The effects of new life-prolonging drugs for metastatic castration-resistant prostate cancer (mCRPC) patients in a real-world population.

BACKGROUND: In 2004 docetaxel was the first life-prolonging drug (LPD) registered for metastatic castration-resistant prostate cancer (mCRPC) patients. Between 2011 and 2014 new LPDs for mCRPC (cabazitaxel, abiraterone, enzalutamide, and radium-223) were introduced in the Netherlands. The objective of this study is to assess the impact of the introduction of new LPDs on treatment patterns and overall survival (OS) over time. PATIENTS AND METHODS: CRPC patients diagnosed in the years 2010-2016 in the observational, retrospective CAPRI registry (20 hospitals) were included and followed up to 2018. Two subgroups were analyzed: treatment-naïve patients (subgroup 1, n = 3600) and post-docetaxel patients (subgroup 2, n = 1355). RESULTS: In both subgroups, the use of any LPD increased: from 57% (2010-2011) to 69% (2014-2015) in subgroup 1 and from 65% (2011-2012) to 79% (2015-2016) in subgroup 2. Chemotherapy as first mCRPC-treatment (i.e., docetaxel) and first post-docetaxel treatment (i.e., cabazitaxel or docetaxel rechallenge) decreased (46-29% and 20-9% in subgroup 1 and 2, respectively), while the use of androgen-receptor targeting treatments (ART) increased from 11% to 39% and 46% to 64% in subgroup 1 and 2, respectively. In subgroup 1, median OS (mOS) from diagnosis CRPC increased from 28.5 months to 31.0 months (p = 0.196). In subgroup 2, mOS from progression on docetaxel increased from 7.9 months to 12.5 months (p < 0.001). After multiple imputations of missing values, in multivariable cox-regression analysis with known prognostic parameters, the treatment period was independent significant for OS in subgroup 1 (2014-2015 vs. 2010-2011 with HR 0.749, p < 0.001) and subgroup 2 (2015-2016 vs. 2011-2012 with HR 0.811, p = 0.037). CONCLUSION: Since 2010, a larger proportion of mCRPC patients was treated with LPDs, which was related to an increased mOS.

Advances in targeted alpha therapy for prostate cancer.

Amongst therapeutic radiopharmaceuticals, targeted alpha therapy (TαT) can deliver potent and local radiation selectively to cancer cells as well as the tumor microenvironment and thereby control cancer while minimizing toxicity. In this review, we discuss the history, progress, and future potential of TαT in the treatment of prostate cancer, including dosimetry-individualized treatment planning, combinations with small-molecule therapies, and conjugation to molecules directed against antigens expressed by prostate cancer cells, such as prostate-specific membrane antigen (PSMA) or components of the tumor microenvironment. A clinical proof of concept that TαT is efficacious in treating bone-metastatic castration-resistant prostate cancer has been demonstrated by radium-223 via improved overall survival and long-term safety/tolerability in the phase III ALSYMPCA trial. Dosimetry calculation and pharmacokinetic measurements of TαT provide the potential for optimization and individualized treatment planning for a precision medicine-based cancer management paradigm. The ability to combine TαTs with other agents, including chemotherapy, androgen receptor-targeting agents, DNA repair inhibitors, and immuno-oncology agents, is under investigation. Currently, TαTs that specifically target prostate cancer cells expressing PSMA represents a promising therapeutic approach. Both PSMA-targeted actinium-225 and thorium-227 conjugates are under investigation. The described clinical benefit, safety and tolerability of radium-223 and the recent progress in TαT trial development suggest that TαT occupies an important new role in prostate cancer treatment. Ongoing studies with newer dosimetry methods, PSMA targeting, and novel approaches to combination therapies should expand the utility of TαT in prostate cancer treatment.

Randomized phase III KEYNOTE-045 trial of pembrolizumab versus paclitaxel, docetaxel, or vinflunine in recurrent advanced urothelial cancer: results of >2 years of follow-up.

