Advancing Evidence Generation for Circulating Tumor DNA: Lessons Learned from A Multi-Assay Study of Baseline Circulating Tumor DNA Levels across Cancer Types and Stages.

Circulating tumor DNA (ctDNA) holds promise as a biomarker for predicting clinical responses to therapy in solid tumors, and multiple ctDNA assays are in development. However, the heterogeneity in ctDNA levels prior to treatment (baseline) across different cancer types and stages and across ctDNA assays has not been widely studied. Friends of Cancer Research formed a collaboration across multiple commercial ctDNA assay developers to assess baseline ctDNA levels across five cancer types in early- and late-stage disease. This retrospective study included eight commercial ctDNA assay developers providing summary-level de-identified data for patients with non-small cell lung cancer (NSCLC), bladder, breast, prostate, and head and neck squamous cell carcinoma following a common analysis protocol. Baseline ctDNA levels across late-stage cancer types were similarly detected, highlighting the potential use of ctDNA as a biomarker in these cancer types. Variability was observed in ctDNA levels across assays in early-stage NSCLC, indicative of the contribution of assay analytical performance and methodology on variability. We identified key data elements, including assay characteristics and clinicopathological metadata, that need to be standardized for future meta-analyses across multiple assays. This work facilitates evidence generation opportunities to support the use of ctDNA as a biomarker for clinical response.

Accelerating the development of genetically engineered cellular therapies: a framework for extrapolating data across related products.

BACKGROUND: Significant advancements have been made in the field of cellular therapy as anti-cancer treatments, with the approval of chimeric antigen receptor (CAR)-T cell therapies and the development of other genetically engineered cellular therapies. CAR-T cell therapies have demonstrated remarkable clinical outcomes in various hematological malignancies, establishing their potential to change the current cancer treatment paradigm. Due to the increasing importance of genetically engineered cellular therapies in the oncology treatment landscape, implementing strategies to expedite development and evidence generation for the next generation of cellular therapy products can have a positive impact on patients. METHODS: We outline a risk-based methodology and assessment aid for the data extrapolation approach across related genetically engineered cellular therapy products. This systematic data extrapolation approach has applicability beyond CAR-T cells and can influence clinical development strategies for a variety of immune therapies such as T cell receptor (TCR) or genetically engineered and other cell-based therapies (e.g., tumor infiltrating lymphocytes, natural killer cells and macrophages). RESULTS: By analyzing commonalities in manufacturing processes, clinical trial designs, and regulatory considerations, key learnings were identified. These insights support optimization of the development and regulatory approval of novel cellular therapies. CONCLUSIONS: The field of cellular therapy holds immense promise in safely and effectively treating cancer. The ability to extrapolate data across related products presents opportunities to streamline the development process and accelerate the delivery of novel therapies to patients.

An Analysis of Dosing-Related Postmarketing Requirements for Novel Oncology Drugs Approved by the U.S. Food and Drug Administration, 2012-2022.

The FDA's Oncology Center of Excellence's (OCE) launch of Project Optimus signals increased focus on dose optimization approaches in oncology drug development, particularly toward optimization in the premarket setting. Although sponsors continue to adapt premarket study designs and approaches to align with FDA's expectations for dose optimization, including consideration of the optimal dosage(s), there are still instances where questions remain at the time of approval about whether the approved doses or schedules are optimal. In these cases, FDA can exercise regulatory flexibility by issuing postmarketing requirements (PMR) and avoid delaying patient access to promising therapies. This landscape analysis demonstrates that over the past decade (2012-2022), FDA frequently used PMRs to answer additional questions about dosing for novel oncology approvals. We found more than half of drugs (78/132, 59.1%) had a dosing PMR and observed a recent increase in PMRs intended to evaluate whether a lower dose could be more optimal. These results suggest there are opportunities to adapt premarket dose optimization strategies and leverage innovative development tools to ensure timely identification of the optimal dose.

Liquid biopsies coming of age: biology, emerging technologies, and clinical translation- An introduction to the JITC expert opinion special review series on liquid biopsies.

Liquid biopsies are gaining momentum as minimally invasive means for cancer detection, characterization, monitoring, and interception. Composed of five expert-opinion review articles and five accompanying expert-physician viewpoints, this Journal for ImmunoTherapy of Cancer Special Review Series focuses on capturing and synthesizing the current state of science of liquid biopsies and their clinical relevance for cancer immunotherapy and beyond.

