Brentuximab vedotin exerts profound antiproliferative and pro-apoptotic efficacy in CD30-positive as well as cocultured CD30-negative germ cell tumour cell lines

Antibody-drug conjugates as a novel therapeutic modality to treat recurrent refractory germ cell tumors

This review provides a rationale for using the Food and Drug Administration (FDA)-approved antibody-drug conjugates (ADCs) for implementing as therapy in recurrent refractory germ cell tumors similar to their position in the treatment of other types of chemoresistant solid tumors. Germ cell tumors (GCTs) originate from germ cells; they most frequently develop in ovaries or in the testes, while being the most common type of malignancy in young men. GCTs are very sensitive to cisplatin-based chemotherapy, but therapeutic resistance occurs in a considerable number of cases, which is associated with disease recurrence and poor patient prognosis. ADCs are a novel type of targeted antitumor agents that combine tumor antigen-specific monoclonal antibodies with chemically linked chemotherapeutic drugs (payload) exerting a cytotoxic effect. Several FDA-approved ADCs use as targeting moieties the antigens that are also detected in the GCTs, offering a benefit of this type of targeted therapy even for patients with relapsed/refractory testicular GCTs (rrTGCT) unresponsive to standard chemotherapy.

Antibody-Drug Conjugates: Ushering in a New Era of Cancer Therapy

Antibody-drug conjugates (ADCs) have provided new therapeutic options and significant promise for patients with cancer, particularly where existing treatments are limited. Substantial effort in ADC development is underway globally, with 13 ADCs currently approved and many more in development. The therapeutic benefits of ADCs leverage the ability to selectively target cancer cells through antibody binding, resultant relative sparing of non-malignant tissues, and the targeted delivery of a cytotoxic payload. Consequently, this drug class has demonstrated activity in multiple malignancies refractory to standard therapeutic options. Despite this, limitations exist, including narrow therapeutic windows, unique toxicity profiles, development of therapeutic resistance, and appropriate biomarker selection. This review will describe the development of ADCs, their mechanisms of action, pivotal trials, and approved indications and identify common themes. Current challenges and opportunities will be discussed for this drug class in cancer therapeutics at a time when significant developments in antibody therapies, immunotherapy, and targeted agents are occurring.

Brentuxinmab vedotin, alone or combine with bendamustine in the treatment of natural killer T cell lymphoma

Natural killer (NK)/T cell lymphoma is a highly aggressive subtype of non-Hodgkin lymphoma. The prognosis of patients with natural killer T cell lymphoma (NKTCL) remains poor. More potent treatment strategies are urgently needed to improve the survival of these patients with R/R NKTCL. CD30 expression has been reported to occur in about 40% of NK/T cell lymphoma. Brentuximab vedotin (BV), a monomethyl auristatin E conjugated CD30 antibody, targets CD30 to kill cancer cells. Therapeutic combination of BV and bendamustine has been shown to be highly effective in Hodgkin lymphoma. We investigated efficacy of BV in treating NKTCL as a single therapy, and in combination with bendamustine in vitro and in vivo. We determined CD30 expression levels in 6 NKTCL cell lines. The efficiency of lymphoma cell inhibition by BV correlates with CD30 expression. We also determined the efficacy of BV in combination with bendamustine and found synergistic effects with bendamustine in NKTCL. Combined BV and bendamustine treatment exerted synergistic antiproliferation effect and enhanced cell apoptotic in vitro and in vivo. Brentuximab vedotin and bendamustine synergistically arrested cell cycle at the G2/M phase in NKTCL cell lines. The combination of BV and bendamustine was demonstrated to synergistically damage DNA in NKTCL. This study provides a reference for possible application on using BV for the treatment of NKTCL, either as a single agent or in combination with bendamustine.

