. 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC 
 
Confidential and Proprietary 
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Products, Dosage, and Mode of Administration: 
Investigational Products  
 
Dosage 
Mode of Administration 
BM-Allo.MSC 
~1 × 106 cells/kg 
IV 
Duration of Treatment:  
Subjects in the experimental arm will be administered BM-Allo.MSC (1×106 cells/kg IV) on day 1 and 
day 5 (day 5 only if the subject still requires ventilation on day 5). Subjects will be followed through 
day 60. Subjects in the control arm will be treated with best supportive care and followed through day 
60. 
Duration of Follow-up: 
Subjects who receive study treatment for any reason will be followed via regular visits with a health 
care professional until either death (by any cause) or for a minimum of 30 days after administration of 
BM-Allo.MSC. 
Reference Therapy, Dosage, and Mode of Administration:  
Best supportive care. 
Evaluation of Endpoints: 
Safety: Safety endpoints include assessments of treatment-emergent AEs, SAEs, and changes 
hemoglobin, platelets, and white blood cell (WBC) count safety laboratory tests and vital signs. 
Toxicities will be graded using CTCAE Version 5.0  
Efficacy: Number of subjects reporting each severity rating on the 7-point ordinal scale and number of 
subjects with improved NEW scores and 7-point ordinal scale. 
Statistical Methods: 
All subjects receiving at least one dose of study drug (ie, the treated population) will be included in the 
safety and efficacy analyses. Statistical analysis will be descriptive and presented by treatment arm. No 
statistical testing will be performed. 
Safety Analyses: 
Overall safety will be assessed by descriptive analyses using tabulated frequencies of AEs by grade 
using CTCAE version 5 in terms of treatment-emergent AEs, SAEs, and clinically significant changes 
in safety laboratory tests and vital signs. 
Efficacy Analyses: 
Incidence of subjects reporting each severity rating on the 7-point ordinal scale will be presented. 
Descriptive statistics of improvement in the 7-point ordinal scale and the NEWS will also be presented. 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC 
 
Confidential and Proprietary 
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Figure 1: 
Study Treatment Schema 
 
 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC 
 
Confidential and Proprietary 
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Table 6: 
Schedule of Events 
 
Baseline/Screeninga 
Study Day  
Study Day 
-1 or 1 
1 
5 
8 
15 
22 
29 
EOS 
Windows (days) 
 
± 1 
± 4 
General Assessments 
Informed consent 
X 
 
 
 
 
 
 
 
Inclusion/exclusion 
X 
 
 
 
 
 
 
 
Demographics 
X 
 
 
 
 
 
 
 
Medical history 
X 
 
 
 
 
 
 
 
Confirm contraceptive 
measures 
X 
 
 
 
 
 
 
 
APACHE assessment 
X 
 
 
 
 
 
 
 
High-sensitivity CRP 
X 
 
 
 
 
 
 
 
Physical exam: height, 
weightb 
X 
X 
X 
 
 
 
 
 
Vital signsc 
X 
Daily, throughout study period 
 
SOFA assessment 
X 
X 
 
X 
X 
X 
X 
X 
Ordinal scale (7-point) 
X 
X 
 
X 
X 
X 
X 
X 
NEWS 
X 
X 
 
X 
X 
X 
X 
X 
Concomitant 
medicationsc 
X 
Daily, throughout study period 
X 
Adverse event 
collectionc 
X 
Daily, throughout study period 
X 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC 
 
Confidential and Proprietary 
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Baseline/Screeninga 
Study Day  
Study Day 
-1 or 1 
1 
5 
8 
15 
22 
29 
EOS 
Windows (days) 
 
± 1 
± 4 
Study drug administration 
BM-Allo.MSC 
 
X 
Xd 
 
 
 
 
 
Laboratory Assessments 
Chemistry panele 
X 
X 
 
X 
X 
X 
X 
X 
Hematologyf 
X 
X 
 
X 
X 
X 
X 
X 
Collect whole blood for 
immunogenicity and 
cytokine analyses 
X 
X 
 
X 
X 
X 
X 
X 
Pregnancy testg 
X 
 
 
 
 
 
 
 
a Baseline/screening assessments may be done ≤ 1 calendar day prior to the first dose of BM-Allo.MSC. Day 1 assessments do not need to be repeated if 
baseline/screening is done on study day 1. Assessments performed on day 1 must be performed before dosing. 
b Height required at baseline/screening visit only. Weight on day 1 should be used to calculate drug dose. 
c Vital signs, concomitant medications, and adverse event collection will occur daily throughout the study period (ie, each day beginning day 1 and continuing 
through day 29). Vital signs of temperature, heart rate, blood pressure, oxygen saturation, and respiratory rate will be assessed at every visit.  
d Administered only to subjects still requiring mechanical ventilation on day 5.  
e See Table 5 for additional details on laboratory assessments. Blood draws for lab assessments should occur prior to BM-Allo.MSC administration. 
f Hematology to include CBC with differential (5 part) as outlined in Table 5. Blood draws for lab assessments should occur prior to BM-Allo.MSC 
administration. 
g Serum pregnancy tests for females of child-bearing potential. 
 
