Monomethyl Auristatin E (MMAE), a Payload for Multiple Antibody Drug Conjugates (ADCs), Demonstrates Differential Red Blood Cell Partitioning Across Human and Animal Species

Figures & data

Table 1. Maximum unconjugated MMAE concentration (C_max) detected in plasma from SCID mouse, Sprague Dawley rat, cynomolgus monkey (Lu et. al., 2015) and human (Li et al., 2020) after a single intravenous dose of 1) polatuzumab vedotin or 2) pinatuzumab vedotin. When C_max is normalized to dose (C_max/D), the human C_max/D is 37- to 98-fold higher than the pre-clinical species C_max/D.

Species	ADC Dose level (mg/kg)	Unconjugated MMAE Cmax (ng/mL)	Cmax normalized to dose (Cmax/D)	Fold from human Cmax/D
Human^1	2.4	6.66	2.78	1
Cynomolgus Monkey^1	3	0.085	0.0283	98
SD Rat^2	5	0.306	0.0612	45
SCID Mouse^2	5	0.378	0.0756	37

¹ Dosed with polatuzumab vedotin ² Dosed with pinatuzumab vedotin

Table 2. Average MMAE concentration (%ID/mL) in blood and plasma after a single dose of [³H]-MMAE at 200 μg/kg in SD rat. Blood-to plasma ratio reached a maximum level of 5.13 at 0.75 hour post dose.

Time (hr)	Average blood concentration (%ID/mL)	Average plasma concentration (%ID/mL)	Blood-to-plasma ratio
0.0333	0.301	0.272	0.903
0.0833	0.0616	0.0890	1.44
0.1667	0.0261	0.0668	2.56
0.5	0.0129	0.0497	3.86
0.75	0.0086	0.0439	5.13
1	0.0113	0.0555	4.93
3	0.0116	0.0366	3.16
6	0.0077	0.0378	4.93

Table 3. Average unconjugated MMAE concentration (ng/mL) in blood and plasma after a single dose of pinatuzumab vedotin at 5 mg/kg in SD rat. Blood-to plasma ratio reached a maximum level of 12.2 at 1 hour post dose and leveled off at 1.65 by 72 hours post dose.

Time (hr)	Average blood concentration (ng/mL)	Average plasma concentration (ng/mL)	Blood-to-plasma ratio
0.0833	0.48	LLOQ (<0.0359)	N/A
1	0.555	0.045	12.2
6	0.642	0.162	3.95
24	0.545	0.306	1.78
48	0.405	0.245	1.65
72	0.610	0.370	1.65
96	LLOQ (<0.180)	0.058	N/A
168	LLOQ (<0.180)	0.045	N/A

Table 4. Average unconjugated MMAE concentration (ng/mL) in blood and plasma after a single dose of pinatuzumab vedotin at 5 mg/kg in SCID mouse. Blood-to plasma ratio reached a maximum level of 6.40 at 72 hours post dose and leveled off at around 5.

Time (hr)	Average blood concentration (ng/mL)	Average plasma concentration (ng/mL)	Blood-to-plasma ratio
0.0833	1.37	0.349	3.93
1	0.914	0.378	2.42
6	0.925	0.274	3.38
24	0.716	0.168	4.26
48	0.558	0.124	4.50
72	0.788	0.123	6.40
96	0.474	0.091	5.24
168	0.220	0.044	4.98

Figure 1. Structure of [³H]-MMAE-pinatuzumab vedotin (DAR of 3.4) and the location of the radiolabeled ³H on MMAE.

Figure 3. Systemic PK of unconjugated [³H]-MMAE following single IV administration in rat. Radioactivity of [³H]-MMAE (as % of injected dose per ml of volume) from whole blood and plasma in rats up to 6 hours post administration. Radioactivity concentration was fairly similar between blood and plasma initially, then increase to about 5-fold higher in blood compared to plasma, suggesting a strong partition to red blood cells.

Figure 4. Plasma and whole blood of unconjugated MMAE concentration after a single intravenous dose of pinatuzumab vedotin at 5 mg/kg in rats. All plasma concentration were lower than the blood concentration of the same sample with a maximum blood-to-plasma ratio of 12.2 at 1-hour post-dose to a minimum of 1.65 at 72-hours post-dose. Blood AUC_(1h-72h) compared to plasma AUC_(1h-72h) showed a ratio of 1.99 over this quantifiable time range.

Figure 5. Plasma and whole blood of unconjugated MMAE concentration after a single intravenous dose of pinatuzumab vedotin at 5 mg/kg in mice. At 1-hour post-dose, deconjugated MMAE concentration in the blood was 2.41-fold of that of the plasma concentration. As both blood and plasma concentration decreased, the blood-to-plasma ratio increased to maximum of 6.40 at 72-hours post-dose. Overall, the Blood AUC_(1h-72h) compared to plasma AUC_(1h-72h) showed a ratio of 4.21.