- Email: [email protected]
Organoids as Oracles for Precision Medicine in Rectal Cancer
Cell Stem Cell
In Translation Organoids as Oracles for Precision Medicine in Rectal Cancer Kevin S. Kolahi,1,2 Michitaka Nakano,1 and Calvin J. Kuo1,* 1Department
of Medicine, Division of Hematology, Stanford University School of Medicine, Stanford, CA 94305, USA of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA *Correspondence: [email protected] https://doi.org/10.1016/j.stem.2019.12.003 2Department
Two recent papers in Cell Stem Cell and Nature Medicine (Yao et al. [2019] and Ganesh et al. [2019]) demonstrate the successful use of rectal cancer patient-derived organoids to predict patient responses to neoadjuvant chemoradiation therapy, paving the way toward a new paradigm for precision medicine. For patients with locally advanced rectal cancer, surgery offers a chance for definitive cure. However, recurrence rates are substantial, and tumor excision can be exceptionally challenging because of the anatomical constraints of the bony pelvis, as well as highly morbid because of the disruption of several integral pelvic structures during resection. One method to minimize collateral damage to normal tissues and increase the likelihood of a complete tumor resection is to administer systemic chemotherapy and radiation (‘‘chemoradiation’’) before surgery is attempted; this strategy is termed neoadjuvant therapy (NAT). Compared to adjuvant therapy given after surgery, NAT reduces recurrence rates and improves disease-free survival in patients with locally advanced rectal cancer (Sebag-Montefiore et al., 2009). For these reasons, NAT has become a standard component of the presurgical management of rectal cancer. Unfortunately, responses to NAT are variable, and because current methods cannot reliably predict response, about half of patients will endure the arduous regimen and see little or no benefit (Trakarnsanga et al., 2014). Additionally, the assessment of responses in those actively undergoing NAT is equally problematic using current imaging modalities (Sclafani et al., 2017), a salient issue because surgery can be potentially avoided altogether if the response is deemed excellent (complete responders) (Smith et al., 2019). Thus, a method to predict and evaluate responses to NAT is crucial. Yao et al. (2019) (published in this issue of Cell Stem Cell) and Ganesh et al. (2019) have addressed these unmet clinical needs by using cultures of patient-derived
organoids (PDOs). Colorectal cancer organoids have been previously shown to recapitulate several in vivo aspects, including genetic alterations, tumor heterogeneity, and response to chemotherapy, of the native tumors from which they were derived (van de Wetering et al., 2015). However, Yao et al. (2019) and Ganesh et al. (2019) contribute a substantial advance through their demonstration that the in vitro organoid model can also be used to predict clinical and histopathologic responses to neoadjuvant chemoradiation in rectal cancer. Yao et al. (2019) generated 80 rectal cancer PDO lines and tested their sensitivity to single agent 5-FU, irinotecan, or radiation. Critically, they incorporated a correlation between the observed in vitro responses to the histopathologically determined tumor regression scores (TRGs) after surgical resection in order to define prognostic cut-offs. Under these parameters, the in vitro responses reliably predicted clinical responses with an impressive area under the curve (AUC) of 0.88 and an accuracy of 84%. In a minority of cases (12/80), the predictions from the in vitro organoid assay did not match the observed clinical response, and both false positives and false negatives were observed. Because radiation can promote the generation of tumor-immune responses through liberation of tumor antigens (Demaria et al., 2015), the potential inclusion of immune components (Neal et al., 2018) could be of utility. Ganesh et al. (2019) performed an exhaustive histopathologic and molecular analysis of primary tumors and the derived rectal cancer organoids (‘‘tumoroids’’) to show synonymous morphology
