Inc. and Gamaleya Research Institute, respectively. hAd5-S-Fusion+NETSD, VXA-

COV2-1 and Ad-COVID are under phase 1 clinical evaluations [1].

Despite numerous advantages, the use of HAd5 in clinic is severely hindered by

the widespread pre-exposure of the majority of the population to HAd5. The gene

transfer efficiency of vectors will be reduced by impairing the B- and T-cell re-

sponses when the HAd5 neutralizing antibodies are prevalent in the human popu-

lation. A survey shows that the seroprevalence rates of HAd5 are 40–60% in

America, while in China, 74.2% of the population carries the neutralizing antibodies

against HAd5 [20,21]. The situation may be even worse in other regions of the

world such as Africa and Asian countries.

To overcome this issue, researchers developed alternative human AdV serotypes

which possess low prevalence among the population such as HAd35, HAd11,

HAd26, etc [22–24]. Though less immunogenic, these rare serotypes are used as an

alternative to HAd5, as vaccine vectors (Figure 11.1). Another alternative strategy

is to isolate AdVs from other species such as cattle, chimpanzees, pigs, etc. and

TABLE 11.2 (Continued)

Clinical trials involving adenovirus vector^a

Vector

Target

Disease

Number of

trials in phase

1/2 and 2, 3,

& 4

NCT number

Prostate

2 (phase 1/2)

NCT01931046;

NCT04097002

1 (phase 2)

NCT00583492

Lymphoma

3 (phase 2)

NCT00849524;

NCT00942409;

NCT03544723

Solid tumor/

tissue sarcoma

2 (phase 1/2)

NCT02842125;

NCT01042535

3 (phase 2)

NCT03544723;

NCT04111172;

NCT00704938

Leukemia/

glioblastoma

3 (phase 2)

NCT00849524;

NCT00942409;

NCT04006119

Melanoma

2 (phase 1/2)

NCT01082887;

NCT01397708

2 (phase 2)

NCT03190824;

NCT00704938

Note

a Data from https://clinicaltrials.gov.

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Bioprocessing of Viral Vaccines