 

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Clinical Trial Protocol: QUILT-COVID-19-MSC 
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APPENDIX 4. SPONSOR SIGNATURE 
Study Title: 
Phase 1b Randomized, Open-Label Study of the Safety of 
Therapeutic Treatment with Immunomodulatory Mesenchymal 
Stem Cells in Adults with COVID-19 Infection Requiring 
Mechanical Ventilation 
Study Number: 
QUILT-COVID-19-MSC 
Version Number: 
1 
Final Date: 
08 Apr 2020 
This clinical trial protocol was subject to critical review and has been approved by NantKwest. 
The following personnel contributed to writing and/or approving this protocol: 
Signed: ______________________________ 
Date:  ___________________ 
John Lee, MD 
Senior Vice President Adult Medical Affairs 
NantKwest, Inc. 
9920 Jefferson Blvd 
Culver City, CA 90232 
Email: john.lee@NantKwest.com 
Phone: +1-605-610-6391 
DocuSign Envelope ID: 07FB1FD7-2C0A-483B-A98F-EBB747A24794
4/8/2020

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 1 
 
Confidential and Proprietary 
1 
TITLE PAGE  
PHASE 1B RANDOMIZED, DOUBLE-BLIND, PLACEBO-
CONTROLLED STUDY OF THE SAFETY OF 
THERAPEUTIC TREATMENT WITH 
IMMUNOMODULATORY MESENCHYMAL STEM 
CELLS IN ADULTS WITH COVID-19 INFECTION 
REQUIRING MECHANICAL VENTILATION 
 
Study Number: 
QUILT-COVID-19-MSC 
IND Sponsor: 
NantKwest, Inc. 
9920 Jefferson Blvd 
Culver City, CA 90232 
Sponsor Contact:  
(For medical questions/emergencies) 
Lennie Sender, MD 
Senior Vice President, Medical Affairs 
NantKwest, Inc 
9920 Jefferson Blvd 
Culver City, CA 90232 
Email: lennie.sender@nantkwest.com 
Cell Phone: 714-615-2350 
 
Protocol Version 
Date 
Version 1 
08 Apr 2020 
Version 2 
19 May 2020 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 1 
 
Confidential and Proprietary 
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STATEMENT OF COMPLIANCE 
This trial will be conducted in accordance with Good Clinical Practice (GCP) as described in the 
International Conference on Harmonization (ICH) Guideline for GCP (E6 [R2]) and in 
accordance with United States (US) Code of Federal Regulations (CFR) applicable to clinical 
studies (45 CFR Part 46, 21 CFR Part 50, 21 CFR Part 56, and 21 CFR Part 312) and the general 
ethical principles outlined in the Declaration of Helsinki. The study will receive approval from 
an Institutional Review Board (IRB) prior to commencement. The Principal Investigator will 
assure that no deviation from, or changes to the protocol will take place without prior agreement 
from the sponsor and documented approval from the IRB, except where necessary to eliminate 
an immediate hazard(s) to the trial participants.  
I agree to ensure that all staff members involved in the conduct of this study are informed about 
their obligations in meeting the above commitments.  
 
 
Signed: _____________________________________ Date: ______________ 
 
 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 1 
 
Confidential and Proprietary 
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PROTOCOL SYNOPSIS 
Name of Sponsor/Company: 
NantKwest, Inc.  
Name of Investigational Product: 
BM-Allo.MSC 
Name of Active Ingredient: 
BM-Allo.MSC 
Title of Study:  
Phase 1b Randomized, Double-Blind, Placebo-Controlled Study of the Safety of Therapeutic 
Treatment with Immunomodulatory Mesenchymal Stem Cells in Adults with COVID-19 Infection 
Requiring Mechanical Ventilation 
Study Number: 
QUILT-COVID-19-MSC 
Study Phase: 
Phase 1b 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 1 
 
Confidential and Proprietary 
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Study Objectives: 
Primary Objectives: 
• 
To evaluate preliminary safety of BM-Allo.MSC vs placebo in terms of adverse 
events within 30 days of randomization.  
• 
To evaluate preliminary efficacy of BM-Allo.MSC vs placebo in subjects who have 
tested positive for SARS-CoV-2 (COVID-19) and require ventilator support, as 
assessed by: 
o Mortality and cause of death within 30 days of randomization. 
o Number of ventilator-free days within 60 days of randomization. 
Secondary Objectives: 
• 
To further evaluate preliminary efficacy of BM-Allo.MSC vs placebo in subjects who 
have tested positive for SARS-CoV-2 (COVID-19), as assessed by: 
o Time from randomization to an improvement of one category in the 7-point 
ordinal scale. 
o Change in the 7-point ordinal scale from baseline. 
o Change in National Early Warning Score (NEWS) from baseline. 
o Time from randomization to discharge or to a NEWS of ≤ 2 maintained for 24 
hours, whichever occurs first. 
o Change from baseline in Sequential Organ Failure Assessment (SOFA) score 
on days 8, 15, 22, and 29. 
o Number of days requiring oxygen within 60 days of randomization. 
o Duration of hospitalization from randomization. 
• 
To further evaluate the safety of BM-Allo.MSC in subjects who have tested positive 
for SARS-CoV-2 (COVID-19), as assessed by: 
o Incidence of SAEs within 30 days of randomization. 
o Change from baseline in hemoglobin. 
o Change from baseline in platelets. 
o Change from baseline in white blood cell count. 
o Change from baseline in vital signs. 