Brentuximab Vedotin Plus CHP in Frontline sALCL: Adjusted Estimates of Efficacy and Cost-Effectiveness Removing the Effects of Re-Treatment with Brentuximab Vedotin

BACKGROUND

In the randomised controlled trial ECHELON-2 (NCT01777152; January 2013), brentuximab vedotin (BV) plus cyclophosphamide, doxorubicin and prednisone (CHP) demonstrated improved efficacy compared with CHOP (CHP and vincristine) in frontline CD30+ peripheral T-cell lymphoma (PTCL), an aggressive cancer with poor survival. In ECHELON-2, 70% of patients had systemic anaplastic large cell lymphoma (sALCL), a subtype of PTCL. Of sALCL patients who progressed from BV+CHP and CHOP, 36% (n = 17) and 56% (n = 36) received subsequent BV-containing therapy, respectively. As BV re-treatment was not funded in England at the time, our objective was to estimate adjusted efficacy and cost-effectiveness by excluding BV re-treatment from BV+CHP.

METHODS

To remove the effects of BV re-treatment, the inverse probability of censoring weights (IPCW) and two-stage estimator (TSE) approaches, with and without re-censoring, were applied to overall survival (OS) in the BV+CHP arm of the ECHELON-2 sALCL population. Cost-effectiveness was determined in a three-state partitioned survival (PartSA) model from the perspective of the National Health Service (NHS) in England.

RESULTS

The unadjusted hazard ratio (HR) for death in patients with sALCL with BV+CHP versus CHOP was 0.54 (95% CI 0.34, 0.87; p = 0.011). The model base case used TSE analysis without re-censoring, which provided an adjusted HR for death of 0.55 (95% CI 0.33, 0.86; p = 0.014). Incremental cost-effectiveness ratios (ICERs) including and excluding re-treatment with BV were £29,760/QALY and £27,761/QALY, respectively.

CONCLUSION

TSE without re-censoring provided the most clinically plausible estimate of survival whilst retaining sufficient information for OS extrapolation. After adjustment for BV re-treatment, BV+CHP remains an efficacious and cost-effective treatment in frontline sALCL compared with CHOP.

Brentuximab vedotin induced uveitis

Purpose

To report a case of bilateral Vogt-Koyanagi-Harada (VKH)-like granulomatous pan uveitis secondary to brentuximab vedotin (BV) administration to treat for classical Hodgkin lymphoma (CHL).

Observations

A case of bilateral pan uveitis is described, following administration of BV, with features of VKH-like uveitis: presence of inflammatory cells in the anterior and posterior segment, multiple small serous detachments around the optic disc and retinal pigment epithelium (RPE) folds confirmed by optical coherence tomography (OCT) as well as hypocyanesent dark dots, disc hyperfluorescence and fuzzy vascular patterns seen on indocyanine green and fluorescein angiography. There were no systemic features of VKH disease. Further etiological investigation showed no clear infectious or inflammatory cause. The uveitis responded well to treatment with corticosteroids and cessation of BV. A relapse occurred a few months later when BV treatment was reinitiated, suggesting a probable adverse event to this drug, according to the Naranjo algorithm.

Conclusions

We hypothesize that administration of BV can induce a VKH-like uveitis, caused by loss of function of protective CD30⁺ cells present in the uveal tract, possibly aggravated by collateral damage to surrounding CD30⁻cells and melanocytes, leading to a uveal immune reaction. It is therefore important for the clinicians using BV to be aware of this adverse event. Growing experience with immunotherapy will provide more clinical insights in these complex immune mechanisms in the future.

Overcoming Chemotherapy Resistance in Germ Cell Tumors

Testicular germ cell tumors (GCTs) are highly curable malignancies. Excellent survival rates in patients with metastatic disease can be attributed to the exceptional sensitivity of GCTs to cisplatin-based chemotherapy. This hypersensitivity is probably related to alterations in the DNA repair of cisplatin-induced DNA damage, and an excessive apoptotic response. However, chemotherapy fails due to the development of cisplatin resistance in a proportion of patients. The molecular basis of this resistance appears to be multifactorial. Tracking the mechanisms of cisplatin resistance in GCTs, multiple molecules have been identified as potential therapeutic targets. A variety of therapeutic agents have been evaluated in preclinical and clinical studies. These include different chemotherapeutics, targeted therapies, such as tyrosine kinase inhibitors, mTOR inhibitors, PARP inhibitors, CDK inhibitors, and anti-CD30 therapy, as well as immune-checkpoint inhibitors, epigenetic therapy, and others. These therapeutics have been used as single agents or in combination with cisplatin. Some of them have shown promising in vitro activity in overcoming cisplatin resistance, but have not been effective in clinical trials in refractory GCT patients. This review provides a summary of current knowledge about the molecular mechanisms of cisplatin sensitivity and resistance in GCTs and outlines possible therapeutic approaches that seek to overcome this chemoresistance.