Changes in Circulating Tumor DNA Reflect Clinical Benefit Across Multiple Studies of Patients With Non-Small-Cell Lung Cancer Treated With Immune Checkpoint Inhibitors.

PURPOSE: As immune checkpoint inhibitors (ICI) become increasingly used in frontline settings, identifying early indicators of response is needed. Recent studies suggest a role for circulating tumor DNA (ctDNA) in monitoring response to ICI, but uncertainty exists in the generalizability of these studies. Here, the role of ctDNA for monitoring response to ICI is assessed through a standardized approach by assessing clinical trial data from five independent studies. PATIENTS AND METHODS: Patient-level clinical and ctDNA data were pooled and harmonized from 200 patients across five independent clinical trials investigating the treatment of patients with non-small-cell lung cancer with programmed cell death-1 (PD-1)/programmed death ligand-1 (PD-L1)-directed monotherapy or in combination with chemotherapy. CtDNA levels were measured using different ctDNA assays across the studies. Maximum variant allele frequencies were calculated using all somatic tumor-derived variants in each unique patient sample to correlate ctDNA changes with overall survival (OS) and progression-free survival (PFS). RESULTS: We observed strong associations between reductions in ctDNA levels from on-treatment liquid biopsies with improved OS (OS; hazard ratio, 2.28; 95% CI, 1.62 to 3.20; P < .001) and PFS (PFS; hazard ratio 1.76; 95% CI, 1.31 to 2.36; P < .001). Changes in the maximum variant allele frequencies ctDNA values showed strong association across different outcomes. CONCLUSION: In this pooled analysis of five independent clinical trials, consistent and robust associations between reductions in ctDNA and outcomes were found across multiple end points assessed in patients with non-small-cell lung cancer treated with an ICI. Additional tumor types, stages, and drug classes should be included in future analyses to further validate this. CtDNA may serve as an important tool in clinical development and an early indicator of treatment benefit.

Homologous Recombination Deficiency: Concepts, Definitions, and Assays.

BACKGROUND: Homologous recombination deficiency (HRD) is a phenotype that is characterized by the inability of a cell to effectively repair DNA double-strand breaks using the homologous recombination repair (HRR) pathway. Loss-of-function genes involved in this pathway can sensitize tumors to poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) inhibitors and platinum-based chemotherapy, which target the destruction of cancer cells by working in concert with HRD through synthetic lethality. However, to identify patients with these tumors, it is vital to understand how to best measure homologous repair (HR) status and to characterize the level of alignment in these measurements across different diagnostic platforms. A key current challenge is that there is no standardized method to define, measure, and report HR status using diagnostics in the clinical setting. METHODS: Friends of Cancer Research convened a consortium of project partners from key healthcare sectors to address concerns about the lack of consistency in the way HRD is defined and methods for measuring HR status. RESULTS: This publication provides findings from the group's discussions that identified opportunities to align the definition of HRD and the parameters that contribute to the determination of HR status. The consortium proposed recommendations and best practices to benefit the broader cancer community. CONCLUSION: Overall, this publication provides additional perspectives for scientist, physician, laboratory, and patient communities to contextualize the definition of HRD and various platforms that are used to measure HRD in tumors.

Need for aligning the definition and reporting of cytokine release syndrome (CRS) in immuno-oncology clinical trials.

As cancer immunotherapies continue to expand across all areas of oncology, it is imperative to establish a standardized approach for defining and capturing clinically important toxicities, such as cytokine release syndrome (CRS). In this paper, we provide considerations for categorizing the variety of adverse events that may accompany CRS and for recognizing that presentations of CRS may differ among various immunotherapies (e.g., monoclonal antibodies, CAR T cell therapies and T cell engagers, which can include bispecific antibodies and other constructs). The goals of this paper are to ensure accurate and consistent identification of CRS in patients receiving immunotherapies in clinical studies to aid in reporting; enable more precise evaluation of the therapeutic risk-benefit profile and cross-study analyses; support evidence-based monitoring and management of important toxicities related to cancer immunotherapies; and improve patient care and outcomes. These efforts will become more important as the number and variety of molecular targets for immunotherapies broaden and as therapies with novel mechanisms continue to be developed.