BM-Allo.MSC 
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Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 1 
 
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Study Design: 
This is a phase 1b randomized, double-blind, placebo-controlled study in adult subjects with 
Coronavirus Disease 2019 (COVID-19). This clinical trial will evaluate the preliminary safety and 
efficacy of BM-Allo.MSC vs placebo in treating subjects with severe disease requiring ventilator 
support during COVID-19 infection. Only subjects with moderate or severe ARDS (per Berlin criteria; 
see Appendix 1) will be enrolled in this study. 
COVID-19 infection causes progressive severe lung infection that can lead to death in a significant 
number of infected patients.  Prior work using allogeneic mesenchymal stem cells (MSCs) in severely 
infected individuals has shown promise in reversing the severe consequences of infection in critically 
ill patients. Thus, the potential exists for allogeneic MSCs to slow or halt disease progression and 
reduce time on ventilators in critically ill patients infected with COVID-19, and thus improve disease 
outcomes.  
A total of 45 subjects receiving care in the critical care or ICU setting with mechanical ventilation for 
COVID-19 will be enrolled in this study. Subjects will be randomized 2:1 to the experimental arm 
(30 subjects) and control arm (15 subjects).  
Subjects in the experimental arm will be administered BM-Allo.MSC (~1×106 cells/kg IV) on day 1 
followed by day 5 (±1 day), if subject still requires ventilation on day 5. Subjects will be followed 
through day 60. Subjects in the control arm will be administered placebo on a schedule identical to that 
of the experimental arm and followed through day 60.  The investigational product will contain 
BM-Allo.MSC in 5% albumin (human), USP, and Plasmalyte A USP (1:1 ratio) in a volume of 
100 mL. The placebo will consist of 5% albumin (human), USP, and Plasmalyte A USP (1:1 ratio) in a 
volume of 100 mL. 
All subjects will be assessed using a 7-point ordinal scale that evaluates clinical status at the first 
assessment of each study day. The scale is as follows: 1) death; 2) hospitalized, on invasive mechanical 
ventilation or extracorporeal membrane oxygenation (ECMO); 3) hospitalized, on non-invasive 
ventilation or high-flow oxygen devices; 4) hospitalized, requiring supplemental oxygen; 5) 
hospitalized, not requiring supplemental oxygen; 6) not hospitalized, limitation on activities; 7) not 
hospitalized, no limitations on activities. 
In addition, all subjects will be assessed using the standard National Early Warning Score (NEWS) 
score (Royal College of Physicians 2012). The NEWS score has demonstrated an ability to identify 
patients at risk of poor outcomes and will be used as a measure of efficacy. This score is based on 
7 clinical parameters (respiration rate, oxygen saturation, any supplemental oxygen, temperature, 
systolic blood pressure, heart rate, level of consciousness).  
Safety will be assessed for all subjects and will include monitoring of vital signs and incidence and 
severity of adverse events. Blood samples will be collected for hematology and chemistry analyses. 
Safety will be monitored throughout the study. After the first 5 subjects are randomized (giving at least 
3 subjects in the experimental arm) enrollment will be paused and the NantKwest Safety Review 
Committee (SRC) will perform an evaluation of safety once the 5 subjects have completed the 14 day 
toxicity assessment period. Enrollment will continue if the safety evaluation from the initial 5 subjects 
suggests that the therapy is safe. 

BM-Allo.MSC 
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Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 1 
 
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Primary Endpoints: 
• 
Incidence of AEs within 30 days of randomization. 
• 
Mortality within 30 days of randomization. 
• 
Cause of death within 30 days of randomization 
• 
Number of ventilator-free days within 60 days of randomization. 
Secondary Endpoints: 
• 
Time from randomization to an improvement of one category using the ordinal scale. 
• 
Change in the 7-point ordinal scale from baseline. 
• 
Change in NEWS from baseline. 
• 
Time from randomization to discharge or to a NEWS of ≤ 2 maintained for 24 hours, 
whichever occurs first. 
• 
Change from baseline in Sequential Organ Failure Assessment (SOFA) score on days 8, 
15, 22, and 29. 
• 
Number of days requiring oxygen. 
• 
Duration of hospitalization from randomization. 
• 
Incidence of SAEs within 30 days of randomization 
• 
Change from baseline in hemoglobin, platelets, and white blood cell (WBC) count. 
• 
Changes in vital signs from baseline. 
Enrollment (planned):   
A total of 45 subjects receiving care in the critical care or ICU setting with mechanical ventilation for 
COVID-19 will be randomized 2:1 to the experimental arm (30 subjects) and control arm (15 subjects) 
in this study.  
Eligibility Criteria:  
Inclusion Criteria: 
1. Age ≥ 18 years old. 
2. Able to understand and provide a signed informed consent that fulfills the relevant Institutional 
Review Board (IRB) or Independent Ethics Committee (IEC) guidelines. For subjects that are 
intubated and/or sedated, or otherwise unable to provide consent, prospective consent from a 
legally-authorized representative is required. The subject or his/her legally authorized 
representative must be able to provide consent. 
3. Has laboratory-confirmed positive novel coronavirus (SARS-CoV-2) test, as determined by 
polymerase chain reaction (PCR), or other commercial or public health assay in any specimen 
< 72 hours prior to enrollment, or meets the criteria to guide the evaluation and testing of 
patients under investigation (PUI) for COVID-19 
(https://emergency.cdc.gov/han/2020/HAN00428.asp). 

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Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 1 
 
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4. Requiring mechanical ventilatory support with moderate to severe Acute Respiratory Distress 
Syndrome (ARDS) as determined by the Berlin criteria: 
a. Bilateral opacities present on a chest radiograph or computed tomographic (CT) scan. 
These opacities are not fully explained by pleural effusions, lobar collapse, lung collapse, 
or pulmonary nodules. 
b. Origin of Edema: Respiratory failure not fully explained by cardiac failure or fluid 
overload. 
c. Oxygenation: Moderate to severe impairment of oxygenation must be present, as defined 
by the ratio of arterial oxygen tension to fraction of inspired oxygen (PaO2/FiO2). The 
severity of the hypoxemia defines the severity of the ARDS: 
 
Moderate: PaO2/FiO2 >100 mmHg and ≤ 200 mmHg, on ventilator settings 
that include PEEP ≥ 5 cm H2O 
 
