Current status of prognostication in classical Hodgkin lymphoma

Incorporating Monoclonal Antibodies into the First-Line Treatment of Classical Hodgkin Lymphoma

The long-term survival of Hodgkin lymphoma (HL) patients treated according to the current standard of care is excellent. Combined-modality schedules (ABVD plus radiotherapy) in early-stage disease, along with treatment intensity adaptation to early metabolic response assessed by PET/CT in advanced stage HL, have been the cornerstones of risk stratification and treatment decision-making, minimizing treatment-related complications while keeping efficacy. Nevertheless, a non-negligible number of patients are primary refractory or relapse after front-line treatment. Novel immunotherapeutic agents, namely Brentuximab Vedotin (BV) and immune checkpoint inhibitors (CPI), have already shown outstanding efficacy in a relapsed/refractory setting in recent landmark studies. Several phase 2 single-arm studies suggest that the addition of these agents in the frontline setting could further improve long-term disease control permitting one to reduce the exposure to cytotoxic drugs. However, a longer follow-up is needed. At the time of this writing, the only randomized phase 3 trial so far published is the ECHELON-1, which compares 1 to 1 BV-AVD (Bleomycin is replaced by BV) with standard ABVD in untreated advanced-stage III and IV HL. The ECHELON-1 trial has proven that BV-AVD is safe and more effective both in terms of long-term disease control and overall survival. Just recently, the results of the S1826 SWOG trial demonstrated that the combination nivolumab-AVD (N-AVD) is better than BV-AVD, while preliminary results of other randomized ongoing phase 3 trials incorporating anti-PD-1 in this setting will be soon available. The aim of this review is to present the recent data regarding these novel agents in first-line treatment of HL and to highlight current and future trends which will hopefully reshape the overall management of this disease.

Biomodulatory Treatment Regimen, MEPED, Rescues Relapsed and Refractory Classic Hodgkin's Disease

Introduction: Current combined intensive chemotherapy and radiation regimens yield excellent survival rates in advanced classic Hodgkin’s lymphoma (cHL). However, acute toxicity in elderly, comorbid patients can be challenging and long-term survival in refractory patients remains poor.

Patients and Methods: We report on six patients with r/r HL, three patients with long-term follow-up, three newly treated, after biomodulatory therapy. All patients received MEPED (treosulfan 250 mg p.o. daily, everolimus 15 mg p.o. daily to achieve serum trough levels of 15 ng/ml, pioglitazone 45 mg p.o. daily, etoricoxib 60 mg p.o. daily and dexamethasone 0.5 mg p.o. daily). Patients had either received every at that time approved systemic treatment or were ineligible for standard treatment, including immune checkpoint inhibition (ICPi) due to prior demyelinating autoimmune polyneuropathy, myasthenia gravis and previous allogeneic hematopoietic-stem-cell transplant (alloHSCT). Medication was administered continuously from day 1. One patient with relapse after alloHSCT received trofosfamide 50 mg daily instead of treosulfan to avoid risk of increased myelotoxicity. The patients were treated in individual healing attempts outside a clinical trial after institutional review board approval. ¹⁸F-fluoro-2-deoxy-d-glucose positron emission tomography combined with computed tomography scan (FDG-PET/CT) was performed to monitor treatment and follow-up.

Results: In the three newly treated patients, CT scans showed partial remissions after 2–5 months on MEPED treatment. Two patients had achieved PET Deauville score 2 and 3, while the third remained positive at Deauville score 5. One patient achieving PR became eligible for alloHSCT, while the other two patients continued treatment with MEPED. All patients eventually achieved continuous complete remission (cCR), one after consecutive alloHSCT, one after discontinuing MEPED consolidation for >1 year and one on on-going MEPED consolidation, respectively. Only one patient experienced Grade 3 toxicity (bacterial pneumonia) requiring temporary discontinuation of MEPED for 10 days. All three previously published patients received allo HSCT for consolidation and have achieved cCR.

Conclusions: MEPED is well tolerated with low toxicity and highly efficacious in relapsed/refractory cHL, including severely comorbid patients. Due to its immunomodulatory components, MEPED might also have a synergistic potential when combined with ICPi but requires further evaluation within a clinical trial.

