Safety and immunogenicity of the SARS-CoV-2 LYB001 RBD-based VLP vaccine (CHO cell) phase 1 in Chinese adults: a randomized, double-blind, positive-parallel-controlled study

Figures & data

Figure 1. Study flow diagram. from 20 July 2022 to January 2023, a total of 100 eligible participants (age ≥18) out of 149 volunteers screened had been enrolled, who randomly assigned to receive 3 doses totally with LYB001 30 μg (n = 40), or LYB001 60 μg (n = 40) or vaccine ZF2001 (n = 20) at 1:1 in age subgroups (aged 18 ~ 59 years, ≥60 years). Blood samples were collected at day 14 after each vaccination, day 28 after the third dose vaccination to evaluate the post-vaccination immunogenicity. Serological samples were measured by neutralization test, ELISA and ELISPOT essay. Those were collected and assessed on the day of Day 0 (baseline), Day42 (at day 14 after the second dose vaccination), Day 70/Day 84 (the 14th day and the 28th day after the third dose vaccination) based on humoral immunity, cellular immunity and anti-VLP platform. During the second dose vaccination, 1 participant in group of vaccine LYB001 30 μg lost in follow-up visits; during the third dose vaccination, 1 in group of vaccine LYB001 60 μg, and 2 in control group were lost in follow-up visits.

Table 1. Demographic characteristics and baseline of all participants in the phase 1 trial.

		Younger group (aged 18–59 years)				Elderly group (aged ≥60 years)
		LYB001		ZF2001	P value	LYB001		ZF2001	P value
		30 μg	60 μg	control		30 μg	60 μg	control
No. of paticipants (N, missing)		20(0)	20(0)	10(0)		20(0)	20(0)	10(0)
Sex (n, n/N)	Male	4(4/20)	10(10/20)	4(4/10)	0.1358	11(11/20)	8(8/20)	7(7/10)	0.2831
	Female	16(16/20)	10(10/20)	6(6/10)		9(9/20)	12(12/20)	3(3/10)
Age(years, mean±sd)		44.15 ± 12.83	48.44 ± 10.30	49.59 ± 12.34	0.3849	65.81 ± 2.74	65.40 ± 3.27	67.21 ± 3.86	0.3462
Race (n, n/N)	Chinese	20(20/20)	20(20/20)	10(10/10)	-	20(20/20)	20(20/20)	10(10/10)	-
BMI(kg/m^2, mean±sd)		25.00 ± 5.00	25.00 ± 3.00	25.00 ± 4.00	0.8334	25.00 ± 2.00	26.00 ± 4.00	23.00 ± 3.00	0.0502
History of allergy (n, n/N)	No	18(18/20)	19(19/20)	9(9/10)	1.0000	19(19/20)	20(20/20)	10(10/10)	1.0000
	Yes	2(2/20)	1(1/20)	1(1/10)		1(1/20)	0(0)	0(0)
Medical Histroy(n, n/N)	No	15(15/20)	17(17/20)	7(7/10)	0.6793	12(12/20)	11(11/20)	4(4/10)	0.5807
	Yes	5(5/20)	3(3/20)	3(3/10)		8(8/20)	9(9/20)	6(6/10)

Table 2. The solicited adverse events (AEs)* and adverse reactions (ARs)* from the first dose to the 28th day after three dose vaccination, and unsolicited adverse events based on NMPA guidelines by age and dose subgroups.

