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The topoisomerase I (TOP1) inhibitor irinotecan could be effective in treating triple-negative breast cancer (TNBC), according to results from a preclinical study published in Science Translational Medicine.
Florence Coussy, MD, PhD, of Institut Curie, Paris, and colleagues evaluated the antitumor activity of the Food and Drug Administration–approved TOP1 inhibitor irinotecan in 40 patient-derived xenografts (PDXs) of TNBC.
Other treatments, such as noncamptothecin TOP1 inhibitors (indotecan and indimitecan) and irinotecan plus VE-822 (an ataxia telangiectasia and Rad3-related protein [ATR] inhibitor), were also evaluated in the PDX models.
Tumor samples were collected from patients with primary breast cancer at the time of surgery (55%), residual breast cancer after neoadjuvant treatment (40%), or axillary lymph node metastases (5%). The patients had a mean age of 56 years (range, 29-89 years).
The researchers assessed BRCAness using the homologous recombination deficiency–large-scale state transition assay. Additional potential markers of response, including expression of retinoblastoma transcriptional corepressor 1 (RB1) and Schlafen family member 11 (SLFN11), were detected on transcriptomic analysis and validated using immunohistochemistry analyses.
The researchers found that 37.5% (n = 15) of TNBC PDX models achieved a partial or complete response to irinotecan therapy, while 22.5% (n = 9) of models had stable disease. BRCAness, RB1 loss, and high SLFN11 expression were deemed potential markers of response to irinotecan and other clinical TOP1 inhibitors.
The researchers then evaluated 250 breast cancer patients treated with anthracycline-based chemotherapy and found that lower expression of SLFN11 was associated with worse survival.
“We also [found] that, in the absence of SLFN11, response to irinotecan can be increased by adding an ATR inhibitor and that the clinical TOP1 inhibitors are highly efficient in BRCA1-mutant and BRCAness-positive TNBC PDXs,” the researchers reported.
They acknowledged that a key limitation of this study was the absence of tumor samples from patients who had received a TOP1 inhibitor.
“Overall, our findings are in line with the notion that concomitant defects in DNA repair and checkpoints render cancer cells highly vulnerable to TOP1 inhibitors,” the researchers concluded.
The study was funded by the National Cancer Institute, PIC3i NCI-Curie, and Site de Recherche Intégrée sur le Cancer. One author is an inventor of indotecan and indimitecan. Two authors are coinventors of the method used to detect inactivation of the homologous recombination pathway, which is licensed to Myriad Genetics.
SOURCE: Coussy F et al. Sci Transl Med. 2020 Feb 19. doi: 10.1126/scitranslmed.aax2625.
The topoisomerase I (TOP1) inhibitor irinotecan could be effective in treating triple-negative breast cancer (TNBC), according to results from a preclinical study published in Science Translational Medicine.
Florence Coussy, MD, PhD, of Institut Curie, Paris, and colleagues evaluated the antitumor activity of the Food and Drug Administration–approved TOP1 inhibitor irinotecan in 40 patient-derived xenografts (PDXs) of TNBC.
Other treatments, such as noncamptothecin TOP1 inhibitors (indotecan and indimitecan) and irinotecan plus VE-822 (an ataxia telangiectasia and Rad3-related protein [ATR] inhibitor), were also evaluated in the PDX models.
Tumor samples were collected from patients with primary breast cancer at the time of surgery (55%), residual breast cancer after neoadjuvant treatment (40%), or axillary lymph node metastases (5%). The patients had a mean age of 56 years (range, 29-89 years).
The researchers assessed BRCAness using the homologous recombination deficiency–large-scale state transition assay. Additional potential markers of response, including expression of retinoblastoma transcriptional corepressor 1 (RB1) and Schlafen family member 11 (SLFN11), were detected on transcriptomic analysis and validated using immunohistochemistry analyses.