Severe: PaO2/FiO2 ≤100 mmHg on ventilator settings that include PEEP ≥5 cm 
H2O 
Subjects receiving extracorporeal membrane oxygenation (ECMO) will not be enrolled in this 
study. 
5. High-sensitivity C-reactive Protein (hs-CRP) serum level > 4.0 mg/dL 
6. Acute Physiology and Chronic Health Evaluation (APACHE IV) score > 5 
7. Agrees to the collection of nasopharyngeal (NP) swabs and venous blood per protocol. 
8. Ability to attend required study visits and return for adequate follow-up, as required by this 
protocol. 
9. Agreement to practice effective contraception for female subjects of child-bearing potential 
and non-sterile males. Female subjects of child-bearing potential must agree to use effective 
contraception while on study and for at least 1 month after the last dose of BM-Allo.MSC. 
Non-sterile male subjects must agree to use a condom while on study and for up to 1 month 
after the dose of BM-Allo.MSC. Effective contraception includes surgical sterilization (eg, 
vasectomy, tubal ligation), two forms of barrier methods (eg, condom, diaphragm) used with 
spermicide, intrauterine devices (IUDs), oral contraceptives, and abstinence. 
Exclusion Criteria: 
1. Known hypersensitivity to any component of the study medication(s). 
2. Signs of multisystem organ failure. Liver function tests (LFTs) > 5x normal. 
3. Intubated > 72 continuous hours. 
4. Assessed by the Investigator to be unable or unwilling to comply with the requirements of the 
protocol. 
5. Pregnant and nursing women. A negative serum pregnancy test during screening (within 
72 hours prior to the first dose) must be documented before MSCs are administered to a female 
subject of child-bearing potential. 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 1 
 
Confidential and Proprietary 
8 
Products, Dosage, and Mode of Administration: 
Investigational Products  
 
Dosage 
Mode of Administration 
BM-Allo.MSC 
~1 × 106 cells/kg 
IV 
Duration of Treatment:  
Subjects in the experimental arm will be administered BM-Allo.MSC (~1×106 cells/kg IV) on day 1 
followed by day 5 (±1 day), if subject still requires ventilation on day 5. Subjects will be followed 
through day 60. Subjects in the control arm will be treated with placebo on a schedule identical to that 
of the experimental arm and followed through day 60. 
Duration of Follow-up: 
Subjects who receive study treatment for any reason will be followed via regular visits with a health 
care professional until either death (by any cause) or for a minimum of 30 days after administration of 
BM-Allo.MSC. 
Reference Therapy, Dosage, and Mode of Administration:  
Subjects randomized to the control arm will receive an IV infusion of placebo, consisting of the vehicle 
solution used for the cell suspension product. The vehicle solution consists of 5% albumin (human), 
USP, and Plasmalyte A USP (1:1 ratio) in a volume of 100 mL. 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 1 
 
Confidential and Proprietary 
9 
Evaluation of Endpoints: 
Safety: Safety endpoints include assessments of treatment-emergent AEs, SAEs, and changes 
hemoglobin, platelets, and white blood cell (WBC) count safety laboratory tests and vital signs. 
Toxicities will be graded using CTCAE Version 5.0  
Efficacy: Mortality and cause of death within 30 days of randomization, number of ventilator-free days 
with 60 days of randomization, number of subjects reporting each severity rating on the 7-point ordinal 
scale, and number of subjects with improved NEW scores and 7-point ordinal scale. 
Statistical Methods: 
All subjects receiving at least one dose of study drug (ie, the Safety population) will be included in the 
safety and efficacy analyses. Statistical analysis will be descriptive and presented by treatment arm. No 
statistical testing will be performed. 
Safety Analyses: 
Overall safety will be assessed by descriptive analyses using tabulated frequencies of AEs by grade 
using CTCAE version 5 in terms of treatment-emergent AEs, SAEs, and AEs by grade and clinically 
significant changes in safety laboratory tests and vital signs. 
Efficacy Analyses: 
The mortality rate within 30 days of randomization and 95% confidence interval will be summarized. 
Cause of death will be summarized. The mean number of ventilator-free days and number of days 
requiring oxygen within 60 days of randomization and the mean duration of hospitalization will be 
summarized. 
Time from randomization to an improvement of one category on the 7-point ordinal scale will be 
summarized. The mean change from baseline on the 7-point ordinal scale at each post-baseline 
evaluation time point will be summarized. 
The mean change from baseline for each parameter of NEWS and the overall score at each 
post-baseline evaluation time point will be summarized. Time from randomization to discharge or to a 
NEWS of ≤ 2 maintained for 24 hours, whichever occurs first will be summarized. The mean change 
from baseline in SOFA score at each post-baseline evaluation time point will be summarized.   

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 1 
 
Confidential and Proprietary 
10 
Figure 1: 
Study Treatment Schema 
 
 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 1 
 
Confidential and Proprietary 
39 
Table 5: 
Schedule of Events 
 
Baseline/Screeninga 
Study Day  
Study Day 
-1 or 1 
1 
5 
8 
15 
22 
29 
60/EOS 
Windows (days) 
 
± 1 
± 4 
General Assessments 
Informed consent 
X 
 
 
 
 
 
 
 
Inclusion/exclusion 
X 
 
 
 
 
 
 
 
Demographics 
X 
 
 
 
 
 
 
 
Medical history 
X 
 
 
 
 
 
 
 
Confirm contraceptive 
measures 
X 
 
 
 
 
 
 
 
APACHE assessment 
X 
 
 
 
 
 
 
 
High-sensitivity CRP 
X 
 
 
 
 
 
 
 
Physical exam: height, 
weightb 
X 
X 
X 
 
 
 
