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The Broad Anti-AML Activity of the CD33/CD3 BiTE Antibody Construct, AMG 330, Is Impacted by Disease Stage and Risk.

Harrington KH, Gudgeon CJ, Laszlo GS, Newhall KJ, Sinclair AM, Frankel SR, Kischel R, Chen G, Walter RB - PLoS ONE (2015)

Bottom Line: With healthy donor T-cells added, AMG 330 cytotoxicity depended on the drug dose and effector:target (E:T) cell ratio.AMG 330 cytotoxicity also appeared greater in specimens from patients with favorable-risk disease as compared to other specimens.Together, our data demonstrate that AMG 330 is highly active in primary AML specimens across the entire disease spectrum, while suggesting the presence of yet undefined, CD33-independent, relative resistance mechanisms in specific patient subsets.

View Article: PubMed Central - PubMed

Affiliation: Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America.

ABSTRACT
The CD33/CD3-bispecific T-cell engaging (BiTE) antibody construct, AMG 330, potently lyses CD33+ leukemic cells in vitro. Using specimens from 41 patients with acute myeloid leukemia (AML), we studied the factors that might contribute to clinical response or resistance. For this purpose, thawed aliquots of primary AML samples were immunophenotypically characterized and subjected to various doses of AMG 330 in the presence or absence of healthy donor T-cells. After 48 hours, drug-specific cytotoxicity was quantified and correlated with CD33 expression levels, amounts of T-cells present, and other disease characteristics. AMG 330 caused modest cytotoxicity that was correlated with the amount of autologous T-cells (P = 0.0001) but not CD33 expression, as AMG 330 exerted marked cytotoxic effects in several specimens with minimal CD33 expression. With healthy donor T-cells added, AMG 330 cytotoxicity depended on the drug dose and effector:target (E:T) cell ratio. High cytotoxic activity was observed even with minimal CD33 expression, and AMG 330 cytotoxicity and CD33 expression correlated only at high E:T cell ratio and high AMG 330 doses (P<0.003). AMG 330 resulted in significantly higher cytotoxicity in specimens from patients with newly diagnosed AML than those with relapsed/refractory disease despite similar levels of CD33 on myeloblasts. AMG 330 cytotoxicity also appeared greater in specimens from patients with favorable-risk disease as compared to other specimens. Together, our data demonstrate that AMG 330 is highly active in primary AML specimens across the entire disease spectrum, while suggesting the presence of yet undefined, CD33-independent, relative resistance mechanisms in specific patient subsets.

No MeSH data available.


Related in: MedlinePlus

Relationship between CD33 expression and AMG 330-induced cytotoxicity.Relationship between CD33 expression on leukemic blasts (expressed as arbitrary fluorescence intensity) and drug-induced cytotoxicity with AMG 330 at 250 pg/mL (open symbol) and 500 pg/mL (closed symbol) in the presence of T-cells from a single healthy donor at an E:T cell ratio of (A) 1:3, (B) 1:1, and (C) 3:1, determined after 48 hours.
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pone.0135945.g003: Relationship between CD33 expression and AMG 330-induced cytotoxicity.Relationship between CD33 expression on leukemic blasts (expressed as arbitrary fluorescence intensity) and drug-induced cytotoxicity with AMG 330 at 250 pg/mL (open symbol) and 500 pg/mL (closed symbol) in the presence of T-cells from a single healthy donor at an E:T cell ratio of (A) 1:3, (B) 1:1, and (C) 3:1, determined after 48 hours.

Mentions: As shown in Fig 2, the cytotoxic activity of AMG 330 was strictly dependent on the drug dose (e.g. P<0.0001 at E:T = 1:3) and the E:T cell ratio (e.g. P<0.0001 at 500 pg/mL). However, high activity of AMG 330 was even observed in specimens with very low CD33 expression on AML blasts. Similar to the experiments in which no healthy donor T-cells were added, there was no significant correlation between drug-induced cytotoxicity and CD33 expression levels on AML blasts at lower E:T cell ratios (with E:T = 1:3, P = 0.86 and P = 0.50 at 250 and 500 pg/mL, respectively; with E:T = 1:1, P = 0.43 and P = 0.16 at 250 and 500 pg/mL, respectively; Fig 3A and 3B). On the other hand, in experiments in which an E:T cell ratio of 3:1 was used, there was a statistically significant correlation between CD33 expression on AML blasts and AMG 330-induced cytotoxicity (at 250 pg/mL: r = 0.457 [0.165–0.676], P = 0.0027; at 500 pg/mL: r = -0.465 [0.174–0.681], P = 0.0022; Fig 3C).


