The role of topotecan in the treatment of brain metastases

Radiation therapy, tissue radiosensitization, and potential synergism in the era of novel antibody-drug conjugates

Antibody-drug conjugates (ADCs) represent a therapeutic class of agents designed to selectively deliver cytotoxic payloads to cancer cells. With the increasingly positioning of ADCs in the clinical practice, combinations with other treatment modalities, including radiation therapy (RT), will open new opportunities but also challenges. This review evaluates ADC-RT interactions, examining therapeutic synergies and potential caveats. ADC payloads can be radiosensitizing, enhancing cytotoxicity when used in combination with RT. Antigens targeted by ADCs can have various tissue expressions, resulting in possible off-target toxicities by tissue radiosensitization. Notably, the HER-2-directed ADC trastuzumab emtansine has appeared to increase the risk of radionecrosis when used concomitantly with brain RT, as glial cells can express HER2, too. Other possible organ-specific effects are discussed, such as pulmonary and cardiac toxicities. The lack of robust clinical data on the ADC-RT combination raises concerns regarding specific side effects and the ultimate trade-off of toxicity and safety of some combined approaches. Clinical studies are needed to assess ADC-RT combination safety and efficacy.

ATM-Inhibitor AZD1390 Is a Radiosensitizer for Breast Cancer CNS Metastasis

PURPOSE

Limited effective treatments are currently available for central nervous system (CNS) metastasis (CM). This is largely driven by the inability of current therapeutics to penetrate the blood brain barrier (BBB) and the lack of preclinical models for testing new therapies. Here we study the efficacy of AZD1390, a BBB penetrating ataxia-telangiectasia mutated inhibitor, as a radiosensitizer for breast cancer CM treatment.

EXPERIMENTAL DESIGN

Three patient-derived xenograft (PDX) tumors including 2 HER2+ and 1 triple-negative breast cancer harboring DNA damage response (DDR) gene mutations, were implanted subcutaneously in the flank of mice to assess tumor growth inhibition by AZD1390 combined with radiation. Animal survival was further assessed by implanting the best responding PDX model orthotopically in the brain.

RESULTS

Pretreatment with AZD1390 followed by radiation therapy inhibited growth of PDX tumors implanted in the flank, and improved survival in orthotopic models with average survival of 222 days compared with 123 days in controls. Administration of AZD1390 posttreatment for 21 days had no further benefits. While the combination therapy resulted in sustained tumor inhibition, sporadic regrowth was observed in some mice 50 to 100 days posttreatment in all models. Gene expression comparing these tumors with complete responders demonstrated changes in upregulation of oncogenic proteins, which are potential drivers of tumor growth after treatment.

CONCLUSIONS

Our results demonstrate that AZD1390 effectively sensitizes breast cancer CM to radiation therapy in DDR mutant tumors. This study demonstrates the potential of using AZD1390 as a novel therapeutic agent for patients with breast cancer CM.

An Elusive Target: Inhibitors of JC Polyomavirus Infection and Their Development as Therapeutics for the Treatment of Progressive Multifocal Leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a rare demyelinating disease caused by infection with JC Polyomavirus (JCPyV). Despite the identification of the disease and isolation of the causative pathogen over fifty years ago, no antiviral treatments or prophylactic vaccines exist. Disease onset is usually associated with immunosuppression, and current treatment guidelines are limited to restoring immune function. This review summarizes the drugs and small molecules that have been shown to inhibit JCPyV infection and spread. Paying attention to historical developments in the field, we discuss key steps of the virus lifecycle and antivirals known to inhibit each event. We review current obstacles in PML drug discovery, including the difficulties associated with compound penetrance into the central nervous system. We also summarize recent findings in our laboratory regarding the potent anti-JCPyV activity of a novel compound that antagonizes the virus-induced signaling events necessary to establish a productive infection. Understanding the current panel of antiviral compounds will help center the field for future drug discovery efforts.

Therapeutic Options for Brain Metastases in Gynecologic Cancers

OPINION STATEMENT

Brain metastases (BM) are rare in gynecologic cancers. Overall BM confers a poor prognosis but other factors such as number of brain lesions, patient age, the presence of extracranial metastasis, the Karnofsky Performance Status (KPS) score, and the type of primary cancer also impact prognosis. Taking a patient's whole picture into perspective is crucial in deciding the appropriate management strategy. The management of BM requires an interdisciplinary approach that frequently includes oncology, neurosurgery, radiation oncology and palliative care. Treatment includes both direct targeted therapies to the lesion(s) as well as management of the neurologic side effects caused by mass effect. There is limited evidence of when screening for BM in the gynecology oncology patient is warranted but it is recommended that any cancer patient with new focal neurologic deficit or increasing headaches should be evaluated. The primary imaging modality for detection of BM is MRI, but other imaging modalities such as CT and PET scan can be used for certain scenarios. New advances in radiation techniques, improved imaging modalities, and systemic therapies are helping to discover BM earlier and provide treatments with less detrimental side effects.

TOP1 inhibition induces bifurcated JNK/MYC signaling that dictates cancer cell sensitivity

Rationale: Triple-negative breast cancer (TNBC) does not respond to anti-estrogen and anti-HER2 therapies and is commonly treated by chemotherapy. TNBC has a high recurrence rate, particularly within the first 3 years. Thus, there is an urgent clinical need to develop more effective therapies for TNBC. Topoisomerase I (TOP1) inhibitors cause DNA damage, making these drugs desirable for TNBC treatment since DNA repair machinery is defective in this subtype of breast cancer. Among the main molecular subtypes of breast cancer, the TNBC cell lines exhibited the highest TOP1 inhibition sensitivity. However, clinically used TOP1 inhibitors, such as topotecan and irinotecan, have shown limited clinical applications and the reasons remain unclear. Understanding the mechanism of differential responses to TOP1 blockade and identifying the predictive markers for cancer cell sensitivity will help further TOP1-targeted therapy for TNBC treatment and improve the clinical use of TOP1 inhibitors. Methods: Viability assays were used to evaluate breast cancer cell sensitivity to topotecan and other TOP1 inhibitors as well as TOP2 inhibitors. An in vitro-derived topotecan-resistant TNBC cell model and TNBC xenograft models were employed to confirm cancer cell response to TOP1 blockade. RNA-seq was used to identify potential predictive markers for TNBC cell response to TOP1 blockade. Western blotting and qRT-PCR were performed to measure the protein levels and RNA expression. ATAC-seq and luciferase reporter assays were used to examine MYC transcriptional regulations. The effects of MYC and JNK in cancer cell response to TOP1 inhibition were validated via loss-of-function and gain-of-function experiments. Results: We observed two distinct and diverging cancer cell responses - sensitive versus resistant to TOP1 inhibition, which was confirmed by TNBC xenograft mouse models treated by topotecan. TNBC cells exhibited bifurcated temporal patterns of ATR pathway activation upon TOP1 inhibitor treatment. The sensitive TNBC cells showed an "up then down" dynamic pattern of ATR/Chk1 signaling, while the resistant TNBC cells exhibited a "persistently up" profile. On the contrary, opposite temporal patterns of induced expression of MYC, a key regulator and effector of DNA damage, were found in TNBC cells treated by TOP1 inhibitors. Mechanistically, we showed that TOP1-induced JNK signaling upregulated MYC expression. Furthermore, pharmacological inhibition of ATR reversed TNBC cell resistance to topotecan, whereas MYC knockdown and JNK inhibition reduced cancer cell sensitivity. Conclusions: Dynamic temporal profiles of induced ATR/Chk1 and JNK activation as well as MYC expression, may predict cancer cell response to TOP1 inhibitors. JNK activation-mediated constitutive elevation of MYC expression may represent a novel mechanism governing cancer cell sensitivity to TOP1-targeting therapy. Our results may provide implications for identifying TNBC patients who might benefit from the treatment with TOP1 inhibitors.