	Younger group (aged 18–59 years)				Elderly group (aged ≥60 years)				Overall (aged ≥18 years)
	LYB001		ZF2001		LYB001		ZF2001		LYB001		ZF2001
	30 μg	60 μg	control		30 μg	60 μg	control		30 μg	60 μg	control
Adverse events(AEs)	(N = 20)	(N = 20)	(N = 10)	P value	(N = 20)	(N = 20)	(N = 10)	P value	(N = 40)	(N = 40)	(N = 20)	P value
Solicited AEs within 14 days (n, n/N)
Any	12(12/20)	13(13/20)	4(4/10)	0.414	8(8/20)	9(9/20)	4(4/10)	0.940	20(20/40)	22(22/40)	8(8/20)	0.549
Grade ≥3^#	0(0)	0(0)	1(1/10)	0.200	0(0)	2(2/20)	0(0)	0.347	0(0)	2(2/40)	1(1/20)	0.416
Injection site/local ARs (n, n/N)
Any	10(10/20)	7(7/20)	4(4/10)	0.624	5(5/20)	4(4/20)	1(1/10)	0.742	15(15/40)	11(11/40)	5(5/20)	0.508
Grade ≥3^#	0(0)	0(0)	1(1/10)	0.200	0(0)	1(1/20)	0(0)	1.000	0(0)	1(1/40)	1(1/20)	0.677
Pain	9(9/20)	7(7/20)	3(3/10)	0.683	5(5/20)	4(4/20)	1(1/10)	0.742	14(35)	11(11/40)	4(4/20)	0.465
Induration	1(1/20)	2(2/20)	1(1/10)	1.000	0(0)	0(0)	0(0)	–	1(1/40)	2(2/40)	1(1/20)	1.000
Swelling	5(5/20)	4(4/20)	2(2/10)	1.000	0(0)	2(2/20)	0(0)	0.347	5(5/40)	6(6/40)	2(2/20)	0.857
Erythema	1(1/20)	0(0)	2(2/10)	0.098	0(0)	1(1/20)	0(0)	1.000	1(1/40)	1(1/40)	2(2/20)	0.325
Rash	0(0)	1(1/20)	0(0)	1.000	0(0)	0(0)	0(0)	–	0(0)	1(1/40)	0(0)	1.000
Petechiae	0(0)	0(0)	1(1/10)	0.200	0(0)	0(0)	0(0)	–	0(0)	0(0)	1(1/20)	0.200
Pruritus	4(4/20)	4(4/20)	3(3/10)	0.819	0(0)	2(2/20)	1(1/10)	0.408	4(4/40)	6(6/40)	4(4/20)	0.559
Systemic ARs (n, n/N)
Any	7(7/20)	11(11/20)	2(2/10)	0.153	7(7/20)	8(8/20)	4(4/10)	0.938	14(14/40)	19(19/40)	6(6/20)	0.339
Grade ≥3^#	0(0)	0(0)	0(0)	–	0(0)	1(1/20)	0(0)	1.000	0(0)	1(1/40)	0(0)	1.000
Fever	0(0)	0(0)	0(0)	–	0(0)	1(1/20)	1(1/10)	1.000	0(0)	1(1/40)	0(0)	1.000
Drowsiness	1(1/20)	0(0)	0(0)	1.000	0(0)	0(0)	0(0)	–	1(1/40)	0(0)	0(0)	1.000
Headache	1(1/20)	2(2/20)	0(0)	0.796	0(0)	1(1/20)	1(1/10)	0.674	1(1/40)	3(3/40)	1(1/20)	0.838
Dizziness	1(120)	1(1/20)	0(0)	1.000	0(0)	0(0)	1(1/10)	0.200	1(1/40)	1(1/40)	1(1/20)	1.000
Muscle pain	2(2/20)	1(1/20)	0(0)	0.796	0(0)	1(1/20)	0(0)	1.000	2(2/40)	2(2/40)	0(0)	0.682
Cough	0(0)	2(2/20)	0(0)	0.347	1(1/20)	0(0)	0(0)	1.000	1(1/40)	2(2/40)	0(0)	0.802
Hypersensitivity	0(0)	0(0)	1(10)	0.200	0(0)	0(0)	0(0)	–	0(0)	0(0)	1(1/20)	0.200
Petechiae	0(0)	0(0)	0(0)	1.000	0(0)	1(1/20)	0(0)	1.000	0(0)	1(1/40)	0(0)	1.000
Fatigue	2(2/20)	5(5/20)	0(0)	0.187	0(0)	1(1/20)	0(0)	1.000	2(2/40)	6(6/40)	0(0)	0.110
Nausea	2(2/20)	1(1/20)	0(0)	0.796	0(0)	1(1/20)	0(0)	1.000	2(2/40)	2(2/40)	0(0)	0.682
Vomiting	1(1/20)	0(0)	0(0)	1.000	0(0)	0(0)	1(1/10)	0.200	1(1/40)	0(0)	1(1/20)	0.677
Unsolicited AEs within 28 days (n, n/N)
Any	2(2/20)	2(2/20)	2(2/10)	0.727	1(1/20)	0(0)	0(0)	1.000	3(3/40)	2(2/40)	2(2/20)	–
Grade ≥3^#	0(0)	0(0)	0(0)	–	0(0)	0(0)	0(0)	–	0(0)	0(0)	0(0)	–

*AEs were defined as that any untoward medical occurrence in a clinical investigation subject administered the investigational vaccine and which does not necessarily have a causal relationship with this treatment; which may be manifested as symptoms and signs, illness, or laboratory abnormalities.

