Conventional-Dose versus High-Dose Chemotherapy for Relapsed Germ Cell Tumors

SEOM-GG clinical guidelines for the management of germ-cell testicular cancer (2023)

Testicular germ cell tumors are the most common tumors in adolescent and young men. They are curable malignancies that should be treated with curative intent, minimizing acute and long-term side effects. Inguinal orchiectomy is the main diagnostic procedure, and is also curative for most localized tumors, while patients with unfavorable risk factors for recurrence, or those who are unable or unwilling to undergo close follow-up, may require adjuvant treatment. Patients with persistent markers after orchiectomy or advanced disease at diagnosis should be staged and classified according to the IGCCCG prognostic classification. BEP is the most recommended chemotherapy, but other schedules such as EP or VIP may be used to avoid bleomycin in some patients. Efforts should be made to avoid unnecessary delays and dose reductions wherever possible. Insufficient marker decline after each cycle is associated with poor prognosis. Management of residual masses after chemotherapy differs between patients with seminoma and non-seminoma tumors. Patients at high risk of relapse, those with refractory tumors, or those who relapse after chemotherapy should be managed by multidisciplinary teams in experienced centers. Salvage treatment for these patients includes conventional-dose chemotherapy (TIP) and/or high-dose chemotherapy, although the best regimen and strategy for each subgroup of patients is not yet well established. In late recurrences, early complete surgical resection should be performed when feasible. Given the high cure rate of TGCT, oncologists should work with patients to prevent and identify potential long-term side effects of the treatment. The above recommendations also apply to extragonadal retroperitoneal and mediastinal tumors.

Pediatric Extracranial Germ Cell Tumors: Review of Clinics and Perspectives in Application of Autologous Stem Cell Transplantation

Pediatric extracranial germ cell tumors (GCTs) are rare, accounting for approximately 3.5% of childhood cancers. Since the introduction of platinum-based chemotherapy, the survival rate of patients has improved to more than 80%. However, poor-risk subtypes of pediatric extracranial GCTs do not respond well to chemotherapy, leading to refractory or relapsed (R/R) diseases. For example, long-term survival rates of mediastinal GCTs or choriocarcinoma are less than 50%. According to reports in recent years for adult patients with R/R GCTs, the use of high-dose chemotherapy (HDCT) combined with autologous stem cell transplantation (ASCT) has clinical advantages; however, HDCT combined with ASCT has rarely been reported in pediatric GCTs. The R/R and poor-risk groups of pediatric GCTs could benefit from HDCT and ASCT.

Testis-expressed gene 11 inhibits cisplatin-induced DNA damage and contributes to chemoresistance in testicular germ cell tumor

Testicular germ cell tumor (TGCT) is a rare cancer but the most common tumor among adolescent and young adult males. Patients with advanced TGCT often exhibit a worse prognosis due to the acquisition of therapeutic resistance. Cisplatin-based chemotherapy is a standard treatment for advanced TGCTs initially sensitive to cisplatin, as exemplified by embryonal carcinoma. The acquisition of cisplatin resistance, however, could be a fatal obstacle for TGCT management. To identify cisplatin resistance-related genes, we performed transcriptome analysis for cisplatin-resistant TGCT cells compared to parental cells. In two types of cisplatin-resistant TGCT cell models that we established from patient-derived TGCT cells, and from the NEC8 cell line, we found that mRNA levels of the high-mobility-group nucleosome-binding gene HMGN5 and meiosis-related gene TEX11 were remarkably upregulated compared to those in the corresponding parental cells. We showed that either HMGN5 or TEX11 knockdown substantially reduced the viability of cisplatin-resistant TGCT cells in the presence of cisplatin. Notably, TEX11 silencing in cisplatin-resistant TGCT cells increased the level of cleaved PARP1 protein, and the percentage of double-strand break marker γH2AX-positive cells. We further demonstrated the therapeutic efficiency of TEX11-specific siRNA on in vivo xenograft models derived from cisplatin-resistant patient-derived TGCT cells. Taken together, the present study provides a potential insight into a mechanism of cisplatin resistance via TEX11-dependent pathways that inhibit apoptosis and DNA damage. We expect that our findings can be applied to the improvement of cisplatin-based chemotherapy for TGCT, particularly for TEX11-overexpressing tumor.