Efficacy of PD-1/PD-L1 Inhibitors versus Chemotherapy in Lung Cancer with Brain Metastases: A Systematic Review and Meta-Analysis

Immune checkpoint inhibitors (ICIs) are widely used to treat local or metastatic lung cancer. However, the efficacy of ICI in patients with brain metastases (BM) from lung cancer is unknown. This study aimed to evaluate the efficacy of PD-1/PD-L1 ICIs compared with chemotherapy for patients with lung cancer with BM. Electronic databases (PubMed, Embase, The Cochrane Library, and Web of Science) were searched. The meta-analysis assessed overall survival (OS) and progression-free survival (PFS) of the PD-1/PD-L1 inhibitors axis and its relationship with pathological type, drug modality, and the treatment line number in patients with BM from lung cancer. We included 694 patients with BM from lung cancer from 11 randomized controlled trials. Statistical analysis showed that compared with chemotherapy, PD-1/PD-L1 inhibitors could significantly prolong OS (hazard ratio (HR) = 0.75, 95%confidence interval (95%CI) = 0.51–0.99) and PFS (HR = 0.65, 95%CI = 0.51–0.80). In the subgroup analysis, ICIs plus chemotherapy improved PFS (HR = 0.60, 95%CI = 0.40–0.80), but not OS (HR = 0.75, 95%CI = 0.30–1.19). The efficacy of ICI monotherapy in patients with BM was significantly different between OS and PFS: OS pooled HR = 0.81 (95%CI = 0.57–1.05) and PFS = 0.78 (95%CI = 0.62–0.94). Among different pathological types, the OS pooled HR was 0.67 (95%CI = 0.39–0.95) for non-small cell lung cancer (NSCLC) and 0.94 (95%CI = 0.56–1.33) for small cell lung cancer (SCLC); the PFS pooled HR was 0.58 (95%CI = 0.39–0.76) for NSCLC and 0.79 (95%CI = 0.65–0.93) for SCLC. Subgroups analysis of treatment line showed that no advantage for OS with ICIs as first-line or subsequent-line therapy, whereas ICIs as first-line (HR = 0.63, 95%CI = 0.53–0.74) and second-line (HR = 0.62, 95%CI = 0.62–0.96) benefitted PFS. This meta-analysis implied that compared with chemotherapy, PD-1/PD-L1 inhibitors significantly improved efficacy treatment of patients with BM from lung cancer. Further studies are needed to confirm the role of ICIs in different pathological types and drug treatment modalities.

Dual-response electrochemical electrode for sensitive monitoring of topotecan and mitomycin as anticancer drugs in real samples

This research paper employed an innovative electrochemical electrode to simultaneously determine topotecan (TPT) and mitomycin (MMC) as anticancer agents. For this purpose, a novel nanocomposite was synthesized using a hydrothermal procedure. The nanocomposites were characterized using FTIR, STEM, FESEM, mapping analysis, EDX, and XRD methods. The novelty of this work is the successful synthesis of Fe₃O₄ decorated on the surface of CuCo₂S₄ (Fe₃O₄@CuCo₂S₄) nanocomposites showed two separate anodic peaks at 0.8 V for TPT and 1.0 V for MMC with potential separation of 0.2 V. This was enough for the simultaneous electrochemical determination of topotecan and mitomycin on a glassy carbon electrode (GCE), simultaneously. At optimized conditions, the developed electrode exhibited linear responses with TPT and MMC concentration in the ranges of 0.01-0.89 and 0.89-8.95 μM for topotecan and 0.1-19.53 μM for mitomycin. The detection limits were observed as 6.94 nM and 80.00 nM for topotecan and mitomycin, respectively. The fabricated Fe₃O₄@CuCo₂S₄/GCE showed high sensitivity, long-term stability, and repeatability towards the sensing of TPT and MMC simultaneously and can be utilized in real samples. The obtained results confirmed that the fabricated Fe₃O₄@CuCo₂S₄/GCE nanocomposites can be utilize in the simultaneous electrochemical determination of topotecan and mitomycin in real samples.

Real-Time Positron Emission Tomography Evaluation of Topotecan Brain Kinetics after Ultrasound-Mediated Blood-Brain Barrier Permeability

Glioblastoma (GBM) is the most common primary adult brain malignancy with an extremely poor prognosis and a median survival of fewer than two years. A key reason for this high mortality is that the blood-brain barrier (BBB) significantly restricts systemically delivered therapeutics to brain tumors. High-intensity focused ultrasound (HIFU) with microbubbles is a methodology being used in clinical trials to noninvasively permeabilize the BBB for systemic therapeutic delivery to GBM. Topotecan is a topoisomerase inhibitor used as a chemotherapeutic agent to treat ovarian and small cell lung cancer. Studies have suggested that topotecan can cross the BBB and can be used to treat brain metastases. However, pharmacokinetic data demonstrated that topotecan peak concentration in the brain extracellular fluid after systemic injection was ten times lower than in the blood, suggesting less than optimal BBB penetration by topotecan. We hypothesize that HIFU with microbubbles treatment can open the BBB and significantly increase topotecan concentration in the brain. We radiolabeled topotecan with 11C and acquired static and dynamic positron emission tomography (PET) scans to quantify [11C] topotecan uptake in the brains of normal mice and mice after HIFU treatment. We found that HIFU treatments significantly increased [11C] topotecan brain uptake. Moreover, kinetic analysis of the [11C] topotecan dynamic PET data demonstrated a substantial increase in [11C] topotecan volume of distribution in the brain. Furthermore, we found a decrease in [11C] topotecan brain clearance, confirming the potential of HIFU to aid in the delivery of topotecan through the BBB. This opens the potential clinical application of [11C] topotecan as a tool to predict topotecan loco-regional brain concentration in patients with GBMs undergoing experimental HIFU treatments.

Patient-derived xenografts of central nervous system metastasis reveal expansion of aggressive minor clones

BACKGROUND

The dearth of relevant tumor models reflecting the heterogeneity of human central nervous system metastasis (CM) has hindered development of novel therapies.

METHODS

We established 39 CM patient-derived xenograft (PDX) models representing the histological spectrum, and performed phenotypic and multi-omic characterization of PDXs and their original patient tumors. PDX clonal evolution was also reconstructed using allele-specific copy number and somatic variants.

RESULTS

PDXs retained their metastatic potential, with flank-implanted PDXs forming spontaneous metastases in multiple organs, including brain, and CM subsequent to intracardiac injection. PDXs also retained the histological and molecular profiles of the original patient tumors, including retention of genomic aberrations and signaling pathways. Novel modes of clonal evolution involving rapid expansion by a minor clone were identified in 2 PDXs, including CM13, which was highly aggressive in vivo forming multiple spontaneous metastases, including to brain. These PDXs had little molecular resemblance to the patient donor tumor, including reversion to a copy number neutral genome, no shared nonsynonymous mutations, and no correlation by gene expression.

CONCLUSIONS

We generated a diverse and novel repertoire of PDXs that provides a new set of tools to enhance our knowledge of CM biology and improve preclinical testing. Furthermore, our study suggests that minor clone succession may confer tumor aggressiveness and potentiate brain metastasis.