The researchers found that 37.5% (n = 15) of TNBC PDX models achieved a partial or complete response to irinotecan therapy, while 22.5% (n = 9) of models had stable disease. BRCAness, RB1 loss, and high SLFN11 expression were deemed potential markers of response to irinotecan and other clinical TOP1 inhibitors.
The researchers then evaluated 250 breast cancer patients treated with anthracycline-based chemotherapy and found that lower expression of SLFN11 was associated with worse survival.
“We also [found] that, in the absence of SLFN11, response to irinotecan can be increased by adding an ATR inhibitor and that the clinical TOP1 inhibitors are highly efficient in BRCA1-mutant and BRCAness-positive TNBC PDXs,” the researchers reported.
They acknowledged that a key limitation of this study was the absence of tumor samples from patients who had received a TOP1 inhibitor.
“Overall, our findings are in line with the notion that concomitant defects in DNA repair and checkpoints render cancer cells highly vulnerable to TOP1 inhibitors,” the researchers concluded.
The study was funded by the National Cancer Institute, PIC3i NCI-Curie, and Site de Recherche Intégrée sur le Cancer. One author is an inventor of indotecan and indimitecan. Two authors are coinventors of the method used to detect inactivation of the homologous recombination pathway, which is licensed to Myriad Genetics.
SOURCE: Coussy F et al. Sci Transl Med. 2020 Feb 19. doi: 10.1126/scitranslmed.aax2625.
The topoisomerase I (TOP1) inhibitor irinotecan could be effective in treating triple-negative breast cancer (TNBC), according to results from a preclinical study published in Science Translational Medicine.
Florence Coussy, MD, PhD, of Institut Curie, Paris, and colleagues evaluated the antitumor activity of the Food and Drug Administration–approved TOP1 inhibitor irinotecan in 40 patient-derived xenografts (PDXs) of TNBC.
Other treatments, such as noncamptothecin TOP1 inhibitors (indotecan and indimitecan) and irinotecan plus VE-822 (an ataxia telangiectasia and Rad3-related protein [ATR] inhibitor), were also evaluated in the PDX models.
Tumor samples were collected from patients with primary breast cancer at the time of surgery (55%), residual breast cancer after neoadjuvant treatment (40%), or axillary lymph node metastases (5%). The patients had a mean age of 56 years (range, 29-89 years).
The researchers assessed BRCAness using the homologous recombination deficiency–large-scale state transition assay. Additional potential markers of response, including expression of retinoblastoma transcriptional corepressor 1 (RB1) and Schlafen family member 11 (SLFN11), were detected on transcriptomic analysis and validated using immunohistochemistry analyses.
The researchers found that 37.5% (n = 15) of TNBC PDX models achieved a partial or complete response to irinotecan therapy, while 22.5% (n = 9) of models had stable disease. BRCAness, RB1 loss, and high SLFN11 expression were deemed potential markers of response to irinotecan and other clinical TOP1 inhibitors.
The researchers then evaluated 250 breast cancer patients treated with anthracycline-based chemotherapy and found that lower expression of SLFN11 was associated with worse survival.
“We also [found] that, in the absence of SLFN11, response to irinotecan can be increased by adding an ATR inhibitor and that the clinical TOP1 inhibitors are highly efficient in BRCA1-mutant and BRCAness-positive TNBC PDXs,” the researchers reported.
They acknowledged that a key limitation of this study was the absence of tumor samples from patients who had received a TOP1 inhibitor.
“Overall, our findings are in line with the notion that concomitant defects in DNA repair and checkpoints render cancer cells highly vulnerable to TOP1 inhibitors,” the researchers concluded.
The study was funded by the National Cancer Institute, PIC3i NCI-Curie, and Site de Recherche Intégrée sur le Cancer. One author is an inventor of indotecan and indimitecan. Two authors are coinventors of the method used to detect inactivation of the homologous recombination pathway, which is licensed to Myriad Genetics.
SOURCE: Coussy F et al. Sci Transl Med. 2020 Feb 19. doi: 10.1126/scitranslmed.aax2625.
FROM SCIENCE TRANSLATIONAL MEDICINE