4 Cell Stem Cell 26, January 2, 2020 ª 2019 Elsevier Inc.
and genomic alterations, again underscoring the high fidelity of the PDO model. They further leveraged this model to test responses to NAT, including components of the standard FOLFOX chemotherapy regimen for rectal cancer (5-FU, leucovorin, and oxaliplatin) or radiation. Notably, the PDO responses significantly paralleled the patients’ progression-free survival. Moreover, these authors exploited the versatility of the PDOs to create in vivo endoluminal rectal cancer mouse models. The transplanted tumors exhibited the same in vivo metastatic route of tumor spread as was observed in the corresponding patients, metastasizing to the lung in one case and to the liver in another (see Figure 1). Predictions of either good or poor responses are clinically significant for several reasons. For those individuals predicted to demonstrate a good response, the decision to pursue NAT is justified. Interestingly, both Ganesh et al. (2019) and Yao et al. (2019) found that the assessment of in vitro responses to at least one agent is highly predictive of a clinical response to combination therapy. Whether or not it follows that those agents deemed ineffective in vitro were superfluous and could be omitted from the combination regimen is unclear since this observation carries substantial implications for sparing patients from unnecessary treatment. On the other hand, alternative agents might be explored in those cases where a poor response is predicted. For example, Ganesh et al. (2019) demonstrated that KRAS mutational status correlated with a lack of PDO responses to the anti-EGFR antibody cetuximab. Conceivably, predictions afforded by studies like these could one day be
Cell Stem Cell
In Translation Rectal cancer patient Chemoradiation
biopsy
Correlate outcomes
Generate organoids
Chemoradiation Patient-derived tumor organoids
response to improve their clinical predictive value. The work presented by the two groups previewed here represents a significant advance in the use of organoid culture as a functional, rather than descriptive, assessment tool for therapeutic response prediction in rectal cancer. Importantly, both groups achieved a high rate (>75%) of successful PDO rectal cancer establishment, suggesting that these or similar technologies might be useful to a majority of NAT patients. At least in the current studies, organoids appear to faithfully model in vitro patient-specific tumor biology, despite potential bias from tumor heterogeneity, enabling testing of alternative, individualized NAT regimens. These results dovetail with similar efforts using organoids for colon cancer chemoprediction (Ooft et al., 2019). One can look forward to future studies facilitating the design of next-generation randomized trials using organoid-derived therapeutic regimen predictions as entry criteria, potentially transforming oncologic treatment paradigms and ushering in a new era of precision medicine. REFERENCES Demaria, S., Golden, E.B., and Formenti, S.C. (2015). Role of local radiation therapy in cancer immunotherapy. JAMA Oncol. 1, 1325–1332.
In vivo transplantation Figure 1. Design of Neoadjuvant Chemoradiotherapy Sensitvity Prediction Studies in Patient-Derived Rectal Cancer Organoids Ganesh et al. (2019) and Yao et al. (2019) generated patient-derived rectal cancer organoids and tested their response to neoadjuvant chemoradiation. Organoid responses were predictive of patient outcomes after surgical resection, underscoring the clinical translational potential of the organoid model for rectal cancer patients undergoing neoadjuvant chemotherapy. Ganesh et al. (2019) additionally demonstrated that in vivo transplanted organoids model in vivo clinical behavior, including metastatic potential, of rectal cancer.
leveraged by clinicians to personalize current standardized regimens. Yao et al. (2019) also address a biostatistical gap in the translational organoid field by calculating the accuracy of their predictions. Notably, the prognostic cutoffs for the models devised by Yao et al. (2019) to quantify the accuracy of organoid predictions of clinical response were generated from fitting retrospectively observed clinical response data
and have not yet been tested in a prospective fashion. Further progress will require additional statistical validation, including examining the accuracy of organoid response predictions in cases that are independent from those that the original model was derived from (e.g., test and validation cohorts). Potentially, models such as those used by Ganesh et al. (2019) and Yao et al. (2019) could incorporate the magnitude or sensitivity of
Ganesh, K., Wu, C., O’Rourke, K.P., Szeglin, B.C., Zheng, Y., Sauve´, C.G., Adileh, M., Wasserman, I., Marco, M.R., Kim, A.S., et al. (2019). A rectal cancer organoid platform to study individual responses to chemoradiation. Nat. Med. 25, 1607–1614. Neal, J.T., Li, X., Zhu, J., Giangarra, V., Grzeskowiak, C.L., Ju, J., Liu, I.H., Chiou, S.-H., Salahudeen, A.A., Smith, A.R., et al. (2018). Organoid modeling of the tumor immune microenvironment. Cell 175, 1972–1988.e16. Ooft, S.N., Weeber, F., Dijkstra, K.K., McLean, C.M., Kaing, S., van Werkhoven, E., Schipper, L., Hoes, L., Vis, D.J., van de Haar, J., et al. (2019). Patient-derived organoids can predict response to chemotherapy in metastatic colorectal cancer patients. Sci Transl Med 11, eaay2574. Sclafani, F., Brown, G., Cunningham, D., Wotherspoon, A., Mendes, L.S.T., Balyasnikova, S., Evans, J., Peckitt, C., Begum, R., Tait, D., et al. (2017). Comparison between MRI and pathology in the assessment of tumour regression grade in rectal cancer. Br. J. Cancer 117, 1478–1485. Sebag-Montefiore, D., Stephens, R.J., Steele, R., Monson, J., Grieve, R., Khanna, S., Quirke, P., Couture, J., de Metz, C., Myint, A.S., et al. (2009). Preoperative radiotherapy versus selective postoperative chemoradiotherapy in patients with rectal cancer (MRC CR07 and NCIC-CTG C016): A multicentre, randomised trial. Lancet 373, 811–820.