The expression of CD30 and its clinico-pathologic significance in peripheral T-cell lymphomas

INTRODUCTION

Recent studies have shown that CD30 expression can be an important feature of peripheral and cutaneous T-cell lymphomas (PTCLs and CTCLs) and CD30 testing has increased in importance with the emergence of CD30-directed therapy.

AREAS COVERED

This article reviews the literature on CD30-related biology, prevalence, and therapy in patients with PTCL or CTCL. We searched the PubMed database from 1 January 2010 to 28 April 2020, using terms 'CD30' ('peripheral T-cell lymphomas' or 'cutaneous T-cell lymphoma') and 'immunohistochemistry' or 'flow cytometry' or 'pathology,' and synonyms including terms for T-cell lymphoma subtypes.

EXPERT OPINION

CD30 is expressed at relatively high rates of prevalence across a broad range of PTCLs and CTCLs. CD30 expression may be critical to the development of a subset of PTCLs and also a biomarker for treatment choice in some subtypes. Large-scale randomized, controlled studies have shown that CD30-directed treatment with brentuximab vedotin is significantly more effective against CD30-expressing PTCL and CTCL than current standard-of-care regimens. However, accurate CD30 evaluation is limited by inconsistencies in detection methodology and expression cutoffs defining CD30-expressing disease. Greater understanding of CD30 testing and reporting will enable more patients with CD30-expressing PTCL and CTCL to be identified and treated appropriately.

Biological bases of cancer immunotherapy

Immunotherapy has changed the landscape of cancer treatment and has significantly improved the outcome of several cancer types including breast, lung, colorectal and prostate. Neoantigen recognition and immune checkpoint inhibitors are nowadays the milestones of different immunotherapeutic regimes; however, high cost, primary and acquired resistance and the high variability of responses make their extensive use difficult. The development of better predictive biomarkers that represent tumour diversity shows promise because there is a significant body of clinical data showing a spectrum of immunotherapeutic responses that might be related back to their specific characteristics. This article makes a conceptual and historical review to summarise the main advances in our understanding of the role of the immune system in cancer, while describing the methodological details that have been successfully implemented on cancer treatments and that may hold the key to improved therapeutic approaches.

Promising novel therapies for relapsed and refractory testicular germ cell tumors

INTRODUCTION

Germ cell tumors (GCTs) are the most common solid malignancies in young men. The overall cure rate of GCT patients in metastatic stage is excellent, however; patients with relapsed or refractory disease have poor prognosis. Attempts to treat refractory disease with novel effective treatment to improve prognosis have been historically dismal and the ability to predict prognosis and treatment response in GCTs did not sufficiently improve in the last three decades.

AREAS COVERED

We performed a comprehensive literature search of PubMed/MEDLINE to identify original and review articles (years 1964-2020) reporting on current improvement salvage treatment in GCTs and novel treatment options including molecularly targeted therapy and epigenetic approach. Review articles were further searched for additional original articles.

EXPERT OPINION

Despite multimodal treatment approaches the treatment of relapsed or platinum-refractory GCTs remains a challenge. High-dose chemotherapy (HDCT) regimens with autologous stem-cell transplant (ASCT) from peripheral blood showed promising results in larger retrospective studies. Promising results from in vitro studies raised high expectations in molecular targets. So far, the lacking efficacy in small and unselected trials do not shed a light on targeted therapy. Currently, wide inclusion of patients into clinical trials is highly advised.

