BACKGROUND

Despite medical advances, multidrug-resistant (MDR) gliomas continue to challenge the patients. In this study, I evaluate a new strategy in which the unique sequence of High-Intensity Focused Ultrasound (HIFU) and low-dose generic chemotherapeutic is utilized to attack MDR glioma cells.

METHODS

This strategy, motivated by recent clinical trials in which HIFU was used to non-invasively disrupt the blood-brain barrier and to treat brain tumors, led to the in vitro study during which human glioma cell line U87 (ATCC), modified for overexpression of epidermal growth factor receptor (EGFR), was paradoxically treated with low-dose Etoposide (VP-16).

Day 1: Each data sample consisted of ∼10K cells grown inside a well of 8-well glass slides (Lab-Tek). Each slide was then filled with growth media, sealed, submerged in a 37ºC degassed water bath and secured onto a fixture. The targets for HIFU therapy are the center points of the 4 quadrants of each well's base. The constant HIFU parameters for each slide were acoustic pressure 4.5 MPa, repetition rate 1 Hz, focal-zone depth and 30 sec/sonication/center point while HIFU duty cycle (DC) ranged 0-50% among slides. After HIFU treatment, the slides were incubated for 24h.

Day 2: Cell media for each slide was replaced with fresh media containing [VP-16] 0-100 uM prior to repeating the HIFU procedure from day 1.

Day 4: After 48h of exposure to VP-16, cell survivability study was performed using cell-count technique to determine the contribution of HIFU-mediated necrosis as well as VP-16-mediated apoptosis.

RESULTS

Cell survivability decreased by increasing [VP-16] or HIFU DC. In VP-16-only group (HIFU DC 0%), average survivability was 85% (n = 4) at [VP-16] 1 uM. In HIFU-only group ([VP-16] 0 uM), average survivability was 34% (n = 4) at DC 50%. In contrast, average survivability was 12% (n = 4), using [VP-16] 1 uM and DC 50%.

CONCLUSION

The unique sequence of HIFU and low-dose Etoposide virtually eliminated MDR glioma cells on day 4.

in vitro Treatment of Multidrug-Resistant Glioma Cell Line U87 Using HIFU-Etoposide Sequence

[Etoposide] = [VP-16], (uM)00.5151050100
Average cell survivability (%) ± SD on day 4 (Etoposide only; DC 0%; n = 4) 100 ± 47 (control) 62 ± 23 85 ± 13 41 ± 5 37 ± 7 25 ± 4 21 ± 6 
Average cell survivability (%) ± SD on day 4 (DC 50%; n = 4) 34 ± 5 (HIFU only) 14 ± 7 12 ± 6 6 ± 2 4 ± 2 3 ± 1 4 ± 1 
[Etoposide] = [VP-16], (uM)00.5151050100
Average cell survivability (%) ± SD on day 4 (Etoposide only; DC 0%; n = 4) 100 ± 47 (control) 62 ± 23 85 ± 13 41 ± 5 37 ± 7 25 ± 4 21 ± 6 
Average cell survivability (%) ± SD on day 4 (DC 50%; n = 4) 34 ± 5 (HIFU only) 14 ± 7 12 ± 6 6 ± 2 4 ± 2 3 ± 1 4 ± 1 

Note: The above data suggests that, in principle, drug resistance may be reversible and that the unique sequence of HIFU and a low-dose generic drug may be a promising alternative to current treatments (multidrug regimen, surgery or radiotherapy) against other MDR solid cancers. In addition to high efficacy within a relatively short time, the low cost and the potential absence of drug side effects from using low-dose generic chemotherapeutic are exciting motivations to further investigate this new cancer treatment in animal studies.

Citation Format: Howard Q. Vo. Elimination of multidrug-resistant glioma cells using unique sequence of high-intensity focused ultrasound and low-dose generic chemotherapeutic. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2145.