Sequential administration of temozolomide and fotemustine: depletion of O6-alkyl guanine-DNA transferase in blood lymphocytes and in tumours

A Multicenter Randomized Bioequivalence Study of a Novel Ready-to-Use Temozolomide Oral Suspension vs. Temozolomide Capsules

BACKGROUND

Temozolomide (TMZ) oral suspension (Ped-TMZ, KIZFIZO®) is being developed for the treatment of relapsed or refractory neuroblastoma, a rare cancer affecting infants and young children. The study assessed the safety and the bioequivalence of this novel pediatric formulation with existing TMZ oral capsules.

METHODS

In vitro dissolution profiles and the bioequivalence were evaluated following the European Medicines Agency "Guidelines on the investigation of Bioequivalence". The phase I, multicenter, randomized, open-label, crossover, single-dose bioequivalence study enrolled 36 adult patients with glioblastoma multiforme or lower-grade glioma. Each patient received 200 mg/m2 Ped-TMZ suspension and TMZ capsules (Temodal®) on 2 consecutive days, with the order being randomly assigned. Fourteen blood samples were collected up to 10 h post-dosing. Bioequivalence was assessed by comparing the 90% confidence interval for the ratio of the geometric means of maximum TMZ plasma concentration (Cmax) and the area under the curve (AUCt). Other endpoints included further pharmacokinetic parameters and safety.

RESULTS

Both formulations exhibited a fast in vitro dissolution profile with more than 85% of TMZ dissolved within 15 min. For the bioequivalence study, thirty patients completed the trial as per the protocol. The ratio of Ped-TMZ/TMZ capsule geometric means (90% CI) for AUCt and Cmax were 97.18% (95.05-99.35%) and 107.62% (98.07-118.09%), respectively, i.e., within the 80-125% bioequivalence limits. No buccal toxicity was associated with Ped-TMZ liquid formulation.

CONCLUSIONS

This study showed that Ped-TMZ oral suspension and TMZ oral capsule treatment are immediate release and bioequivalent medicines. There were also no unexpected safety signals or local toxicity (funded by ORPHELIA Pharma; ClinicalTrials.gov number, NCT04467346).

Expression Profiling of Primary and Recurrent Glioblastomas Reveals a Reduced Level of Pentraxin 3 in Recurrent Glioblastomas

Glioblastomas (GBM) are highly infiltrative tumors and despite intensive treatment tumor recurrence is inevitable. The immune microenvironment in recurrent GBM is poorly characterized, but it is potentially influenced by therapeutic interventions with surgery, radiotherapy, and chemotherapy. The aim of this study was to obtain a deeper insight in the immune microenvironment in primary and recurrent GBM. Primary and recurrent glioblastoma samples from 18 patients were identified and expression profiling of 770 myeloid innate immune-related markers was performed. Leukemia inhibitory factor and pentraxin 3 were expressed at lower levels in recurrent tumors. Using in silico data and immunohistochemical staining, this was validated for pentraxin 3. Both high leukemia inhibitory factor and pentraxin 3 expression appeared to be associated with shorter survival in primary and recurrent GBM using in silico data. In primary GBM, gene set analysis also showed higher expression of genes involved in metabolism, extracellular matrix remodeling and complement activation, whereas genes involved in T cell activation and checkpoint signaling were expressed at higher levels in recurrent GBM. The reduced level of pentraxin 3 in recurrent glioblastomas and the gene set analysis results suggest an altered microenvironment in recurrent GBM that might be more active.

The Role of Checkpoint Inhibitors in Glioblastoma

Given its poor prognosis, glioblastoma represents an area of high unmet clinical need. Standard of care for the treatment of glioblastoma in the frontline setting is limited to surgical resection, radiation, and temozolomide, with the more recent addition of Tumor Treating Fields. Several agents, including bevacizumab, lomustine, and carmustine have been approved in the recurrent setting. To date, no therapies have demonstrated substantial survival benefit beyond standard of care. An expanding understanding of the role of the immune system in fighting cancer has led to the development and approval of various immunotherapeutic approaches across solid tumors. In glioblastoma, the notion of a highly immune-restricted central nervous system has also evolved, further providing the rationale for testing therapies that promote immune trafficking to the CNS and infiltration into the tumor to counteract the immunosuppressive mechanisms that support tumor progression. There are five broad categories of immunotherapies currently being tested in GBM: vaccines, cytokine therapy, oncolytic viral therapy, chimeric antigen receptor T cell therapy, and checkpoint inhibitors. This review focuses on checkpoint inhibitors in GBM, the rationale for its use, preclinical data, and early clinical experience. Efficacy data are limited, and while a number of late-stage trials are ongoing, early trials showed no benefit in survival. There is a dizzying array of combinations being tested in clinical studies with an urgent need for a rational approach to determine the role of checkpoint inhibitors in glioblastoma, including the optimal combinations, and identification of biomarkers or predictive models to determine which patients may benefit from immunotherapy.