BACKGROUND: Novel second-line treatments are needed for patients with advanced urothelial cancer (UC). Interim analysis of the phase III KEYNOTE-045 study showed a superior overall survival (OS) benefit of pembrolizumab, a programmed death 1 inhibitor, versus chemotherapy in patients with advanced UC that progressed on platinum-based chemotherapy. Here we report the long-term safety and efficacy outcomes of KEYNOTE-045. PATIENTS AND METHODS: Adult patients with histologically/cytologically confirmed UC whose disease progressed after first-line, platinum-containing chemotherapy were enrolled. Patients were randomly assigned 1 : 1 to receive pembrolizumab [200 mg every 3 weeks (Q3W)] or investigator's choice of paclitaxel (175 mg/m2 Q3W), docetaxel (75 mg/m2 Q3W), or vinflunine (320 mg/m2 Q3W). Primary end points were OS and progression-free survival (PFS) per Response Evaluation Criteria in Solid Tumors, version 1.1 (RECIST v1.1) by blinded independent central radiology review (BICR). A key secondary end point was objective response rate per RECIST v1.1 by BICR. RESULTS: A total of 542 patients were enrolled (pembrolizumab, n = 270; chemotherapy, n = 272). Median follow-up as of 26 October 2017 was 27.7 months. Median 1- and 2-year OS rates were higher with pembrolizumab (44.2% and 26.9%, respectively) than chemotherapy (29.8% and 14.3%, respectively). PFS rates did not differ between treatment arms; however, 1- and 2-year PFS rates were higher with pembrolizumab. The objective response rate was also higher with pembrolizumab (21.1% versus 11.0%). Median duration of response to pembrolizumab was not reached (range 1.6+ to 30.0+ months) versus chemotherapy (4.4 months; range 1.4+ to 29.9+ months). Pembrolizumab had lower rates of any grade (62.0% versus 90.6%) and grade ≥3 (16.5% versus 50.2%) treatment-related adverse events than chemotherapy. CONCLUSIONS: Long-term results (>2 years' follow-up) were consistent with those of previously reported analyses, demonstrating continued clinical benefit of pembrolizumab over chemotherapy for efficacy and safety for treatment of locally advanced/metastatic, platinum-refractory UC. TRIAL REGISTRATION: ClinicalTrials.gov: NCT02256436.

Health-related quality of life analysis in stage III melanoma patients treated with adjuvant dendritic cell therapy.

BACKGROUND: Health-related quality of life (HRQoL) is an important issue in the rapidly evolving field of adjuvant treatment for stage III melanoma. Dendritic cell vaccination is one of the adjuvant forms of therapy currently investigated. METHODS: We enrolled adults with stage III melanoma to receive adjuvant dendritic cell vaccination after a complete radical lymph node dissection. HRQoL assessment was one of the secondary endpoints of this trial and investigated with the EORTC-QLQ-C30 questionnaire at baseline and week 26. RESULTS: Fifteen patients with a median age of 50 years were included in the study, with twelve evaluable patients on study at time of the second questionnaire. Global health status and role functioning improved clinically relevant with a mean difference of 15 (p = 0.010) and 26 points (p = 0.005), respectively. DISCUSSION: Despite the small number of patients, we found a clinically relevant improved global health status. Besides, compared to the other investigated therapies, toxicity of dendritic cell vaccination is low, which supports our finding. CONCLUSION: This is the first description of HRQoL in melanoma patients receiving dendritic cell vaccination. We show the expected improvement in global health status after surgical treatment of stage III melanoma. Thus, adjuvant dendritic cell vaccination does not seem to hamper this improvement, as shown in our small explorative study.

Review: Effectiveness of implementation strategies to increase physical activity uptake during and after cancer treatment.

BACKGROUND: The purpose of this review was to assess the effectiveness of different strategies to implement physical activity during and after cancer treatment. DESIGN: We searched for studies containing strategies to implement physical activity in cancer care that meet the inclusion criteria of the Cochrane EPOC group. The primary outcome was physical activity uptake. We expressed the effectiveness of the strategies as the percentage of studies with improvement. RESULTS: Nine studies met the inclusion criteria. Patient groups doing physical activities via an implementation strategy had better outcomes than those receiving usual care: 83% of the studies showed improvement. Strategies showing significant improvement compared to usual care employed healthcare professionals to provide individual counselling or advice for exercise or interactive elements such as audit and feedback systems. When comparing the different strategies 1) interactive elements or 2) elements tailored to the needs of the patients had better physical activity uptake. CONCLUSIONS: Implementation strategies containing individual and interactive elements, tailored to the individual needs of patients, are more successful in improving physical activity uptake.

Heat shock protein expression in cerebral X-linked adrenoleukodystrophy reveals astrocyte stress prior to myelin loss.