Targeting EpCAM by a Bispecific Trifunctional Antibody Exerts Profound Cytotoxic Efficacy in Germ Cell Tumor Cell Lines

Outcome in high-risk patients with refractory or relapsed germ cell tumours (GCT) remains poor. Novel strategies enhancing therapeutic efficacy whilst limiting therapeutic burden are warranted, yet immunotherapy approaches geared towards activating endogenous antitumor responses have not been successful thus far. Redirection of cytotoxic effector cells by bispecific antibodies represents a promising approach in this setting. We demonstrate that the Epithelial Cell Adhesion Molecule (EpCAM) is broadly expressed in GCT cell lines of different histologic origin including seminoma, choriocarcinoma (CHC), and embryonal carcinoma (EC). In these GCT lines of variable EpCAM surface expression, targeting T cells by the prototypic bispecific EpCAM/CD3-antibody (bAb) Catumaxomab together with natural killer (NK) cell engagement via the Fc domain promotes profound cytotoxicity across a broad range of antibody dilutions. In contrast, tumor cell lysis mediated by either immune cell subset alone is influenced by surface density of the target antigen. In the CHC line JAR, NK cell-dependent cytotoxicity dominates, which may be attributed to differential surface expression of immunomodulatory proteins such as MHC-I, CD24, and Fas receptors on CHC and EC. In view of redirecting T cell therapy mediated by bispecific antibodies, such differences in GCT immunophenotype potentially favoring immune escape are worth further investigation.

Practical Approaches on CD30 Detection and Reporting in Lymphoma Diagnosis

While our understanding of the biology of CD30 in lymphoma continues to evolve, our need to detect and measure its expression at the protein level remains critically important for diagnosis and patient care. In addition to its diagnostic and prognostic utility, CD30 has emerged as a vehicle for drug targeting through the antibody-drug conjugate brentuximab-vedotin (BV). Given the numerous ways that CD30 is utilized and its emergence as a predictive/prognostic biomarker, pathologists must come to a general consensus on the best reporting structure and methodology to ensure appropriate patient care. In this manuscript, we review the indications for testing, various modalities for testing, technical challenges, pitfalls, and potential standards of reporting. The following questions will try to be addressed in the current review article: What defines a "POSITIVE" level of CD30 expression?; How do we evaluate and report CD30 expression?; What are the caveats in the evaluation of CD30 expression?

Testicular germ cell tumor: a comprehensive review

Testicular tumors are the most common tumors in adolescent and young men and germ cell tumors (TGCTs) account for most of all testicular cancers. Increasing incidence of TGCTs among males provides strong motivation to understand its biological and genetic basis. Gains of chromosome arm 12p and aneuploidy are nearly universal in TGCTs, but TGCTs have low point mutation rate. It is thought that TGCTs develop from premalignant intratubular germ cell neoplasia that is believed to arise from the failure of normal maturation of gonocytes during fetal or postnatal development. Progression toward invasive TGCTs (seminoma and nonseminoma) then occurs after puberty. Both inherited genetic factors and environmental risk factors emerge as important contributors to TGCT susceptibility. Genome-wide association studies have so far identified more than 30 risk loci for TGCTs, suggesting that a polygenic model fits better with the genetic landscape of the disease. Despite high cure rates because of its particular sensitivity to platinum-based chemotherapy, exploration of mechanisms underlying the occurrence, progression, metastasis, recurrence, chemotherapeutic resistance, early diagnosis and optional clinical therapeutics without long-term side effects are urgently needed to reduce the cancer burden in this underserved age group. Herein, we present an up-to-date review on clinical challenges, origin and progression, risk factors, TGCT mouse models, serum diagnostic markers, resistance mechanisms, miRNA regulation, and database resources of TGCTs. We appeal that more attention should be paid to the basic research and clinical diagnosis and treatment of TGCTs.