Cell Stem Cell 26, January 2, 2020 5
Cell Stem Cell
In Translation Smith, J.J., Strombom, P., Chow, O.S., Roxburgh, C.S., Lynn, P., Eaton, A., Widmar, M., Ganesh, K., Yaeger, R., Cercek, A., et al. (2019). Assessment of a watch-and-wait strategy for rectal cancer in patients w a complete responseaAfter neoadjuvant therapy. JAMA Oncol. 5, e185896–e185896. Trakarnsanga, A., Go¨nen, M., Shia, J., Nash, G.M., Temple, L.K., Guillem, J.G., Paty, P.B.,
6 Cell Stem Cell 26, January 2, 2020
Goodman, K.A., Wu, A., Gollub, M., et al. (2014). Comparison of tumor regression grade systems for locally advanced rectal cancer after multimodality treatment. J. Natl. Cancer Inst. 106, 1731. van de Wetering, M., Francies, H.E., Francis, J.M., Bounova, G., Iorio, F., Pronk, A., van Houdt, W., van Gorp, J., Taylor-Weiner, A., Kester, L., et al. (2015). Prospective derivation of a living organoid
biobank of colorectal cancer patients. Cell 161, 933–945. Yao, Y., Xu, X., Yang, L., Zhu, J., Wan, J., Shen, L., Xia, F., Fu, G., Deng, Y., Pan, M., et al. (2019). Patient-derived organoids predict chemoradiation responses of locally advanced rectal cancer. Cell Stem Cell 26, 17–26.
In Translation Organoids as Oracles for Precision Medicine in Rectal Cancer Kevin S. Kolahi,1,2 Michitaka Nakano,1 and Calvin J. Kuo1,* 1Department
of Medicine, Division of Hematology, Stanford University School of Medicine, Stanford, CA 94305, USA of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA *Correspondence: [email protected] https://doi.org/10.1016/j.stem.2019.12.003 2Department
Two recent papers in Cell Stem Cell and Nature Medicine (Yao et al. [2019] and Ganesh et al. [2019]) demonstrate the successful use of rectal cancer patient-derived organoids to predict patient responses to neoadjuvant chemoradiation therapy, paving the way toward a new paradigm for precision medicine. For patients with locally advanced rectal cancer, surgery offers a chance for definitive cure. However, recurrence rates are substantial, and tumor excision can be exceptionally challenging because of the anatomical constraints of the bony pelvis, as well as highly morbid because of the disruption of several integral pelvic structures during resection. One method to minimize collateral damage to normal tissues and increase the likelihood of a complete tumor resection is to administer systemic chemotherapy and radiation (‘‘chemoradiation’’) before surgery is attempted; this strategy is termed neoadjuvant therapy (NAT). Compared to adjuvant therapy given after surgery, NAT reduces recurrence rates and improves disease-free survival in patients with locally advanced rectal cancer (Sebag-Montefiore et al., 2009). For these reasons, NAT has become a standard component of the presurgical management of rectal cancer. Unfortunately, responses to NAT are variable, and because current methods cannot reliably predict response, about half of patients will endure the arduous regimen and see little or no benefit (Trakarnsanga et al., 2014). Additionally, the assessment of responses in those actively undergoing NAT is equally problematic using current imaging modalities (Sclafani et al., 2017), a salient issue because surgery can be potentially avoided altogether if the response is deemed excellent (complete responders) (Smith et al., 2019). Thus, a method to predict and evaluate responses to NAT is crucial. Yao et al. (2019) (published in this issue of Cell Stem Cell) and Ganesh et al. (2019) have addressed these unmet clinical needs by using cultures of patient-derived