Cinnamaldehyde Enhances Antimelanoma Activity through Covalently Binding ENO1 and Exhibits a Promoting Effect with Dacarbazine

At present, melanoma is a common malignant tumor with the highest mortality rate of all types of skin cancer. Although the first option for treating melanoma is with chemicals, the effects are unsatisfactory and include poor medication response and high resistance. Therefore, developing new medicines or a novel combination approach would be a significant breakthrough. Here, we present cinnamaldehyde (CA) as a potential candidate, which exerted an antitumor effect in melanoma cell lines. Chemical biology methods of target fishing, molecular imaging, and live cell tracing by an alkynyl-CA probe revealed that the α-enolase (ENO1) protein was the target of CA. The covalent binding of CA with ENO1 changed the stability of the ENO1 protein and affected the glycolytic activity. Furthermore, our results demonstrated that dacarbazine (DTIC) showed a high promoting effect with CA for antimelanoma both in vivo and in vitro. The combination improved the DTIC cell cycle arrest in the S phase and markedly impacted melanoma growth. As a covalent inhibitor of ENO1, CA combined with DTIC may be beneficial in patients with drug resistance in antimelanoma therapy.

The specific role of O6-methylguanine-DNA methyltransferase inhibitors in cancer chemotherapy

The DNA repair protein, O⁶-methylguanine DNA methyltransferase (MGMT), can confer resistance to guanine O⁶-alkylating agents. Therefore, inhibition of resistant MGMT protein is a practical approach to increase the anticancer effects of such alkylating agents. Numerous small molecule inhibitors were synthesized and exhibited potential MGMT inhibitory activities. Although they were nontoxic alone, they also inhibited MGMT in normal tissues, thereby enhancing the side effects of chemotherapy. Therefore, strategies for tumor-specific MGMT inhibition have been proposed, including local drug delivery and tumor-activated prodrugs. Over-expression of MGMT in hematopoietic stem cells to protect bone marrow from the toxic effects of chemotherapy is also a feasible selection. The future prospects and challenges of MGMT inhibitors in cancer chemotherapy were also discussed.

The search for a melanoma-tailored chemotherapy in the new era of personalized therapy: a phase II study of chemo-modulating temozolomide followed by fotemustine and a cooperative study of GOIM (Gruppo Oncologico Italia Meridionale)

Background

It is frequently asked whether chemotherapy can still play a role in metastatic melanoma considering the effectiveness of the available drugs today, including antiCTLA4/antiPD1 immunotherapy and antiBRAF/antiMEK inhibitors. However, only approximately half of patients respond to these drugs, and the majority progress after 6–11 months. Therefore, a need for other therapeutic options is still very much apparent.

We report the first large trial of a sequential full dose of fotemustine (FM) preceded by a low dose of temozolomide (TMZ) as a chemo-modulator in order to inactivate the DNA repair action of O(6)-methylguanine DNA-methyltransferase (MGMT). Primary endpoints were overall response and safety. We also evaluated specific biological parameters aiming to tailor these chemotherapies to selected patients.

Methods

A total of 69 consecutive patients were enrolled. The main features included a median age of 60 years (21–81) and M1c stage, observed in 74% of the patients, with brain metastases in 15% and high LDH levels in 42% of the patients. The following schedule was used: oral TMZ 100 mg/m² on days 1 and 2 and FM iv 100 mg/m² on day 2, 4 h after TMZ; A translational study aiming to analyse MGMT methylation status and base-excision repair (BER) gene expression was performed in a subset of 14 patients.

Results

We reported an overall response rate of 30.3% with 3 complete responses and a disease control rate of 50.5%. The related toxicity rate was low and mainly of haematological types. Although our population had a very poor prognosis, we observed a PFS of 6 months and an OS of 10 months. A non-significant correlation with response was found with the mean expression level of the three genes involved in the BER pathway (APE1, XRCC1 and PARP1), whereas no association was found with MGMT methylation status.

Conclusion

This schedule could represent a good alternative for patients who are not eligible for immune or targeted therapy or whose previous therapies have failed.

Trial registration

EUDRACT 2009–016487-36l; date of registration 23 June 2010.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4479-2) contains supplementary material, which is available to authorized users.

A Phase III study of radiation therapy (RT) and O⁶-benzylguanine + BCNU versus RT and BCNU alone and methylation status in newly diagnosed glioblastoma and gliosarcoma: Southwest Oncology Group (SWOG) study S0001

AIMS

To determine the efficacy of methylguanine methyltransferase (MGMT) depletion + BCNU [1,3-bis(2-chloroethyl)-1- nitrosourea: carmustine] therapy and the impact of methylation status in adults with glioblastoma multiforme (GBM) and gliosarcoma.

METHODS

Methylation analysis was performed on GBM patients with adequate tissue samples. Patients with newly diagnosed GBM or gliosarcoma were eligible for this Phase III open-label clinical trial. At registration, patients were randomized to Arm 1, which consisted of therapy with O(6)-benzylguanine (O(6)-BG) + BCNU 40 mg/m(2) (reduced dose) + radiation therapy (RT) (O6BG + BCNU arm), or Arm 2, which consisted of therapy with BCNU 200 mg/m(2) + RT (BCNU arm).

RESULTS

A total of 183 patients with newly diagnosed GBM or gliosarcoma from 42 U.S. institutions were enrolled in this study. Of these, 90 eligible patients received O(6)-BG + BCNU + RT and 89 received BCNU + RT. The trial was halted at the first interim analysis in accordance with the guidelines for stopping the study due to futility (<40 % improvement among patients on the O6BG + BCNU arm). Following adjustment for stratification factors, there was no significant difference in overall survival (OS) or progression-free survival (PFS) between the two groups (one sided p = 0.94 and p = 0.88, respectively). Median OS was 11 [95 % confidence interval (CI) 8-13] months for patients in the O6BG + BCNU arm and 10 (95 % CI 8-12) months for those in the BCNU arm. PFS was 4 months for patients in each arm. Adverse events were reported in both arms, with significantly more grade 4 and 5 events in the experimental arm.

