Abstract 5407: A pan-cancer PDX histology image repository with genomic and pathological annotations for deep learning analysis

Patient-derived xenografts (PDXs) model human intra-tumoral heterogeneity in the context of the intact tissue of immunocompromised mice. Histological imaging via hematoxylin and eosin (H&E) staining is performed on PDX samples for routine assessment and, in principle, captures the complex interplay between tumor and stromal cells. Deep learning (DL)-based analysis of large human H&E image repositories has extracted inter-cellular and morphological signals correlated with disease phenotype and therapeutic response. Here, we present an extensive, pan-cancer repository of nearly 1,000 PDX and paired human progenitor H&E images. These images, curated from the PDXNet consortium, are associated with genomic and transcriptomic data, clinical metadata, pathological assessment of cell composition, and, in several cases, detailed pathological annotation of tumor, stroma, and necrotic regions. We demonstrate that DL can be applied to these images to classify tumor regions with an accuracy of 0.87. Further, we show that DL can predict xenograft-transplant lymphoproliferative disorder, the unintended outgrowth of human lymphocytes at the transplantation site, with an accuracy of 0.97. This repository enables PDX-specific investigations of cancer biology through histopathological analysis and contributes important model system data that expand on existing human histology repositories. We expect the PDXNet Image Repository to be valuable for controlled digital pathology analysis, both for the evaluation of technical issues such as stain normalization and for development of novel computational methods based on spatial behaviors within cancer tissues.

Citation Format: Brian S. White, Xing Yi Woo, Soner Koc, Todd Sheridan, Steven B. Neuhauser, Shidan Wang, Yvonne A. Evrard, John David Landua, R Jay Mashl, Sherri R. Davies, Bingliang Fang, Maria Gabriela Raso, Kurt W. Evans, Matthew H. Bailey, Yeqing Chen, Min Xiao, Jill Rubinstein, Ali Foroughi pour, Lacey Elizabeth Dobrolecki, Maihi Fujita, Junya Fujimoto, Guanghua Xiao, Ryan C. Fields, Jacqueline L. Mudd, Xiaowei Xu, Melinda G. Hollingshead, Shahanawaz Jiwani, PDXNet consortium, Tiffany A. Wallace, Jeffrey A. Moscow, James H. Doroshow, Nicholas Mitsiades, Salma Kaochar, Chong-xian Pan, Moon S. Chen, Luis G. Carvajal-Carmona, Alana L. Welm, Bryan E. Welm, Ramaswamy Govindan, Shunqiang Li, Michael A. Davies, Jack A. Roth, Funda Meric-Bernstam, Yang Xie, Meenhard Herlyn, Li Ding, Michael T. Lewis, Carol J. Bolt, Dennis A. Dean, Jeffrey H. Chuang. A pan-cancer PDX histology image repository with genomic and pathological annotations for deep learning analysis. [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 5407.

Genetically diverse mouse platform to xenograft cancer cells

The lack of genetically diverse preclinical animal models in basic biology and efficacy testing has been cited as a potential cause of failure in clinical trials. We developed and characterized five diverse RAG1 null mouse strains as models that allow xenografts to grow. In these strains, we characterized the growth of breast cancer, leukemia and glioma cell lines. We found a wide range of growth characteristics that were far more dependent on strain than tumor type. For the breast cancer cell line, we characterized the spectrum of xenograft/tumor growth at structural, histological, cellular and molecular levels across each strain, and found that each strain captures unique structural components of the stroma. Furthermore, we showed that the increase in tumor-infiltrating myeloid CD45+ cells and the amount of circulating cytokine IL-6 and chemokine KC (also known as CXCL1) is associated with a higher tumor size in different strains. This resource is available to study established human xenografts, as well as difficult-to-xenograft tumors and growth of hematopoietic stems cells, and to decipher the role of myeloid cells in the development of spontaneous cancers.

