An experimental COVID-19 genetic vaccine animal study involving 28 BALB/c mice, aimed at investigating the pathogenesis of myocarditis following modRNA COVID-19 vaccination, unexpectedly provided crucial insights into the carcinogenicity of these products [
33]. Fourteen animals received saline solution, while the remaining were intravenously infused with the modRNA vaccine (BNT162b2). Surprisingly, two days after the booster vaccination (16 days after the first), one of the mice experienced spontaneous death with marked organomegaly and widespread malignant infiltration of the heart, lungs, liver, kidneys, and spleen, consistent with B-cell lymphoblastic lymphoma. This was noted at just 14 weeks of age. It is noteworthy, that the information sheet for the ENVIGO BALB/c model reports a zero incidence of background rates of lymphatic leukaemia [
34]. The authors state that while a definitive causal relationship between the modRNA vaccine and the observed lymphoma in the animal cannot be established, the temporal sequence of events suggests its involvement in this rare haematologic neoplasm.
In the overwhelming majority of cases, there is a
de novo onset of proliferative disorders affecting the lymphoid lineage, encompassing both B and T phenotypes. The Pfizer/BioNTech vaccine appears to be the most implicated (16 cases). The onset of symptoms following vaccine inoculation has generally been very brief, even within a few days, as seen for instance in the cases reported by Kreher et al., Ukishima et al. and Panou et al. [
44,
45,
47]. In one case, acute lymphoblastic leukemia occurred in a 47-year-old woman who had been in remission for two years from a B-cell lymphoma [
39]. Two cases of T-cell lymphomas exhibited a recurrence of previously well-controlled conditions (mucosis fungoides and lymphomatoid papulosis) [
47]. Notably, in lymphoma cases, four cases showed onset at the inoculation site [
43,
44,
46,
50], and three cases manifested in draining lymph nodes (axillary and lateral cervical) [
35,
38,
48]. An interesting case involves angioimmunoblastic T-cell lymphoma, where rapid progression was observed after the booster dose [
42]. The patient, previously vaccinated with 2 doses of Comirnaty
® 5 and 6 months earlier, had developed a rare form of lymphoma and underwent a staging PET/CT on September 8. Fourteen days later, the patient received a booster dose of the same vaccine in preparation for chemotherapy, and repeated a PET/CT on September 30. The initial PET/CT revealed the presence of hypermetabolic lymph nodes mainly in the supra-clavicular, cervical, and left axillary regions, as wells as restricted gastro-intestinal hypermetabolic lesions. However, the second PET/CT revealed a dramatic increase in nodal and gastro-intestinal hypermetabolic lesions, as well as asymmetrical metabolic progression in the cervical, supra-clavicular and axillary areas.
Potential Carcinogenic Mechanisms Induced by COVID-19 modRNA Vaccines
Several mechanisms have been proposed by which the current modRNA COVID-19 vaccines may exert a carcinogenic effect, inducing both de novo tumour formation and the recurrence of neoplastic diseases in remission. It is also evident, that the genetic material and the vaccine derived spike protein have a significant impact on the immune system and may compromise immune surveillance against altered cellular clones in a manner that could lead to cancer.
The main alterations induced by modRNA COVID-19 vaccines reported in literature, that may have an oncogenic outcome are listed below:
(
i) The alteration of the inhibitory immune checkpoint mediated by the programmed cell death protein 1 (PD-1, CD279), which is primarily found on T-cells, mature B-cells, and other immune cells. The overexpression of the programmed death-ligand 1 (PD-L1), observed in vaccinated individuals, leads to T-cell immunosuppression, impairing cancer surveillance [
54].
(
ii) The interaction between the S2 subunit of the spike protein and the oncosuppressor proteins p53, BRCA1, and BRCA2, which regulate downstream genes in response to numerous cellular stress and play a crucial role in preventing cancer [
55].
(
iii) The impairment in type I interferon (IFN) signalling, which play essential roles in inflammation, immunomodulation, tumour cell recognition, and T-cell responses [
56]. Differential gene expression analysis of peripheral dendritic cells revealed dramatic upregulation of type I and type II IFNs in COVID-19 patients, but not in vaccinees. All this supports the possibility that COVID-19 genetic vaccines actively suppress the production of type I IFN which play a fundamental role in the immune reaction in response to multiple stressors, especially viral infections and tumours. In the presence of a viral infection, the production of type I IFN drastically increases and IFN-α, released in the lymph nodes, induces B-cells to differentiate into plasmablasts and subsequently, thanks to IL6, to evolve into antibody-secreting plasma cells. As regards the anti-tumour action of IFNs, this occurs through both direct and indirect mechanisms. Direct effects include cell cycle arrest, induction of cell differentiation, initiation of apoptosis, and activation of natural killer and CD8
+ T-cells. The indirect anti-tumour effects are mainly due to the activation of transcription factors which improve the expression of at least 150 genes also involved in apoptosis.
(
iv) Increased Transforming Growth Factor Beta (TGF-β) Production. The interaction between the SARS-CoV-2 spike protein and the angiotensin-converting enzyme 2 (ACE2) induces TGF-β release by cells such as alveolar and tissue macrophages, lung epithelial cells, endothelial cells and B lymphocytes, promoting epithelial-mesenchymal transition (EMT) [
57]. This process could explain the particular rapidity of onset and evolution of tumour forms arising following the administration of the COVID-19 genetic vaccines. In fact, the TGF-β is a growth factor capable of inducing in already differentiated cells a “regression” towards the mesenchymal state (a state typical of the early stages of embryonic life), with the ability to metastasize and greater biological aggressiveness.
