Phase II trial of gemcitabine in refractory germ cell tumors

Malignant germ cells tumor of the ovary

Malignant ovarian germ cell tumors are rare and diverse malignancies, accounting for approximately 5% of all ovarian cancers. Primarily affecting young women, these tumors present unique challenges, particularly in balancing effective treatment with fertility preservation. Early diagnosis is common due to the rapid tumor growth and symptoms such as abdominal pain and distension, leading to favorable prognoses when combined with the high chemosensitivity of platinum-based regimens. Fertility-sparing surgery is the cornerstone of treatment for stage I disease, often followed by close surveillance to minimize the long-term toxicities of chemotherapy. Pathology is pivotal for diagnosis, incorporating immunohistochemical markers to differentiate malignant ovarian germ cell tumors subtypes, including dysgerminomas, yolk sac tumors, and immature teratomas. Advanced imaging modalities like ultrasound, magnetic resonance imaging, and computed tomography are essential for staging, monitoring treatment response, and detecting recurrences. Despite high cure rates, long-term follow-up is crucial to manage late toxicities, such as gonadal dysfunction and secondary malignancies. Recurrent malignant ovarian germ cell tumors present significant therapeutic challenges. High-dose chemotherapy with stem-cell transplantation offers promise in select cases, while the role of secondary cytoreductive surgery and radiotherapy is limited to specific indications. Emerging targeted therapies and novel approaches, such as KIT inhibitors for dysgerminomas with KIT mutations, remain experimental, with limited success reported so far. The rarity and heterogeneity of malignant ovarian germ cell tumors impede large-scale research efforts, underscoring the need for greater understanding of their molecular and genetic landscape to develop more effective and personalized therapies.

PARP inhibitors in testicular germ cell tumors: what we know and what we are looking for

Testicular germ cell tumors (TGCTs), the most common malignancies affecting young men, are characterized by high sensitivity to cisplatin-based chemotherapy, which leads to high cure rates even in metastatic disease. However, approximately 30% of patients with metastatic TGCTs relapse after first-line treatment and those who can be defined as platinum-refractory patients face a very dismal prognosis with only limited chemotherapy-based treatment options and an overall survival of few months. Hence, to understand the mechanisms underlying cisplatin resistance is crucial for developing new treatment strategies. This narrative review explores the potential role of PARP inhibitors (PARPis) in overcoming cisplatin resistance in TGCTs, starting from the rationale of their ability to induce DNA damage in cells with homologous recombination repair (HRR). Thus far, PARPis have failed to show meaningful clinical activity in platinum-refractory TGCT patients, either alone or in combination with chemotherapy. However, few responses to PARPis in TGCTs have been detected in patients with BRCA1/2, ATM or CHEK2 mutations, reinforcing the idea that patients should be optimally selected for tailored treatments in the era of personalized medicine. Future preclinical and clinical research is needed to further investigate the molecular mechanisms of cisplatin resistance and to identify novel therapeutic strategies in resistant/refractory TGCTs patients.

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.

Gemcitabine, carboplatin and veliparib in multiple relapsed/refractory germ cell tumours: The GCT-SK-004 phase II trial

Background Patients with multiple relapsed/refractory germ cell tumours (GCTs) have an extremely poor prognosis. PARP (poly-ADP-ribose polymerase) is overexpressed in GCTs compared to normal testes, and PARP overexpression is an early event in GCT development. This study aimed to determine the efficacy and toxicity of gemcitabine, carboplatin and the PARP inhibitor veliparib in patients with multiple relapsed/refractory GCTs. Methods Fifteen patients with multiple relapsed/refractory GCTs were enrolled in this phase II study from October 2016 to October 2020. Gemcitabine was administered at a dose of 800 mg/m2 on days 1 and 8 every 3 weeks; carboplatin at a target AUC of 4 on day 1 every 3 weeks; and veliparib at a dose of 250 mg b.i.d. throughout. The primary end point was 12-month progression-free survival (PFS). Results The median number of treatment cycles was 4 (range 2-8). Twelve-month PFS was achieved in 1 (6.7 %) patient. The median PFS was 3.1 months (95 % CI 2.2-3.9), and the median overall survival was 10.5 months (95 % CI 8.9-11.1). Partial remission was achieved in 4 (26.7 %) patients, and disease stabilization was observed in 5 (33.3 %) patients. A favourable response was achieved in 3 (20.0 %) patients. Treatment was well tolerated; however, 11 (73.3 %) patients experienced grade 3/4 neutropenia, 10 (66.7 %) experienced thrombocytopenia, 5 (33.3 %) anaemia and 2 (13.3 %) febrile neutropenia. Conclusions This study failed to achieve its primary endpoint, and our data suggest limited efficacy of gemcitabine, carboplatin and veliparib for multiple relapsed/refractory GCTs. ClinicalTrials.gov Identifier: NCT02860819, registered August 9, 2016.

