Discussion
SARS-CoV-2 is associated with a wide range of symptoms ranging from a
mild clinical phenotype with fever and cough to severe respiratory
and/or multi-organ failure. SARS-CoV-2 has considerable morbidity and
mortality, particularly among people with advanced age and
co-morbities37. A significant factor contributing to
the morbidity and mortality of this infection is the pulmonary and
systemic inflammatory response38. Multiple SARS-CoV-2
proteins and viral RNAs trigger inflammation. Endosomal and cytoplasmic
viral RNA binds TLR and NOD pathway receptors38;
ORF3a, ORF3b, ORF7a, ORF8a, ORF9b and E envelope proteins are
pro-apoptotic, release NF-κB or activate the NLRP3
inflammasome39,42. Subsequently, inflammasome caspases
cleave interferon signal pathway components cGAS, MAVS, and IRF3
blocking antiviral interferon responses at the same time as the marked
inflammatory reaction43.
We were struck by the minimal clinical findings in this high-risk,
elderly woman with a co-existing hematopoietic malignancy. Our patient
was on chronic ruxolitinib therapy for myelofibrosis. Ruxolitinib
inhibits JAKs and TYK2 and thus downstream STATs and cytokine expression
in T lymphocytes, neutrophils, and dendritic cells44.
We speculate whether our patient’s minimal clinical symptoms throughout
her infection could be linked to the immunosuppressive effect of the
drug. Ruxolitinib may reduce the SARS-CoV-2 inflammatory state, improve
the quality of life, and perhaps prolong survival from this devastating
disease. This speculation is supported by several pilot studies. A trial
by Giudice et al. demonstrated a significant improvement in respiratory
symptoms and radiographic pulmonary lesions in seven SARS-CoV-2 patients
with acute respiratory distress syndrome treated with a combination of
ruxolitinib and eculizumab, an anti-C5a complement monoclonal
antibody45. A retrospective study by La Rosee et al.
showed ≥ 25% reduction in COVID-19 Inflammation Scores (CIS) after
seven days of treatment with ruxolitinib in a subset of 14 patients with
CIS ≥ 10 46. The CIS score measured chest x-ray
abnormalities, levels of CRP, ferritin, triglycerides, IL6, fibrinogen,
blood white cell count, blood lymphocyte count, d-dimer, PTT and
presence or absence of fever. Moreover, Cao et al conducted a
multicenter, randomized control trial evaluating the efficacy of
ruxolitinib in 43 patients with severe SARS-CoV-2 infection. Ruxolitinib
recipients showed a significant improvement in chest computed tomography
and faster recovery from lymphopenia compared to the control
group47. This trial also revealed that ruxolitinib was
well tolerated with infrequent toxicities30.
Theoretically, higher rates of aberrant JAK 2 activating mutations in
older myeloproliferative neoplasm patients could enhance the
hyperinflammatory state induced by SARS-CoV-233.
Nevertheless, treatment with ruxolitinib should proceed cautiously as
ruxolitinib and SARS-CoV-2 have both been associated with coagulopathy
and increased frequency of thromboembolic events48.
An interesting facet of this case is the sustained positivity of the
patient’s SARS-CoV-2 test. She was repeatedly tested for viral RNA
clearance by nasal swab RT-PCR secondary to her immunocompromised state
and because she required a negative test prior to discharge to her
nursing facility. Many SARS-CoV-2 infected individuals have persistently
positive RT-PCR tests for weeks to months after clinical
recovery49. Based on viral culture, the percent of
these individuals who remain infectious approaches zero by 10 to 15 days
after the onset of symptoms49-51. However, shedding of
infectious SARS-CoV-2 has been demonstrated by viral culture or inferred
by the presence of subgenomic RNA in a subset of individuals, including
immunosuppressed hosts, for months following
infection52,53. Higher Cq values of SARS-CoV-2 RT-PCR
reflects lower viral loads and multiple studies have demonstrated
inability to culture infectious virus above certain Cq
thresholds50. As demonstrated in Table 1, the Cq of
the ten subsequent RT-PCR samples by nasopharyngeal swab ranged from
35.7 to 42.5 with a mean of 38.2. Based on the referenced literature,
these values likely represent the presence of low quantities of viral
RNA (vRNA) or vRNA fragments that are non-infectious, although the Cq
thresholds are not directly comparable across assays. We were unable to
culture infectious virus from our patient at day 98. However, it should
be noted that respiratory viral culture is insensitive, and lack of
viral growth in vitro does not ensure lack of infectiousness.