The potential of brentuximab vedotin, alone or in combination with current clinical therapies, in the treatment of testicular germ cell tumors

Testicular germ cell tumors (TGCTs) are the commonest tumors in young men. With the advancement of chemotherapies, most TGCTs are successfully cured, even when diagnosed at an advanced and metastatic stage. However, a proportion of often young patients, median age 35-40, with advanced disease are not cured and will inevitably die. Therefore, there is an unmet need in this small population of young patients who are candidates for experimental approaches. We investigated a new therapeutic option for this group of patients, aiming to significantly improve their outcome. In recent years, many targeted therapies have been developed which demonstrated high efficacy and low toxicity. Brentuximab vedotin, a monomethyl auristatin E conjugated CD30 antibody, targets CD30 to kill cancer cells. As a large proportion of TGCTs express CD30, in particular embryonal carcinomas, we investigated in vitro the efficacy of brentuximab vedotin in treating TGCTs as a single therapy and in combination with commonly used chemotherapy drugs. We determined CD30 expression levels in 12 TGCT cell lines, including three cisplatin resistant sublines. In general, the efficiency of cancer cell inhibition by brentuximab vedotin correlates with CD30 expression, but there were some exceptions. We also determined the efficacy of brentuximab vedotin in combination with commonly used chemotherapy drugs and found synergistic/additive effects with etoposide, paclitaxel and SN-38. However, cisplatin, the most commonly used chemotherapy drug in TGCT treatment, exhibited antagonism and we showed that cisplatin selectively kills CD30 positive cells. We also found that certain agents, which have been reported to induce CD30 expression in other human malignant diseases, including DNA demethylation drugs, methotrexate and CD30 ligands, were unable to enhance CD30 expression or brentuximab vedotin efficacy in TGCT cells. This study will help to design clinical trials using brentuximab vedotin for the treatment of TGCTs, either as a single agent or in combination with current clinical therapies.

Current pharmacotherapy for testicular germ cell cancer

INTRODUCTION

With the implementation of platinum-based chemotherapy, germ cell tumors (GCTs) became a model for a curable solid tumor, with survival rates of 95% in all patients with >80% survival in metastatic stages.

AREAS COVERED

Herein, the authors review the current standards of adjuvant chemotherapy for stage I GCTs as well as first-line and salvage treatments for metastatic disease. Novel approaches for refractory disease are also reviewed.

EXPERT OPINION

Active surveillance should be considered for all stage I patients and is the preferred approach for stage I seminoma. In stage I non-seminomas with vascular invasion, one cycle of bleomycin, etoposide, and cisplatin (BEP) substantially reduces the relapse risk. For most advanced GCTs, BEP remains the first-line standard of care. For poor prognosis disease treatment, stratification according to tumor marker decline is recommended. The role of primary high-dose chemotherapy (HDCT) for selected very high-risk patients remains to be prospectively evaluated. Salvage HDCT at relapse seems superior to conventional chemotherapy, retrospectively. The treatment of multiply relapsed disease remains challenging. The gemcitabine/oxaliplatin/paclitaxel (GOP) protocol is considered the standard for refractory disease. However, overall, outcomes are poor and new treatment approaches are urgently needed with targeted therapies so far failing to yield relevant clinical activity.

Therapeutic approaches for refractory germ cell cancer

INTRODUCTION

Most germ cell cancer patients with metastatic disease are cured by cisplatin-based combination chemotherapy. 30% of metastatic patients will develop relapse or progress despite adequate first-line treatment and will require salvage therapy, with about 10% of metastasized patients ultimately developing platinum-resistant and fatal disease. Areas covered: Based on a comprehensive literature search of MEDLINE, EMBASE and conference proceedings of ESMO, ASCO and EAU meetings, this review provides an overview on current and potential future treatment options for platinum-refractory germ cell cancer patients including cytostatics and molecularly targeted therapies. Expert commentary: Treatment of platinum-refractory disease remains challenging and long-term survival is rarely achieved despite multimodal treatment approaches. Targeted treatment approaches do not yet play a role in the treatment of platinum-refractory disease due to lacking efficacy in small, unselected clinical trials. Inclusion of patients into clinical trials is strongly recommended.