High-dose chemotherapy for relapsed germ cell tumours: outcomes in low-volume specialized centres

OBJECTIVE

To report treatment patterns and survival outcomes of patients with relapsed and refractory metastatic germ cell tumours (GCTs) treated with high-dose chemotherapy (HDCT) and autologous stem-cell transplantation in low-volume specialized centres within the widely dispersed populations of Australia and New Zealand between 1999 and 2019.

PATIENTS AND METHODS

We conducted a retrospective analysis of 111 patients across 13 institutions. Patients were identified from the Australasian Bone Marrow Transplant Recipient Registry. We reviewed treatment regimens, survival outcomes, deliverability and toxicities. Primary endpoints included overall (OS) and progression-free survival (PFS). Cox proportional hazards models were used to test the association of survival outcomes with patient and treatment factors.

RESULTS

The median (range) age was 30 (14-68) years and GCT histology was non-seminomatous in 84% of patients. International Prognostic Factors Study Group (IPFSG) prognostic risk category was very low/low, intermediate, high and very high in 18%, 36%, 25% and 21% of patients, respectively. Salvage conventional-dose chemotherapy (CDCT) was administered prior to HDCT in 59% of patients. Regimens included paclitaxel, ifosfamide, carboplatin and etoposide (50%), carboplatin and etoposide (CE; 28%), carboplatin, etoposide and ifosfamide (CEI; 6%), carboplatin, etoposide and cyclophosphamide (CEC; 5%), CEC-paclitaxel (6%) and other (5%). With a median follow-up of 4.4 years, the 1-, 2- and 5-year PFS rates were 62%, 57% and 52%, respectively, and OS rates were 73%, 65% and 61%, respectively. There were five treatment-related deaths. Progression on treatment occurred in 17%. In a univariable analysis, worse International Germ Cell Cancer Collaborative Group (IGCCCG) and IPFSG prognostic groups were associated with inferior survival outcomes. An association of inferior survival was not found with the number of high-dose cycles received nor when HDCT was delivered after salvage CDCT.

CONCLUSION

This large dual-national registry-based study reinforces the efficacy and deliverability of HDCT for relapsed and refractory metastatic GCT in low-volume specialized centres in Australia and New Zealand, with survival outcomes comparable to those found in international practice.

Utility of a next-generation framework for assessment of genomic damage: A case study using the pharmaceutical drug candidate etoposide

We present a hypothetical case study to examine the use of a next-generation framework developed by the Genetic Toxicology Technical Committee of the Health and Environmental Sciences Institute for assessing the potential risk of genetic damage from a pharmaceutical perspective. We used etoposide, a genotoxic carcinogen, as a representative pharmaceutical for the purposes of this case study. Using the framework as guidance, we formulated a hypothetical scenario for the use of etoposide to illustrate the application of the framework to pharmaceuticals. We collected available data on etoposide considered relevant for assessment of genetic toxicity risk. From the data collected, we conducted a quantitative analysis to estimate margins of exposure (MOEs) to characterize the risk of genetic damage that could be used for decision-making regarding the predefined hypothetical use. We found the framework useful for guiding the selection of appropriate tests and selecting relevant endpoints that reflected the potential for genetic damage in patients. The risk characterization, presented as MOEs, allows decision makers to discern how much benefit is critical to balance any adverse effect(s) that may be induced by the pharmaceutical. Interestingly, pharmaceutical development already incorporates several aspects of the framework per regulations and health authority expectations. Moreover, we observed that quality dose response data can be obtained with carefully planned but routinely conducted genetic toxicity testing. This case study demonstrates the utility of the next-generation framework to quantitatively model human risk based on genetic damage, as applicable to pharmaceuticals.

Current Management of Refractory Germ Cell Tumors

PURPOSE OF REVIEW

Germ cell tumors (GCTs) are the most common solid tumors affecting men between ages of 20 and 34 years. Most of the cases, even in advanced disease, will have good prognosis. However, around 20-30% of advanced disease will be refractory or develop relapse after treatment. Herein, we review the current management of refractory/relapsed GCTs.