Abstract 1202: A repository of PDX histology images for exploring spatial heterogeneity and cancer dynamics

Patient-derived xenografts (PDXs) recapitulate intratumoral spatial heterogeneity and simulate a tumor microenvironment in which human immune and stromal cells in the PDX are replaced over passages by murine cells partially lacking immune function. Histological imaging enables exploring the spatial heterogeneity and dynamics of cancer, stromal, and immune cell interactions as correlates of tumor stage and therapeutic response over passages. We created a repository of curated, haematoxylin and eosin (H&E) images as a community resource for addressing these questions.

Images were generated at five sites within the NCI’s PDX Development and Trial Centers Research Network (PDXNet) and the NCI Patient-Derived Models Repository. Over 900 images, including 739 from PDXs and 190 from paired patients, are hosted on the Seven Bridges Genomics Cancer Genomics Cloud. They represent 42 cancer subtypes, including breast cancer (n=134), colon adenocarcinoma (COAD; n=94), pancreatic cancer (n=87), lung adenocarcinoma (LUAD; n=80), melanoma (n=71), and squamous cell lung cancer (LUSC; n=65). Paired human/PDX images are available for each of these cancers. Human and/or PDX images generated following patient treatment are available for 37 of the subtypes. Most images are from early passages (P0: 158; P1: 292; P2: 152; P3: 69; >P3: 55). Annotations include sex, age, race, ethnicity, and, for most images, pathological assessment of tissue-level percent cancer, stromal, and necrotic cell content (n=639) and tumor stage (n=650). RNA and exome sequencing data are available for 99 and 228 images, respectively, matched at the patient or sample level.

Quality control was performed using HistoQC. Cells were segmented and labeled as neoplastic, necrotic, immune, stromal, or other using Hover-Net and predictions of total neoplastic cell area correlated with whole-slide pathological assessment of cancer cell percentage (COAD: r=0.51; LUSC: r=0.59). HD-Staining, another classification approach, was applied to a subset of images and our clinical annotations will facilitate validation of this and related methods. Features of 512 x 512 pixel tiles were computed using the Inception V3 convolutional neural network pre-trained on ImageNet. Unsupervised clustering of these features demonstrate inter-patient heterogeneity within pathologist-annotated tumor regions. A classifier developed using pathologist-annotated cancer, stromal, and necrotic regions and trained on the features in LUSC images (n=10 images) achieved a cross-validation accuracy of 96% for cancer tiles across (n=5) LUAD images. Accuracy was lower for stromal classification (90%), likely reflecting current limitations of our small, but growing, labeled training set.

Our repository of clinically-annotated PDX H&E images should aid the community in studying spatial heterogeneity and in training deep learning-based image analysis methods.

Citation Format: Brian S. White, Xingyi Woo, Soner Koc, Todd Sheridan, Steven B. Neuhauser, Akshat M. Savaliya, Lacey E. Dobrolecki, John D. Landua, Matthew H. Bailey, Maihi Fujita, Kurt W. Evans, Bingliang Fang, Junya Fujimoto, Maria Gabriela Raso, Shidan Wang, Guanghua Xiao, Yang Xie, Sherri R. Davies, Ryan C. Fields, R Jay Mashl, Jacqueline L. Mudd, Yeqing Chen, Min Xiao, Xiaowei Xu, Melinda G. Hollingshead, Shahanawaz Jiwani, PDXNet Consortium, Yvonne A. Evrard, Tiffany A. Wallace, Jeffrey A. Moscow, James H. Doroshow, Nicholas Mitsiades, Salma Kaochar, Chong-xian Pan, Moon S. Chen, Luis G. Carvajal-Carmona, Alana L. Welm, Bryan E. Welm, Michael T. Lewis, Ramaswamy Govindan, Li Ding, Shunqiang Li, Meenhard Herlyn, Michael A. Davies, Jack A. Roth, Funda Meric-Bernstam, Carol J. Bult, Brandi Davis-Dusenbery, Dennis A. Dean, Jeffrey H. Chuang. A repository of PDX histology images for exploring spatial heterogeneity and cancer dynamics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1202.