 
 
Vital signsc 
X 
Daily, throughout study period 
 
SOFA assessment 
X 
X 
 
X 
X 
X 
X 
X 
Ordinal scale (7-point) 
X 
X 
 
X 
X 
X 
X 
X 
NEWSc 
X 
Daily, throughout study period 
X 
Concomitant 
medicationsc 
X 
Daily, throughout study period 
X 
Adverse event 
collectionc 
X 
Daily, throughout study period 
X 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 1 
 
Confidential and Proprietary 
40 
 
Baseline/Screeninga 
Study Day  
Study Day 
-1 or 1 
1 
5 
8 
15 
22 
29 
60/EOS 
Windows (days) 
 
± 1 
± 4 
Study drug administration 
BM-Allo.MSC or 
Placebo  
 
X 
Xd 
 
 
 
 
 
Laboratory Assessments 
Collect NP swabs 
X 
X 
 
 
 
 
 
 
Chemistry panele 
X 
X 
 
X 
X 
X 
X 
X 
Hematologyf 
X 
X 
 
X 
X 
X 
X 
X 
Collect whole blood for 
immunogenicity and 
cytokine analyses 
X 
X 
 
X 
X 
X 
X 
X 
Pregnancy testg 
X 
X 
 
 
 
 
 
 
a Baseline/screening assessments may be done ≤ 1 calendar day prior to the first dose of BM-Allo.MSC or placebo. Day 1 assessments do not need to be 
repeated if baseline/screening is done on study day 1. Assessments performed on day 1 must be performed before dosing. 
b Height required at baseline/screening visit only. Weight on day 1 should be used to calculate drug dose. 
c Vital signs, concomitant medications, NEWS assessment, and adverse event collection will occur daily throughout the study period (ie, each day beginning 
day 1 and continuing through day 29). Vital signs of temperature, heart rate, blood pressure, oxygen saturation, and respiratory rate will be assessed at every 
visit.  
d Dose to be administered on day 1 followed by day 5 (±1 day), if subject still requires ventilation on day 5. 
e See Table 4 for additional details on laboratory assessments. Blood draws for lab assessments should occur prior to BM-Allo.MSC or placebo administration. 
f Hematology to include CBC with differential (5 part) as outlined in Table 4. Blood draws for lab assessments should occur prior to BM-Allo.MSC or placebo 
administration. 
g Serum pregnancy tests for females of child-bearing potential. 
 
 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 2 
 
Confidential and Proprietary 
1 
TITLE PAGE  
PHASE 1B RANDOMIZED, DOUBLE-BLIND, PLACEBO-
CONTROLLED STUDY OF THE SAFETY OF 
THERAPEUTIC TREATMENT WITH 
IMMUNOMODULATORY MESENCHYMAL STEM 
CELLS IN ADULTS WITH COVID-19 INFECTION 
REQUIRING MECHANICAL VENTILATION 
 
Study Number: 
QUILT-COVID-19-MSC 
IND Sponsor: 
NantKwest, Inc. 
9920 Jefferson Blvd 
Culver City, CA 90232 
Sponsor Contact:  
(For medical questions/emergencies) 
Lennie Sender, MD 
Senior Vice President, Medical Affairs 
NantKwest, Inc 
9920 Jefferson Blvd 
Culver City, CA 90232 
Email: lennie.sender@nantkwest.com 
Cell Phone: 714-615-2350 
 
Protocol Version 
Date 
Version 1 
08 Apr 2020 
Version 2 
19 May 2020 
Version 3 
10 Sep 2020 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 2 
 
Confidential and Proprietary 
2 
STATEMENT OF COMPLIANCE 
This trial will be conducted in accordance with Good Clinical Practice (GCP) as described in the 
International Conference on Harmonization (ICH) Guideline for GCP (E6 [R2]) and in 
accordance with United States (US) Code of Federal Regulations (CFR) applicable to clinical 
studies (45 CFR Part 46, 21 CFR Part 50, 21 CFR Part 56, and 21 CFR Part 312) and the general 
ethical principles outlined in the Declaration of Helsinki. The study will receive approval from 
an Institutional Review Board (IRB) prior to commencement. The Principal Investigator will 
assure that no deviation from, or changes to the protocol will take place without prior agreement 
from the sponsor and documented approval from the IRB, except where necessary to eliminate 
an immediate hazard(s) to the trial participants.  
I agree to ensure that all staff members involved in the conduct of this study are informed about 
their obligations in meeting the above commitments.  
 
 
Signed: _____________________________________ Date: ______________ 
 
 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 2 
 
Confidential and Proprietary 
3 
PROTOCOL SYNOPSIS 
Name of Sponsor/Company: 
NantKwest, Inc.  
Name of Investigational Product: 
BM-Allo.MSC 
Name of Active Ingredient: 
BM-Allo.MSC 
Title of Study:  
Phase 1b Randomized, Double-Blind, Placebo-Controlled Study of the Safety of Therapeutic 
Treatment with Immunomodulatory Mesenchymal Stem Cells in Adults with COVID-19 Infection 
Requiring Mechanical Ventilation 
Study Number: 
QUILT-COVID-19-MSC 
Study Phase: 
Phase 1b 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 2 
 