Exploring the Potential of External Control Arms created from Patient Level Data: A case study in non-small cell lung cancer.

Randomized controlled trials (RCTs) are the gold standard for evaluation of new medical products. However, RCTs may not always be ethical or feasible. In cases where the investigational product is available outside the trial (e.g., through accelerated approval), patients may fail to enroll in clinical trials or drop out early to take the investigational product. These challenges to enrolling or maintaining a concurrent control arm may compromise timely recruitment, retention, or compliance. This can threaten the study's integrity, including the validity of results. External control arms (ECAs) may be a promising augmentation to RCTs when encountered with challenges that threaten the feasibility and reliability of a randomized controlled clinical trial. Here, we propose the use of ECAs created from patient-level data from previously conducted clinical trials or real-world data in the same indication. Propensity score methods are used to balance observed disease characteristics and demographics in the previous clinical trial or real-world data with those of present-day trial participants assigned to receive the investigational product. These methods are explored in a case study in non-small cell lung cancer (NSCLC) derived from multiple previously conducted open label or blinded phase 2 and 3 multinational clinical trials initiated between 2004 and 2013. The case study indicated that when balanced for baseline characteristics, the overall survival estimates from the ECA were very similar to those of the target randomized control, based on Kaplan-Meier curves and hazard ratio and confidence interval estimates. This suggests that in the future, a randomized control may be able to be augmented by an ECA without compromising the understanding of the treatment effect, assuming sufficient knowledge, measurement, and availability of all or most of the important prognostic variables.

Real-world Overall Survival Using Oncology Electronic Health Record Data: Friends of Cancer Research Pilot.

In prior work, Friends of Cancer Research convened multiple data partners to establish standardized definitions for oncology real-world end points derived from electronic health records (EHRs) and claims data. Here, we assessed the performance of real-world overall survival (rwOS) from data sets sourced from EHRs by evaluating the ability of the end point to reflect expected differences from a previous randomized controlled trial across five data sources, after applying inclusion/exclusion criteria. The KEYNOTE-189 clinical trial protocol of platinum doublet chemotherapy (chemotherapy) vs. programmed cell death protein 1 (PD-1) in combination with platinum doublet chemotherapy (PD-1 combination) in first-line nonsquamous metastatic non-small cell lung cancer guided retrospective cohort selection. The Kaplan-Meier product limit estimator was used to calculate 12-month rwOS with 95% confidence intervals (CIs) in each data source. Cox proportional hazards models estimated hazard ratios (HRs) and associated 95% CIs, controlled for prognostic factors. Once the inclusion/exclusion criteria were applied, the five resulting data sets included 155 to 1,501 patients in the chemotherapy cohort and 36 to 405 patients in the PD-1 combination cohort. Twelve-month rwOS ranged from 45% to 58% in the chemotherapy cohort and 44% to 68% in the PD-1 combination cohort. The adjusted HR for death ranged from 0.80 (95% CI: 0.69, 0.93) to 1.15 (95% CI: 0.71, 1.85), controlling for age, gender, performance status, and smoking status. This study yielded insights regarding data capture, including ability of real-world data to precisely identify patient populations and the impact of criteria on end points. Sensitivity analyses could elucidate data set-specific factors that drive results.

Continuing to Broaden Eligibility Criteria to Make Clinical Trials More Representative and Inclusive: ASCO-Friends of Cancer Research Joint Research Statement.

PURPOSE: Restrictive clinical trial eligibility criteria (EC) limit the number of patients who can enroll and potentially benefit from protocol-driven, investigational treatment plans and reduce the generalizability of trial results to the broader population. Following publication of expert stakeholder recommendations for broadening EC in 2017, the American Society of Clinical Oncology (ASCO) and Friends of Cancer Research (Friends) convened working groups to produce additional recommendations and analyze the potential impact on clinical trials using real-world data. EXPERIMENTAL DESIGN: Multistakeholder working groups were appointed by an ASCO-Friends leadership group to propose recommendations for more inclusive EC related to: washout periods, concomitant medications, prior therapies, laboratory reference ranges and test intervals, and performance status. RESULTS: The four working groups, ASCO Board of Directors, and Friends leadership support the recommendations included in this statement to modernize EC related to washout periods, concomitant medications, prior therapies, laboratory references ranges and test intervals, and performance status to make trial populations more inclusive and representative of cancer patient populations. CONCLUSIONS: Implementation of the recommendations is intended to result in greater ease of determining patient eligibility. Increased opportunities for patient participation in research will help address longstanding underrepresentation of certain groups in clinical trials and produce evidence that is more informative for a broader patient population. More patients eligible will also likely speed clinical trial accrual.See related commentary by Giantonio, p. 2369.