CONCLUSIONS

The addition of O(6)-BG to the standard regimen of radiation and BCNU for the treatment patients with newly diagnosed GBM and gliosarcoma did not provide added benefit and in fact caused additional toxicity.

Interleukin-13 receptor alpha 2-targeted glioblastoma immunotherapy

Glioblastoma (GBM) is the most lethal primary brain tumor, and despite several refinements in its multimodal management, generally has very poor prognosis. Targeted immunotherapy is an emerging field of research that shows great promise in the treatment of GBM. One of the most extensively studied targets is the interleukin-13 receptor alpha chain variant 2 (IL13Rα2). Its selective expression on GBM, discovered almost two decades ago, has been a target for therapy ever since. Immunotherapeutic strategies have been developed targeting IL13Rα2, including monoclonal antibodies as well as cell-based strategies such as IL13Rα2-pulsed dendritic cells and IL13Rα2-targeted chimeric antigen receptor-expressing T cells. Advanced therapeutic development has led to the completion of several clinical trials with promising outcomes. In this review, we will discuss the recent advances in the IL13Rα2-targeted immunotherapy and evaluate the most promising strategy for targeted GBM immunotherapy.

Advances in the management of glioblastoma: the role of temozolomide and MGMT testing

Glioblastoma (GB) is one of the most lethal forms of cancer, with an invasive growth pattern that requires the use of adjuvant therapies, including chemotherapy and radiation, to prolong survival. Temozolomide (TMZ) is an oral chemotherapy with a limited side effect profile that has become the standard of care in GB treatment. While TMZ has made an impact on survival, tumor recurrence and TMZ resistance remain major challenges. Molecular markers, such as O6-methylguanine-DNA methyltransferase methylation status, can be helpful in predicting tumor response to TMZ, and therefore guides clinical decision making. This review will discuss the epidemiology and possible genetic underpinnings of GB, how TMZ became the standard of care for GB patients, the pharmacology of TMZ, the practical aspects of using TMZ in clinic, and how molecular diagnostics – particularly the use of O6-methylguanine-DNA methyltransferase status – affect clinical management.

Impact of temozolomide on immune response during malignant glioma chemotherapy

Malignant glioma, or glioblastoma, is the most common and lethal form of brain tumor with a median survival time of 15 months. The established therapeutic regimen includes a tripartite therapy of surgical resection followed by radiation and temozolomide (TMZ) chemotherapy, concurrently with radiation and then as an adjuvant. TMZ, a DNA alkylating agent, is the most successful antiglioma drug and has added several months to the life expectancy of malignant glioma patients. However, TMZ is also responsible for inducing lymphopenia and myelosuppression in malignant glioma patients undergoing chemotherapy. Although TMZ-induced lymphopenia has been attributed to facilitate antitumor vaccination studies by inducing passive immune response, in general lymphopenic conditions have been associated with poor immune surveillance leading to opportunistic infections in glioma patients, as well as disrupting active antiglioma immune response by depleting both T and NK cells. Deletion of O6-methylguanine-DNA-methyltransferase (MGMT) activity, a DNA repair enzyme, by temozolomide has been determined to be the cause of lymphopenia. Drug-resistant mutation of the MGMT protein has been shown to render chemoprotection against TMZ. The immune modulating role of TMZ during glioma chemotherapy and possible mechanisms to establish a strong TMZ-resistant immune response have been discussed.

DNA repair pathways and their implication in cancer treatment

Many cytotoxic agents used in cancer treatment exert their effects through their ability to directly or indirectly damage DNA and thus resulting in cell death. Major types of DNA damage induced by anticancer treatment include strand breaks (double or single strand), crosslinks (inter-strand, intra-strand, DNA-protein crosslinks), and interference with nucleotide metabolism and DNA synthesis. On the other hand, cancer cells activate various DNA repair pathways and repair DNA damages induced by cytotoxic drugs. The purpose of the current review is to present the major types of DNA damage induced by cytotoxic agents, DNA repair pathways, and their role as predictive agents, as well as evaluate the future perspectives of the novel DNA repair pathways inhibitors in cancer therapeutics.

Effect of alternative temozolomide schedules on glioblastoma O(6)-methylguanine-DNA methyltransferase activity and survival

Background:

O⁶-methylguanine-DNA methyltransferase (MGMT) expression in glioblastoma correlates with temozolomide resistance. Dose-intense temozolomide schedules deplete MGMT activity in peripheral blood mononuclear cells; however, no published data exist evaluating the effect of temozolomide schedules on intracranial tumour MGMT activity.

Methods:

Human glioblastoma cells (GBM43) with an unmethylated MGMT promoter were implanted intracranially in immunodeficient rodents. Three weeks later, animals received temozolomide 200 mg m⁻² for 5 days (schedule A, standard dose) or 100 mg m⁻² for 21 days (schedule B, dose intense).

Results:

Tumour MGMT activity was depleted by day 6 in both treatment groups compared with baseline. O⁶-methylguanine-DNA methyltransferase activity returned to baseline by day 22 in the schedule A group, but remained suppressed in the schedule B group. By day 29, MGMT activity had returned to baseline in both groups. Mean tumour volume was significantly decreased compared with untreated controls with either schedule (P<0.01), although neither schedule was superior (P=0.60). Median survival was 64, 42, and 28 days for schedule A, schedule B, and no drug, respectively (P<0.001 A or B vs control, P=NS A vs B).