Confidential and Proprietary 
4 
Study Objectives: 
Primary Objectives: 
• 
To evaluate preliminary safety of BM-Allo.MSC vs placebo in terms of adverse 
events within 30 days of randomization.  
• 
To evaluate preliminary efficacy of BM-Allo.MSC vs placebo in subjects who have 
tested positive for SARS-CoV-2 (COVID-19) and require ventilator support, as 
assessed by: 
o Mortality and cause of death within 30 days of randomization. 
o Number of ventilator-free days within 60 days of randomization. 
Secondary Objectives: 
• 
To further evaluate preliminary efficacy of BM-Allo.MSC vs placebo in subjects who 
have tested positive for SARS-CoV-2 (COVID-19), as assessed by: 
o Time from randomization to an improvement of one category in the 7-point 
ordinal scale. 
o Change in the 7-point ordinal scale from baseline. 
o Change in National Early Warning Score (NEWS) from baseline. 
o Time from randomization to discharge or to a NEWS of ≤ 2 maintained for 24 
hours, whichever occurs first. 
o Change from baseline in Sequential Organ Failure Assessment (SOFA) score 
on days 8, 15, 22, and 29. 
o Number of days requiring oxygen within 60 days of randomization. 
o Duration of hospitalization from randomization. 
• 
To further evaluate the safety of BM-Allo.MSC in subjects who have tested positive 
for SARS-CoV-2 (COVID-19), as assessed by: 
o Incidence of SAEs within 30 days of randomization. 
o Change from baseline in hemoglobin. 
o Change from baseline in platelets. 
o Change from baseline in white blood cell count. 
o Change from baseline in vital signs. 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 2 
 
Confidential and Proprietary 
5 
Study Design: 
This is a phase 1b randomized, double-blind, placebo-controlled study in adult subjects with 
Coronavirus Disease 2019 (COVID-19). This clinical trial will evaluate the preliminary safety and 
efficacy of BM-Allo.MSC vs placebo in treating subjects with severe disease requiring ventilator 
support during COVID-19 infection. Only subjects with moderate or severe ARDS (per Berlin criteria; 
see Appendix 1) will be enrolled in this study. 
COVID-19 infection causes progressive severe lung infection that can lead to death in a significant 
number of infected patients.  Prior work using allogeneic mesenchymal stem cells (MSCs) in severely 
infected individuals has shown promise in reversing the severe consequences of infection in critically 
ill patients. Thus, the potential exists for allogeneic MSCs to slow or halt disease progression and 
reduce time on ventilators in critically ill patients infected with COVID-19, and thus improve disease 
outcomes.  
A total of 45 subjects receiving care in the critical care or ICU setting with mechanical ventilation for 
COVID-19 will be enrolled in this study. Subjects will be randomized 2:1 to the experimental arm 
(30 subjects) and control arm (15 subjects).  
Subjects in the experimental arm will be administered BM-Allo.MSC (0.7-1.3×106 cells/kg IV) on 
day 1 followed by day 5 (±1 day), if subject still requires ventilation on day 5. Subjects will be 
followed through day 60. Subjects in the control arm will be administered placebo on a schedule 
identical to that of the experimental arm and followed through day 60.   
BM-Allo.MSC and placebo may be provided to the clinical treatment site as a cryopreserved 
preparation. The cryopreserved product will contain BM-Allo.MSC in 5% albumin (human), USP, and 
CryoStor 10 (CS10) (in 1:1 ratio) in a volume of 100 mL. The placebo will consist of 5% albumin 
(human), USP, and CS10 (1:1 ratio) in a volume of 100 mL. 
All subjects will be assessed using a 7-point ordinal scale that evaluates clinical status at the first 
assessment of each study day. The scale is as follows: 1) death; 2) hospitalized, on invasive mechanical 
ventilation or extracorporeal membrane oxygenation (ECMO); 3) hospitalized, on non-invasive 
ventilation or high-flow oxygen devices; 4) hospitalized, requiring supplemental oxygen; 5) 
hospitalized, not requiring supplemental oxygen; 6) not hospitalized, limitation on activities; 7) not 
hospitalized, no limitations on activities. 
In addition, all subjects will be assessed using the standard National Early Warning Score (NEWS) 
score (Royal College of Physicians 2012). The NEWS score has demonstrated an ability to identify 
patients at risk of poor outcomes and will be used as a measure of efficacy. This score is based on 
7 clinical parameters (respiration rate, oxygen saturation, any supplemental oxygen, temperature, 
systolic blood pressure, heart rate, level of consciousness).  
Safety will be assessed for all subjects and will include monitoring of vital signs and incidence and 
severity of adverse events. Blood samples will be collected for hematology and chemistry analyses. 
Safety will be monitored throughout the study. After the first 5 subjects are randomized (giving at least 
3 subjects in the experimental arm) enrollment will be paused and the NantKwest Safety Review 
Committee (SRC) will perform an evaluation of safety once the 5 subjects have completed the 14 day 
toxicity assessment period. Enrollment will continue if the safety evaluation from the initial 5 subjects 
suggests that the therapy is safe. 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 2 
 