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.

ESMO Consensus Conference on testicular germ cell cancer: diagnosis, treatment and follow-up

The European Society for Medical Oncology (ESMO) consensus conference on testicular cancer was held on 3-5 November 2016 in Paris, France. The conference included a multidisciplinary panel of 36 leading experts in the diagnosis and treatment of testicular cancer (34 panel members attended the conference; an additional two panel members [CB and K-PD] participated in all preparatory work and subsequent manuscript development). The aim of the conference was to develop detailed recommendations on topics relating to testicular cancer that are not covered in detail in the current ESMO Clinical Practice Guidelines (CPGs) and where the available level of evidence is insufficient. The main topics identified for discussion related to: (1) diagnostic work-up and patient assessment; (2) stage I disease; (3) stage II-III disease; (4) post-chemotherapy surgery, salvage chemotherapy, salvage and desperation surgery and special topics; and (5) survivorship and follow-up schemes. The experts addressed questions relating to one of the five topics within five working groups. Relevant scientific literature was reviewed in advance. Recommendations were developed by the working groups and then presented to the entire panel. A consensus vote was obtained following whole-panel discussions, and the consensus recommendations were then further developed in post-meeting discussions in written form. This manuscript presents the results of the expert panel discussions, including the consensus recommendations and a summary of evidence supporting each recommendation. All participants approved the final manuscript.

Salvage Chemotherapy With Gemcitabine, Paclitaxel, Ifosfamide, and Cisplatin for Relapsed Germ Cell Cancer

BACKGROUND

Metastatic germ cell tumors remain potentially curable when treated with salvage chemotherapy at first relapse. In the present phase I/II study, we sought to improve on the response rate and duration of the TIP (paclitaxel, ifosfamide, cisplatin) regimen by adding gemcitabine (Gem-TIP).

MATERIALS AND METHODS

Twenty patients were recruited after failure of first-line cisplatin-containing chemotherapy. The primary objectives were to determine the maximum tolerated dose of gemcitabine when combined with TIP and to establish the dose intensity of the TIP drugs in this combination. The secondary objectives were the response rates, failure-free survival, and overall survival.

RESULTS

The maximum tolerated dose of gemcitabine was 1200 mg/m2. The mean relative dose intensity was 95% (95% confidence interval [CI], 90.2%-99.2%) for gemcitabine, 96% (95% CI, 92.9%-98.7%) for paclitaxel, 92% (95% CI, 84.5%-98.8%) for ifosfamide, and 94% (95% CI, 89.3%-99.0%) for cisplatin. The overall complete response rate was 50%; another 30% of the patients achieved a partial response. The 1-year failure-free survival and overall survival rates were 68% (95% CI, 43%-84%) and 89.5% (95% CI, 64%-97%), respectively.

CONCLUSION

Gemcitabine can be added to TIP chemotherapy at the full dose, with manageable toxicity and no detrimental effect on the dose intensity of the TIP drugs. The response rate and duration were improved compared with those reported from the Medical Research Council TIP trial; further evaluation is warranted.

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.

Current Management of Refractory Germ Cell Tumors and Future Directions

PURPOSE OF REVIEW

We review current management strategies for patients with relapsed and refractory germ cell tumors (GCTs), defined as relapsed or persistent disease following at least one line of cisplatin-based chemotherapy. Additionally, we discuss future directions in the management of these patients.