Deconvolution Microscopy: A Platform for Rapid On-Site Evaluation (ROSE) of Fine Needle Aspiration (FNA) Specimens that Enables Recovery of the Sample

CONTEXT

Rapid on-site evaluation (ROSE) optimizes the performance of cytology, but requires skilled handling, and smearing can make the material unavailable for some ancillary tests. There is a need to facilitate ROSE without sacrificing part of the sample.

OBJECTIVE

We evaluated the image quality of inexpensive deconvolution fluorescence microscopy for optically sectioning non-smeared FNA tissue fragments.

DESIGN

A portion of residual material from 14 FNA samples was stained for 3 minutes in Hoechst 33342 and Sypro^TM Red to label DNA and protein respectively, transferred to an imaging chamber, and imaged at 200X or 400X magnification at 1 micron intervals using a GE DeltaVision inverted fluorescence microscope. A deconvolution algorithm was applied to remove out of plane signal, and resulting images were inverted and pseudocolored to resemble an H&E section. Five cytopathologists blindly diagnosed 2 to 4 representative image stacks per case (total 70 evaluations), and later compared them to conventional epifluorescent images.

RESULTS

Accurate definitive diagnoses were rendered in 45 of 70 (64%) total evaluations; equivocal diagnoses (atypical or suspicious) were made in 21 of 70 (30%). There were two false positive and two false negative "definite" diagnoses in three cases (4/70; 6%). Cytopathologists preferred deconvolved images compared to raw images (p< 0.01). The imaged fragments were recovered and prepared into a ThinPrep or cell block without discernable alteration.

CONCLUSIONS

Deconvolution improves image quality of FNA fragments compared to epifluorescence, often allowing definitive diagnosis while enabling the ROSE material to be subsequently triaged.

Mesonephric Like-Carcinoma (MLCA) of the Uterus with a Predominant Spindled Morphology: A Case Report

Introduction/Objective

Mesonephric-like carcinoma of the uterus is an increasingly recognized carcinoma with mesonephric differentiation, but without association with mesonephric remnants. We present a case of a 60-year-old woman presented with postmenopausal bleeding.

Methods/Case Report

Pelvic MRI showed possibly a cervical lobulated lesion (4.4cm) extending into the endocervical canal. Initial biopsy of this mass showed a spindle cell neoplasm raising possibility of an endometrial stromal sarcoma. On subsequent radical hysterectomy, there was a mass arising in the lower uterine segment (LUS) with circumferential cervical involvement. The tumor was comprised of sheets of epithelioid to spindle cells with scant cytoplasm and indistinct cell borders. Abundant mitotic figures and foci of necrosis were identified. Focal areas showed dense sclerosis with cords of cells, and only rare areas showed tubule formation with scant secretions. By immunohistochemistry (IHC), the tumor cells were positive for keratin AE1/AE3 (strong, diffuse), TTF-1, p63, p16, CD10 (with luminal accentuation); PAX8, desmin and caldesmon showed focal/rare positivity. Other markers were negative, including GATA3 (patchy, weak), ER and PR. Mismatch repair proteins were intact. Next-generation sequencing (NGS) revealed a KRAS mutation. Considering strong expression of epithelial markers, focal tubule formation with positive TTF-1 and negative GATA-3 labeling, and absence of identified mesonephric remnants, the tumor was classified as a high-grade mesonephric-like carcinoma of the uterus (LUS). Pelvic lymph nodes were negative (pT2 N0), and the patient is receiving cisplatin and external beam radiation.

Results (if a Case Study enter NA)

NA

Conclusion

MLCA with a prominent spindled/sarcomatoid component can be difficult to diagnose. Ancillary testing including a broad IHC panel with TTF-1, GATA-3 and NGS may be useful to aid in the diagnosis.