(
v) The presence of LNP-encapsulated DNA contamination originating from residual plasmid DNA from DNA plasmids used during the manufacturing process of the Pfizer/BioNTech and Moderna modRNA genetic vaccines [
58,
59]. The residual DNA detected in the modRNA genetic vaccines is high in copy number and contains elements such as: functional promoters, open reading frames (ORFs), origins of replication and nuclear targeting sequences [
59]. In the case of the Pfizer/BioNTech genetic vaccine, such plasmids have been engineered with a mammalian SV40 promoter-enhancer-
ori from the oncogenic virus Simian Virus 40 (SV40) along with a nuclear targeting sequence (NTS) [
58,
59]. This human compatible promoter is not required for the expression of these plasmids in the
E. coli bacterial expression system and its presence is highly unusual as it poses a significant oncogenic risk that is not needed for the plasmid’s stated purpose. The FDA has guidance for plasmid DNA-based genetic vaccines and while the modRNA are not defined as DNA based-vaccines, the contaminating plasmids’ design is consistent with this application and it is expected that portions of the contaminating plasmid DNA with eukaryotic promoters and enhancers will pose the same risks of insertional mutagenesis. FDA advises the following: “
Plasmid biodistribution, persistence and integration studies were initially recommended to examine whether subjects in DNA vaccine trials were at heightened risk from the long-term expression of the encoded antigen, either at the site of injection or an ectopic site, and/or plasmid integration. Theoretical concerns regarding DNA integration include the risk of tumorigenisis if insertion reduces the activity of a tumor suppressor or increases the activity of an oncogene. In addition, DNA integration may result in chromosomal instability through the induction of chromosomal breaks or rearrangements.” [
60]. Additionally, the presence of the contaminating plasmids is far above the regulated limits for naked DNA contamination on vaccines [
58,
59]. As recently reported by Cancer Geneticist Prof. Buckhaults [
61] and by Toxicologist and Molecular Biologist Janci Lindsay, Ph.D. [
62] before the South Carolina Senate Medical Affairs Ad-Hoc Committee, these are extremely serious and unexplainable contaminants of the Pfizer/BioNTech modRNA vaccines, because they increase the likelihood that these contaminating sequences from this oncogenic virus as well as other sequences contained within the plasmids and encapsulated within the LNPs, will integrate into the DNA of the vaccinees with consequences that are difficult to predict. Insertional mutagenesis is often leading to cancer, and in fact, gene therapy has long been known to bear an oncogenic risk as recognized by the FDA in their guidance on plasmid DNA vaccines [
60], and the previous studies cited [
23,
24,
25]. According to Buckhaults, the urgency of the pandemic crisis induced the pharmaceutical companies to take some “shortcuts”, using bacteria for the mass production of the modRNA vaccines. The SV40 DNA sequences derive from a plasmid engineered for the modRNA production in bacteria, specifically modified to include the
SPIKE gene. Pfizer/BioNTech tried to solve the problem by adding the enzyme deoxyribonuclease to chop the plasmid into millions of small fragments. However, according to Prof. Buckhaults, this actually increased the risks because the more fragments there are, the more likely it is that one of them will fit into the genome and interfere with crucial genes. Prof. Buckhaults and Dr. Lindsay expressed their concern about the theoretical, but very real risk of future cancer in some people, depending on where foreign pieces of DNA integrate in the genome, potentially disrupting suppressor genes or activating oncogenes. In fact, as relayed earlier the SV40 virus is a known oncogenic virus when intact [
63,
64]. There is also the additional potential for the modRNA to be reverse transcribed to DNA through the reverse transcriptase activity of LINE-1, as previously demonstrated by Aldén et al., especially in tissues such as the testes and ovaries as well as the bone marrow that are rich in this transcription factor [
59,
65].
(
vi) The role of the immunoglobulin subtype IgG4 in cancer immune evasion. Wang et al. found that IgG4-containing B lymphocytes and IgG4 concentration were significantly increased in cancer tissues, as well as in the serum of patients with cancer [
66]. Both were positively correlated with worse prognoses and increased cancer malignancy. Previous works reported that IgG4 was generated locally in melanoma, playing an important role in removing the tumour from the control of the immune system and therefore facilitating its development [
67,
68]. Increased production of IgG4 is normally associated with prolonged exposure to antigens, and their interaction with antibodies of the IgG and IgE classes through their Fc domains has been reported [
69]. IgG4 is in fact endowed with a dual role, as it can suppress or stop inflammation by competing with inflammatory IgE for binding to the antigen, in the case of allergies and infections from helminths and filarial parasites or, on the contrary, IgG4 can lead to serious autoimmune [
70] and tumour diseases, playing an essential role in the “immune evasion” of cancer cells. Recent studies indicate that repeated modRNA vaccinations against COVID-19 shift the antibody response towards the IgG4 subclass with a decrease in FcγR-dependent effector activity and an increased mortality in case of COVID-19 infection [
71,
72,
73]. In cohorts of healthy healthcare workers, it was demonstrated that several months after the second dose the SARS-CoV-2-specific antibodies were increasingly composed of non-inflammatory IgG4, which were further enhanced by a third modRNA vaccination and/or by infections of SARS-CoV-2 variants [
72]. IgG4 antibodies, among all spike-specific IgG antibodies, increased on average from 0.04% shortly after the second vaccination, to almost 20% (19.27%) after the third vaccination [
73]. In conclusion, the increase in IgG4 following repeated administration of modRNA vaccines is undoubted and this generates serious concerns regarding the involvement of IgG4 in the “immune evasion” of cancer cells.
(
vii) The incorporation of m1Ψ into the modRNA of the genetic vaccines causes ribosomal frame-shifting during translation, which can lead to the production of numerous peptide products that are expressed differently in each individual [
29]. Given that these unidentified peptides may have unknown antigenic and auto-immune potential, they pose a serious risk for carcinogenesis that should be deeply investigated.