RECENT FINDINGS

Recent studies involving targeted therapies have been disappointing. Nevertheless, studies of the management of refractory germ cell cancer are ongoing, with a focus on optimal utilization of high-dose chemotherapy and autologous stem cell transplant, as well as the role of immune checkpoint inhibitors in refractory germ cell tumors. Studies aiming to identify those patients who may benefit from more intensive treatment up front to prevent the development of refractory disease are also in progress. Testicular germ cell tumors are among the most curable of all solid tumor malignancies, with cure being possible even in the refractory, metastatic setting. Treatment of refractory disease remains a challenging clinical scenario, but potentially practice changing studies are ongoing.

Current chemotherapeutic approaches for recurrent or refractory germ cell tumors

INTRODUCTION

Up to 25% of patients with metastatic testicular germ cell tumour (GCT) are not cured by first line therapy and require treatment for refractory or relapsed disease.

METHODS

A literature search was conducted through PubMed, Medline, Cochrane and EMBASE from January 1950 to April 2014 for articles relating to trials of chemotherapy for patients with relapsed or refractory germ cell tumours. Relevant review papers and conference proceedings were hand searched for additional references.

RESULTS

A range of conventional dose chemotherapy (CDCT) regimens can provide durable remissions in 20-30% of patients at first or subsequent salvage.

CONCLUSIONS

This article reviews the evidence underlying commonly used salvage CDCT based on ifosfamide and cisplatin such as TIP, VIP and VeIP; other active combinations; and single agent salvage regimens. The treatment of growing teratoma syndrome and malignant transformation of teratoma will also be discussed. Companion articles will explore the role of high dose chemotherapy (HDCT) and novel targeted agents.

Synthesis and in vitro evaluation of novel acyclic and cyclic nucleoside analogs with a thiadiazole ring

The synthesis of six thiadiazole nucleoside analogs is reported: 5-diacetylamino-1,2,4-thiadiazol-3-one (1), 5-amino-2- (tetrahydrofuran-2-yl)-1,2,4-thiadiazol-3-one (2), 5-amino-3-[(2′-hydroxyethoxy)methyl]-1,3,4-thiadiazol-2-one (3), 5-amino-3-(4′-hydroxy-2′-hydroxymethyl-butyl)-1,3,4-thiadiazole-2-thione (4), (R)-5-amino-3-(2′,3′-dihydroxypropyl)-1,3,4-thiadiazole-2-thione (5), and (S)-5-amino-3-(2′,3′-dihydroxypropyl)-1,3,4-thiadiazole-2-thione (6). The synthesis, characterization, and properties of these new synthesized thiadiazole derivatives are discussed. A dimerization of 5-amino-3H-1,3,4-thiadiazole-2-thione (14) by sodium nitrite resulting in di-(5-amino-1,3,4-thiadiazol-2-yl) disulfide (19) is also reported. The preliminary in vitro evaluation of these newly synthesized compounds is discussed.

Use of gemcitabine with multi-stage surgical resection as successful second-line treatment of metastatic pancreatoblastoma

Pancreatoblastoma is a rare pediatric pancreatic malignancy. It confers a worse prognosis if there is metastatic or unresectable disease. We report a case of a 12-year-old boy who presented with pancreatoblastoma of the head of the pancreas with multiple intrahepatic metastases. We successfully treated him using aggressive chemotherapy, multi-stage surgery, and gemcitabine chemotherapy, which has not been described as treatment for pancreatoblastoma. Rare childhood malignancies such as pancreatoblastoma require a coordinated, multidisciplinary approach and frequent reassessment of therapeutic interventions. Complete surgical resection is important for cure and may require complex, aggressive, multiple-stage surgical procedures with concurrent or novel chemotherapy.