RECENT FINDINGS

Salvage treatment of GCTs has been a controversial topic for the last few decades. Conventional dose chemotherapy (CDCT), high-dose chemotherapy (HDCT) with stem cell infusion, and surgical salvage were proven to be effective and curative options in some cases. The international randomized trial (TIGER) will ultimately answer which chemotherapy approach may be optimal. Furthermore, the usage of immunotherapy is still under investigation with limited data so far in the setting of relapsed/refractory GCTs. Curative paradigms including with CDCT and HDCT are possible, although novel approaches beyond HDCT are still needed to eliminate mortality from this disease.

Salvage management of patients with relapsing testicular germ cell tumors

PURPOSE OF REVIEW

This review aims to summarize the latest evidence of medical and surgical treatment options for patients with relapsing testicular germ cell tumors.

RECENT FINDINGS

Depending on International Germ Cell Cancer Classification Group risk classification 10-50% of patients with metastatic TGCT develop relapse which needs further multimodality treatment. With regard to therapy, early relapses are stratified according to their prognostic risk profile which results in a 3-year overall survival between 6% in the very high to 77% in the very low risk group. Prognostic risk score dictates systemic therapy which might be second line chemotherapy (TIP, PEI) or high dose chemotherapy. Any residual masses following salvage chemotherapy need to be completely resected due the presence of viable cancer and/or teratoma in more than 50% of cases. Targeted therapy in men with druggable mutations is for individualized cases only. Patients with late relapses developing more than 2 years after first-line chemotherapy are best managed by surgery. Desperation surgery is reserved for those patients with rising markers during or immediately after chemotherapy and good risk factors such as rising alpha-fetoprotein, <3 metastatic sites and complete resectability. Multimodality treatment will result in long-term cure of 25% to 60%. Due to the complexity of treatment, chemotherapy as well as surgery should be performed in highly experienced centres only.

SUMMARY

Multimodality treatment to salvage relapsing patients with metastatic testis cancer requires extensive experience for both systemic therapy and surgery. If done properly, it will result in moderate to high cure rates. Personalized therapeutic options are currently evaluated in clinical trials.

Visible haematuria-an unusual presentation of metastatic testicular mixed germ cell tumour

A 29-year-old male patient presented to the emergency department with haematuria and flank pain. Ten months agopreviously, he had undergone orchidectomy and adjuvant chemotherapy for a testicular mixed germ cell tumour. Cystoscopy revealed a large bladder wall mass. The final diagnosis of yolk sac tumour was established after transurethral resection of the lesion. The patient was treated with salvage chemotherapy and placed on short-interval biochemical and radiological surveillance to assess treatment response.

Testicular Germ Cell Tumors Acquire Cisplatin Resistance by Rebalancing the Usage of DNA Repair Pathways

Simple Summary

Germ cell tumors are a model of curable solid tumors due to their unique sensitivity to cisplatin-based chemotherapy. Patients are typically young adults, and despite high cure rate, about 20% of them do not achieve remission or relapse, and 50% of them succumb to the disease. The mechanisms behind their resistance to therapy are largely unknown. By using Testicular Germ Cell Tumor (TGCT) cell lines as a model, we investigated the mechanism of acquired resistance to cisplatin. We demonstrated that resistance occurred by a fine modulation of the DNA repair pathway choice. Namely, in resistant cells, repair of double-strand breaks by non-homologous end joining was dampened by the reduced expression of TP53-binding protein 1 (53BP1) and DNA-dependent protein kinase (DNA-PKcs). However, cisplatin-induced damage was repaired efficiently by homologous recombination. Additionally, we demonstrate that pharmacological inhibition of poly (ADP-ribose) polymerase (PARP) combined with cisplatin had an additive/synergistic effect on cisplatin-resistant cells, which represents the proof of concept for introducing PARP inhibitors in salvage therapy.

