Abstract 385: Synergistic effects of MIA-602 and its potential for use in ATRA/ATO Resistant APL
Authors: Chale Ravinder S. , Rodriguez Mario , Almeida Stephanie M. , Sclatter Shelly , Singaready Anastasia , Schally Andrew V. , Jimenez Joaquin J. 
Published: April 2023

Introduction: Acute Myeloid Leukemia (AML) is a malignant neoplastic disease arising from myeloid cell lines. AML is characterized by the proliferation of immature, nonfunctional cells in the bone marrow. Acute Promyelocytic Leukemia (APL) is a subtype of AML characterized by proliferation of immature promyelocytes. Growth Hormone Releasing Hormone (GHRH) is a hypothalamic peptide that stimulates the release of Growth Hormone from the anterior pituitary. This study aimed to investigate the role of MIA-602, a growth hormone-releasing hormone receptor (GHRH-R) antagonist as front line-combination therapy in the K-562 in-vitro model of AML as well as its potential for treating ATRA/ATO resistant APL.

Design: Western blot analysis was used to detect the GHRH-R in both K-562 and NB4 cell lines. K562 cells were maintained as a cell suspension in the RPMI medium, with 10% heat-inactivated fetal bovine serum and gentamicin. Doxorubicin treatment concentrations were 0.005, 0.01, and 0.05 μg/μl. Combination therapy concentrations were 0.005, 0.01, and 0.05 μg/μl of doxorubicin and 5 μmol/L of MIA-602. Proliferation was observed and recorded at 24h and 48h. Wild type NB4 cells and NB4 cells resistant to both ATRA and ATO (NB4-RAA) were cultured in suspension. Cell lysates were prepared after incubation with MIA-602. Cell viability was measured at 24, 48, and 72h. Flow cytometry was also performed to assess expression of CD-56.

Results: Incubation of cells with doxorubicin showed a decrease in proliferation in a dose-dependent manner. Co-incubation of K562 cells with MIA-602 and doxorubicin showed a significantly greater reduction in proliferation (p&lt;0.05). Co-administration of doxorubicin and MIA-602 was shown to have a synergistic effect, when compared to doxorubicin alone at all concentrations at 24 and 48h. Viability of both NB4 cell lines decreased at similar levels at 24 h and 48 h when exposed to concentrations of MIA-602 higher than 0.05 μmol/L (p &lt; 0.05). No difference in cell viability was found between naïve NB4 and resistant NB4-RAA when exposed to the same concentrations of MIA-602. Results of flow cytometry revealed significantly increased expression of CD-56 (&gt;5.8-fold; p,0.05) in NB4-RAA cells as compared to the parent cell line.

Discussion: Co-administration of doxorubicin and the GHRH-R antagonist MIA-602 was shown to have a synergistic effect in reducing proliferation of the K-562 AML cell line. Use of MIA-602 in front-line combination therapy with anthracycline-based regimens may help prevent the acquisition of resistance in AML. CD-56 plays an essential role in the regulation of cell survival and stress resistance. Aberrant expression of CD-56 is also associated with reduced complete remission rates, higher relapse rates, and poor overall survival. The equal effectiveness of MIA-602 in cells with increased expression of CD-56 may provide an important therapeutic option in the setting of resistance.

Citation Format: Ravinder S. Chale, Mario Rodriguez, Stephanie M. Almeida, Shelly Sclatter, Anastasia Singaready, Andrew V. Schally, Joaquin J. Jimenez. Synergistic effects of MIA-602 and its potential for use in ATRA/ATO Resistant APL [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 385.