Brain Metastases from Ovarian Cancer: Current Evidence in Diagnosis, Treatment, and Prognosis

With this review, we provide the state of the art concerning brain metastases (BMs) from ovarian cancer (OC), a rare condition. Clinical, pathological, and molecular features, treatment options, and future perspectives are comprehensively discussed. Overall, a diagnosis of high-grade serous OC and an advanced disease stage are common features among patients who develop brain metastases. BRCA1 and BRCA2 gene mutations, as well as the expression of androgen receptors in the primary tumor, are emerging risk and prognostic factors which could allow one to identify categories of patients at greater risk of BMs, who could benefit from a tailored follow-up. Based on present data, a multidisciplinary approach combining surgery, radiotherapy, and chemotherapy seem to be the best approach for patients with good performance status, although the median overall survival (<1 year) remains largely disappointing. Hopefully, novel therapeutic avenues are being explored, like PARP inhibitors and immunotherapy, based on our improved knowledge regarding tumor biology, but further investigation is warranted.

Rare Distant Metastatic Disease of Ovarian and Peritoneal Carcinomatosis: A Review of the Literature

Background: Although metastases of ovarian and peritoneal carcinomatosis are most commonly found within the peritoneal cavity, there is a number of other rare distant sites that have been reported. Our goal is to provide an evidence-based summary of the available literature considering the rare distant metastatic sites of ovarian and peritoneal carcinomatosis. Methods: A comprehensive search of the literature was conducted, with Medline/PubMed being searched for cases of rare metastatic disease originated from primary ovarian and peritoneal cancer with related articles up to 2019 including terms such as "ovarian cancer", "metastases", "peritoneal" and others. Results: The most common mechanism of ovarian cancer metastases consists of primarily dissemination within the peritoneal cavity, while, rare and distant sites can either occur at the beginning or during the course of the disease and they are usually associated with hematogenous route and lymphatic invasion, having poor prognosis, with the least common sites being skin, bone, CNS, eye, placenta, central airways, rare lymph nodes, intra-abdominal organs, heart and breast. Conclusions: The occurrence of metastatic sites described in this review represents the most common rare distant metastatic sites, and even though their patterns of metastases are still not fully clarified due to the rarity of the reports, they offer valuable information considering the pathophysiology of the disease.

Assessing the Effectiveness of Systemic Therapy after Stereotactic Radiosurgery on Cancer Recurrence and All-Cause Mortality

BACKGROUND

Patients with cancer often present with brain metastases in the setting of controlled extracranial disease, for which they receive stereotactic radiosurgery (SRS) and surgical resection. The role of systemic therapy after SRS is unclear. Brain metastasis indicates active cancer dissemination, and microscopic systemic disease may be present despite absence of gross disease as assessed by conventional imaging modalities.

OBJECTIVE

The aim was to determine if post-SRS systemic therapy reduces the risk of brain relapse, systemic relapse, and death in patients with brain metastases and controlled extracranial disease.

METHODS

We retrospectively reviewed the medical records of 67 patients with controlled extracranial disease who received SRS for brain metastases. Kaplan-Meier analysis and Cox proportional hazards regression were used to assess how post-SRS systemic therapy affected the risk of brain relapse, systemic relapse, and all-cause mortality.

RESULTS

In our sample, 31% of patients received systemic therapy after SRS. Post-SRS systemic therapy did not affect median time to brain relapse (P = 0.43), systemic relapse (P = 0.16), or death (P = 0.33) by univariate analysis. After accounting for confounding factors such as cancer histology and age, post-SRS systemic therapy significantly reduced the risk of brain relapse (hazard ratio [HR], 0.22; P = 0.002) but not systemic relapse (HR, 0.38; P = 0.09) or all-cause mortality (HR, 2.16; P = 0.09).

CONCLUSIONS

Only a minority of patients with brain metastases and controlled extracranial disease receive adjuvant systemic therapy after SRS, but those that do have a reduced risk of brain relapse. Post-SRS systemic therapy may act prophylactically to reduce the risk of intracranial cancer recurrence.

Management of Small Cell Lung Cancer: Progress and Updates

Small cell lung cancer (SCLC) remains a major public health problem and accounts for 10% to 15% of all lung cancers. It has unique clinical features such as rapid growth, early metastatic spread, and widespread dissemination. A platinum-etoposide combination is the backbone treatment of SCLC; addition of thoracic and prophylactic cranial irradiation has been shown to improve outcome in limited-stage SCLC and in subgroups of extensive-stage SCLC. Over the last decade, significant progress has been made in characterizing the SCLC tumor biology and its developmental pathways. Most recently, efforts have focused not only on molecular targets, but also on the development of novel drugs targeting tumor evolution and immune escape mechanisms; these approaches are promising and offer opportunities that may finally improve the outcomes of SCLC.

The economic burden of brain metastasis among lung cancer patients in the United States

OBJECTIVE

Brain metastases among lung cancer patients can impair cognitive and functional ability, complicate care, and reduce survival. This study focuses on the economic burden of brain metastasis in lung cancer-direct healthcare costs to payers and indirect costs to patients, payers, and employers-in the US.

METHODS

Retrospective study using claims data from over 60 self-insured Fortune 500 companies across all US census regions (January 1999-March 2013). Adult, non-elderly lung cancer patients with brain metastasis were evaluated over two study periods: (1) pre-diagnosis (≤30 days prior to first observed lung cancer diagnosis to ≤30 days prior to first-observed brain metastasis diagnosis) and (2) post-diagnosis (≤30 days prior to first observed brain metastasis diagnosis to end of continuous eligibility or observation).

OUTCOME MEASURES

Healthcare costs to payers and resource utilization, salary loss to patients, disability payouts for payers, and productivity loss to employers.

RESULTS

A total of 132 patients were followed for a median of 8.4 and 6.6 months in the pre- and post-diagnosis periods, respectively. At diagnosis of brain metastasis, 21.2% of patients were on leave of absence and 6.1% on long-term disability leave. Substantial differences were observed in the pre- vs post-diagnosis periods. Specifically, patients incurred much greater healthcare utilization in the post-diagnosis period, resulting in $25,579 higher medical costs per-patient-per-6-months (PPP6M). During this period, patients missed significantly more work days, generating an incremental burden of $2853 PPP6M in salary loss for patients, $2557 PPP6M in disability payments for payers, and $4570 PPP6M in productivity loss for employers.

LIMITATIONS

Type of primary lung cancer and extent of brain metastasis could not be assessed in the data. The analysis was also limited to patients with comprehensive disability coverage.

CONCLUSIONS

Development of brain metastasis among lung cancer patients is associated with a substantial economic burden to payers, patients, and employers.

Systemic Chemotherapy for Progression of Brain Metastases in Extensive-Stage Small Cell Lung Cancer

Lung cancer is the most common cause of cancer related mortality in men and women. Approximately 15% of lung cancers are small cell type. Chemotherapy and radiation are the mainstay treatments. Currently, the standard chemotherapy regimen includes platinum/etoposide. For extensive small cell lung cancer, irinotecan and cisplatin have also been used. Patients with relapsed small cell lung cancer have a very poor prognosis, and the morbidity increases with brain metastases. Approximately 10%–14% of small cell lung cancer patients exhibit brain metastases at the time of diagnosis, which increases to 50%–80% as the disease progresses. Mean survival with brain metastases is reported to be less than six months, thus calling for improved regimens. Here we present a case series of patients treated with irinotecan for progressive brain metastases in small cell lung cancer, which serves as a reminder of the role of systemic chemotherapy in this setting.

Tumor bed radiosurgery following resection and prior stereotactic radiosurgery for locally persistent brain metastasis

PURPOSE

Despite advances in multimodality management of brain metastases, local progression following stereotactic radiosurgery (SRS) can occur. Often, surgical resection is favored, as it frequently provides immediate symptom relief as well as pathological characterization of any residual tumor. Should the pathological specimen contain viable tumor cells, further radiation therapy is an option to sterilize the tumor bed. We evaluated the use of repeat SRS (rSRS) in lieu of whole-brain radiation therapy (WBRT) as a means of improving local control (LC) while minimizing potential toxicity and dose to the normal brain.