*ARs were defined as that any harmful or undesired reaction that occurs during a clinical trial that may be associated with the investigational vaccine. There is at least a reasonable possibility of causality between the investigational vaccine and the adverse event, and an association cannot be ruled out.

^#Grade ≥3 was defined as severe generally where significant limitation in activity that requires medical attention and treatment and may require hospitalization. For ARs in local site, Grade ≥ 3 was impact on daily life, while in systemic ARs, Grade ≥ 3 was seriously affecting daily life.

Figure 2. LYB001 induced significantly 50% live-virus and pseoduvirus-neutralizing antibody responses, compared with control group of vaccine ZF2001 by dose and age subgroups. a – d, Serum samples were collected at baseline (before prime vaccination), day 42 (at day 14 after the second dose vaccination), and day 70 and 84 (at day 14 and 28 after whole vaccination) in the LYB001 groups of 30 μg and 60 μg, and control group by the younger cohort and elderly cohort. a-b, A panel of real-virus immune responses of 50% SARS-CoV-2-neutralizing antibody GMTs measured by ELISA assay are demonstrated. c-d, A panel of pseoduvirus immune responses of 50% SARS-CoV-2-neutralizing antibody GMTs measured by ELISA assay are shown. Each point represents a serum sample, and each bar represents the mean of GMT with 95% CI by using Clopper-Pearson method. The dashed line indicates the lower limit of quantification (LLOQ). The LLOQ was 1:10 for the virus-neutralizing antibody test and 1:100 for ELISA. Neutralizing antibody responses of participants in each dose group of LYB001 were compared to the control group using analysis of covariance with log transformation. GMT as geometric mean titers; nAb as neutralizing antibody; TCID₅₀ as 50% tissue culture infective Dose; WT as wild type strain of SARS-CoV-2; BA.4/5 as BA.4 or BA.5 of omicron strain of SARS-CoV-2; YOA as year of age; D0 as the baseline; 14d as 14 days; 28d as 28 days.

Figure 3. LYB001 induced strong S protein-binding antibody responses, compared with control group of vaccine ZF2001 by dose and age subgroups. serum samples were collected at baseline (before prime vaccination), day 42 (at day 14 after the second dose vaccination), and day 70 and 84 (at day 14 and 28 after whole vaccination) in the LYB001 groups of 30 μg and 60 μg, and control group by the younger cohort and elderly cohort. GMTs measured by ELISA assay are demonstrated. Each point represents a serum sample, and each bar represents the mean of GMT with 95% CI by using Clopper–Pearson method. The dashed line indicates the lower limit of quantification (LLOQ). The LLOQ was 1:10 for the virus-neutralizing antibody test and 1:100 for ELISA. S protein binding antibody titers of participants in each dose group of LYB001 were compared to the control group using analysis of covariance with log transformation.

Figure 4. BLYB001 induced strong T cell responses in vaccinated participants compared with control group. blood specimen obtained on day 0 (baseline pre-vaccination), 42 (at day 14 in 2-dose post-vaccination) and 70 (at day 14 in whole vaccination) were stimulated overnight with overlapping peptide pools representing different portions of the wild-type sequence of SARS-CoV-2 for assessment in direct ex vivo IFN-γ ELISpot assay. Each dot represents the mean spot count from triplicate wells for one participant, after subtraction of the medium-only control by age subgroups. a-c, SARS-CoV-2 specific T cell response of IFN-γ (A), IL-2 (b), and IL-4(C) in younger (aged 18–59 years) and elderly (aged ≥60 years) participants are shown. Comparison of each cytokines between dose groups of LYB001 and control group were tested by using Kruskal-Wallis rank sum test based on geometric mean spot with 95% CIs.

Figure 5. LYB001 elicited strong anti-VLP immune responses, compared with control group of vaccine ZF2001 by dose and age subgroups. serum samples were collected at baseline (before prime vaccination), day 70 (at day 14 after whole vaccination), and day 84 (at day 28 after whole vaccination) in the LYB001 groups of 30 μg and 60 μg, and control group by the younger cohort and elderly cohort. GMTs measured by ELISA assay are demonstrated. Each point represents a serum sample, and each bar represents the mean of GMT with 95% CI by using Clopper-Pearson method. Dose groups of LYB001 were compared to the control group using analysis of variance and ANOVA SNK for pairwise comparison of post hoc test.

Data availability statement

Due to the dataset in this study is not open to the public, appropriate access to the dataset can be requested and addressed to the corresponding authors Fengcai Zhu at [email protected], or Jing Jin at [email protected]. There is no current URL for direct access to the dataset, but reasonable requests or collaboration can be made.