Modernizing Clinical Trial Eligibility Criteria: Recommendations of the ASCO-Friends of Cancer Research Laboratory Reference Ranges and Testing Intervals Work Group.

PURPOSE: In clinical research, eligibility criteria promote patient safety and optimize the evidence generated from clinical trials. However, overly stringent eligibility criteria, including laboratory requirements, may limit enrollment, resulting in delayed trial completion and potentially limiting applicability of trial results to a general practice population. EXPERIMENTAL DESIGN: Starting in 2018, a working group consisting of experts in direct patient care, the FDA, industry, and patient advocacy developed recommendations to guide the optimal use of laboratory reference ranges and testing intervals in clinical trial eligibility criteria and study procedures. The working group evaluated current eligibility criteria across different clinical trial phases and performed a literature review to evaluate the impact of and justification for laboratory test eligibility requirements and testing intervals in clinical trials. Recommendations were developed on the basis of the goals of promoting safety and optimizing the evidence generated, while also expanding eligibility and applicability, and minimizing excess burden of trial participation. RESULTS: In general, we found little variation over time and trial phase in laboratory test requirements, suggesting that these eligibility criteria are not refined according to ongoing clinical experience. We propose recommendations to optimize the use of laboratory tests when considering eligibility criteria. CONCLUSIONS: Tailoring the use of laboratory test requirements and testing intervals may increase the number and diversity of patients in clinical trials and provide clinical data that more closely represent the general practice populations.See related commentary by Giantonio, p. 2369.

Omissions of Care in Nursing Homes: A Uniform Definition for Research and Quality Improvement.

Omission of care in US nursing homes can lead to increased risk for harm or adverse outcomes, decreased quality of life for residents, and increased healthcare expenditures. However, scholars and policymakers in long-term care have taken varying approaches to defining omissions of care, which makes efforts to prevent them challenging. Subject matter experts and a broad range of nursing home stakeholders participated in iterative rounds of engagement to identify key concepts and aspects of omissions of care and develop a consensus-based definition that is clear, meaningful, and actionable for nursing homes. The resulting definition is "Omissions of care in nursing homes encompass situations when care-either clinical or nonclinical-is not provided for a resident and results in additional monitoring or intervention or increases the risk of an undesirable or adverse physical, emotional, or psychosocial outcome for the resident." This concise definition is grounded in goal-concordant, resident-centered care, and can be used for a variety quality improvement purposes and for research.

A National Assessment of Diagnostic Test Use for Patients with Advanced NSCLC and Factors Influencing Physician Decision-Making.

BACKGROUND: Diagnostic tests, including US Food and Drug Administration (FDA)-approved tests and laboratory-developed tests, are frequently used to guide care for patients with cancer, and, recently, have been the subject of several policy discussions and insurance coverage determinations. As the use of diagnostic testing has evolved, stakeholders have raised questions about the lack of standardized test performance metrics and the risk this poses to patients. OBJECTIVES: To describe the use of diagnostic testing for patients with advanced non-small-cell lung cancer (NSCLC), to analyze the utilization of FDA-approved versus laboratory-developed diagnostic tests, and to evaluate the impact of existing regulatory and coverage frameworks on diagnostic test ordering and physician treatment decision-making for patients with advanced NSCLC. METHODS: We conducted a 2-part study consisting of an online survey and patient chart review from March 1, 2019, to March 25, 2019, of physicians managing patients with advanced NSCLC. Respondents qualified for this study if they managed at least 5 patients with advanced NSCLC per month and had diagnosed at least 1 patient with advanced NSCLC in the 12 months before the survey. A total of 150 physicians completed the survey; before completing the survey, they were instructed to review between 4 and 8 charts of patients with stage IV NSCLC from their list of active patients. RESULTS: A total of 150 practicing oncologists who manage patients with advanced NSCLC responded to the survey and reviewed a total of 815 patient charts. Of these 815 patients, 812 (99.6%) were tested for at least 1 biomarker, including 73% of patients who were tested for EGFR, 70% tested for ALK, 58% tested for BRAF V600E, and 38% of patients tested for ROS1, by FDA-approved diagnostic tests. In all, 185 (83%) patients who tested positive for EGFR and 60 (83%) patients who tested positive for ALK received an FDA-approved targeted therapy for their biomarker. A total of 98 (65%) physicians responded that the patient's insurance coverage factored into their decision to order diagnostic tests and 69 (45%) physicians responded that cost or the patient's insurance coverage could influence them not to prescribe an indicated targeted therapy. CONCLUSION: The survey results indicate that diagnostic testing has become routine in the treatment of patients with advanced NSCLC, the use of FDA-approved diagnostic tests has increased, and insurance coverage and cost influence patient access to diagnostic testing as well as to targeted treatment options.