SNPs in genes encoding for IL-10, TNF-α, and NFκB p105/p50 are associated with clinical prognostic factors for patients with Hodgkin lymphoma

Classical Hodgkin lymphoma (cHL) is a B-cell-derived malignant neoplasia that has a unique histological distribution, in which the scarce malignant Hodgkin and Reed-Sternberg cells are surrounded by nonmalignant inflammatory cells. The interactions between the malignant and inflammatory cells are mediated by aberrantly produced cytokines, which play an important role in tumor immunopathogenesis. Single nucleotide polymorphisms (SNPs) in genes encoding cytokines and their regulatory proteins may influence the peripheral levels of these molecules and affect disease’s pathobiology. In this study, we evaluate SNPs in the promoter regions of the genes encoding for two key cytokines in Hodgkin lymphoma: IL-10 (SNP/pIL10–592, rs1800872; and SNP/pIL10–1082, rs1800896) and TNF-α (SNP/pTNF -238, rs361525; and SNP/pTNF -862, rs1800630), as well as an SNP in the intronic region of the NFκB1 gene (SNP/iNFKB1, rs1585215), an important regulator of cytokine gene expression. We then look to their possible association with clinical and laboratory features in cHL patients. Seventy-three patients with cHL are genotyped by qPCR-high resolution melting. The SNPs’ genotypes are analyzed individually for each SNP, and when more than two allelic combinations are identified, the genotypes are also divided into two groups according to proposed biological relevance. By univariate analysis, patients harboring SNP/pTNF -238 AG genotype more frequently have EBV-associated cHL compared to homozygous GG, whereas the presence of mediastinal disease (bulky and nonbulky) is more common in the pIL10–592 AC/CC group compared to the AA homozygous group. Patients with SNP/iNFKB1 AA genotype more frequently have stage IV and extranodal disease at diagnosis. These results indicate that some SNPs’ genotypes for IL-10 and TNF-α genes are associated with prognostic parameters in cHL. For the first time, the SNP/iNFKB1 is described in association with clinical features of the disease.

Defining the Inflammatory Plasma Proteome in Pediatric Hodgkin Lymphoma

Simple Summary

Hodgkin lymphoma (HL) is a common type of cancer that is characterized by rare, malignant cells among an inflammatory microenvironment. Specific systemic, inflammatory plasma proteins have demonstrated prognostic significance in adult HL; however, systemic inflammation has not been well-characterized in childhood HL. The aim of our study was to better define the inflammatory pre-therapy plasma proteome and identify plasma proteins associated with clinical features of childhood HL. We measured plasma concentrations of 135 proteins in 56 pediatric subjects with newly diagnosed HL and 47 healthy pediatric controls. We found that the plasma protein profile was distinct from controls, and unique proteins were associated with high-risk disease (IL-10, TNF-α, IFN-γ, IL-8), slow early therapy response (CCL13, IFN-λ1, IL-8), and relapse (TNFSF10). These proteins could be used to improve risk stratification, and thus optimize outcomes and minimize unnecessary toxic exposures for those with childhood HL.

Abstract

Hodgkin lymphoma (HL) histopathology is characterized by rare malignant Reed–Sternberg cells among an inflammatory infiltrate. We hypothesized that characteristics of inflammation in pediatric HL lesions would be reflected by the levels of inflammatory cytokines or chemokines in pre-therapy plasma of children with HL. The study objectives were to better define the inflammatory pre-therapy plasma proteome and identify plasma biomarkers associated with extent of disease and clinical outcomes in pediatric HL. Pre-therapy plasma samples were obtained from pediatric subjects with newly diagnosed HL and healthy pediatric controls. Plasma concentrations of 135 cytokines/chemokines were measured with the Luminex platform. Associations between protein concentration and disease characteristics were determined using multivariate permutation tests with false discovery control. Fifty-six subjects with HL (mean age: 13 years, range 3–18) and 47 controls were analyzed. The cytokine/chemokine profiles of subjects with HL were distinct from controls, and unique cytokines/chemokines were associated with high-risk disease (IL-10, TNF-α, IFN-γ, IL-8) and slow early response (CCL13, IFN-λ1, IL-8). TNFSF10 was significantly elevated among those who ultimately relapsed and was significantly associated with worse event-free survival. These biomarkers could be incorporated into biologically based risk stratification to optimize outcomes and minimize toxicities in pediatric HL.