Do sporadic Peutz-Jeghers polyps exist? Experience of a large teaching hospital

Most types of sporadic gastrointestinal (GI) polyps vastly outnumber their syndromic counterparts. In contrast, the incidence of sporadic Peutz-Jeghers polyps (PJP) is unknown. We examined all potential PJP seen at our hospital over a 22-year (y) period to assess the incidence of sporadic PJP. The pathology database of a large hospital was searched for "Peutz-Jeghers polyp(s)," yielding 121 polyps from 38 patients. The polyps were reviewed by 3 pathologists to confirm the diagnosis. Clinical information to confirm or refute a diagnosis of Peutz-Jeghers syndrome (PJS) was collected. Of the 102 polyps included after histologic review, 94 polyps arose in patients meeting the World Health Organization criteria for PJS. These PJS polyps were eliminated from further analysis. Clinical information was obtained for the remaining 8 patients with potential "sporadic" PJP (1 to 50 y; mean=14 y; median=4 y). Of the 8 potential sporadic PJP, only 3 polyps from 3 patients had unequivocal PJP histologic features, all from the small intestine. All 3 patients had clinical histories suggesting syndromic PJP although they did not meet World Health Organization criteria, that is, 2 developed pancreatic cancer, 1 had bilateral "ovarian cystic masses" and a glomus tympanicum tumor, and 1 had strong family history of GI malignancies. The 5 remaining patients each had a colonic polyp with features suggestive, but not definitely diagnostic of, PJP. In these cases, prolapse lesions could not be excluded. One patient had a history of high-grade dysplasia in a tubulovillous adenoma in the colon at 53 years, but no family cancer history. Another had a family GI cancer history. Another had a history of pituitary adenoma at age 39, and the last had ductal breast carcinoma diagnosed 4 years before the discovery of the polyp. Our findings suggest that if sporadic PJP exist, they are extremely rare. Moreover, our data suggest that individuals with a single PJP may have a cumulative lifetime risk of cancer similar to those with the syndrome.

The Role of P501S and PSA in the Diagnosis of Metastatic Adenocarcinoma of the Prostate

BACKGROUND

Adenocarcinoma of the prostate can present as metastatic carcinoma with no known primary. Prostatic origin can be confirmed in most of these cases by immunohistochemistry for prostate-specific antigen (PSA) and prostate-specific acid phosphatase. In a small subset of high-grade prostate carcinomas, both markers are negative and therefore are not helpful for confirming prostatic origin. Recently, novel marker proteins that are preferentially expressed in prostate tissue were identified. One such marker is P501S or prostein, a 553-amino acid protein that is localized to the Golgi complex. It is expressed in both benign and neoplastic prostate tissues, but not in any other normal or malignant tissue examined to date. Owing to its apparent specificity, prostein may be a good marker to demonstrate prostatic origin in metastatic prostate cancer.

DESIGN

Five-micron sections of a tissue microarray were subjected to immunohistochemistry with a monoclonal mouse anti-P501S (clone 10E3, Dako, Carpintera, CA) antibody and a monoclonal mouse anti-PSA (clone ER-PR8, Dako, Carpintera, CA) antibody. The tissue microarray contains 78 cases of metastatic prostatic adenocarcinoma, 20 cases of primary prostatic adenocarcinoma, and 20 cases of benign prostate tissue from the peripheral zone as well as samples of benign brain, pancreas, kidney, thyroid, testis, skeletal muscle, and fibroconnective tissue.

RESULTS

Similar staining (intensity and extent) was identified for both markers in the majority of metastatic tumors (11 distant sites, 42 pelvic lymph nodes), in all 20 primary tumors and in all benign prostate and nonprostate tissues. The P501S stain had perinuclear cytoplasmic (Golgi) distribution even in poorly differentiated tumors and metastases. Two distant metastases were negative for PSA but retained focal weak positivity for P501S. Two other distant metastases were weakly PSA positive, but strongly P501S positive. Metastases in the pelvic lymph nodes were positive for both markers in 53 cases and 1 lymph node metastasis was strongly PSA positive but P501S negative. In summary, 67 of the 69 cases (97%) of metastatic prostate carcinomas were PSA positive, whereas 68 of the 69 cases showed at least focal weak reactivity for P501S (99%). None of the tumors were negative for both markers.