MATERIALS/METHODS

A retrospective review was performed to identify patients with brain metastases who underwent SRS and then surgical resection for locally recurrent or persistent disease. From 2004 to 2014, 13 consecutive patients or 15 lesions were treated with rSRS after resection, either post-operatively to the tumor bed (n = 10, 66.6%) or after a second local recurrence (n = 5, 33.3%). LC, distant brain failure (DBF), and radiation toxicity were determined using patient records, RECIST criteria v1.1, and CTCAE v4.03.

RESULTS

At a median follow-up interval of 9.0 months (range 1.8-54.9 months) from time of rSRS, five patients remain alive. Following rSRS, 13 of the 15 (86.6%) lesions were locally controlled with an estimated 100% LC at 6 months and 75% LC at 1 year. However, 11 of the 15 (73.3%) treated lesions developed DBF after rSRS with 3 of 13 patients proceeding to WBRT. Two of 15 (13.3%) resulted in either grade 2 radionecrosis with grade 3 seizures or grade 3 radionecrosis.

CONCLUSION

Repeat SRS represents a potential salvage therapy for patients with locally recurrent brain metastases, providing additional tumor control with acceptable toxicity, even in the setting of prior SRS and surgical resection. rSRS may be reasonable to use as an alternative to WBRT in this setting.

Brain metastasis from uterine serous carcinoma: A case report and review of literature

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Brain metastasis from UPSC is rare, with 9 cases in the literature.

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UPSC may resemble other endometrial cancers in regard to brain metastatic behavior.

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When appropriate, it seems that multimodal therapy offers the best outcomes.

Chemotherapeutic drugs that penetrate the blood–brain barrier affect the development of hyperactive delirium in cancer patients

Objective:

Delirium is a frequently encountered psychiatric disease in terminal cancer patients. However, the mechanism of delirium is unclear. The aim of our study was to investigate the relationship between administration of chemotherapy drugs that penetrate the blood–brain barrier (BBB) and the development of delirium in cancer patients.

Method:

We retrospectively analyzed 166 cancer patients (97 males, 69 females) continuously who died between September of 2007 and January of 2010 using a review of medical charts. Multiple logistic regression analysis was employed to investigate the effects of antineoplastic drugs penetrating the BBB on development of delirium in cancer patients with control for other risk factors.

Results:

In multivariate analysis, antineoplastic drugs that penetrated the BBB were significantly associated with development of delirium (OR = 18.92, CI95 = 1.08–333.04, p < 0.001).

Significance of results:

The use of chemotherapy drugs that penetrate the BBB may be a risk factor for delirium. This information may allow palliative care doctors and medical oncologists to predict which patients are at increased risk for delirium.

Brain metastasis: new opportunities to tackle therapeutic resistance

Brain metastasis is a devastating complication of cancer with unmet therapeutic needs. The incidence of brain metastasis has been rising in cancer patients and its response to treatment is limited due to the singular characteristics of brain metastasis (i.e., blood-brain-barrier, immune system, stroma). Despite improvements in the treatment and control of extracranial disease, the outcomes of patients with brain metastasis remain dismal. The mechanisms that allow tumor cells to promulgate metastases to the brain remain poorly understood. Further work is required to identify the molecular alterations inherent to brain metastasis in order to identify novel therapeutic targets and explicate the mechanisms of resistance to systemic therapeutics. In this article, we review current knowledge of the unique characteristics of brain metastasis, implications in therapeutic resistance, and the possibility of developing biomarkers to rationally guide the use of targeted agents.

R-loops in proliferating cells but not in the brain: implications for AOA2 and other autosomal recessive ataxias

Disruption of the Setx gene, defective in ataxia oculomotor apraxia type 2 (AOA2) leads to the accumulation of DNA/RNA hybrids (R-loops), failure of meiotic recombination and infertility in mice. We report here the presence of R-loops in the testes from other autosomal recessive ataxia mouse models, which correlate with fertility in these disorders. R-loops were coincident in cells showing high basal levels of DNA double strand breaks and in those cells undergoing apoptosis. Depletion of Setx led to high basal levels of R-loops and these were enhanced further by DNA damage both in vitro and in vivo in tissues with proliferating cells. There was no evidence for accumulation of R-loops in the brains of mice where Setx, Atm, Tdp1 or Aptx genes were disrupted. These data provide further evidence for genome destabilization as a consequence of disrupted transcription in the presence of DNA double strand breaks arising during DNA replication or recombination. They also suggest that R-loop accumulation does not contribute to the neurodegenerative phenotype in these autosomal recessive ataxias.

Phase II clinical trial of whole-brain irradiation plus three-dimensional conformal boost with concurrent topotecan for brain metastases from lung cancer

BACKGROUND

Patients with brain metastases from lung cancer have poor prognoses and short survival time, and they are often excluded from clinical trials. Whole-cranial irradiation is considered to be the standard treatment, but its efficacy is not satisfactory. The purpose of this phase II clinical trial was to evaluate the preliminary efficacy and safety of the treatment of whole-brain irradiation plus three-dimensional conformal boost combined with concurrent topotecan for the patients with brain metastases from lung cancer.

METHODS

Patients with brain metastasis from lung cancer received concurrent chemotherapy and radiotherapy: conventional fractionated whole-brain irradiation, 2 fields/time, 1 fraction/day, 2 Gy/fraction, 5 times/week, and DT 40 Gy/20 fractions; for the patients with ≤ 3 lesions with diameter ≥ 2 cm, a three-dimensional (3-D) conformal localised boost was given to increase the dosage to 56-60 Gy; and during radiotherapy, concurrent chemotherapy with topotecan was given (the chemoradiotherapy group, CRT). The patients with brain metastasis from lung cancer during the same period who received radiotherapy only were selected as the controls (the radiotherapy-alone group, RT).

RESULTS

From March 2009 to March 2012, both 38 patients were enrolled into two groups. The median progression-free survival(PFS) time , the 1- and 2-year PFS rates of CRT group and RT group were 6 months, 42.8%, 21.6% and 3 months, 11.6%, 8.7% (χ2 = 6.02, p = 0.014), respectively. The 1- and 2-year intracranial lesion control rates of CRT and RT were 75.9% , 65.2% and 41.6% , 31.2% (χ2 = 3.892, p = 0.049), respectively. The 1- and 2-year overall survival rates (OS) of CRT and RT were 50.8% , 37.9% and 40.4% , 16.5% (χ2 = 1.811, p = 0.178), respectively. The major side effects were myelosuppression and digestive toxicities, but no differences were observed between the two groups.

CONCLUSION

Compared with radiotherapy alone, whole-brain irradiation plus 3-D conformal boost irradiation and concurrent topotecan chemotherapy significantly improved the PFS rate and the intracranial lesion control rate of patients with brain metastases from lung cancer, and no significant increases in side effects were observed. Based on these results, this treatment method is recommended for phase III clinical trial.