Salvage Therapy for Hodgkin's Lymphoma: A Review of Current Regimens and Outcomes

Relapse/refractory Hodgkin lymphoma patients are still a clinical concern. Indeed, despite more effective first-line chemotherapy regimens and better stratification of unresponsive patients by clinical factors and use of early PET, roughly one-third of such patients need salvage chemotherapy and consolidation with high-dose chemotherapy. In this paper, the authors review the different salvage treatments, with special emphasis on newer combinations with brentuximab vedotin or check point inhibitors. The overall response rate is constantly increasing, with a complete remission rate approaching 80%. Functional response evaluation by PET imaging is a strong predictive factor of longer survival, and more sophisticated tools, such as detection of circulating tumour DNA, are emerging to refine the disease-status assessment after treatment. Consolidation by high-dose chemotherapy is still considered the standard of care in chemosensitive patients, leading to a high fraction of patients towards long-term disease control. Maintenance therapy with BV is now approved, reducing disease relapse/progression. An increasing number of Hodgkin lymphoma patients will be cured after first- and second-line therapy, and long-term toxicity needs to be continuously assessed and avoided.

Histology of pediatric classic Hodgkin lymphoma: From diagnosis to prognostic stratification

AIMS

Classic Hodgkin lymphoma (cHL) is a common malignancy of the pediatric age. Although clinical-radiological features are routinely used for disease risk stratification, the role of tumor histology has yet to be defined. This study aimed to characterize the clinical-pathological features of a large cohort of pediatric cHL specifically investigating the relevance of tumor histology for the prognostic stratification of patients.

METHODS AND RESULTS

The study considered 96 clinically annotated cases of pediatric cHL treated according to the AIEOP-LH2004 protocol. The following histological parameters were considered: (i) cHL variant; (ii) grade of nodular sclerosis (NS); (iii) staining for Bcl2 and p53, and expression of B-cell (BCA) and T-cell antigens (TCA) by Hodgkin/Reed-Sternberg cells. The study population consisted of 51 males and 45 females (median age: 13.6 years) with five-year overall and progression-free survival of 94% and 81%, respectively. Most cases featured NS morphology (96%) with a prevalence of NS1 over NS2 grades. Two NS2 variants were recognized (sarcomatous/syncytial and fibrohistiocytic). A consistent subset of cases disclosed positivity for BCA (34%), TCA (26%), p53 (13%), and Bcl2 (19%). Clinical-pathological correlations showed a more aggressive clinical course for NS2 over NS1 cases. The NS2 fibrohistiocytic variant was associated with the worst outcome. No other histological features correlated with prognosis.

CONCLUSIONS

Pediatric cHL is a clinically and histologically heterogeneous neoplasm. The majority of cases disclose NS morphology and aberrant phenotypes are frequently encountered. In the pediatric population, NS grading and NS2 subtyping bear significant prognostic impact.

An update on disease biomarkers for Hodgkin lymphoma

Introduction: Hodgkin Lymphoma (HL) carries an overall excellent prognosis for young patients treated with multimodal therapy. Predicting an individual patient's prognosis is currently heavily dependent on imaging modalities such as Positron Emission Tomography (PET).Areas covered: Potential biomarkers from serum, tissue, circulating nucleic acids and non-tumor derived cells have all been reported to be of prognostic relevance in HL. We review a range of these biomarkers and discuss the integration of new biomarkers into individualized patient care.Expert opinion: Better prognostic markers are needed to predict an individuals response to HL therapy. Interim PET-scan improves the ability to predict long-term treatment responders. However, it is our opinion that supplementation of PET results with additional biomarkers (including circulating tumor DNA, protein biomarkers, tissue genotyping and metabolic tumor volume) are likely to improve risk stratification for future patients with HL.

Formation of the Immunosuppressive Microenvironment of Classic Hodgkin Lymphoma and Therapeutic Approaches to Counter It

Classic Hodgkin lymphoma (cHL) is characterized by a few tumor cells surrounded by a protective, immunosuppressive tumor microenvironment composed of normal cells that are an active part of the disease. Hodgkin and Reed-Sternberg (HRS) cells evade the immune system through a variety of different mechanisms. They evade antitumor effector T cells and natural killer cells and promote T cell exhaustion. Using cytokines and extracellular vesicles, they recruit normal cells, induce their proliferation and "educate" (i.e. reprogram) them to become immunosuppressive and protumorigenic. Therefore, alternative treatment strategies are being developed to target not only tumor cells but also the tumor microenvironment. Here we summarize current knowledge on the ability of HRS cells to build their microenvironment and to educate normal cells to become immunosuppressive. We also describe therapeutic strategies to counteract formation of the tumor microenvironment and related processes leading to T cell exhaustion and repolarization of immunosuppressive tumor-associated macrophages.