AIMS: X-linked adrenoleukodystrophy (X-ALD) is a genetic white matter disorder in which demyelination occurs due to accumulation of very long-chain fatty acids. Inflammation in the brain white matter is a hallmark of the pathology of cerebral X-ALD, but the underlying pathogenic mechanisms are still largely unknown. In other inflammatory demyelinating disorders, such as multiple sclerosis, the expression of heat shock proteins (HSPs) in combination with interferon-γ (IFN-γ) has been suggested to play a prominent role in the initiation of demyelination and inflammation. We therefore investigated these pathways in X-ALD lesions. METHODS: By immunohistochemistry, we examined the expression of small HSPs (HSPB1, HSPB5, HSPB6, HSPB8) and higher molecular weight HSPs (HSPA, HSPD1), and the expression of elements of the IFN-γ pathway on autopsy material of five patients with X-ALD. RESULTS: The expression of the larger HSPs, HSPA and HSPD1, as well as small HSPs is increased in X-ALD lesions compared with normal-appearing white matter. Such upregulation can already be detected before demyelination and inflammation occur, and it is predominant in astrocytes. The IFN-γ pathway does not seem to play a leading role in the observed inflammation. CONCLUSIONS: The finding that astrocytes show signs of cellular stress before demyelination suggests that they play a major role early in the pathogenesis of cerebral X-ALD, and may therefore be involved in the initiation of inflammation and demyelination.

Metastatic castration-resistant prostate cancer: new therapies, novel combination strategies and implications for immunotherapy.

For the past decade, docetaxel has remained the global standard of care for frontline treatment of metastatic castration-resistant prostate cancer (mCRPC). Until recently, there were limited options for patients with mCRPC following docetaxel failure or resistance, but now the approved treatment choices for these patients have expanded to include abiraterone acetate, cabazitaxel and enzalutamide. Additionally, the radioactive therapeutic agent radium-223 dichloride has been recently approved in patients with CRPC with bone metastases. Although each of these agents has been shown to convey significant survival benefit as a monotherapy, preclinical findings suggest that combining such innovative strategies with traditional treatments may achieve additive or synergistic effects, further augmenting patient benefit. This review will discuss the transformation of the post-docetaxel space in mCRPC, highlighting the spectrum of newly approved agents in this setting in the USA and the European Union, as well as summarizing treatments with non-chemotherapeutic mechanisms of action that have demonstrated promising results in recent phase 3 trials. Lastly, this review will address the potential of combinatorial regimens in mCRPC, including the pairing of novel immunotherapeutic approaches with chemotherapy, radiotherapy or androgen ablation.

The evolving role of immunotherapy in prostate cancer.

The prognosis for men with metastatic, castration-resistant prostate cancer (CRPC) is limited, and patients have very few treatment options, particularly if the treatment failed with docetaxel (Taxotere). As a result, there is a requirement for novel approaches to therapy. Using immunotherapy to induce immune responses to prostate cancer in preclinical and clinical studies appears to be a valid therapeutic approach. In a pivotal phase III trial, treatment with sipuleucel-T, an autologous cellular vaccine consisting of activated antigen-presenting cells loaded with prostatic acid phosphatase (PAP), gave a median overall survival of 25.8 months compared with 21.7 months for placebo-treated patients, resulting in a 22% relative reduction in the risk of death. Based on these results, sipuleucel-T became the first therapeutic vaccine approved for any type of cancer in the USA. PROSTVAC(®)-VF, a poxvirus-based vaccine engineered to present prostate-specific antigen (PSA) and three immune costimulatory molecules, and GVAX, a vaccine consisting of two prostate cancer cell lines (LnCAP and PC3) and genetically modified to secrete granulocyte-macrophage colony-stimulating factor (GM-CSF), both showed promising results in phase II studies, although GVAX failed to meet its primary end point of overall survival when compared with docetaxel in a phase III study. T-cell modulation is another potential immunotherapeutic strategy for CRPC. Ipilimumab, an antibody against the cytotoxic T-lymphocyte-associated antigen-4, is being evaluated in phase I/II studies, both alone and in combination with chemotherapy, radiotherapy or GVAX, with activity in prostate cancer. CRPC is one of the few tumour types where immunotherapy is the current standard of care. Further research, however, will be necessary to improve antitumour responses and clinical benefits, including the use of novel combinatorial approaches.

Randomised phase II/III study of docetaxel with or without risedronate in patients with metastatic Castration Resistant Prostate Cancer (CRPC), the Netherlands Prostate Study (NePro).