CONCLUSIONS

Immunohistochemistry for P501S is a sensitive and highly specific marker for identifying prostate tissue. The large majority of metastatic prostatic adenocarcinomas are P501S positive (99%). A small subset of metastatic prostatic adenocarcinoma shows significant differences in staining intensity and extent for PSA and P501S and, therefore, combined use of these markers may result in increased sensitivity for detecting prostatic origin.

Multinucleated foreign body giant cells in placental membrane

We report the pathologic finding of a multinucleated foreign body giant cell reaction to squames and fetal hair in the placental membranes in a 37-week 1-day intrauterine gestation. This reaction appeared to have developed in association with repeated intrauterine procedures performed in the third trimester, including cordocentesis for fetal blood sampling, intrauterine blood transfusion, and amnioreduction for polyhydramnios. This type of reaction most likely was directed to prolonged amniotic fluid leakage that occurred spontaneously or after intrauterine procedures in the second half of the second trimester and the third trimester. Careful examination of the placental membranes and recognition of the foreign body giant cell reaction may provide etiologic insight in cases of unexplained oligohydramnios.

Tumor markers in the detection of recurrent transitional cell carcinoma of the bladder: a brief review

OBJECTIVE

To determine the status of the most promising tumor markers of bladder cancer, including comparison with cytology, technical complexity and utility in patient management.

STUDY DESIGN

An extensive literature search was performed, and multiple markers were evaluated. The markers with the greatest potential for use as an adjunct to cytology were reviewed to determine the value of clinical implementation. Markers with a paucity of clinical research and poor results in clinical trials were omitted from review, as were genetic and cytologic prognostic determinants.

RESULTS

NMP22, bladder tumor antigen, fibrin/fibrinogen degradation products, telomerase and QUANTICYT image analysis cytometry produced the most favorable and reproducible results. Each test obtained favorable sensitivities in comparison with cytology, especially in the detection of low grade lesions. Many also retrospectively placed patients in high- and low-risk groups based on the test results, allowing increased follow-up time between cystoscopies. However, inability to detect some high grade lesions reduces their utility.

CONCLUSION

Continued clinical trials using these and other predictors of bladder cancer will eventually find a test that is suitable, in sensitivity and specificity, for use in urology clinics. Until that time, these tests may be useful in conjunction with cytology to prolong the interval between cystoscopies.

Effects of hypokalemia on cardiac growth

In neonatal myocytes grown in culture, reductions in extracellular potassium concentration produced a hypertrophic response as assessed by induction of early response genes, atrial natriuretic peptide and skeletal actin, and repression of the alpha3 isoform of the sodium pump in a dose dependent manner. The degree of alpha3 repression appeared to be dose dependent with decreases in media (K). Similarly, decreases in media potassium concentrations caused increases in cytosolic calcium concentration in a dose dependent manner; moreover these increases in cytosolic calcium concentration correlated quite well with repression of alpha3 expression. In contrast, although moderate reductions of potassium concentration induced upregulation of skACT and ANP, severely reduced potassium concentrations caused repression of skACT and ANP expression. In parallel studies performed in vivo, 3-5 weeks dietary K restriction induced molecular phenotypical changes similar to that seen in the neonatal myocyte model without demonstrable growth as assessed by the heart weight/body weight ratio. However, when rates subjected to dietary K restriction were subsequently subjected to acute aortic constriction, cardiac growth was greater than in rats fed a control diet. These data suggest that hypokalemia may produce molecular phenotypic alterations consistent with cardiac hypertrophy as well as contribute to hypertrophy in an in vivo model.

