A Study to Assess the Safety, Tolerability and Effectiveness of Monoclonal Antibodies to Treat Hospitalized Patients with COVID-19


About this study

The purpose of this study is to evaluate the effectiveness, safety, and tolerability of REGN10933+REGN10987 in hospitalized adult patients with COVID-19.

Participation eligibility

Participant eligibility includes age, gender, type and stage of disease, and previous treatments or health concerns. Guidelines differ from study to study, and identify who can or cannot participate. There is no guarantee that every individual who qualifies and wants to participate in a trial will be enrolled. Contact the study team to discuss study eligibility and potential participation.

Inclusion Criteria:

  • Has provided informed consent (signed by study patient or legally acceptable representative).
  • Male or female adult ≥ 18 years of age (or country’s legal age of adulthood) at randomization.
  • Laboratory-confirmed SARS-CoV-2 infection as determined by a RT-PCR result from any specimen (or other commercial or public health assay) ≤ 72 hours from randomization and no alternative explanation for current clinical condition.
  • COVID-19 symptom onset ≤ 7 days.
  • Hospitalized for COVID-19 illness for < 72 hours with at least 1 of the following at randomization; patients meeting more than one criterion will be categorized in the most severely affected category:
    • Cohort 1: Maintains O2 saturation > 93% on low-flow oxygen via nasal cannula, simple face mask, or other similar device;
    • Cohort 2: High-intensity oxygen therapy without mechanical ventilation, where high-intensity is defined as receiving supplemental oxygen delivered by 1 of the following devices:
      • Non-rebreather mask (with an SpO2 ≤ 96% while receiving an oxygen flow rate of at least 10 L/min).
      • High-flow device (e.g., AIRVO™ or Optiflow™) with at least 50% FiO2.
      • Non-invasive ventilator, including continuous positive airway pressure (CPAP), to treat hypoxemia (excluding isolated use for sleep-disordered breathing).
    • Cohort 3: On mechanical ventilation

Exclusion Criteria:

  • Phase 1 only: Patients maintaining O2 saturation > 94% on room air.
  • In the opinion of the investigator, unlikely to survive for > 48 hours from screening.
  • Receiving extracorporeal membrane oxygenation (ECMO).
  • Has new-onset stroke or seizure disorder during hospitalization.
  • Initiated on renal replacement therapy due to COVID-19.
  • Has circulatory shock requiring vasopressors at randomization.
    • Note: Patients who require vasopressors for sedation-related hypotension or reasons other than circulatory shock may be eligible in this study.
  • Patients who have received convalescent plasma or IVIG in the past 5 months or plan to receive during the study period for any indication.
  • Participation in a clinical research study, including any double-blind study, evaluating an investigational product within 30 days and less than 5 half-lives of the investigational product prior to the screening visit.
    • Note: The use of remdesivir, hydroxychloroquine, or other treatments (except for COVID- 19 convalescent plasma or IVIG) being used for COVID-19 treatments in the context of the local standard-of-care or an open-label study or compassionate use protocol is permitted.
  • Any physical examination findings, history of illness, and/or concomitant medications that, in the opinion of the study investigator, might confound the results of the study or pose an additional risk to the patient by their participation in the study.
  • Known allergy or hypersensitivity to components of study drug.
  • Pregnant or breastfeeding women.
  • Continued sexual activity in women of childbearing potential (WOCBP)* or sexually active men who are unwilling to practice highly effective contraception prior to the initial dose/start of the first treatment, during the study, and for at least 6 months after the last dose.
  • Highly effective contraceptive measures in women include:
    • Stable use of combined (estrogen and progestogen containing) hormonal contraception (oral, intravaginal, transdermal) or progestogen-only hormonal contraception (oral, injectable, implantable) associated with inhibition of ovulation initiated 2 or more menstrual cycles prior to screening;
    • Intrauterine device (IUD);
    • Intrauterine hormone-releasing system (IUS);
    • Bilateral tubal ligation;
    • Vasectomized partner,† and/or;
    • Sexual abstinence‡,§;
    • Male study participants with WOCBP partners are required to use condoms unless they are vasectomized† or practice sexual abstinence.‡,§.

* WOCBP are defined as women who are fertile following menarche until becoming postmenopausal, unless permanently sterile. A postmenopausal state is defined as no menses for 12 months without an alternative medical cause. A high follicle stimulating hormone (FSH) level in the postmenopausal range may be used to confirm a postmenopausal state in women not using hormonal contraception or hormonal replacement therapy. However, in the absence of 12 months of amenorrhea, a single FSH measurement is insufficient to determine the occurrence of a postmenopausal state. The above definitions are according to Clinical Trial Facilitation Group (CTFG) guidance. Pregnancy testing and contraception are not required for women with documented hysterectomy or tubal ligation. Permanent sterilization methods include hysterectomy, bilateral salpingectomy, and bilateral oophorectomy.

† Vasectomized partner or vasectomized study participant must have received medical assessment of the surgical success.

‡ Sexual abstinence is considered a highly effective method only if defined as refraining from heterosexual intercourse during the entire period of risk associated with the study drugs. The reliability of sexual abstinence needs to be evaluated in relation to the duration of the clinical trial and the preferred and usual lifestyle of the patient.

§ Periodic abstinence (calendar, symptothermal, post-ovulation methods), withdrawal (coitus interruptus), spermicides only, and lactational amenorrhea method (LAM) are not acceptable methods of contraception. Female condom and male condom should not be used together.


Participating Mayo Clinic locations

Study statuses change often. Please contact the study team for the most up-to-date information regarding possible participation.

Mayo Clinic Location Status

Rochester, Minn.

Mayo Clinic principal investigator

Raymund Razonable, M.D.

Closed for enrollment

More information


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Additional contact information

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Phone: 800-664-4542 (toll-free)

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