Conclusions:

Dose-intense temozolomide prolongs tumour MGMT activity depletion compared with standard dosing, however, survival was not improved in this model.

Sorafenib, a multikinase inhibitor, enhances the response of melanoma to regional chemotherapy

Melanoma responds poorly to standard chemotherapy due to its intrinsic chemoresistance. Multiple genetic and molecular defects, including an activating mutation in the BRaf kinase gene, are associated with melanoma, and the resulting alterations in signal transduction pathways regulating proliferation and apoptosis are thought to contribute to its chemoresistance. Sorafenib, a multikinase inhibitor that targets BRaf kinase, is Food and Drug Administration approved for use in advanced renal cell and hepatocellular carcinomas. Although sorafenib has shown little promise as a single agent in melanoma patients, recent clinical trials suggest that, when combined with chemotherapy, it may have more benefit. We evaluated the ability of sorafenib to augment the cytotoxic effects of melphalan, a regional chemotherapeutic agent, and temozolomide, used in systemic and regional treatment of melanoma, on a panel of 24 human melanoma-derived cell lines and in an animal model of melanoma. Marked differences in response to 10 micromol/L sorafenib alone were observed in vitro across cell lines. Response to sorafenib significantly correlated with extracellular signal-regulated kinase (ERK) downregulation and loss of Mcl-1 expression (P < 0.05). Experiments with the mitogen-activated protein kinase/ERK kinase inhibitor U0126 suggest a unique role for ERK downregulation in the observed effects. Sorafenib in combination with melphalan or temozolomide led to significantly improved responses in vitro (P < 0.05). In the animal model of melanoma, sorafenib in combination with regional melphalan or regional temozolomide was more effective than either treatment alone in slowing tumor growth. These results show that sorafenib in combination with chemotherapy provides a novel approach to enhance chemotherapeutic efficacy in the regional treatment of in-transit melanoma.

Targeting DNA repair pathways: a novel approach to reduce cancer therapeutic resistance

Increased chemo-resistance and radio-resistance of cancer cells is a major obstacle in the treatment and management of malignant cancers. An important mechanism that underlies the development of such therapeutic resistance is that cancer cells recognize DNA lesions induced by DNA-damaging agents and by ionizing radiation, and repair these lesions by activating various DNA repair pathways. Therefore, Use of pharmacological agents that can inhibit certain DNA repair pathways in cancer cells has the potential for enhancing the targeted cytotoxicity of anticancer treatments and reversing the associated therapeutic resistance associated with DNA repair; such agents, offering a promising opportunity to achieve better therapeutic efficacy. Here we review the major DNA repair pathways and discuss recent advances in the development of novel inhibitors of DNA repair pathways; many of these agents are under preclinical/clinical investigation.

Correlation of O6-methylguanine methyltransferase (MGMT) promoter methylation with clinical outcomes in glioblastoma and clinical strategies to modulate MGMT activity

Resistance to alkylating agents via direct DNA repair by O(6)-methylguanine methyltransferase (MGMT) remains a significant barrier to the successful treatment of patients with malignant glioma. The relative expression of MGMT in the tumor may determine response to alkylating agents, and epigenetic silencing of the MGMT gene by promoter methylation plays an important role in regulating MGMT expression in gliomas. MGMT promoter methylation is correlated with improved progression-free and overall survival in patients treated with alkylating agents. Strategies to overcome MGMT-mediated chemoresistance are being actively investigated. These include treatment with nontoxic pseudosubstrate inhibitors of MGMT, such as O(6)-benzylguanine, or RNA interference-mediated gene silencing of MGMT. However, systemic application of MGMT inhibitors is limited by an increase in hematologic toxicity. Another strategy is to deplete MGMT activity in tumor tissue using a dose-dense temozolomide schedule. These alternative schedules are well tolerated; however, it remains unclear whether they are more effective than the standard dosing regimen or whether they effectively deplete MGMT activity in tumor tissue. Of note, not all patients with glioblastoma having MGMT promoter methylation respond to alkylating agents, and even those who respond will inevitably experience relapse. Herein we review the data supporting MGMT as a major mechanism of chemotherapy resistance in malignant gliomas and describe ongoing studies that are testing resistance-modulating strategies.

New developments in the treatment of malignant gliomas

Malignant gliomas represent an heterogeneous group of brain tumors both in terms of natural history and response to treatment. The standard therapeutic approach for treating glioblastomas is a combination of radiotherapy and concomitant/adjuvant temozolomide, and methylguanine-DNA methyltransferase promoter methylation is now recognized as an important factor for predicting both prognosis and response to alkylating agents. In the future, the discovery of targeted therapies will increasingly allow personalized medical treatments. Anaplastic oligodendroglial tumors display a better prognosis and are more chemosensitive than glioblastomas; the discovery of molecular factors of prognostic significance, such as 1p/19q codeletion, will lead to different treatment strategies for different subgroups of patients. Gliomatosis cerebri is a rare diffuse glioma, and upfront chemotherapy is increasingly being employed instead of whole-brain radiotherapy to avoid/delay cognitive defects in long surviving patients, despite the lack of data to support this.

Temozolomide in combination with fotemustine in patients with metastatic melanoma

PURPOSE

Temozolomide and fotemustine are both active drugs for treating metastatic melanoma. The present study was designed to assess the efficacy and safety of combination therapy with temozolomide + fotemustine in patients with metastatic melanoma.