Reducing the frequency of errors in medicine using information technology

BACKGROUND

Increasing data suggest that error in medicine is frequent and results in substantial harm. The recent Institute of Medicine report (LT Kohn, JM Corrigan, MS Donaldson, eds: To Err Is Human: Building a Safer Health System. Washington, DC: National Academy Press, 1999) described the magnitude of the problem, and the public interest in this issue, which was already large, has grown.

GOAL

The goal of this white paper is to describe how the frequency and consequences of errors in medical care can be reduced (although in some instances they are potentiated) by the use of information technology in the provision of care, and to make general and specific recommendations regarding error reduction through the use of information technology.

RESULTS

General recommendations are to implement clinical decision support judiciously; to consider consequent actions when designing systems; to test existing systems to ensure they actually catch errors that injure patients; to promote adoption of standards for data and systems; to develop systems that communicate with each other; to use systems in new ways; to measure and prevent adverse consequences; to make existing quality structures meaningful; and to improve regulation and remove disincentives for vendors to provide clinical decision support. Specific recommendations are to implement provider order entry systems, especially computerized prescribing; to implement bar-coding for medications, blood, devices, and patients; and to utilize modern electronic systems to communicate key pieces of asynchronous data such as markedly abnormal laboratory values.

CONCLUSIONS

Appropriate increases in the use of information technology in health care- especially the introduction of clinical decision support and better linkages in and among systems, resulting in process simplification-could result in substantial improvement in patient safety.

Granulocyte-colony stimulating factor impedes recovery from damage caused by cytotoxic agents through increased differentiation at the expense of self-renewal

G-CSF is routinely used to hasten recovery from chemotherapy-induced neutropenia. We have recently shown that G-CSF, when combined with stem cell-damaging cytotoxic agents, results in enhanced stem cell damage and loss of marrow reserve. To investigate the mechanisms of stem cell damage caused by G-CSF, we gave C57BL/6 (B6) mice repeated doses of cyclophosphamide ([CY] 84 mg/kg) or carmustine ([BCNU] 13.2 mg/kg) and G-CSF (250 microg/kg/day) for either four days or eight days. Two different regimens of G-CSF were chosen to study the influence of increased proliferation on hematopoiesis which was measured at the end of the first, third and sixth 14-day cycle of each cytotoxic agent and 7 and 20 weeks after completion of all cycles. A spectrum of hematopoietic indices was measured including WBC, bone marrow cellularity, granulocyte/macrophage-colony-forming cells (GM-CFC), colony-forming cells with high proliferative-potential (HPP-CFC), cobblestone area-forming cells ([CAFC]-day 7 and CAFC-day 28), and long-term marrow repopulating ability in vivo. Despite the absence of differences in peripheral blood cell counts or bone marrow cellularity 14 days after each dose, progenitor cell levels (HPP-CFC, GM-CFC, and CAFC-7) were increased up to 2.5-fold with cytotoxic agent and G-CSF administration compared with cytotoxic agent administration alone. Mice given G-CSF for eight days had the greatest number of progenitors suggesting a dose-response relationship for G-CSF administration. G-CSF resulted in a decrease in hematopoietic stem cell (CAFC-28) content when measured two weeks after each cycle of saline, CY, and BCNU. Twenty weeks after six cycles of BCNU, the reduction in stem cell levels persisted and was further decreased when G-CSF was added to BCNU for four or eight days. Data from this study suggest that the most likely explanation for the damaging effects of G-CSF is that G-CSF directly or indirectly induces stem cells to differentiate into more committed hematopoietic cells resulting in a loss of marrow reserve. This effect is enhanced in animals with an already compromised hematopoietic stem cell compartment as seen with repeated doses of BCNU.