Salvage chemotherapy with paclitaxel, ifosfamide, and cisplatin (TIP) in relapsed or cisplatin-refractory germ cell tumors

BACKGROUND

In relapsed germ cell tumors, salvage chemotherapy with paclitaxel, ifosfamide, and cisplatin (TIP) is a well-established regimen for patients with favorable features such as a primary testicular tumor and prior complete remission (CR) after the initial chemotherapy. We reviewed patients who had received salvage TIP chemotherapy, and evaluated the efficacy of TIP, linking it to patient characteristics.

PATIENTS AND METHODS

Between August 1998 and May 2009, a total of 14 patients were treated with salvage TIP chemotherapy. 10 of 14 had cisplatin-refractory disease, and none of the patients were expected to show a favorable outcome to conventional-dose salvage chemotherapy.

RESULTS

Of the 14 patients, 5 (37.5%) showed a favorable response (CR in 1 patient, partial response (PR) in 4 patients) to TIP alone, and 1 had CR with subsequent surgery after TIP. 2 patients with CR and another 2 patients who attained disease stabilization are still alive at 81.3, 25.4, 69.3, and 27.4 months, respectively. After a median follow-up of 41.0 months (range 11.1-137.6), the median overall survival time for all patients was 21.1 (range 5.0-112.6).

CONCLUSIONS

Even in the presence of poor prognostic features, salvage TIP chemotherapy can be an active regimen in patients with relapsed or refractory germ cell tumors.

Brief report: phase II multicenter study of temozolomide in patients with cisplatin-resistant germ cell tumors

PURPOSE

To determine the activity and toxicity of temozolomide in a phase II multicenter trial in patients diagnosed with relapsed or cisplatin-refractory germ cell tumors.

PATIENTS AND METHODS

During a recruitment period of 30 months, 20 patients received temozolomide 150 mg/m(2)/day p.o. for 5 days every 4 weeks, escalating to 200 mg/m(2)/day if grade II toxicity was not observed in the first cycle. Eligibility criteria were tumor progression or relapse after previous cisplatin and ifosfamide-containing chemotherapy, creatinine clearance of >40 ml/min, and a performance status of 0-2.

RESULTS

The median age was 38 years (range 27-56). Seventeen patients had nonseminomatous tumors, and 3 had seminomatous tumors. Six of the patients had extragonadal primary tumors (3 retroperitoneal and 3 mediastinal). The median number of prior cisplatin-containing cycles was 11 (range 7-20). Eight patients received prior high-dose chemotherapy and 14 were refractory or absolutely refractory to cisplatin. A total of 45 cycles were administered. Two partial responses lasting 9 and 3.5 months (overall response rate 10%, 95% CI 1.2-31.7) were observed. One of these responses was seen in a patient with a cisplatin-refractory tumor that had previously been treated with high-dose chemotherapy. The median time to progression and the median overall survival were 1.5 and 3.1 months, respectively. Grade III hematological toxicity consisted of thrombocytopenia in 2 patients and anemia in 1 patient. No grade IV toxicity was observed.

CONCLUSIONS

Temozolomide had some activity in heavily pretreated patients resistant to cisplatin-based chemotherapy.

Update on management of seminoma

Testicular germ cell tumors and, in particular, seminomas are exquisitely radiation and chemotherapy-sensitive and most presentations are highly curable. In recent years the management focus has been on reducing late sequelae of treatment. For Stage I disease surveillance and adjuvant carboplatin, chemotherapy has become an option. The efficacy of combination chemotherapy has been established for advanced metastatic disease. Through a review of the available literature this article outlines the recent changes in the management of seminoma.

Preclinical and clinical activity of sunitinib in patients with cisplatin-refractory or multiply relapsed germ cell tumors: a Canadian Urologic Oncology Group/German Testicular Cancer Study Group cooperative study

BACKGROUND

The objective of the study was to investigate the activity of sunitinib in a cell line model and subsequently in patients with cisplatin-refractory or multiply relapsed germ cell tumors (GCT).

METHODS

The effect of sunitinib on cell proliferation in cisplatin-sensitive and cisplatin-refractory GCT cell lines was evaluated after 48-h sunitinib exposure by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay, and IC(50) (concentration that causes 50% inhibition of growth) doses were determined. Sunitinib was subsequently administered at a dose of 50 mg/day for 4 weeks followed by a 2-week break to 33 patients using a Simon two-stage design.