Overlapping functions of ABC transporters in topotecan disposition as determined in gene knockout mouse models

It is established that efflux transporters of the ATP-binding cassette (ABC) superfamily can affect the pharmacokinetics of drugs through mechanisms pertaining to drug absorption, elimination, and distribution. To characterize the role of multiple transporters in topotecan's pharmacokinetics, total (lactone+carboxylate) and lactone forms were measured by liquid chromatography/tandem mass spectrometry (LC/MS-MS) in plasma, bile, urine, and feces following intravenous administration at doses of 1 and 4 mg/kg to eight mouse strains: C57BL/6 [wild-type (WT)], Abcb1(-/-), Abcc2(-/-), Abcc4(-/-), Abcg2(-/-), Abcc2;Abcb1(-/-), Abcc2;Abcg2(-/-), and Abcc4;Abcg2(-/-). Compared with WT mice and at both dose levels, the plasma areas under the curve for topotecan lactone were not significantly different in the Abcc2(-/-), Abcc4(-/-), and Abcb1(-/-) strains, whereas significant differences were found in Abcg2(-/-), Abcc2;Abcb1(-/-) (only at the high dose), Abcc4;Abcg2(-/-), and Abcc2;Abcg2(-/-) mice and ranged from 2.1- to 3.3-fold higher. Consistent with these changes, the fecal and biliary excretion of topotecan was reduced, whereas renal elimination was elevated in Abcg2(-/-)-based strains. Similarly, the Abcc2;Abcb1(-/-) strain also had elevated renal elimination and reduced fecal excretion of topotecan lactone. This was more pronounced at the 4 mg/kg dose level, suggesting possible saturation of Abcg2. The Abcc4 transporter was found not to be a major determinant of topotecan pharmacokinetics. It is concluded that Abcg2 has the most significant effect on topotecan elimination, whereas both Abcb1 and Abcc2 have overlapping functions with Abcg2. As such it is relevant to examine how polymorphisms in these transporters influence topotecan activity in patients and whether coadministration of transport modulators could positively affect efficacy without increasing toxicity.

Innovative therapeutic strategies in the treatment of brain metastases

Brain metastases (BM) are the most common intracranial tumors and their incidence is increasing. Untreated brain metastases are associated with a poor prognosis and a poor performance status. Metastasis development involves the migration of a cancer cell from the bulk tumor into the surrounding tissue, extravasation from the blood into tissue elsewhere in the body, and formation of a secondary tumor. In the recent past, important results have been obtained in the management of patients affected by BM, using surgery, radiation therapy, or both. Conventional chemotherapies have generally produced disappointing results, possibly due to their limited ability to penetrate the blood-brain barrier. The advent of new technologies has led to the discovery of novel molecules and pathways that have better depicted the metastatic process. Targeted therapies such as bevacizumab, erlotinib, gefitinib, sunitinib and sorafenib, are all licensed and have demonstrated improved survival in patients with metastatic disease. In this review, we will report current data on targeted therapies. A brief review about brain metastatic process will be also presented.

Examination of blood-brain barrier (BBB) integrity in a mouse brain tumor model

The present study evaluates, both functionally and biochemically, brain tumor-induced alterations in brain capillary endothelial cells. Brain tumors were induced in Balb/c mice via intracranial injection of Lewis Lung carcinoma cells into the right hemisphere of the mouse brain using stereotaxic apparatus. Blood-brain barrier (BBB) permeability was assessed at various stages of tumor development, using both radiolabeled tracer permeability and magnetic resonance imaging with gadolinium diethylene-triamine-pentaacetate contrast enhancement (Gad-DTPA). The expression of the drug efflux transporter, P-glycoprotein (P-gp), in the BBB at various stages of tumor development was also evaluated by Western blot and immunohistochemistry. Median mouse survival following tumor cell injection was 17 days. The permeability of the BBB to (3)H-mannitol was similar in both brain hemispheres at 7 and 10 days post-injection. By day 15, there was a twofold increase in (3)H-mannitol permeability in the tumor bearing hemispheres compared to the non-tumor hemispheres. Examination of BBB permeability with Gad-DTPA contrast enhanced MRI indicated cerebral vascular permeability changes were confined to the tumor area. The permeability increase observed at the later stages of tumor development correlated with an increase in cerebral vascular volume suggesting angiogenesis within the tumor bearing hemisphere. Furthermore, the Gad-DPTA enhancement observed within the tumor area was significantly less than Gad-DPTA enhancement within the circumventricular organs not protected by the BBB. Expression of P-gp in both the tumor bearing and non-tumor bearing portions of the brain appeared similar at all time points examined. These studies suggest that although BBB integrity is altered within the tumor site at later stages of development, the BBB is still functional and limiting in terms of solute and drug permeability in and around the tumor.

CK2-mediated hyperphosphorylation of topoisomerase I targets serine 506, enhances topoisomerase I-DNA binding, and increases cellular camptothecin sensitivity

Topoisomerase I is the target for a potent class of chemotherapeutic drugs derived from the plant alkaloid camptothecin that includes irinotecan and topotecan. In this study we have identified a novel site of CK2-mediated topoisomerase I (topo I) phosphorylation at serine 506 (PS506) that is relevant to topo I function and to cellular responses to these topo I-targeted drugs. CK2 treatment induced hyperphosphorylation of recombinant topo I and expression of the PS506 epitope, and resulted in increased binding of topo I to supercoiled plasmid DNA. Hyperphosphorylated topo I was approximately three times more effective than the basal phosphorylated enzyme at relaxing plasmid supercoils but had similar DNA cleavage activity once bound to DNA. The PS506 epitope was expressed in cancer cell lines with elevated CK2 activity, hyperphosphorylated topo I, and increased sensitivity to camptothecin. In contrast, PS506 was not detected in normal cells or cancer cell lines with lower levels of CK2 activity. By experimentally manipulating CK2 activity in cancer cell lines, we demonstrate a cause and effect relationship between CK2 activity, PS506 expression, camptothecin-induced cellular DNA damage, and cellular camptothecin sensitivity. Our results show that the PS506 epitope is an indicator of dysregulated, hyperphosphorylated topo I in cancer cells, and may thus serve as a diagnostic or prognostic biomarker and predict tumor responsiveness to widely used topo I-targeted therapies.

Roles for endothelin receptor B and BCL2A1 in spontaneous CNS metastasis of melanoma

Metastatic spread of melanoma to the central nervous system (CNS) is a common and devastating manifestation of disease progression, which, despite its clinical importance, remains poorly understood with respect to underlying molecular mechanisms. Using a recently developed preclinical model of spontaneous melanoma CNS metastasis, we have identified alterations in expression of endothelin receptor B (EDNRB) as a potential factor that influences brain metastatic potential. Induced overexpression of this gene mediated enhanced overall metastatic disease, and resulted in an increased incidence of spontaneous CNS metastases. In contrast, the overexpression of other highlighted genes, such as BCL2A1, did not affect the incidence of CNS metastases but nevertheless appears to facilitate intracranial tumor growth. The prometastatic effect in the CNS associated with EDNRB appears to be mediated by the interaction with its ligands resulting in enhanced tumor cell proliferation and thus intracranial melanoma growth. That EDNRB contributes to melanoma metastasis is underscored by the fact that its therapeutic inhibition by the EDNRB-specific inhibitor A192621 translated into improved outcomes when treating mice with either visceral metastases or intracranial tumors. The identification of an influential role of EDNRB in CNS melanoma spontaneous metastasis may provide both a target for therapeutic intervention as well as a potential prognostic marker for patients having an increased predisposition for incidence of CNS melanoma metastases.