Confidential and Proprietary 
6 
Primary Endpoints: 
• 
Incidence of AEs within 30 days of randomization. 
• 
Mortality within 30 days of randomization. 
• 
Cause of death within 30 days of randomization 
• 
Number of ventilator-free days within 60 days of randomization. 
Secondary Endpoints: 
• 
Time from randomization to an improvement of one category using the ordinal scale. 
• 
Change in the 7-point ordinal scale from baseline. 
• 
Change in NEWS from baseline. 
• 
Time from randomization to discharge or to a NEWS of ≤ 2 maintained for 24 hours, 
whichever occurs first. 
• 
Change from baseline in Sequential Organ Failure Assessment (SOFA) score on days 8, 
15, 22, and 29. 
• 
Number of days requiring oxygen. 
• 
Duration of hospitalization from randomization. 
• 
Incidence of SAEs within 30 days of randomization 
• 
Change from baseline in hemoglobin, platelets, and white blood cell (WBC) count. 
• 
Changes in vital signs from baseline. 
Enrollment (planned):   
A total of 45 subjects receiving care in the critical care or ICU setting with mechanical ventilation for 
COVID-19 will be randomized 2:1 to the experimental arm (30 subjects) and control arm (15 subjects) 
in this study.  
Eligibility Criteria:  
Inclusion Criteria: 
1. Age ≥ 18 years old. 
2. Able to understand and provide a signed informed consent that fulfills the relevant Institutional 
Review Board (IRB) or Independent Ethics Committee (IEC) guidelines. For subjects that are 
intubated and/or sedated, or otherwise unable to provide consent, prospective consent from a 
legally-authorized representative is required. The subject or his/her legally authorized 
representative must be able to provide consent. 
3. Has laboratory-confirmed positive novel coronavirus (SARS-CoV-2) test, as determined by 
polymerase chain reaction (PCR), or other commercial or public health assay in any specimen 
< 72 hours prior to enrollment, or meets the criteria to guide the evaluation and testing of 
patients under investigation (PUI) for COVID-19 
(https://emergency.cdc.gov/han/2020/HAN00428.asp). 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 2 
 
Confidential and Proprietary 
7 
4. Requiring mechanical ventilatory support with moderate to severe Acute Respiratory Distress 
Syndrome (ARDS) as determined by the Berlin criteria: 
a. Bilateral opacities present on a chest radiograph or computed tomographic (CT) scan. 
These opacities are not fully explained by pleural effusions, lobar collapse, lung collapse, 
or pulmonary nodules. 
b. Origin of Edema: Respiratory failure not fully explained by cardiac failure or fluid 
overload. 
c. Oxygenation: Moderate to severe impairment of oxygenation must be present, as defined 
by the ratio of arterial oxygen tension to fraction of inspired oxygen (PaO2/FiO2). The 
severity of the hypoxemia defines the severity of the ARDS: 
 
Moderate: PaO2/FiO2 >100 mmHg and ≤ 200 mmHg, on ventilator settings 
that include PEEP ≥ 5 cm H2O 
 
Severe: PaO2/FiO2 ≤100 mmHg on ventilator settings that include PEEP ≥5 cm 
H2O 
Subjects receiving extracorporeal membrane oxygenation (ECMO) will not be enrolled in this 
study. 
5. High-sensitivity C-reactive Protein (hs-CRP) serum level > 4.0 mg/dL 
6. Acute Physiology and Chronic Health Evaluation (APACHE IV) score > 5 
7. Agrees to the collection of nasopharyngeal (NP) swabs and venous blood per protocol. 
8. Ability to attend required study visits and return for adequate follow-up, as required by this 
protocol. 
9. Agreement to practice effective contraception for female subjects of child-bearing potential 
and non-sterile males. Female subjects of child-bearing potential must agree to use effective 
contraception while on study and for at least 1 month after the last dose of BM-Allo.MSC. 
Non-sterile male subjects must agree to use a condom while on study and for up to 1 month 
after the dose of BM-Allo.MSC. Effective contraception includes surgical sterilization (eg, 
vasectomy, tubal ligation), two forms of barrier methods (eg, condom, diaphragm) used with 
spermicide, intrauterine devices (IUDs), oral contraceptives, and abstinence. 
Exclusion Criteria: 
1. Known hypersensitivity to any component of the study medication(s), including dimethyl 
sulfoxide (DMSO). 
2. Signs of multisystem organ failure. Liver function tests (LFTs) > 5x normal. 
3. Intubated > 72 continuous hours. 
4. Assessed by the Investigator to be unable or unwilling to comply with the requirements of the 
protocol. 
5. Pregnant and nursing women. A negative serum pregnancy test during screening (within 
72 hours prior to the first dose) must be documented before MSCs are administered to a female 
subject of child-bearing potential. 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 2 
 
Confidential and Proprietary 
8 
Products, Dosage, and Mode of Administration: 
Investigational Products  
 
Dosage 
Mode of Administration 
BM-Allo.MSC 
0.7-1.3 × 106 cells/kg 
IV 
Duration of Treatment:  
Subjects in the experimental arm will be administered BM-Allo.MSC (0.7-1.3×106 cells/kg IV) on 
day 1 followed by day 5 (±1 day), if subject still requires ventilation on day 5. Subjects will be 
followed through day 60. Subjects in the control arm will be treated with placebo on a schedule 
identical to that of the experimental arm and followed through day 60. 
Duration of Follow-up: 
Subjects who receive study treatment for any reason will be followed via regular visits with a health 
care professional until either death (by any cause) or for a minimum of 30 days after administration of 
BM-Allo.MSC. 
Reference Therapy, Dosage, and Mode of Administration:  
Subjects randomized to the control arm will receive an IV infusion of placebo, provided to the clinical 
treatment site as a cryopreserved preparation. The cryopreserved placebo consists of 5% albumin 
(human), USP, and CryoStor 10 (1:1 ratio) in a volume of 100 mL. 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 2 
 