RESULTS

Sunitinib demonstrated comparable dose-dependent growth inhibition in cisplatin-sensitive and cisplatin-resistant cell lines, with IC(50) between 3.0 and 3.8 μM. Patient characteristics were as follows: median of 2 (1-6) cisplatin-containing regimens; high-dose chemotherapy 67%; late relapse 33%; and cisplatin refractory or absolute cisplatin refractory 54%. Toxic effects included fatigue (39%), anorexia (21%), diarrhea (27%), mucositis (45%), nausea (33%), hand-foot syndrome (12%), dyspepsia (27%), and skin rash (18%). No unexpected side-effects were observed. Thirty -two of 33 patients were assessable for response. Three confirmed partial responses (PRs) and one unconfirmed PR were seen for a total response rate of 13%. Median progression-free survival (PFS) was 2 months, with a 6-month PFS rate of 11%.

CONCLUSIONS

Sunitinib shows in vitro activity in cisplatin-resistant GCT cell lines. Modest clinical activity in heavily pretreated GCT patients was observed.

Multidisciplinary management of malignant ovarian germ cell tumours

OBJECTIVES

Malignant ovarian germ cell tumours (MOGCT) are rare cancers of young women. Limited prospective trials exist from which evidence-based management can be developed. This review summarizes the available literature concerning MOGT in order to provide the clinician with information relevant to their multidisciplinary management.

METHODS

MEDLINE was searched between 1966 and 2010 for all publications in English where the studied population included women diagnosed with malignant ovarian germ cell tumours.

RESULTS

The majority of patients can be cured with fertility-preserving surgery with or without combination chemotherapy. Long term survival approaches 100% in early stage disease and is approximately 75% in advanced stage disease. Most studies suggest that the treatment has little, if any, effect on future fertility and limited data suggest that there is no adverse effect on the future quality of life.

CONCLUSION

MOGCTs are rare tumours of young women the majority of which can be successfully treated with fertility-preserving surgery with or without chemotherapy with preservation of reproductive function. Minimisation of chemotherapy in good prognostic groups and improved treatment in resistant and relapsed MOGCT are important goals for the future. Further studies are needed to quantify the late adverse effects of treatment in long term survivors.

Lenalidomide in patients with cisplatin-refractory and multiply relapsed germ cell tumors

OBJECTIVE

Treatment options are still limited in patients with cisplatin-refractory and multiply relapsed germ cell tumors. We evaluated the efficacy and tolerability of lenalidomide within a compassionate use concept.

PATIENTS AND METHODS

Four patients multiply relapsed after platin-based chemotherapies without any further standard treatment option received 25 mg lenalidomide orally on days 1-21 of a 28-day cycle.

RESULTS

All four patients were pretreated with a median number of seven lines of previous chemotherapy (range 4-8), all including platin-based high-dose chemotherapy. After 4 weeks of lenalidomide treatment all patients had progressive disease with increase in serum tumor markers and progression in computed tomography. Median survival time was 8 weeks (range 5-17). The toxicity profile was favorable. No severe toxicities related to lenalidomide occurred in these patients.

CONCLUSION

Lenalidomide was well tolerated but did not show efficacy in heavily pretreated patients with cisplatin-refractory and multiply relapsed germ cell tumors.

High-dose chemotherapy plus stem cell transplantation in advanced germ cell cancer: a review

CONTEXT

High-dose chemotherapy (HDCT) with stem cell transplantation (SCT) has been investigated as a treatment strategy for advanced germ cell cancer (GCC) for >2 decades. In an effort to improve on the overall cure rates of 80% achievable with conventional chemotherapy, researchers have investigated this therapeutic option as a first-line therapy for those with poor-prognosis disease and as a salvage therapy for those with relapsed or refractory disease.

OBJECTIVE

The primary objective of this review is to define the role of HDCT plus SCT in advanced GCC. Prognostic indicators for this group of patients are also presented.