MGCD0103 induces apoptosis and simultaneously increases the expression of NF-κB and PD-L1 in classical Hodgkin's lymphoma

At present there is no consensus on the treatment of classical Hodgkin's lymphoma (CHL) following relapse. The aim of the present study was to access the class I-selective histone deacetylase (HDAC) inhibitor (HDACI) MGCD0103 on the expression levels of Bcl-2, nuclear factor (NF)-κB and programmed death-ligand 1 (PD-L1) in CHL, to explore the possible therapeutic value of MGCD0103 in combined relative target drugs for patients with CHL. In L1236 and L428 cell lines, apoptosis and cell cycle stage were identified using flow cytometry, and the effects of HDACI on CHL were assessed in terms of Bcl-2, NF-κB and PD-L1 expression levels, which were detected by western blotting and co-focusing experiments. The results demonstrated that MGCD0103 could induce cell apoptosis and cell cycle arrest, down-regulate Bcl-2 and increase NF-κB and PD-L1 expression levels in L1236 and L428 cell lines. MGCD0103 decreases Bcl-2 levels and upregulates PD-L1, which indicates that the combined use of HDACIs and a PD-L1 inhibitor in theory may improve treatment outcomes in patients with CHL. MGCD0103 may also up-regulate NF-κB, which seems to induce resistance towards anti-apoptotic drugs. Clinical trials combining HDACIs with NF-κB and/or PD-L1 inhibitors should be designed to further improve treatment outcomes for patients with CHL.

Nano-delivery system targeting to cancer stem cell cluster of differentiation biomarkers

Cancer stem cells (CSCs) are one of the most important origins of cancer progression and metastasis. CSCs have unique self-renewal properties and diverse cell membrane receptors that induced the resistance to the conventional chemotherapeutic agents. Therefore, the therapeutic removal of CSCs could result in the cancer cure with lack of recurrence and metastasis. In this regard, targeting CSCs in accordance to their specific biomarkers is a talented attitude in cancer therapy. Various CSCs surface biomarkers have been described, which some of them exhibited similarities on different cancer cell types, while the others are cancer specific and have just been reported on one or a few types of cancers. In this review, the importance of CSCs in cancer development and therapeutic response has been stated. Different CSCs cluster of differentiation (CD) biomarkers and their specific function and applications in the treatment of cancers have been discussed, Special attention has been made on targeted nano-delivery systems. In this regard, several examples have been illustrated concerning specific natural and artificial ligands against CSCs CD biomarkers that could be decorated on various nanoparticulated drug delivery systems to enhance therapeutic index of chemotherapeutic agents or anticancer gene therapy. The outlook of CSCs biomarkers discovery and therapeutic/diagnostic applications was discussed.

Epstein-Barr virus latent membrane protein-1 up-regulates cytokines and correlates with older age and poorer prognosis in Hodgkin lymphoma

AIMS

Previously, we reported an association between Epstein-Barr virus (EBV)-positive Hodgkin lymphoma (HL), older age, and poorer prognosis. The aim of this study was to investigate the mechanisms underlying this association.

METHODS AND RESULTS

Transfection of HL cell lines with EBV latent membrane protein-1 (LMP1) resulted in up-regulation of many cytokine genes as assessed by the use of oligonucleotide microarrays. The up-regulation of cytokines was validated by using an inflammatory cytokine protein array: macrophage inflammatory protein (MIP)-1α, MIP-1β, and interleukin (IL)-13. Immunostaining of HL samples (n = 104) showed that expression of MIP-1α, MIP-1β and IL-13 correlated with EBV infection and LMP1 expression. Combined expression of these cytokines was more common in patients aged >60 years (P < 0.001), and was associated with a poorer prognosis (P = 0.042). In another cohort, serum levels of MIP-1α, MIP-1β and IL-13 were increased in HL patients (n = 53) and highest in EBV-positive HL patients as compared with healthy controls (n = 40). Xenograft mice injected with EBV-positive HL cells had higher serum levels of MIP-1α, MIP-1β and IL-13 than mice injected with EBV-negative HL cells, although there was no difference in growth.