METHODS

Forty patients (median age 50.5 and 22 males) with pathologically confirmed, unresectable, AJCO stage IV melanoma were enrolled into the study. The primary endpoints were tumor response and safety. Patients received oral temozolomide 125 mg/m(2) on days 1-7 and intravenous fotemustine 80 mg/m(2) on day 3 every 3 weeks.

RESULTS

Fourteen (35%) patients achieved an objective response, including 3 (7.5%) complete and 11 (27.5%) partial responses. Median overall survival time was 6.7 months and 6-month survival rate was 57.4%. Myelosupression, particularly thrombocytopenia, was the primary toxicity.

CONCLUSION

The regimen, temozolomide combined with fotemustine, is an active and moderately safe first-line chemotherapy regimen with acceptable and easily manageable toxicities in patients with metastatic melanoma.

Targeting DNA repair as a promising approach in cancer therapy

An increased DNA-repair activity in tumour cells has been associated with resistance to treatment to DNA-directed drugs, while defects in DNA repair pathways result in hypersensitivity to these agents. In the past years the unravelling of the molecular basis of these DNA pathways, with a better understanding of the DNA damage caused by different anticancer agents, has provided the rationale for the use of some DNA repair inhibitors to optimise the therapeutic use of DNA-damaging agents currently used in the treatment of tumours. In addition, the possibility to specifically target the differences in DNA repair capacity between normal and tumour cells has recently emerged as an exciting possibility. The present review will mainly cover those approaches that are currently under clinical investigation.

New chemotherapy options for the treatment of malignant gliomas

This review focuses on the recent advances in chemotherapy of malignant gliomas, with special emphasis on the most common primary brain tumor in adults, glioblastoma. The demonstration of the superiority of concomitant and adjuvant temozolomide with standard radiotherapy over radiotherapy alone in patients with newly diagnosed glioblastomas by means of phase III international trial has been the major advance in the care of these patients so far. Moreover, patients whose tumors display the hypermethylation of the promoter of the gene for the repairing enzyme O-methylguanine-DMA methyltransferase are most likely to benefit from the combination regimen. The advantage of a postsurgical local administration of carmustine by slow-release polymers ('gliadel wafers') is more modest, and the efficacy and safety of a sequence of carmustine wafers followed by temozolomide combined with radiotherapy remain to be defined. Different DNA repair modulation strategies are being investigated to further improve the results: dose-dense regimens of temozolomide, combination of temozolomide with specific inhibitors of O-methylguanine-DMA methyltransferase and combination of temozolomide with specific inhibitors of base excision repair [poly(ADP-ribose) polymerase inhibitors]. Other developments include the combination of cytotoxic, cytostatic and targeted therapies. Multitargeted compounds that simultaneously affect multiple signaling pathways, such as those involving epidermal growth factor receptor, platelet-derived growth factor receptor and vascular endothelial growth factor receptor, are increasingly employed. In the future, innovative trial designs (factorial and adaptative designs), pretreatment molecular profiling of individual tumors and the adoption of biological end-points (changes in serum tumor markers, measures of target inhibition), in addition to the traditional clinical and radiographic end-points, will be needed to achieve further advances.

Phase II study of temozolomide and thalidomide in patients with metastatic melanoma in the brain: high rate of thromboembolic events (CALGB 500102)

BACKGROUND

Preliminary studies suggesting that extended-dose temozolomide with thalidomide is safe and active in patients with metastatic melanoma have led to frequent use of this oral regimen. To confirm these observations the combination was tested in a multicenter Phase II trial in patients with melanoma brain metastases.

METHODS

Eligible patients had melanoma brain metastases, with or without systemic metastases. The primary endpoint was response rate in brain metastases. Patients received temozolomide at a dose of 75 mg/m2/day for 6 weeks with a 2-week rest between cycles, and thalidomide (escalated to 400 mg/day for patients age < 70 years or to 200 mg/day for patients age > or = 70 years). A 2-stage design required > or = 3 responses in the first 21 patients before enrolling 29 additional patients in the second stage.

RESULTS

Sixteen eligible patients were enrolled. No objective responses were observed. The median survival was 23.9 weeks. Seven patients withdrew because of tumor progression; 7 were removed during Cycle 1 because of adverse events, including allergic reaction (1 patient), severe fatigue (1 patient), sudden death (1 patient), and thromboembolic events (pulmonary embolism in 3 patients and deep vein thrombosis in 1 patient); 2 patients withdrew when the study was suspended and subsequently closed. No associations could be established between baseline characteristics and toxicity.

CONCLUSIONS

The proportion of patients with lethal or potentially life-threatening adverse events was high (0.31, 95% confidence interval, 0.11-0.59), and the absence of objective responses made it unlikely that further accrual would demonstrate the efficacy of the regimen. These observations provide little support for the use of this combination for melanoma brain metastases unless safe and effective methods to prevent thrombosis are developed.

A phase I/II study of lomustine and temozolomide in patients with cerebral metastases from malignant melanoma

Temozolomide is an alkylating agent with activity in the treatment of melanoma metastatic to the brain. Lomustine is a nitrosurea that crosses the blood brain barrier and there is evidence to suggest that temozolomide may reverse resistance to lomustine. A multicentre phase I/II study was conducted to assess the maximum-tolerated dose (MTD), safety and efficacy of the combination of temozolomide and lomustine in melanoma metastatic to the brain. Increasing doses of temozolomide and lomustine were administered in phase I of the study to determine the MTD. Patients were treated at the MTD in phase II of the study to six cycles, disease progression or unacceptable toxicity. Twenty-six patients were enrolled in the study. In phase I of the study, the MTD was defined as temozolomide 150 mg m⁻² days 1–5 every 28 days and lomustine 60 mg m^–2 on day 5 every 56 days. Dose-limiting neutropaenia and thrombocytopaenia were observed at higher doses. Twenty patients were treated at this dose in phase II of the study. No responses to therapy were observed. Median survival from starting chemotherapy was 2 months. The combination of temozolomide and lomustine in patients with brain metastases from melanoma does not demonstrate activity. The further evaluation of this combination therefore is not warranted.