EVIDENCE ACQUISITION

A Medline search of English-language literature was performed to identify studies published in the last 20 yr relating to the use of HDCT plus SCT in advanced GCC. Phase 1, phase 2, and phase 3 trials were included, as were retrospective reviews and meta-analyses.

EVIDENCE SYNTHESIS

Phase 2 trials investigating HDCT plus SCT as a therapeutic option for advanced germ cell cancer have indicated a survival advantage over conventional chemotherapy. This has not been confirmed in the phase 3 setting. Alternative chemotherapeutic strategies and options following failure of HDCT plus SCT are discussed.

CONCLUSIONS

Studies to date have not indicated a survival advantage for the use of HDCT plus SCT in advanced germ cell cancer. Many questions, however, remain unanswered, and further research is required to identify whether optimising the strategy of HDCT plus SCT will improve outcome in this predominantly young group of patients.

Kinetic investigation of the inhibitory effect of gemcitabine on DNA polymerization catalyzed by human mitochondrial DNA polymerase

Gemcitabine, 2'-deoxy-2', 2'-difluorocytidine (dFdC), is a drug approved for use against various solid tumors. Clinically, this moderately toxic nucleoside analog causes peripheral neuropathy, hematological dysfunction, and pulmonary toxicity in cancer patients. Although these side effects closely mimic symptoms of mitochondrial dysfunction, there is no direct evidence to show gemcitabine interferes with mitochondrial DNA replication catalyzed by human DNA polymerase gamma. Here we employed presteady state kinetic methods to directly investigate the incorporation of the 5'-triphosphorylated form of gemcitabine (dFdCTP), the excision of the incorporated monophosphorylated form (dFdCMP), and the bypass of template base dFdC catalyzed by human DNA polymerase gamma. Opposite template base dG, dFdCTP was incorporated with a 432-fold lower efficiency than dCTP. Although dFdC is not a chain terminator, the incorporated dFdCMP decreased the incorporation efficiency of the next 2 correct nucleotides by 214- and 7-fold, respectively. Moreover, the primer 3'-dFdCMP was excised with a 50-fold slower rate than the matched 3'-dCMP. When dFdC was encountered as a template base, DNA polymerase gamma paused at the lesion and one downstream position but eventually elongated the primer to full-length product. These pauses were because of a 1,000-fold decrease in nucleotide incorporation efficiency. Interestingly, the polymerase fidelity at these pause sites decreased by 2 orders of magnitude. Thus, our pre-steady state kinetic studies provide direct evidence demonstrating the inhibitory effect of gemcitabine on the activity of human mitochondrial DNA polymerase.

Rapid determination of gemcitabine in plasma and serum using reversed-phase HPLC

Gemcitabine (2'2'-difluorodeoxycytidine) is a pyrimidine analog used in the treatment of a variety of solid tumors. After intravenous (i.v.) administration, it is rapidly inactivated to 2'-deoxy-2',2'-difluorouridine (dFdU). A sensitive analytical method for the quantitation of gemcitabine is required for the assessment of alternative dosage and treatment schemes. A rapid and robust RP-HPLC assay for analysis of gemcitabine in human and animal plasma and serum was developed and validated using 2'-deoxyuridine (dU) and 5-fluoro-2'-deoxyuridine (5FdU) as internal standards. It is based on protein precipitation, the use of an Atlantis dC18 column of 100 mm length (inner diameter, 4.6 mm; particle size, 3 microm) and isocratic elution using a 10 mM phosphate buffer, pH 3.0, followed by isocratic elution with the same buffer containing 3% of ACN. For gemcitabine, RSD values for intraday and interday precision were < 4.4 and 5.3%, respectively, the LOQ was 20 ng/mL, and the assay was linear in the range of 0.020-20 microg/mL with an accuracy of > or =89%. The recovery for gemcitabine, dU and 5FdU was 86-98%. The assay was applied to determine gemcitabine levels in plasma samples of patients collected during and shortly after conventional infusion of 25-30 mg/kg body mass (levels: 2.0-18.9 microg/mL) and rats that received lower doses (1.5 mg/kg) via i.v., subcutaneous and oral drug administration (levels: 0.20-2.60 microg/mL). It could also be applied to estimate dFdU levels in human plasma.