Abstract

Despite germ cell tumors (GCTs) responding to cisplatin-based chemotherapy at a high rate, a subset of patients does not respond to treatment and have significantly worse prognosis. The biological mechanisms underlying the resistance remain unknown. In this study, by using two TGCT cell lines that have acquired cisplatin resistance after chronic exposure to the drug, we identified some key proteins and mechanisms of acquired resistance. We show that cisplatin-resistant cell lines had a non-homologous end-joining (NHEJ)-less phenotype. This correlated with a reduced basal expression of TP53-binding protein 1 (53BP1) and DNA-dependent protein kinase (DNA-PKcs) proteins and reduced formation of 53BP1 foci after cisplatin treatment. Consistent with these observations, modulation of 53BP1 protein expression altered the cell line’s resistance to cisplatin, and inhibition of DNA-PKcs activity antagonized cisplatin cytotoxicity. Dampening of NHEJ was accompanied by a functional increase in the repair of DNA double-strand breaks (DSBs) by the homologous recombination repair pathway. As a result, cisplatin-resistant cells were more resistant to PARP inhibitor (PARPi) monotherapy. Moreover, when PARPi was given in combination with cisplatin, it exerted an additive/synergistic effect, and reduced the cisplatin dose for cytotoxicity. These results suggest that treatment of cisplatin-refractory patients may benefit from low-dose cisplatin therapy combined with PARPi.

Survival Outcomes After High-dose Chemotherapy and Stem Cell Transplantation in the Salvage Setting for Relapsed or Refractory Germ Cell Cancers

BACKGROUND/AIM

High-dose chemotherapy (HDCT) and stem cell transplantation (SCT) have been established as the standard of care in patients with relapsed germ cell tumours (GCTs). We evaluated the safety, efficacy and tolerability of HDCT/ SCT in patients with relapsed GCTs.

PATIENTS AND METHODS

Twenty-eight patients with relapsed GCTs, treated with HDCT, were included in this study. The conditioning regime was carboplatin, etoposide, cyclophosphamide and paclitaxel. Clinical, radiological imaging and tumour markers determined treatment outcomes.

RESULTS

Median age was 35 years (range=21-57 years) with 26 males and 2 females. Median time to first relapse was 6 months. Median time to progression after 2^nd line chemotherapy was 17.3 months. Fourteen patients hadMedian survival was 62 months and 16 patients (57%) are in clinical follow-up with surveillance.

CONCLUSION

In relapsed GCT patients, median survival may exceed 5 years post-HDCT and SCT.

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.

Testicular Cancer, Version 2.2020, NCCN Clinical Practice Guidelines in Oncology

Testicular cancer is relatively uncommon and accounts for <1% of all male tumors. However, it is the most common solid tumor in men between the ages of 20 and 34 years, and the global incidence has been steadily rising over the past several decades. Several risk factors for testicular cancer have been identified, including personal or family history of testicular cancer and cryptorchidism. Testicular germ cell tumors (GCTs) comprise 95% of malignant tumors arising in the testes and are categorized into 2 main histologic subtypes: seminoma and nonseminoma. Although nonseminoma is the more clinically aggressive tumor subtype, 5-year survival rates exceed 70% with current treatment options, even in patients with advanced or metastatic disease. Radical inguinal orchiectomy is the primary treatment for most patients with testicular GCTs. Postorchiectomy management is dictated by stage, histology, and risk classification; treatment options for nonseminoma include surveillance, systemic therapy, and nerve-sparing retroperitoneal lymph node dissection. Although rarely occurring, prognosis for patients with brain metastases remains poor, with >50% of patients dying within 1 year of diagnosis. This selection from the NCCN Guidelines for Testicular Cancer focuses on recommendations for the management of adult patients with nonseminomatous GCTs.

Immunotherapy: last bullet in platinum refractory germ cell testicular cancer

Testicular germ cell tumors are chemosensitive with very high cure-rates even in the metastatic setting. However, patients with platinum-refractory and relapsing tumors after autologous stem cell transplant have very poor outcomes despite salvage treatments, and with no effective alternative therapies. Immunotherapy, notably with PD-1 inhibitors, has proven to be very effective in treating various solid tumors. This review summarizes the experience with anti-PD-1 agents (pembrolizumab, nivolumab) in the treatment of testicular germ cell tumor relapsing after multiple lines of treatment, and exposes future trials evaluating newer checkpoint inhibitors in this setting.