Intra-arterial hepatic fotemustine for the treatment of liver metastases from uveal melanoma: experience in 101 patients

BACKGROUND

Exclusive liver metastases occur in up to 40% of patients with uveal melanoma associated with a median survival of 2-7 months. Single agent response rates with commonly available chemotherapy are below 10%. We have investigated the use of fotemustine via direct intra-arterial hepatic (i.a.h.) administration in patients with uveal melanoma metastases.

PATIENTS AND METHODS

A total of 101 patients from seven centers were treated with i.a.h. fotemustine, administered intra-arterially weekly for a 4-week induction period, and then as a maintenance treatment every 3 weeks until disease progression, unacceptable toxicity or patient refusal.

RESULTS

A median of eight fotemustine infusions per patient were delivered (range 1-26). Catheter related complications occurred in 23% of patients; however, this required treatment discontinuation in only 10% of the patients. The overall response rate was 36% with a median overall survival of 15 months and a 2-year survival rate of 29%. LDH, time between diagnosis and treatment start and gender were significant predictors of survival.

CONCLUSIONS

Locoregional treatment with fotemustine is well tolerated and seems to improve outcome of this poor prognosis patient population. Median survival rates are among the longest reported and one-third of the patients are still alive at 2 years.

Dose finding and O6-alkylguanine-DNA alkyltransferase study of cisplatin combined with temozolomide in paediatric solid malignancies

Cisplatin may have additive activity with temozolomide due to ablation of the DNA repair protein O⁶-alkylguanine-DNA alkyltransferase (MGMT). This phase I/II study determined recommended combination doses using the Continual Reassessment Method, toxicities and antitumour activity in paediatric patients, and evaluated MGMT in peripheral blood mononuclear cells (PBMCs) in order to correlate with haematological toxicity. In total, 39 patients with refractory or recurrent solid tumours (median age ∼13 years; 14 pretreated with high-dose chemotherapy, craniospinal irradiation, or having bone marrow involvement) were treated with cisplatin, followed the next day by oral temozolomide for 5 days every 4 weeks at dose levels 80 mg m⁻²/150 mg m⁻² day⁻¹, 80/200, and 100/200, respectively. A total of 38 patients receiving 113 cycles (median 2, range 1–7) were evaluable for toxicity. Dose-limiting toxicity was haematological in all but one case. Treatment-related toxicities were thrombocytopenia, neutropenia, nausea-vomiting, asthenia. Hearing loss was experienced in five patients with prior irradiation to the brain stem or posterior fossa. Partial responses were observed in two malignant glioma, one brain stem glioma, and two neuroblastoma. Median MGMT activity in PBMCs decreased after 5 days of temozolomide treatment: low MGMT activity correlated with increased severity of thrombocytopenia. Cisplatin–temozolomide combinations are well tolerated without additional toxicity to single-agent treatments; the recommended phase II dosage is 80 mg m⁻² cisplatin and 150 mg m⁻² × 5 temozolomide in heavily treated, and 200 mg m⁻² × 5 temozolomide in less-heavily pretreated children.

DNA repair pathways in drug resistance in melanoma

Metastatic melanoma has a poor prognosis due to resistance to multiple chemotherapy regimens. The mainstay of treatment remains dacarbazine, with cisplatin being a commonly used alternative. Melanoma displays marked resistance to the DNA-damaging effects of these drugs. Intrinsic and acquired resistance involves multiple cellular pathways of damage recognition, repair and apoptosis. Increased understanding of these pathways is identifying novel targets that it is hoped will make inroads into the treatment of this lethal disease.

Phase II trial of cisplatin plus temozolomide, in recurrent and progressive malignant glioma patients

We report a phase II trial of cisplatinum and temozolomide (TMZ) combination in recurrent malignant glioma patients. The DNA repair protein O(6)-alkylguanine-DNA alkyltransferase (AGAT) is important in glioblastoma resistance to alkylating antitumor agents. In vitro, cisplatin (CDDP) decreases MGMT activity in a time- and dose-dependent manner. Thirty-three recurrent malignant glioma patients (20 GBM-13 AA) were treated at recurrence or progression with a CDDP and TMZ association. On days 1 and 2, iv CDDP (40 mg/sqm) was administered. TMZ (at the dose of 200 mg/sqm) was administered as a single oral daily-dose on days 2-6 (starting 24 h after the first CDDP dose), the cycle was repeated every 4 weeks. All patients had been previously treated with surgery followed by radiotherapy and CDDP + BCNU chemotherapy. The primary endpoint of the study was progression free survival at 6 months (PFS-6). Secondary endpoints included radiological response and toxicities. Thirty-three patients received a total of 113 courses (median 3 range 1-11). Complete responses were not observed, partial responses were 18.8% with an additional 39.9% of stable disease. For the whole group of patients the PFS at 6 and 12 months was 52% and 15% with a median TTP of 33 weeks. PFS-6 for GBM and Anaplastic astrocytoma (AA) were 35% and 69%, respectively. PFS-12 for GBM and AA were 13.8% and 17.3%, respectively. Median TTP was 21.3 and 39.5 weeks, respectively. The principal toxic effects of the regimen were: neutropenia (5 WHO grade IV), thrombocytopenia (4 WHO grade IV), nausea and vomiting.