ACR Appropriateness Criteria® follow-up and retreatment of brain metastases

Multiple options for retreatment are available, which include whole-brain radiation therapy, stereotactic radiosurgery, surgery, chemotherapy, and supportive care. Size, number, timing, location, histology, performance status, and extracranial disease status all need to be carefully considered when choosing a treatment modality. There are no randomized trials examining the retreatment of brain metastases. Repeat whole-brain radiation has been examined in a single-institution experience, showing the potential for clinical responses in selected patients. Local control rates as high as 91% using stereotactic radiosurgery for relapses after whole-brain radiation are reported. Surgery can be indicated in progressive and/or hemorrhagic lesions causing mass effect. The role of chemotherapy in the recurrent setting is limited but some agents may have activity on the basis of experiences on a smaller scale. Supportive care continues to be an important option, especially in those with a poor prognosis. Follow-up for brain metastases patients is discussed, examining the modality, frequency of imaging, and imaging options in differentiating treatment effect from recurrence. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of the current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Brain metastasis in patients with uterine cervical cancer

AIM

The purpose of this study was to describe the features of patients with brain metastasis from cervical cancer.

MATERIAL AND METHODS

The medical records of patients with cervical cancer between February 2001 and June 2011 were reviewed retrospectively. Clinical characteristics, symptoms, treatment and survival in patients with brain metastasis were analyzed.

RESULTS

  Eleven patients with brain metastasis from cervical cancer were identified, representing an incidence of brain metastasis in the study population of 0.45%. Median patient age at initial diagnosis of cervical cancer was 50 years (range 33-75 years). Non-squamous cell carcinoma was diagnosed in six (54.5%) of the 11 patients, with small cell carcinoma diagnosed in two patients. Ten of the 11 patients had lung-related metastasis at presentation; eight patients had lung metastasis, one had mediastinal lymph node metastasis, and one had pleural metastasis. The median interval from diagnosis of cervical cancer to identification of brain metastasis was 15.4 months (range 3.4-83.3 months). Nine patients presented with neurologic symptoms, such as headache, nausea, vomiting, seizure and extremity weakness. Initially, six patients received whole brain radiotherapy: three patients received chemotherapy; one underwent surgery; and one patient refused treatment. The median survival time after diagnosis of the brain metastases was 5.9 months (range 0.7-19 months).

CONCLUSION

The prognosis after diagnosis of the brain metastasis in patients with uterine cervical cancer is poor. The small cell type and lung metastasis seem to be related with brain metastasis and may be regarded as risk factors.

Preclinical approaches to study the biology and treatment of brain metastases

Metastatic spread to the central nervous system (CNS) is a common and devastating manifestation of major cancer types. Its incidence is associated with poor prognosis manifested by neurological deterioration leading to diminished quality of life and an extremely short median survival. CNS metastasis is becoming an increasingly important clinical problem. This is especially the case for certain types of cancers for which effective treatments of visceral disease are available. As a result of the present limitations in treating CNS metastases, this manifestation of tumor progression remains an unmet clinical need. Despite its significance, our general understanding of the mechanisms that regulate the brain-metastatic phenotype is currently meager. Both the analysis of mechanistic aspects of brain metastasis and the development of effective treatments necessitate the use of appropriate in vivo models that recapitulate the interaction of the tumor cells with the microenvironment of the brain. Here we review the available preclinical models of CNS metastasis and their use as tools to advance knowledge of the biology of the disease (with the aim of identifying relevant molecular determinants, prognostic biomarkers, and therapeutic targets) as well as examining effective approaches for treatment.

Topotecan and ifosfamide systemic chemotherapy for CNS involvement of solid tumors

The prognosis of patients with CNS involvement of solid tumors is poor. In these patients, systemic chemotherapy has a theoretical advantage of concurrent treatment of systemic disease and reduced risk of neurotoxicity. Here, we report on the efficacy and toxicity of topotecan/ifosfamide (TOPO/IFO) combination chemotherapy in patients treated for CNS involvement of different solid malignancies. Fourteen patients with CNS manifestations (seven with brain metastases, two meningeal carcinomatosis, and five both) of solid tumors (seven with breast cancer, six lung cancer, and one unknown primary cancer) received TOPO/IFO treatment. Eleven patients each were pretreated with 1-6 systemic therapy regimens and whole-brain irradiation. Patients received a total of 34 (median 2) TOPO/IFO cycles. TOPO dosage was 3.6 mg/m(2) (1.2 mg/m(2), days 1-3) and IFO dosage 3,000 mg/m(2) (1,500 mg/m(2), days 1-2) per cycle. Of 12 patients with brain metastases, one patient had partial remission, three stable disease, two progressed, and six had no radiologic CNS response evaluation. Response of meningeal carcinomatosis was found in two and progressive disease in two (three patients not evaluated). Neurologic improvement or stabilization was observed in six of twelve evaluable patients. No systemic tumor response was seen in seven evaluated patients. Grade 3/4 toxicities in eleven evaluable patients were leukopenia (n = 9), infection (n = 6), and thrombopenia (n = 5). Median time to treatment failure was 43 days and median overall survival 107 days. Symptom control was frequently achieved with TOPO/IFO systemic chemotherapy despite a low objective response rate. The feasibility of this treatment is impaired by severe hematotoxicity.

Dose-dense temozolomide regimen for the treatment of brain metastases from melanoma, breast cancer, or lung cancer not amenable to surgery or radiosurgery: a multicenter phase II study

BACKGROUND

Brain metastases reduce survival because therapeutic options are limited. This phase II study evaluated the efficacy of single-agent therapy with alternating weekly, dose-dense temozolomide in pretreated patients with brain metastases prospectively stratified by primary tumor type.

METHODS

Eligible patients had bidimensionally measurable brain metastases from histologically/cytologically confirmed melanoma, breast cancer (BC), or non-small-cell lung cancer (NSCLC). Prior chemotherapy, radiotherapy, and whole-brain radiotherapy (WBRT) were allowed. Patients received temozolomide 150 mg/m(2)/day (days 1-7 and 15-21 every 28- or 35-day cycle).

RESULTS

In the intent-to-treat population (N = 157; 53 melanoma, 51 BC, and 53 NSCLC), one patient had complete response, nine (6%) had partial responses, and 31 (20%) had stable disease in the brain. Median progression-free survival was 56, 58, and 66 days for melanoma, BC, and NSCLC, respectively. Median overall survival was 100 days for melanoma, 172 days for NSCLC, and not evaluable in the BC group. Thrombocytopenia was the most common adverse event causing dose modification or treatment discontinuation. Grade 4 toxic effects were rare.

CONCLUSIONS

This alternating weekly, dose-dense temozolomide regimen was well tolerated and clinically active in heavily pretreated patients with brain metastases, particularly in patients with melanoma. Combining temozolomide with WBRT or other agents may improve clinical outcomes.

Antimetastatic activity of MONCPT in preclinical melanoma mice model

Previous study demonstrated that MONCPT, a topoisomerase I inhibitor, exhibited potent anti-proliferation and anti-angiogenesis activity in vitro and in vivo. In this study, we report the efficacy of MONCPT against the development of melanoma metastasis by an intravenous injection of green fluorescent protein-transfected mice melanoma carcinoma (B16F10-GFP) cells in C57BL/6 mice. MONCPT (2.0, 5.0 and 12.5 mg/kg/2 days) markedly decreased B16F10-GFP pulmonary metastases by 12.8%, 53.1% and 76.3%, respectively; whereas higher doses of MONCPT (31.0 mg/kg/2 days) significantly inhibited the tumor growth of B16F10 xenograft model. In the in vitro experiment, MONCPT suppressed the B16F10-GFP cell invasion and migration without affecting cell survival. Further studies demonstrated that MONCPT decreased the secretion of matrix metalloproteinase (MMP)-9 and VEGF, and reduced the protein expression of HIF-1α as well as the phosphorylation level of ERK in B16F10-GFP cells. These in vivo and in vitro results indicate that MONCPT possesses both the potent antimetastatic ability and the tumor growth-inhibition activity, and the dual function promises MONCPT as a potential therapeutic agent for tumor metastasis and tumor growth of melanoma carcinoma.