The persistent positivity of her SARS-CoV-2 testing may be potentially
secondary to the immunosuppressive effective of the
ruxolitinib34. Ruxolitinib targets components of both
the innate and adaptive immune system. JAK/TYR2 proteins are downstream
for both innate immune cytokines and adaptive immune interferon
receptors54. Therefore, suppression of the pathway
places a person susceptible to various infections22.
With these defense mechanisms impaired, the drug contributes to
increased risk of reactivation of silent viral, bacterial and fungal
infections55,56. This viral susceptibility is due to
JAK/TYR2 inhibitors suppressing cytokines, such as interferon, and NK
cells22. This case addresses the issue of hampered
anti-viral defense caused by ruxolitinib through the supplementation of
interferon with subsequent T cell activation to fight SARS-CoV-2
infection. Our patient was able to clear the vRNA approximately 30 days
after the administration of a total of four treatments of pegylated
interferon-α2a while continuing treatment with ruxolitinib.
Viruses such as SARS-CoV-2 have evolved to facilitate their own
infectivity and to evade host detection and immune response. SARS-CoV-2
activation of pro-inflammatory pathways described
above39-41 generates intracellular caspases that
degrade interferon and interferon signaling
polypeptides43. Previous data on SARS-CoV and MERS-CoV
outbreaks have revealed additional mechanisms of coronavirus type I
interferon suppression41,48,57,58. To date, data
exists showing that 12 of the 29 SARS CoV-2 proteins block IFN
production early: nsp1 inhibits 40S ribosome participation in IFN
translation; nsp3 blocks RIG-1 PAMP signaling; nsp10 performs
2-O-methyltransferase cap on vRNA to hide the vRNA; nsp13 binds and
inhibits TBK1 PAMP signaling; nsp14 performs N7methyltransferase caps on
vRNA again to disguise the virus; nsp15 remove 5’pU tracts from vRNA to
avoid vRNA detection; nsp16 assists in 2-O-methyltransferase cap
formation on vRNA; ORF3b binds and blocks IRF3 signaling; ORF6 inhibits
karyopherin so cytoplasmic to nuclear PAMP signaling is blocked; M
protein binds and blocks TRAF/TBK1 signaling; orf9b binds and blocks
MAVS PAMP signaling and N protein binds and blocks RIGI PAMP signaling.
SARS-CoV-2 produces a delayed first line antiviral defense followed by
excessive inflammatory cytokinemia and dysfunctional T and NK cell
responses33,48.
Interferons have been successfully used in the treatment of viral
infections, such as hepatitis C, autoimmune diseases such as multiple
sclerosis, and hematologic malignancies such as essential
thrombocythemia, polycythemia vera, and
myelofibrosis59-61. In SARS-CoV-2, interferon therapy
in phase 2 and phase 3 randomized clinical trials have shown reduced the
duration of virus infection, reduced inflammatory markers including IL6
and CRP and reduced mortality when administered
early41,62-68. As a note of caution, type I
interferons administered in later stages may cause progressive tissue
damage leading to a deleterious hyperinflammation characterized by the
excessive macrophage activation and hypercoagulation seen in patients
with acute disease38. Interestingly, pharmacologic
interferon treatment inhibits inflammation early by repressing the NLRP3
inflammasome via STAT1 and STAT369. We hypothesized
that administration of interferon in our patient who was minimally
symptomatic would strengthen anti-viral defense and potentially lead to
viral RNA clearance. Our results support the hypothesis.