Phase 2 study of temozolomide and Caelyx in patients with recurrent glioblastoma multiforme

Temozolomide has established activity in the treatment of recurrent glioblastoma multiforme (GBM). Caelyx (liposomal doxorubicin) has established activity in a broad range of tumors but has not been extensively evaluated in the treatment of GBM. Phase 1 data suggest that temozolomide and Caelyx can be combined safely at full dose. In this phase 2 study, combination temozolomide (200 mg/m(2) orally, days 1-5) and Caelyx (40 mg/m(2) i.v., day 1) was given every 4 weeks to a cohort of 22 patients with recurrent GBM, who received a total of 109 cycles (median 3.5 cycles). The median age of the patients was 55 years (range, 31-80 years), and 17 were male. All patients had received radiotherapy, but only 2 had received prior chemotherapy. One patient (5%) had a complete response, 3 patients (14%) had a partial response, and 11 patients (50%) had stable disease. The median time to progression for the cohort was 3.2 months (range, 1-13 months). Median overall survival was 8.2 months (range, 1-16+ months). Seven patients (32%) were progression free at 6 months. Hematological toxicity included grade 3/4 neutropenia in 4 patients (18%) and grade 3/4 thrombocytopenia in 4 patients (18%). Grade 3 non-hematologic toxicity included rash in 3 patients (14%), nausea and vomiting in 1 patient (4%), hypersensitivity reaction to Caelyx in 3 patients (14%), and palmar-plantar toxicity in 1 patient (4%). We conclude that the combination of temozolomide and Caelyx is well tolerated, results in a modest objective response rate, but has encouraging disease stabilization in the treatment of recurrent GBM.

Marked inactivation of O6-alkylguanine-DNA alkyltransferase activity with protracted temozolomide schedules

Temozolomide, an oral DNA methylator that inactivates the DNA repair enzyme O(6)-alkylguanine-DNA alkyltransferase (AGAT), has demonstrated anticancer activity on protracted schedules. Protracted schedules may lead to an 'autoenhancement' of temozolomide's inherent cytotoxic potential by cumulative reduction of the cell's capacity for AGAT-mediated DNA repair and resistance. This study was undertaken to characterise AGAT inactivation and regeneration in the peripheral blood mononuclear cells (PBMCs) of patients treated on two protracted temozolomide schedules. O(6)-alkyl guanine-DNA alkyltransferase activity was measured in the PBMCs of patients treated on two phase I protracted temozolomide studies. Patients were treated daily for either 7 days every 2 weeks (Schedule A) or 21 days every 4 weeks (Schedule B). The effects of various temozolomide doses (75-175 mg m(-2)), treatment duration (7-21 days), and temozolomide plasma levels on AGAT inactivation and regeneration, as well as the relation between AGAT inactivation and toxicity, were studied. O(6)-alkyl guanine-DNA alkyltransferase activity in PBMCs was measured serially in 52 patients. Marked inactivation of AGAT occurred following 7 days of temozolomide treatment, with mean AGAT activity decreasing by 72% (P<0.0001). Similarly, mean AGAT activity decreased by 63 and 73% after 14 and 21 days of treatment, respectively (P<0.001 for both comparisons). O(6)-alkyl guanine-DNA alkyltransferase inactivation was greater after 7 days of treatment with higher doses of temozolomide than lower doses and remained markedly reduced 7 days post-treatment. However, AGAT inactivation following temozolomide treatment for 14 and 21 days was similar at all doses. On the continuous 21-day schedule, AGAT inactivation was significantly greater in patients who experienced severe thrombocytopenia than those who did not (90.3+/-5.5 vs 72.5+/-16.1%, P<0.045). In conclusion, protracted administration of temozolomide, even at relatively low daily doses, leads to significant and prolonged depletion of AGAT activity, which may enhance the antitumour activity of the agent.

Improvement of chemotherapy efficacy by inactivation of a DNA-repair pathway

Tumour resistance and dose-limiting toxic effects restrict treatment with most chemotherapeutic drugs. Elucidation of the mechanisms of these effects could permit the development of ways to improve the effectiveness of currently used agents until better therapeutic agents are developed. Several types of alkylating agents are used in the treatment of cancer. The DNA repair protein, O6-alkylguanine-DNA alkyltransferase (ATase) is an important cellular resistance mechanism to one class of alkylating agents. This enzyme removes potentially lethal damage from DNA and experiments in vitro and in vivo have shown that its inactivation can reverse resistance to such agents. Clinical trials of drugs that inactivate ATase are underway and early results indicate that they are active in tumour tissues. However, the ATase present in normal tissues, particularly bone marrow, is also inactivated, necessitating a reduction in the dose of alkylating agent. An important question is whether, in the absence of any tumour-specific delivery strategy, such drugs will improve therapeutic effectiveness; initial reports are not promising.

Phase I study of fotemustine in pediatric patients with refractory brain tumors

BACKGROUND

Fotemustine is a nitrosourea with theoretic and preclinical advantages over the original analogs, carmustine and lomustine, in the treatment of brain tumors. This is the first pediatric Phase I study of fotemustine.