organoids (PDOs). Colorectal cancer organoids have been previously shown to recapitulate several in vivo aspects, including genetic alterations, tumor heterogeneity, and response to chemotherapy, of the native tumors from which they were derived (van de Wetering et al., 2015). However, Yao et al. (2019) and Ganesh et al. (2019) contribute a substantial advance through their demonstration that the in vitro organoid model can also be used to predict clinical and histopathologic responses to neoadjuvant chemoradiation in rectal cancer. Yao et al. (2019) generated 80 rectal cancer PDO lines and tested their sensitivity to single agent 5-FU, irinotecan, or radiation. Critically, they incorporated a correlation between the observed in vitro responses to the histopathologically determined tumor regression scores (TRGs) after surgical resection in order to define prognostic cut-offs. Under these parameters, the in vitro responses reliably predicted clinical responses with an impressive area under the curve (AUC) of 0.88 and an accuracy of 84%. In a minority of cases (12/80), the predictions from the in vitro organoid assay did not match the observed clinical response, and both false positives and false negatives were observed. Because radiation can promote the generation of tumor-immune responses through liberation of tumor antigens (Demaria et al., 2015), the potential inclusion of immune components (Neal et al., 2018) could be of utility. Ganesh et al. (2019) performed an exhaustive histopathologic and molecular analysis of primary tumors and the derived rectal cancer organoids (‘‘tumoroids’’) to show synonymous morphology
4 Cell Stem Cell 26, January 2, 2020 ª 2019 Elsevier Inc.
and genomic alterations, again underscoring the high fidelity of the PDO model. They further leveraged this model to test responses to NAT, including components of the standard FOLFOX chemotherapy regimen for rectal cancer (5-FU, leucovorin, and oxaliplatin) or radiation. Notably, the PDO responses significantly paralleled the patients’ progression-free survival. Moreover, these authors exploited the versatility of the PDOs to create in vivo endoluminal rectal cancer mouse models. The transplanted tumors exhibited the same in vivo metastatic route of tumor spread as was observed in the corresponding patients, metastasizing to the lung in one case and to the liver in another (see Figure 1). Predictions of either good or poor responses are clinically significant for several reasons. For those individuals predicted to demonstrate a good response, the decision to pursue NAT is justified. Interestingly, both Ganesh et al. (2019) and Yao et al. (2019) found that the assessment of in vitro responses to at least one agent is highly predictive of a clinical response to combination therapy. Whether or not it follows that those agents deemed ineffective in vitro were superfluous and could be omitted from the combination regimen is unclear since this observation carries substantial implications for sparing patients from unnecessary treatment. On the other hand, alternative agents might be explored in those cases where a poor response is predicted. For example, Ganesh et al. (2019) demonstrated that KRAS mutational status correlated with a lack of PDO responses to the anti-EGFR antibody cetuximab. Conceivably, predictions afforded by studies like these could one day be
Cell Stem Cell
In Translation Rectal cancer patient Chemoradiation
biopsy
Correlate outcomes
Generate organoids
Chemoradiation Patient-derived tumor organoids
response to improve their clinical predictive value. The work presented by the two groups previewed here represents a significant advance in the use of organoid culture as a functional, rather than descriptive, assessment tool for therapeutic response prediction in rectal cancer. Importantly, both groups achieved a high rate (>75%) of successful PDO rectal cancer establishment, suggesting that these or similar technologies might be useful to a majority of NAT patients. At least in the current studies, organoids appear to faithfully model in vitro patient-specific tumor biology, despite potential bias from tumor heterogeneity, enabling testing of alternative, individualized NAT regimens. These results dovetail with similar efforts using organoids for colon cancer chemoprediction (Ooft et al., 2019). One can look forward to future studies facilitating the design of next-generation randomized trials using organoid-derived therapeutic regimen predictions as entry criteria, potentially transforming oncologic treatment paradigms and ushering in a new era of precision medicine. REFERENCES Demaria, S., Golden, E.B., and Formenti, S.C. (2015). Role of local radiation therapy in cancer immunotherapy. JAMA Oncol. 1, 1325–1332.