The Broad Anti-AML Activity of the CD33/CD3 BiTE Antibody Construct, AMG 330, Is Impacted by Disease Stage and Risk.

Harrington KH, Gudgeon CJ, Laszlo GS, Newhall KJ, Sinclair AM, Frankel SR, Kischel R, Chen G, Walter RB - PLoS ONE (2015)

Relationship between CD33 expression and AMG 330-induced cytotoxicity.Relationship between CD33 expression on leukemic blasts (expressed as arbitrary fluorescence intensity) and drug-induced cytotoxicity with AMG 330 at 250 pg/mL (open symbol) and 500 pg/mL (closed symbol) in the presence of T-cells from a single healthy donor at an E:T cell ratio of (A) 1:3, (B) 1:1, and (C) 3:1, determined after 48 hours.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4549148&req=5

pone.0135945.g003: Relationship between CD33 expression and AMG 330-induced cytotoxicity.Relationship between CD33 expression on leukemic blasts (expressed as arbitrary fluorescence intensity) and drug-induced cytotoxicity with AMG 330 at 250 pg/mL (open symbol) and 500 pg/mL (closed symbol) in the presence of T-cells from a single healthy donor at an E:T cell ratio of (A) 1:3, (B) 1:1, and (C) 3:1, determined after 48 hours.
Mentions: As shown in Fig 2, the cytotoxic activity of AMG 330 was strictly dependent on the drug dose (e.g. P<0.0001 at E:T = 1:3) and the E:T cell ratio (e.g. P<0.0001 at 500 pg/mL). However, high activity of AMG 330 was even observed in specimens with very low CD33 expression on AML blasts. Similar to the experiments in which no healthy donor T-cells were added, there was no significant correlation between drug-induced cytotoxicity and CD33 expression levels on AML blasts at lower E:T cell ratios (with E:T = 1:3, P = 0.86 and P = 0.50 at 250 and 500 pg/mL, respectively; with E:T = 1:1, P = 0.43 and P = 0.16 at 250 and 500 pg/mL, respectively; Fig 3A and 3B). On the other hand, in experiments in which an E:T cell ratio of 3:1 was used, there was a statistically significant correlation between CD33 expression on AML blasts and AMG 330-induced cytotoxicity (at 250 pg/mL: r = 0.457 [0.165–0.676], P = 0.0027; at 500 pg/mL: r = -0.465 [0.174–0.681], P = 0.0022; Fig 3C).

Bottom Line: With healthy donor T-cells added, AMG 330 cytotoxicity depended on the drug dose and effector:target (E:T) cell ratio.AMG 330 cytotoxicity also appeared greater in specimens from patients with favorable-risk disease as compared to other specimens.Together, our data demonstrate that AMG 330 is highly active in primary AML specimens across the entire disease spectrum, while suggesting the presence of yet undefined, CD33-independent, relative resistance mechanisms in specific patient subsets.

View Article: PubMed Central - PubMed

Affiliation: Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America.

ABSTRACT
The CD33/CD3-bispecific T-cell engaging (BiTE) antibody construct, AMG 330, potently lyses CD33+ leukemic cells in vitro. Using specimens from 41 patients with acute myeloid leukemia (AML), we studied the factors that might contribute to clinical response or resistance. For this purpose, thawed aliquots of primary AML samples were immunophenotypically characterized and subjected to various doses of AMG 330 in the presence or absence of healthy donor T-cells. After 48 hours, drug-specific cytotoxicity was quantified and correlated with CD33 expression levels, amounts of T-cells present, and other disease characteristics. AMG 330 caused modest cytotoxicity that was correlated with the amount of autologous T-cells (P = 0.0001) but not CD33 expression, as AMG 330 exerted marked cytotoxic effects in several specimens with minimal CD33 expression. With healthy donor T-cells added, AMG 330 cytotoxicity depended on the drug dose and effector:target (E:T) cell ratio. High cytotoxic activity was observed even with minimal CD33 expression, and AMG 330 cytotoxicity and CD33 expression correlated only at high E:T cell ratio and high AMG 330 doses (P<0.003). AMG 330 resulted in significantly higher cytotoxicity in specimens from patients with newly diagnosed AML than those with relapsed/refractory disease despite similar levels of CD33 on myeloblasts. AMG 330 cytotoxicity also appeared greater in specimens from patients with favorable-risk disease as compared to other specimens. Together, our data demonstrate that AMG 330 is highly active in primary AML specimens across the entire disease spectrum, while suggesting the presence of yet undefined, CD33-independent, relative resistance mechanisms in specific patient subsets.

No MeSH data available.


Related in: MedlinePlus