Confidential and Proprietary 
9 
Evaluation of Endpoints: 
Safety: Safety endpoints include assessments of treatment-emergent AEs, SAEs, and changes 
hemoglobin, platelets, and white blood cell (WBC) count safety laboratory tests and vital signs. 
Toxicities will be graded using CTCAE Version 5.0  
Efficacy: Mortality and cause of death within 30 days of randomization, number of ventilator-free days 
with 60 days of randomization, number of subjects reporting each severity rating on the 7-point ordinal 
scale, and number of subjects with improved NEW scores and 7-point ordinal scale. 
Statistical Methods: 
All subjects receiving at least one dose of study drug (ie, the Safety population) will be included in the 
safety and efficacy analyses. Statistical analysis will be descriptive and presented by treatment arm. No 
statistical testing will be performed. 
Safety Analyses: 
Overall safety will be assessed by descriptive analyses using tabulated frequencies of AEs by grade 
using CTCAE version 5 in terms of treatment-emergent AEs, SAEs, and AEs by grade and clinically 
significant changes in safety laboratory tests and vital signs. 
Efficacy Analyses: 
The mortality rate within 30 days of randomization and 95% confidence interval will be summarized. 
Cause of death will be summarized. The mean number of ventilator-free days and number of days 
requiring oxygen within 60 days of randomization and the mean duration of hospitalization will be 
summarized. 
Time from randomization to an improvement of one category on the 7-point ordinal scale will be 
summarized. The mean change from baseline on the 7-point ordinal scale at each post-baseline 
evaluation time point will be summarized. 
The mean change from baseline for each parameter of NEWS and the overall score at each 
post-baseline evaluation time point will be summarized. Time from randomization to discharge or to a 
NEWS of ≤ 2 maintained for 24 hours, whichever occurs first will be summarized. The mean change 
from baseline in SOFA score at each post-baseline evaluation time point will be summarized.   

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 2 
 
Confidential and Proprietary 
10 
Figure 1: 
Study Treatment Schema 
 
 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 2 
 
Confidential and Proprietary 
39 
Table 5: 
Schedule of Events 
 
Baseline/Screeninga 
Study Day  
Study Day 
-1 or 1 
1 
5 
8 
15 
22 
29 
60/EOS 
Windows (days) 
 
± 1 
± 4 
General Assessments 
Informed consent 
X 
 
 
 
 
 
 
 
Inclusion/exclusion 
X 
 
 
 
 
 
 
 
Demographics 
X 
 
 
 
 
 
 
 
Medical history 
X 
 
 
 
 
 
 
 
Confirm contraceptive 
measures 
X 
 
 
 
 
 
 
 
APACHE assessment 
X 
 
 
 
 
 
 
 
High-sensitivity CRP 
X 
 
 
 
 
 
 
 
Physical exam: height, 
weightb 
X 
X 
X 
 
 
 
 
 
Vital signsc 
X 
Daily, throughout study period 
 
SOFA assessment 
X 
X 
 
X 
X 
X 
X 
X 
Ordinal scale (7-point) 
X 
X 
 
X 
X 
X 
X 
X 
NEWSc 
X 
Daily, throughout study period 
X 
Concomitant 
medicationsc 
X 
Daily, throughout study period 
X 
Adverse event 
collectionc 
X 
Daily, throughout study period 
X 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 2 
 
Confidential and Proprietary 
40 
 
Baseline/Screeninga 
Study Day  
Study Day 
-1 or 1 
1 
5 
8 
15 
22 
29 
60/EOS 
Windows (days) 
 
± 1 
± 4 
Study drug administration 
BM-Allo.MSC or 
Placebo  
 
X 
Xd 
 
 
 
 
 
Laboratory Assessments 
Collect NP swabs 
X 
X 
 
 
 
 
 
 
Chemistry panele 
X 
X 
 
X 
X 
X 
X 
X 
Hematologyf 
X 
X 
 
X 
X 
X 
X 
X 
Collect whole blood for 
immunogenicity and 
cytokine analyses 
X 
X 
 
X 
X 
X 
X 
X 
Pregnancy testg 
X 
X 
 
 
 
 
 
 
a Baseline/screening assessments may be done ≤ 1 calendar day prior to the first dose of BM-Allo.MSC or placebo. Day 1 assessments do not need to be 
repeated if baseline/screening is done on study day 1. Assessments performed on day 1 must be performed before dosing. 
b Height required at baseline/screening visit only. Weight on day 1 should be used to calculate drug dose. 
c Vital signs, concomitant medications, NEWS assessment, and adverse event collection will occur daily throughout the study period (ie, each day beginning 
day 1 and continuing through day 29). Vital signs of temperature, heart rate, blood pressure, oxygen saturation, and respiratory rate will be assessed at every 
visit.  
d Dose to be administered on day 1 followed by day 5 (±1 day), if subject still requires ventilation on day 5. 
e See Table 4 for additional details on laboratory assessments. Blood draws for lab assessments should occur prior to BM-Allo.MSC or placebo administration. 
f Hematology to include CBC with differential (5 part) as outlined in Table 4. Blood draws for lab assessments should occur prior to BM-Allo.MSC or placebo 
administration. 
g Serum pregnancy tests for females of child-bearing potential. 
 

BM-Allo.MSC 
NantKwest, Inc. 
Clinical Trial Protocol: QUILT-COVID-19-MSC Amendment 2 
APPENDIX 4. SPONSOR SIGNATURE 
Study Title: 
Phase I b Randomized, Double-Blind, Placebo-Controlled Study 
of the Safety of Therapeutic Treatment with lmmunomodulatory 
Mesenchymal Stem Cells in Adults with COVID-19 Infection 
Requiring Mechanical Ventilation 
Study Number: 
QUILT-COVID-19-MSC 
Version Number: 
3 
Final Date: 
10 Sep 2020 
This clinical trial protocol was subject to critical review and bas been approved by NantKwest. 
The following personnel contributed to writing and/or approving this protocol: 
Signed: 
Lennie Sender, MD 
Senior Vice President, Medical Affairs 
NantKwest, Inc 
9920 Jefferson Blvd 
Culver City, CA 90232 
Email: lennie.sender@nantkwest.com 
Cell Phone: 714-615-2350 
Confidential and Proprietary 
66 
.. 
Date: 
__ 
.. . 
- I