Accelerating the development of innovative cellular therapy products for the treatment of cancer.

The field of cell therapy is rapidly emerging as a priority area for oncology research and drug development. Currently, two chimeric antigen receptor T-cell therapies are approved by the US Food and Drug Administration and other agencies worldwide for two types of hematologic cancers. To facilitate the development of these therapies for patients with life-threatening cancers with limited or no therapeutic options, science- and risk-based approaches will be critical to mitigating and balancing any potential risk associated with either early clinical research or more flexible manufacturing paradigms. Friends of Cancer Research and the Parker Institute for Cancer Immunotherapy convened an expert group of stakeholders to develop specific strategies and proposals for regulatory opportunities to accelerate the development of cell therapies as promising new therapeutics. This meeting took place in Washington, DC on May 17, 2019. As academia and industry expand research efforts and cellular product development pipelines, this report summarizes opportunities to accelerate entry into the clinic for exploratory studies and optimization of cell products through manufacturing improvements for these promising new therapies.

Heparanase promotes myeloma stemness and in vivo tumorigenesis.

Heparanase is known to enhance the progression of many cancer types and is associated with poor patient prognosis. We recently reported that after patients with multiple myeloma were treated with high dose chemotherapy, the tumor cells that emerged upon relapse expressed a much higher level of heparanase than was present prior to therapy. Because tumor cells having stemness properties are thought to seed tumor relapse, we investigated whether heparanase had a role in promoting myeloma stemness. When plated at low density and grown in serum-free conditions that support survival and expansion of stem-like cells, myeloma cells expressing a low level of heparanase formed tumor spheroids poorly. In contrast, cells expressing a high level of heparanase formed significantly more and larger spheroids than did the heparanase low cells. Importantly, heparanase-low expressing cells exhibited plasticity and were induced to exhibit stemness properties when exposed to recombinant heparanase or to exosomes that contained a high level of heparanase cargo. The spheroid-forming heparanase-high cells had elevated expression of GLI1, SOX2 and ALDH1A1, three genes known to be associated with myeloma stemness. Inhibitors that block the heparan sulfate degrading activity of heparanase significantly diminished spheroid formation and expression of stemness genes implying a direct role of the enzyme in regulating stemness. Blocking the NF-κB pathway inhibited spheroid formation and expression of stemness genes demonstrating a role for NF-κB in heparanase-mediated stemness. Myeloma cells made deficient in heparanase exhibited decreased stemness properties in vitro and when injected into mice they formed tumors poorly compared to the robust tumorigenic capacity of cells expressing higher levels of heparanase. These studies reveal for the first time a role for heparanase in promoting cancer stemness and provide new insight into its function in driving tumor progression and its association with poor prognosis in cancer patients.

Tumor mutational burden standardization initiatives: Recommendations for consistent tumor mutational burden assessment in clinical samples to guide immunotherapy treatment decisions.