Reduction of marrow hematopoietic progenitor and stem cell content is not sufficient for enhanced syngeneic engraftment

The mechanisms regulating long-term engraftment of primitive stem cells are largely unknown. Most conditioning strategies use myeloablative agents for experimental or clinical hematopoietic stem cell transplantation. Host conditioning regimens, in part, have been designed on the assumption that transplanted cells home to specific marrow sites and if these sites are occupied by host stem cells, engraftment will not take place. However, there is now evidence that stable long-term syngeneic engraftment may occur in the absence of host marrow stem cell depletion. To further study the association of engraftment with stem cell depletion, we investigated whether the marked egress of hematopoietic progenitor and stem cells from the marrow into the peripheral blood in C57BL6 mice following a single dose of cyclophosphamide (day 1) and four days of G-CSF (days 3-6) afforded an increased opportunity for long-term syngeneic donor engraftment. During and after mobilization, glucose phosphate isomerase (GPI)-1(b) mice received 30 x 10(6) GPI-1(a) marrow cells without further myeloablation. The level of donor/recipient chimerism was assessed in cell lysates after six months. Increased long-term syngeneic donor engraftment was observed prior to mobilization (before day 6), during a period of active hematopoietic regeneration following the administration of cyclophosphamide. Hematopoietic regeneration was evidenced by a reduced but rapidly increasing marrow cellularity and an increased proportion of hematopoietic progenitors in S-phase. In contrast, long-term syngeneic donor engraftment was not increased over controls during the period of maximum progenitor and stem cell mobilization (after day 5). At this time there were minimal numbers of progenitor and stem cells in the marrow. These data suggest that in the absence of host stem cell ablation, maximal engraftment does not occur during marrow progenitor or stem cell depletion, suggesting that the presence of "open" marrow sites is not a prerequisite for engraftment. The mechanisms for increased engraftment during progenitor cell regeneration following cyclophosphamide need further investigation. Understanding the mechanisms for engraftment without host stem cell ablation may allow strategies for improved long-term engraftment of syngeneic or autologous stem cells with reduced post-transplant toxicity.

Granulocyte colony-stimulating factor enhances bone marrow stem cell damage caused by repeated administration of cytotoxic agents

Despite the increasing use of cytokines to circumvent the acute dose-limiting myelotoxicity of cancer treatment, little is known about the combined effects of cytotoxic agents and cytokines on the primitive stem cells responsible for long-term hematopoiesis. In an experimental model, we administered cytotoxic agents that have variable effects on primitive stem cells in C57BL/6 (B6)-mice. Mice received six every-other-week doses of cyclophosphamide (CY, 84 mg/kg), VP-16 (24 mg/kg) + cisplatinum (2.4 mg/kg), carboplatinum (50 mg/kg), chlorambucil (12 mg/kg), BCNU (13.2 mg/kg), or TBI (80 cGy). Granulocyte colony-stimulating factor (G-CSF; 250 microg/kg/day) was administered subcutaneously twice daily on days 3 to 6 after each dose of the cytotoxic agent. Comparison with animals receiving the cytotoxic agent alone was made to investigate the effects of G-CSF on long-term hematopoiesis. Hematopoiesis was measured 20 weeks after the last dose of the cytotoxic agent by assessment of peripheral blood counts, marrow cellularity, progenitor cell content (colony-forming units-spleen; CFU-S), and primitive stem cell number (long-term repopulating ability and day 28 and day 35 cobblestone area-forming cell [CAFC] frequencies). Exposure to cytotoxic agents alone resulted in a significant decrease in primitive stem cells (as measured by repopulating units [RU] and day 28 and day 35 CAFC content) in animals given carboplatinum, chlorambucil, BCNU, and TBI, but not in animals treated with cyclophosphamide or VP-16 and cisplatinum. The addition of G-CSF resulted in a significant decrease in stem cell content when compared with no G-CSF administration in animals treated with chlorambucil, BCNU, or TBI. Thus, G-CSF administered after repeated exposure to cytotoxic agents, appeared to damage the primitive stem cell compartment when used in combination with agents known to damage primitive stem cells. These results, although obtained in an experimental model, should raise concerns for the indiscriminate use of G-CSF in the clinic.