Reirradiation of multiple brain metastases with helical tomotherapy. A multifocal simultaneous integrated boost for eight or more lesions

BACKGROUND AND PURPOSE

: Recurrent brain metastases or new brain lesions after whole-brain radiotherapy represent a therapeutic challenge. While several treatment methods for single or few lesions have been described, options for multiple lesions are limited. This case report is intended to show an approach of whole-brain reirradiation with a simultaneous multifocal integrated boost using helical tomotherapy. Technique, feasibility, and acute side effects are presented.

PATIENTS AND METHODS

: Two patients with multiple relapsed brain metastases (eight and eleven lesions) were reirradiated after previous whole-brain radiotherapy (total dose of 40 Gy 18 months before). Whole-brain reirradiation was performed using helical tomotherapy with a total dose of 15 Gy (single dose 1.5 Gy) and a multifocal simultaneous integrated boost with a total dose of 30 Gy (single dose 3 Gy) to the brain lesions. The boost planning target volume was delineated around the lesions visible on MRI plus a 2-mm margin. Follow-up of these patients was 6 and 12 months.

RESULTS

: Radiation plans with excellent conformity and homogeneity were obtained. High dose exposure to normal brain tissue was kept minimal. Mean radiation time was 13 min. The only acute side effect observed was a mild headache over 2 days at the end of treatment. So far, no further side effects and no signs of recurrence have been observed.

CONCLUSION

: Helical tomotherapy offers new treatment options for the reirradiation of multiple brain metastases. The number of cases treated with the described protocol is very limited but it is considered a promising option for patients that have responded well to the initial radiotherapy and are in a good performance status.

A phase III trial of topotecan and whole brain radiation therapy for patients with CNS-metastases due to lung cancer

Brain metastases represent an important cause of morbidity in patients with lung cancer and are associated with a mean survival of less than 6 months. Thus, new regimens improving the outcome of these patients are urgently needed. On the basis of promising data raised in a phase I/II trial, we initiated an open, randomised, prospective, multicentric phase III trial, comparing whole brain radiation therapy (WBRT; 20 × 2 Gy) alone with WBRT+topotecan (RCT; 0.4 mg m⁻² day⁻¹ × 20). A total of 320 patients with CNS-metastases due to SCLC or NSCLC were projected. The primary end point was overall survival, whereas second end points were local response and progression-free survival. However, until the cutoff date of study completion (i.e., a study duration of 34 months), only a total of 96 (RCT:47, WBRT:49) patients had been recruited, and so an analysis was performed at that time point. Although the numbers of grade 3/4 non-haematological toxicities (besides alopecia 115 (RCT/WBRT: 55 out of 60) were evenly distributed, the 25 haematological events occurred mainly in the combined treatment arm (24 out of 1). Local response, evaluated 2 weeks after treatment, was assessable in 44 (RCT/WBRT: 23 out of 21) patients, showing CR in eight (3 out of 5), PR in 17 (11 out of 6), SD in 14 (8 out of 6) and PD in five (1 out of 4) patients (all differences n.s.). Neither OAS (RCT/WBRT: median (days)): 87 out of 95, range 3–752/4–433; HR 1.32; 95% CI (0.83; 2.10)) nor PFS (median (days)): 71 out of 66, range, 3–399/4–228; HR 1.28, 95% CI (0.73; 2.43) differed significantly. On the basis of these results and the slow recruitment, a continuation of the study did not seem reasonable. The available data show no significant advantage for concurrent radiochemotherapy for patients with lung cancer; however, the recruited number of patients is too low to exhibit a small advantage of combined treatment.

Glutamate regulates the activity of topoisomerase I in mouse cerebellum

Topoisomerase I (topo I) is a nuclear enzyme which participates in most DNA transactions. It was shown to be inhibited in depolarized neurons by poly adenosine diphosphate (ADP)-ribosylation of the enzyme protein. We demonstrated previously an age and sex dependent topo I activity and enzyme protein level in the various regions of mouse brain. A specific distribution pattern of topo I was observed and the inhibitory neurons exhibited the highest enzyme activity and protein level in both the nucleus and the cytoplasm. Here, we show that neurotransmitters (glutamate and gamma-aminobutyric acid (GABA)) regulate the activity of topo I in mouse cerebellum sections. Glutamate exhibited a significant time-dependent inhibition of topo I activity but no effect of the enzyme protein level. GABA in contrary only slightly and transiently inhibited topo I activity. The inhibitory effect of glutamate was mediated by Ca(+2) and by ADP-ribosylation of topo I protein and the glutamate ionotropic receptors were involved. Glutamate also diminished the inhibitory effect of topotecan on topo I. These results point to distinct and highly specific effects of the major neurotransmitters on topo I activity in the cerebellum suggesting that topo I possesses a specific role in the brain which differs from its known biological functions.

P-glycoprotein and breast cancer resistance protein: two dominant transporters working together in limiting the brain penetration of topotecan

PURPOSE

The brain is a pharmacologic sanctuary site, due to the presence of the blood-brain barrier (BBB). Whereas the effect of P-glycoprotein (P-gp) at the BBB is well established, the role of breast cancer resistance protein (BCRP) that is also expressed at the BBB is not.

EXPERIMENTAL DESIGN

We have studied the effect of BCRP by administering topotecan to wild-type (WT), single Mdr1a/b(-/-) and Bcrp1(-/-), and compound Mdr1a/b(-/-)Bcrp1(-/-) knockout mice. Drug levels in plasma and tissues were determined by high-performance liquid chromatography.

RESULTS

The area under the plasma and tissue concentration-time curve (AUC) of topotecan in brains of Mdr1a/b(-/-) and Bcrp1(-/-) mice was only 1.5-fold higher compared with WT mice, but in Mdr1a/b(-/-)Bcrp1(-/-) mice, where both transporters are absent, the AUC increased by 12-fold. The AUC in plasma was approximately 0.75-, 2.4-, and 3.7-fold higher in Mdr1a/b(-/-), Bcrp1(-/-), and Mdr1a/b(-/-)Bcrp1(-/-) mice, respectively, resulting in 2.0-fold (P < 0.01), 0.65-fold (P, not significant), and 3.2-fold (P < 0.01), respectively, higher brain-to-plasma AUC ratios. Results using Mrp4(-/-) mice showed that this transporter had no effect on the brain penetration of topotecan. The P-gp/BCRP inhibitor elacridar fully inhibited P-gp-mediated transport of topotecan, whereas inhibition of Bcrp1-mediated transport by elacridar was minimal.

CONCLUSIONS

Our results using Mdr1a/b(-/-)Bcrp1(-/-) mice clearly show the effect of Bcrp1 at the BBB and also show how two drug transporters act in concert to limit the brain penetration of topotecan. We expect that this finding will also apply to other drugs that are substrates of both P-gp and BCRP. Consequently, to improve the brain penetration of such compounds for targeting intracranial malignancies in patients, it will be essential to use potent inhibitors of both drug transporters.