CONCLUSIONS

EBV infection appears to promote the release of cytokines in HL patients, and negatively impacts on patient survival. Physiological immunosenescence probably explains the association between EBV infection and older age. Cytokine modulation is a potential therapeutic target for EBV-positive HL patients.

Outcome of Hodgkin Lymphoma Patients With a Posttreatment 18F-Fluoro-2-Deoxy-d-Glucose Positron Emission Tomography (FDG-PET)-Negative Residual Mass: Systematic Review and Meta-analysis

To systematically review and meta-analyze the outcome of Hodgkin lymphoma patients with a posttreatment (18)F-fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET)-negative residual mass. A systematic PubMed/MEDLINE database search was performed. The methodological quality of included studies was assessed. The number of patients with a posttreatment non-FDG-avid residual mass and the number of these patients who developed disease relapse during follow-up were extracted from each included study. Heterogeneity in disease relapse proportions across individual studies was assessed using the I2 test, with heterogeneity defined as I(2) > 50%. Using a Freeman-Tukey transformation, the disease relapse proportions from each individual study were then meta-analyzed with either a fixed-effects model (if I2 ≤ 50 %) or a random-effects model (if I2 > 50 %). A total of 5 studies comprising a total of 727 Hodgkin lymphoma patients with an FDG-PET-negative residual mass after first-line therapy were included. The overall quality of included studies was moderate. The proportion of patients with a posttreatment non-FDG-avid residual mass who experienced disease relapse during follow-up ranged between 0% and 13.8%. There was heterogeneity in disease relapse proportions across individual studies (I2 = 61.4%). Pooled disease relapse proportion (random effects) was 6.8% (95% confidence interval: 2.6%-12.5%). The disease relapse rate in Hodgkin lymphoma patients with a FDG-PET-negative residual mass after first-line therapy is approximately 6.8%. Considering the existing literature, the presence of a non-FDG-avid residual mass has not been proven yet to be associated with a worse outcome than a posttreatment FDG-PET-based complete remission status without a residual mass.

Prognostic Biomarkers for Hodgkin Lymphoma

The prognosis of patients with classical Hodgkin lymphoma following chemo- and radiotherapy has been excellent during the last 4 decades. However, the development of secondary malignancies is of major concern. Therefore, the reduction of radiotherapy application is a major objective of ongoing clinical trials. De-escalation of treatment may increase the risk of relapses and thus may lead to reappearance of prognostic factors. Prognostic biomarkers might help to identify patients who are at increased risk of relapse. This review summarizes the current knowledge about potential prognostic biomarkers for patients with classical Hodgkin lymphoma.

Systematic review and meta-analysis on the prognostic value of complete remission status at FDG-PET in Hodgkin lymphoma after completion of first-line therapy

This study aimed to systematically review and meta-analyze the prognostic value of complete remission status at 18F-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) in Hodgkin lymphoma after completion of first-line therapy. A systematic literature search was performed in the MEDLINE database for suitable original articles. The included studies were methodologically assessed using the Quality In Prognosis Studies tool. The proportion of patients who developed disease relapse during follow-up, among those patients who were in complete remission according to FDG-PET at the completion of first-line therapy, was calculated for each included study. Heterogeneity in disease relapse proportions across individual studies was assessed using the I2 statistic, with heterogeneity regarded present if I2<50 %. Weighted summary disease relapse proportion was calculated using either a random effects model (if I2>50) or a fixed effects model (if I2≤50). Ten studies comprising a total number of 1137 Hodgkin lymphoma patients with complete remission status according to FDG-PET after completion of first-line therapy were included. Overall methodological quality of included studies was reasonably good. The disease relapse rate during follow-up among all patients with complete remission status at end-of-treatment FDG-PET ranged from 0 to 26.7 %, with a weighted summary proportion of 7.5 % (95 % confidence interval 3.9–13.8 %) using the random effects model (I2=88.3 %). In conclusion, although the disease relapse rate in Hodgkin lymphoma patients who achieve an FDG-PET-based complete remission after first-line therapy is low from an absolute point of view, it is actually high when considering the generally favorable outcome of Hodgkin lymphoma.