Characterization of tumors utilizing next-generation sequencing methods, including assessment of the number of somatic mutations (tumor mutational burden [TMB]), is currently at the forefront of the field of personalized medicine. Recent clinical studies have associated high TMB with improved patient response rates and survival benefit from immune checkpoint inhibitors; hence, TMB is emerging as a biomarker of response for these immunotherapy agents. However, variability in current methods for TMB estimation and reporting is evident, demonstrating a need for standardization and harmonization of TMB assessment methodology across assays and centers. Two uniquely placed organizations, Friends of Cancer Research (Friends) and the Quality Assurance Initiative Pathology (QuIP), have collaborated to coordinate efforts for international multistakeholder initiatives to address this need. Friends and QuIP, who have partnered with several academic centers, pharmaceutical organizations, and diagnostic companies, have adopted complementary, multidisciplinary approaches toward the goal of proposing evidence-based recommendations for achieving consistent TMB estimation and reporting in clinical samples across assays and centers. Many factors influence TMB assessment, including preanalytical factors, choice of assay, and methods of reporting. Preliminary analyses highlight the importance of targeted gene panel size and composition, and bioinformatic parameters for reliable TMB estimation. Herein, Friends and QuIP propose recommendations toward consistent TMB estimation and reporting methods in clinical samples across assays and centers. These recommendations should be followed to minimize variability in TMB estimation and reporting, which will ensure reliable and reproducible identification of patients who are likely to benefit from immune checkpoint inhibitors.

The Value of Addressing Patient Preferences.

Recent scientific progress is, in some cases, leading to transformative new medicines for diseases that previously had marginal or even no treatment options. This offers great promise for people affected by these diseases, but it has also placed stress on the health care system in terms of the growing cost associated with some new interventions. Effort has been taken to create tools to help patients and health care providers assess the value of new medical innovations. These tools may also provide the basis for assessing the price associated with new medical products. Given the growing expenditures in health care, value frameworks present an opportunity to evaluate new therapeutic options in the context of other treatments and potentially lead to a more economically sustainable health care system. In summary, the contribution to meaningful improvements in health outcomes is the primary focus of any assessment of the value of a new intervention. A component of such evaluations, however, should factor in timely access to new products that address an unmet medical need, as well as the magnitude of that beneficial impact. To achieve these goals, value assessment tools should allow for flexibility in clinical end points and trial designs, incorporate patient preferences, and continually evolve as new evidence, practice patterns, and medical progress advance.

Shed syndecan-1 translocates to the nucleus of cells delivering growth factors and inhibiting histone acetylation: a novel mechanism of tumor-host cross-talk.

The heparan sulfate proteoglycan syndecan-1 is proteolytically shed from the surface of multiple myeloma cells and is abundant in the bone marrow microenvironment where it promotes tumor growth, angiogenesis, and metastasis. In this study, we demonstrate for the first time that shed syndecan-1 present in the medium conditioned by tumor cells is taken up by bone marrow-derived stromal cells and transported to the nucleus. Translocation of shed syndecan-1 (sSDC1) to the nucleus was blocked by addition of exogenous heparin or heparan sulfate, pretreatment of conditioned medium with heparinase III, or growth of cells in sodium chlorate, indicating that sulfated heparan sulfate chains are required for nuclear translocation. Interestingly, cargo bound to sSDC1 heparan sulfate chains (i.e. hepatocyte growth factor) was transported to the nucleus along with sSDC1, and removal of heparan sulfate-bound cargo from sSDC1 abolished its translocation to the nucleus. Once in the nucleus, sSDC1 binds to the histone acetyltransferase enzyme p300, and histone acetyltransferase activity and histone acetylation are diminished. These findings reveal a novel function for shed syndecan-1 in mediating tumor-host cross-talk by shuttling growth factors to the nucleus and by altering histone acetylation in host cells. In addition, this work has broad implications beyond myeloma because shed syndecan-1 is present in high levels in many tumor types as well as in other disease states.

Heparan sulfate in the nucleus and its control of cellular functions.

Heparan sulfate proteoglycans (HSPG) are present on the cell surface, within the extracellular matrix, and as soluble molecules in tissues and blood. HSPGs are known to regulate a wide range of cellular functions predominantly by serving as co-receptors for growth factors, chemokines, and other regulatory proteins that control inflammation, wound healing and tumorigenesis. Several studies have demonstrated the presence of heparan sulfate (HS) or HSPGs in the cell nucleus, but little attention has been focused on their role there. However, evidence is mounting that nuclear HS and HSPGs have important regulatory functions that impact the cell cycle, proliferation, transcription and transport of cargo to the nucleus. The discovery of proteoglycans in the nucleus extends the list of "non-traditional nuclear proteins" that includes, for example, cytoskeletal proteins such as actin and tubulin, and growth factors and their receptors. In this review we discuss the discovery and fascinating roles of HS and HSPGs in the nucleus and propose a number of key questions that remain to be addressed.