METHODS

Patients younger than 21 with recurrent/resistant brain tumors were enrolled in a conventional Phase I study. Fotemustine was administered intravenously every 3 weeks at increasing dose levels starting at 100 mg/m(2). Toxicity and response data were monitored closely.

RESULTS

Fifteen evaluable patients entered the study and received a total of 45 courses of fotemustine (dose range, 100-175 mg/m(2)). Myelosuppression was observed, with the dose-limiting toxicity being Grade 4 neutropenia and thrombocytopenia. Toxicity was delayed and cumulative. The maximum tolerated dose was 150 mg/m(2) every 3 weeks. There were three documented radiologic responses (20% of patients) comprising one partial response and two minor responses in patients with a sarcoma, medulloblastoma, and ependymoma, respectively.

CONCLUSIONS

Fotemustine administered at a dose of 150 mg/m(2) every 3 weeks is well tolerated in children and has antitumor activity in several brain tumors. This is the first dedicated Phase I study of a single agent nitrosourea in a pediatric population. More comparative studies should be undertaken to define the optimum nitrosourea analog for use in children with brain tumors.

Heterogeneity of O6-alkylguanine DNA-alkyltransferase expression in human breast tumours

An important determinant of cellular resistance to chemotherapeutic O6-alkylating agents, which comprise methylating and chloroethylating agents, is the ability of cells to repair alkylation damage at the O6-position of guanine in DNA. This is achieved by a specific DNA repair enzyme O6-alkylguanine DNA-alkyltransferase. In this study O6-alkylguanine DNA-alkyltransferase expression was measured in human breast tumours using both biochemical and immunohistochemical techniques. O6-alkylguanine DNA-alkyltransferase activity was then compared with known clinical prognostic indices to assess the potential role of O6-alkylguanine DNA-alkyltransferase in predicting the behaviour of this common malignancy. The application of both biochemical and immunohistochemical techniques was feasible and practical. Most breast tumours expressed high levels of O6-alkylguanine DNA-alkyltransferase. Immunohistochemical analysis showed marked variation in expression not only between individuals but also within individual tumours, and in the same patient, between metastases and between primary tumour and metastatic site. O6-alkylguanine DNA-alkyltransferase activity in tissue extracts significantly correlated not only with immunohistochemical staining intensity determined by subjective quantitation, but also with measures of protein levels using a computerised image analysis system including mean grey (P<0.001), percentage of cells positive for O6-alkylguanine DNA-alkyltransferase (P<0.001), and integrated optical density (P<0.001). O6-alkylguanine DNA-alkyltransferase expression did not correlate with any of the established clinical prognostic indicators for current treatment regimens. However, immunohistochemical offers a rapid and convenient method for assessing potential utility of O6-alkylating agents or O6-alkylguanine DNA-alkyltransferase inactivating agents in future studies of breast cancer treatment.

NICE verdict on Temozolomide: where next?

British Journal of Cancer (2002) 86, 499–500. DOI: 10.1038/sj/bjc/6600134www.bjcancer.com

© 2002 Cancer Research UK

Current and future developments in the use of temozolomide for the treatment of brain tumours

Brain tumours comprise only 2% of all adult cancers, but they are among the most debilitating malignant diseases. Temozolomide, an alkylating agent that can be administered orally, has been approved for the treatment of recurrent malignant glioma on a daily schedule for 5-day cycles. Continuous administration schedules with a higher dose intensity are being explored, but an improvement in efficiency remains to be shown. The benefit from temozolomide given as a single agent in recurrent disease will be several weeks at best. This drug is therefore now undergoing clinical testing as neoadjuvant chemotherapy or with concomitant radiotherapy in patients with newly diagnosed glioma. Several phase I trials are investigating the combination of temozolomide with other agents active against brain tumours. This review briefly summarises the pharmacological background and clinical development of temozolomide and focuses on current and future clinical exploration of this drug for the treatment of brain tumours.

Fotemustine combined with procarbazine in recurrent malignant gliomas: a phase I study with evaluation of lymphocyte 06-alkylguanine-DNA alkyltransferase activity

The aims of this phase I study in patients with recurrent malignant gliomas were to determine the maximum tolerated dose (MTD) and toxicity profile of fotemustine when combined with a fixed dose of procarbazine (PCZ), and to evaluate the extent of O6-alkylguanine-DNA alkyltransferase (ATase) depletion in circulating lymphocytes during treatment. Sixteen patients received an induction cycle consisting of 100 mg/day oral PCZ for 12 consecutive days and a 1-h intravenous infusion of fotemustine given 4 h after PCZ on days 5 and 12 at escalated doses (50, 75, 100 and 125 mg/m2/day). After a 6-week rest period, a maximum of 4 maintenance cycles (PCZ 300 mg/day, 4 days; fotemustine, day 4) was given every 4 weeks. ATase activity was measured on days 1, 5 and 12 over 4 h after PCZ intake. Fifteen patients had previously received at least one nitrosourea-based chemotherapy, associated with PCZ in 12 cases. The MTD of fotemustine was 125 mg/m2 (days 5 and 12) with myelosuppression as the dose limiting toxicity (DLT). At this dose level, half of patients experienced grade 3 anemia, neutropenia or thrombopenia. No extra-hematological DLT was observed. No significant depletion of ATase activity by PCZ was evidenced. One partial response and 7 stable diseases were obtained leading to a disease control rate of 50%. The median times to progression and survival were 2.6 and 9.7 months, respectively. This combined regimen of PCZ and fotemustine was well tolerated with a good disease control rate in heavily pretreated glioma patients and merits further investigation in phase II studies.