Phase I clinical trial of intrathecal gemcitabine in patients with neoplastic meningitis

PURPOSE

A phase I study of intrathecal (IT) gemcitabine was performed to define a safe dose and characterize the toxicity profile and CSF pharmacokinetics of gemcitabine and its major metabolite 2',2'-difluoro-deoxyuridine (dFdU) in patients 3 years of age and older with neoplastic meningitis.

EXPERIMENTAL DESIGN

Gemcitabine was administered via Ommaya reservoir or lumbar puncture at three dose levels: 5 mg weekly, 5 mg twice-weekly, and 10 mg twice-weekly using a standard phase I dose escalation design. Serial CSF samples were obtained for pharmacokinetic studies in seven patients with Ommaya reservoirs. Serial blood samples for pharmacokinetic studies were also obtained from three patients.

RESULTS

Ten patients were enrolled in this study. Significant neurological toxicities occurred in two patients including myelitis in a patient at the 5 mg twice-weekly dose level and somnolence in a patient at the 10 mg twice-weekly dose level. No complete responses were seen; however, three patients had stable disease. Gemcitabine was rapidly eliminated from the CSF with a terminal half-life of 61 +/- 50 min. No gemcitabine or dFdU was detected in plasma.

CONCLUSIONS

IT gemcitabine was associated with significant neurotoxicity; therefore, its further development for IT use is not recommended.

[Testis germ cell tumours: which chemotherapy, for which patients?]

Germ cell tumours of the testis are curable disease. Two different pathological subtypes are observed: seminoma and non-seminoma. Two tumour stages have been defined: the disease limited to the testis and the advanced disease. In the latter group, the prognosis is established by a specific classification based on the level of serum tumour marker and the location of the metastases. The most active first line chemotherapy is a combination of bleomycine, etoposide and cisplatine. Patients with good prognostic factors receive three cycles of this regimen; patients with poor-risk characteristics receive four cycles of the same regimen. The strategy in non-seminoma patients is to give a first-line chemotherapy adapted to the risk factors, then to complete surgical exeresis of all residual disease. Patients with stage I disease may receive two cycles of the same regimen. The strategy for advanced seminoma is to give first-line good-risk chemotherapy followed by a close observation and in several selected cases a surgical removal of all residual disease. Patients with stage I disease may receive one cycle of carboplatin. Salvage chemotherapy is based on the combination of ifosfamide, cisplatine and either vinblastine or paclitaxel.

An open-label, multicenter phase II trial of capecitabine in patients with cisplatin-refractory or relapsed germ cell tumors

The objective of this multicenter phase II trial was to evaluate the efficacy and tolerability of capecitabine in patients with cisplatin-refractory or relapsed germ cell tumors. Between March 2003-June 2004, 14 patients refractory to at least two regimens of cisplatin-based chemotherapy or with relapse after high-dose chemotherapy and autologous peripheral blood stem cell transplantation received 1250 mg/qm capecitabine orally twice daily for 14 days in 3-week cycles. Treatment was continued until tumor progression. All patients were heavily pretreated with a median number of four previous lines of chemotherapy (range, 2-11) and 86% had relapsed after high-dose chemotherapy with peripheral blood stem cell transplantation. No patient responded to study treatment. Nine patients (64%) had progressive disease after two cycles. Two patients already stopped treatment after one cycle, because of a clinically overt tumor progression. One patient died of his tumor progression at the end of the second cycle. Two patients received four cycles of capecitabine, as progression was less than 30%. The median survival time was 4 months (range, 0-10). The toxicity profile was favorable. Eighty-six percent of the cycles could be applied without dose modifications or delay. Grade III/IV toxicities (diarrhea and anorexia in one patient each) occurred in 7% of the cases. No hematotoxicity grade III/IV was observed. Neutropenia grade I/II was documented in 21%, anemia in 35% and thrombocytopenia in 14% of the patients. Capecitabine was well tolerated, but is not effective in heavily pretreated patients with cisplatin-refractory or relapsed germ cell tumors.