[Small cell lung cancer--state of the art and future perspectives]

Lung cancer is the leading cause of cancer-related death in Portugal. Almost 3500 Portuguese are expected to be diagnosed with lung cancer in 2006; approximately 20% will have small cell lung cancer (SCLC). At presentation, 25% to 30% of patients will have local or regional disease, classified as limited stage disease. The concurrent chemovalidation therapy is the best choice. Once daily thoracic radiation therapy to doses in the range of 50 Gy to 60 Gy would reflect an accepted standard of care in daily practice. Because of the increase toxicity associated with hyper fractionated radiation, this approach is often limited to select patients. Etoposide plus cisplatin are synergistic, well tolerated and result in equal or superior survival compared with other regimens. This is the standard regimen for concomitant therapy in limited stage and for extensive disease SCLC. Despite good chemo sensitivity and radio sensitivity, the prognosis of SCLC is very poor because of the early development of resistance and the associated high tendency to recurrence, making second line treatment of SCLC a problem of real medical relevance. Topotecan now offers an effective and well tolerated monosubstance for second line therapy of recurrent SCLC. There has been a significant increase in median survival for patients with SCLC receiving topotecan plus symptomatic therapy versus symptomatic therapy. The efficacy of this drug is comparable to the efficacy of the three-drug combination CAV. The tolerability can be improved by means of toxicity-adapted dosing. In elderly and in patients with performance status 2, topotecan is also well tolerated and has good efficacy. Initial studies into weekly administration also demonstrate good efficacy. The combination of topotecan with cranial radiotherapy is well tolerated and effective in the treatment of cerebral metastases of SCLC. New classes of agents, such as antiangiogenic agents including bevacizumab, small molecule tyrosine kinase inhibitors and thalidomide are being evaluated with chemotherapy for patients with extensive stage SCLC.

Topotecan as salvage therapy for relapsed or refractory primary central nervous system lymphoma

Treatment for patients with refractory or relapsed primary CNS lymphoma (PCNSL) remains unsatisfactory. Topotecan is an intravenous topoisomerase I inhibitor with good CSF penetration and documented efficacy in patients with relapsed systemic non-Hodgkin's lymphoma. In this study 15 patients with refractory or relapsed PCNSL were treated with intravenous topotecan (1.5 mg/m(2)) for five consecutive days during each 21-day cycle. All 15 patients had measurable, contrast-enhancing tumor on cranial MRI at the time of relapse. Three (20%) patients achieved a complete response after one, three and four cycles, respectively, while three (20%) patients achieved a partial response after two cycles each, for a total response proportion of 40%. Three patients had stable disease at the end of topotecan treatment. Six patients (40%) had progressive disease during treatment. Median overall survival was 981 days (95% CI: 275, NA) and median progression free survival was 60 days (95% CI: 46, 945). Three out of 15 patients had grade 3 thrombocytopenia. Six out of 15 patients had grade 3 neutropenia, while 5/15 patients had grade 4 neutropenia, and 13/15 patients received g-CSF at some point during treatment. There were no deaths directly related to treatment toxicity. Our study shows that topotecan, as a salvage therapy in patients with relapsed or refractory PCNSL, is associated with an overall response proportion of 40% and should be considered in patients who have failed prior methotrexate-based chemotherapy and/or whole brain irradiation. However, progression is frequent and early and most patients required growth factor support due to myelotoxicity.

Chemical radiosensitizers for use in radiotherapy

Radiosensitizers are intended to enhance tumour cell killing while having much less effect on normal tissues. Some drugs target different physiological characteristics of the tumour, particularly hypoxia associated with radioresistance. Oxygen is the definitive hypoxic cell radiosensitizer, the large differential radiosensitivity of oxic vs hypoxic cells being an attractive factor. The combination of nicotinamide to reduce acute hypoxia with normobaric carbogen breathing is showing clinical promise. 'Electron-affinic' chemicals that react with DNA free radicals have the potential for universal activity to combat hypoxia-associated radioresistance; a nitroimidazole, nimorazole, is clinically effective at tolerable doses. Hypoxia-specific cytotoxins, such as tirapazamine, are valuable adjuncts to radiotherapy. Nitric oxide is a potent hypoxic cell radiosensitizer; variations in endogenous levels might have prognostic significance, and routes to deliver nitric oxide specifically to tumours are being developed. In principle, many drugs can be delivered selectively to hypoxic tumours using either reductase enzymes or radiation-produced free radicals to activate drug release from electron-affinic prodrugs. A redox-active agent based on a gadolinium chelate is being evaluated clinically. Pyrimidines substituted with bromine or iodine are incorporated into DNA and enhance free radical damage; fluoropyrimidines act by different mechanisms. A wide variety of drugs that influence the nature or repair of DNA damage are being evaluated in conjunction with radiation; it is often difficult to define the mechanisms underlying chemoradiation regimens. Drugs being evaluated include topoisomerase inhibitors (e.g. camptothecin, topotecan), and the hypoxia-activated anthraquinone AQ4N; alkylating agents include temozolomide. Drugs involved in DNA repair pathways being investigated include the potent poly(ADP ribose)polymerase inhibitor, AG14,361. Proteins involved in cell signalling, such as the Ras family, are attractive targets linked to radioresistance, as are epidermal growth factor receptors and linked kinases (drugs including vandetanib [ZD6,474], cetuximab and gefitinib), and cyclooxygenase-2 (celecoxib). The suppression of radioprotective thiols seems to offer more potential with alkylating agents than with radiotherapy, although it remains a strategy worthy of exploration.

A phase I/II trial of topotecan and radiation therapy for brain metastases in patients with solid tumors

PURPOSE

Outcomes in patients with brain metastases undergoing whole-brain radiotherapy (WBRT) are hardly encouraging, and an improvement in results is therefore needed. One possible approach is the addition of chemotherapeutics. However the data presented thus far are also disappointing. A promising substance in this setting could become topotecan, which is known to cross the blood-brain barrier and additionally offers radiosensitizing effects. Therefore we performed a phase I/II trial to evaluate the feasibility of a concurrent radiochemotherapy regimen.

METHODS AND MATERIALS

From January 1999 to July 2001, a total of 75 patients (10 in phase I and 65 in phase II) were included. The WBRT was applied with a fraction size of 2 Gy/day for a total of 40 Gy. Topotecan was administered as a 30-min infusion with 0.2 to 0.5 mg/m(2)/day for 5 days over 4 weeks within 2 h to radiation therapy.

RESULTS

Because of the higher toxic rates seen in patients receiving 0.5 mg/m(2)/day, the recommended dosage for phase II was 0.4 mg/m(2)/day. In this group Grade 3/4 hematologic and nonhematologic side effects occurred in 19% and 21% of the patients, respectively. The overall response rate was 72% with an overall survival of 17 weeks and 30 weeks among the responders.

CONCLUSIONS

Based on the moderate toxicity profile presented here we recommend to perform a phase III trial to confirm the promising phase I/II data.

Brain metastasis from cervical carcinoma

The aim of this study was to describe the features of patients with brain metastasis from cervical cancer. Twelve patients with brain metastasis from cervical cancer were identified. Information regarding symptoms, treatment, and survival was analyzed. The incidence of brain metastasis in our population was 0.77%. Median patient age at initial diagnosis of cervical cancer was 43.5 years (range 29-57 years) compared with 44.5 years (range 31-58 years) at identification of brain metastasis. Six patients had FIGO stage IB disease; three had stage IIB disease; and one each had stage IIIA, IIIB, and IVB disease. The median interval from diagnosis of cervical cancer to identification of brain metastasis was 17.5 months (range 1.1-96.1 months). All but one patient presented with neurologic symptoms. Eight patients received whole-brain irradiation and steroids, three received steroids alone, and one underwent surgery, followed by irradiation. All the patients who received whole-brain irradiation experienced improvement in their symptoms. Median survival from diagnosis of brain metastasis to death was 2.3 months (range 0.3-7.9 months). Five patients who received chemotherapy after brain irradiation had a median survival of 4.4 months compared to 0.9 months for those who received no additional treatment after brain irradiation (P= .016). Most patients with brain metastasis from cervical cancer presented with neurologic sequelae. Brain irradiation improved these symptoms. Survival after diagnosis of brain metastasis was poor; however, patients who received chemotherapy after brain irradiation appeared to have improved survival.