CD68+ cell count, early evaluation with PET and plasma TARC levels predict response in Hodgkin lymphoma

Early response evaluation with [¹⁸F]fluordeoxyglucose (FDG) positron emission tomography after 2 cycles of chemotherapy (interim PET) has been indicated as the strongest predictor for outcome in classical Hodgkin lymphoma (HL). We studied the prognostic role of the number of tumor‐infiltrating CD68+ cells and of the plasma levels of TARC (thymus and activation‐regulated chemokine) in the context of interim PET in 102 patients with classical HL treated with Adriamycin, Bleomycin, Vinblastine, Dacarbazine (ABVD). After 2 ABVD cycles, interim PET according to Deauville criteria was negative (score 0–3) in 85 patients and positive (score 4–5) in 15 patients (2 patients technically not evaluable). TARC levels were elevated in 89% of patients at diagnosis, and decreased after 2 cycles in 82% of patients. Persistently elevated TARC levels in 18% of patients were significantly associated with a positive PET result (P = 0.007). Strong predictors for progression‐free survival (PFS) were a negative interim PET (85% vs. 28%, P < 0.0001) and CD68+ cell counts <5% (89% vs. 67%, P = 0.006), while TARC levels at diagnosis and at interim evaluation had no prognostic role. In multivariate analysis, interim PET, CD68+ cell counts and presence of B‐symptoms were independently associated with PFS. We conclude that although TARC levels are a biomarker for early response evaluation, they cannot substitute for interim PET as outcome predictor in HL. The evaluation of CD68 counts and B‐symptoms at diagnosis may help to identify low‐risk patients regardless positive interim PET.

Analysis of biological and technical variability in gene expression assays from formalin-fixed paraffin-embedded classical Hodgkin lymphomas

Formalin-fixed paraffin-embedded (FFPE) tissues are invaluable sources of biological material for research and diagnostic purposes. In this study, we aimed to identify biological and technical variability in RT-qPCR TaqMan® assays performed with FFPE-RNA from lymph nodes of classical Hodgkin lymphoma samples. An ANOVA-nested 6-level design was employed to evaluate BCL2, CASP3, IRF4, LYZ and STAT1 gene expression. The most variable genes were CASP3 (low expression) and LYZ (high expression). Total variability decreased after normalization for all genes, except by LYZ. Genes with moderate and low expression were identified and suffered more the effects of the technical manipulation than high-expression genes. Pre-amplification was shown to introduce significant technical variability, which was partially alleviated by lowering to a half the amount of input RNA. Ct and Cy0 quantification methods, based on cycle-threshold and the kinetic of amplification curves, respectively, were compared. Cy0 method resulted in higher quantification values, leading to the decrease of total variability in CASP3 and LYZ genes. The mean individual noise was 0.45 (0.31 to 0.61 SD), indicating a variation of gene expression over ~1.5 folds from one case to another. We showed that total variability in RT-qPCR from FFPE-RNA is not higher than that reported for fresh complex tissues, and identified gene-, and expression level-sources of biological and technical variability, which can allow better strategies for designing RT-qPCR assays from highly degraded and inhibited samples.

Genetic associations in classical hodgkin lymphoma: a systematic review and insights into susceptibility mechanisms

Both targeted and genome-wide studies have revealed genetic associations for susceptibility, prognosis, and treatment-induced secondary malignancies and toxicities in classical Hodgkin lymphoma (cHL). This review gives a systematic and comprehensive overview of significant associations and places them into a biologic context. The strongest susceptibility polymorphisms have been found for the human leukocyte antigen (HLA) genes. These associations are specific for cHL overall or for subgroups based on tumor cell Epstein-Barr virus (EBV) status. These findings strongly suggest that EBV-specific immune responses influence cHL susceptibility in EBV(+) cHL and that immune responses targeting other tumor-associated antigens are important in EBV(-) cHL. Accordingly, most of the numerous other susceptibility loci map to genes that affect functionality of the immune system, underscoring the crucial role of the immune system in cHL development. The number of association studies on cHL prognosis is limited with one consistent association for the drug-metabolizing UGT1A1 gene. PRDM1 is associated with radiation-induced secondary malignancies and a small number of genes are associated with treatment-related toxicities. In conclusion, most loci showing genetic associations in cHL harbor genes with a potential functional relevance for cHL susceptibility.