In vivo transplantation Figure 1. Design of Neoadjuvant Chemoradiotherapy Sensitvity Prediction Studies in Patient-Derived Rectal Cancer Organoids Ganesh et al. (2019) and Yao et al. (2019) generated patient-derived rectal cancer organoids and tested their response to neoadjuvant chemoradiation. Organoid responses were predictive of patient outcomes after surgical resection, underscoring the clinical translational potential of the organoid model for rectal cancer patients undergoing neoadjuvant chemotherapy. Ganesh et al. (2019) additionally demonstrated that in vivo transplanted organoids model in vivo clinical behavior, including metastatic potential, of rectal cancer.
leveraged by clinicians to personalize current standardized regimens. Yao et al. (2019) also address a biostatistical gap in the translational organoid field by calculating the accuracy of their predictions. Notably, the prognostic cutoffs for the models devised by Yao et al. (2019) to quantify the accuracy of organoid predictions of clinical response were generated from fitting retrospectively observed clinical response data
and have not yet been tested in a prospective fashion. Further progress will require additional statistical validation, including examining the accuracy of organoid response predictions in cases that are independent from those that the original model was derived from (e.g., test and validation cohorts). Potentially, models such as those used by Ganesh et al. (2019) and Yao et al. (2019) could incorporate the magnitude or sensitivity of
Ganesh, K., Wu, C., O’Rourke, K.P., Szeglin, B.C., Zheng, Y., Sauve´, C.G., Adileh, M., Wasserman, I., Marco, M.R., Kim, A.S., et al. (2019). A rectal cancer organoid platform to study individual responses to chemoradiation. Nat. Med. 25, 1607–1614. Neal, J.T., Li, X., Zhu, J., Giangarra, V., Grzeskowiak, C.L., Ju, J., Liu, I.H., Chiou, S.-H., Salahudeen, A.A., Smith, A.R., et al. (2018). Organoid modeling of the tumor immune microenvironment. Cell 175, 1972–1988.e16. Ooft, S.N., Weeber, F., Dijkstra, K.K., McLean, C.M., Kaing, S., van Werkhoven, E., Schipper, L., Hoes, L., Vis, D.J., van de Haar, J., et al. (2019). Patient-derived organoids can predict response to chemotherapy in metastatic colorectal cancer patients. Sci Transl Med 11, eaay2574. Sclafani, F., Brown, G., Cunningham, D., Wotherspoon, A., Mendes, L.S.T., Balyasnikova, S., Evans, J., Peckitt, C., Begum, R., Tait, D., et al. (2017). Comparison between MRI and pathology in the assessment of tumour regression grade in rectal cancer. Br. J. Cancer 117, 1478–1485. Sebag-Montefiore, D., Stephens, R.J., Steele, R., Monson, J., Grieve, R., Khanna, S., Quirke, P., Couture, J., de Metz, C., Myint, A.S., et al. (2009). Preoperative radiotherapy versus selective postoperative chemoradiotherapy in patients with rectal cancer (MRC CR07 and NCIC-CTG C016): A multicentre, randomised trial. Lancet 373, 811–820.
Cell Stem Cell 26, January 2, 2020 5
Cell Stem Cell
In Translation Smith, J.J., Strombom, P., Chow, O.S., Roxburgh, C.S., Lynn, P., Eaton, A., Widmar, M., Ganesh, K., Yaeger, R., Cercek, A., et al. (2019). Assessment of a watch-and-wait strategy for rectal cancer in patients w a complete responseaAfter neoadjuvant therapy. JAMA Oncol. 5, e185896–e185896. Trakarnsanga, A., Go¨nen, M., Shia, J., Nash, G.M., Temple, L.K., Guillem, J.G., Paty, P.B.,
6 Cell Stem Cell 26, January 2, 2020
Goodman, K.A., Wu, A., Gollub, M., et al. (2014). Comparison of tumor regression grade systems for locally advanced rectal cancer after multimodality treatment. J. Natl. Cancer Inst. 106, 1731. van de Wetering, M., Francies, H.E., Francis, J.M., Bounova, G., Iorio, F., Pronk, A., van Houdt, W., van Gorp, J., Taylor-Weiner, A., Kester, L., et al. (2015). Prospective derivation of a living organoid
biobank of colorectal cancer patients. Cell 161, 933–945. Yao, Y., Xu, X., Yang, L., Zhu, J., Wan, J., Shen, L., Xia, F., Fu, G., Deng, Y., Pan, M., et al. (2019). Patient-derived organoids predict chemoradiation responses of locally advanced rectal cancer. Cell Stem Cell 26, 17–26.