BACKGROUND: This multicentre, randomised, open label, phase II/III study aimed to investigate the potential benefit of adding risedronate (R) to docetaxel (D) in patients with metastatic Castration Resistant Prostate Cancer (CRPC). PATIENTS AND METHODS: CRPC patients with bone metastasis were randomly assigned to receive D 75 mg/m(2) every 3 weeks and prednisone as first line chemotherapy, with or without R 30 mg oral once daily. The primary end-point was time to progression (TTP). A composite end-point of objective progression by RECIST criteria, PSA progression, or pain progression, whichever occurred first, was applied. The study had 80% power to detect an improvement of 30% in median TTP in the DR group (two-sided α=0.05). RESULTS: Five hundred and ninety-two men (301 D versus 291 DR) were randomised. TTP was 7.4 [D] versus 6.5 [DR] months (p=0.75). PSA and pain response rates were similar, 66.3% [D] versus 65.9% [DR] and 27.9% [D] versus 31.2% [DR], respectively. Median overall survival (OS) was 18.4 [D] versus 19.2 [DR] months (p=0.33). There were no differences in toxicity. CONCLUSION: The addition of the third generation bisphosphonate, risedronate, in the setting of effective first line docetaxel based chemotherapy did not increase efficacy, as indicated by the lack of improvement in TTP, OS, PSA- and pain response.

CA 15-3 as an alternative marker for KL-6 in fibrotic lung diseases.

BACKGROUND: KL-6 is a mucin that is increased in interstitial lung diseases (ILD), and in some malignancies. CA 15-3, a tumor marker for breast cancer, refers to the same mucin but utilizes antibodies against different epitopes. OBJECTIVE: The aim of our study was to evaluate CA 15-3 as a viable alternative to KL-6 as a for ILDs with and without fibrosis. DESIGN: Serum from 242 patients with ILDs and from 327 healthy controls were included and KL-6 and CA 15-3 were measured in all subjects. Regression analyses and ROC curves were used to compare the performances of both markers. RESULTS: KL-6 and CA 15-3 levels were both significantly higher in the ILD patients compared to the controls (p < 0.0001). A weak yet significant correlation was found between serum KL-6 and CA 15-3 levels in the controls (R = 0.39, p < 0.0001), but showed a much higher correlation in the patient group (R = 0.85, p < 0.0001). CA 15-3 correlated best with KL-6 in patients with fibrotic ILDs (R = 0.83, p < 0.0001). KL-6 performed better as a marker compared to CA 15-3 in most ILDs. Both markers performed best in identifying idiopathic pulmonary fibrosis (IPF) and were equally able to differentiate between ILDs with and without fibrosis: (sensitivity and specificity %): 100/97, 95/92, and 90/72, respectively. CONCLUSION: CA 15-3 and KL-6 are equally sensitive and specific in terms of differentiating between ILDs with and without fibrosis. The wide availability, ease of use, and cost effectiveness, make CA 15-3 a viable alternative for KL-6 as a possible marker for pulmonary fibrosis.

Measurements of cerebrospinal fluid concentrations of S100beta protein during and after thoracic endovascular stent grafting.

OBJECTIVES: Thoracic endovascular aortic repair is associated with postoperative spinal cord ischemia in approximately 1 to 12.5% of all cases. S100beta is a protein that is released during acute damage of the central nervous system. This study was performed to determine the concentration of S100beta in cerebrospinal fluid during and after stenting of the thoracic aorta in patients at high risk for spinal cord ischemia. DESIGN: Prospective clinical study. MATERIALS AND METHODS: Eight patients who underwent elective thoracic aortic stent grafting underwent lumbar spinal fluid drainage. These patients were at high risk to develop spinal cord ischemia. METHODS: CSF samples for analysis of S100beta protein were drawn after induction of anesthesia, during stenting, once every hour the following six hours and 20 hours after repair. RESULTS: No significant increase in S100beta protein could be detected in CSF and no neurological deficits were detected postoperatively. CONCLUSIONS: The results of this study show us that there is no significant release of S100beta protein in CSF during stenting of the thoracic aorta in this subgroup of patients at high risk for spinal cord ischemia, consistent with clinical exam that there was no significant damage to the central nervous system.

Explorative immunohistochemical study to evaluate the addition of a topical corticosteroid in the early phase of alefacept treatment for psoriasis.

The aim of this study was to explore the additional effect of betamethasone dipropionate cream in the early phase of an intramuscular (IM) alefacept course, on plaque severity and on modulating T-cell subsets, cells expressing NK-receptors, epidermal proliferation and keratinocyte differentiation in lesional psoriatic skin. Therefore, sixteen patients with moderate-to-severe chronic plaque psoriasis received 15 mg alefacept IM for 12 weeks, followed by a 12-week follow-up period. The first 4 weeks, patients were randomized 1:1 to either betamethasone dipropionate, or the vehicle cream, once daily. Plaque severity (SUM) was assessed and serial biopsies were immunohistochemically stained for T-cell subsets (CD3, CD4, CD8, CD45RO, CD45RA, CD2, CD25, GITR), cells expressing NK-receptors (CD94 and CD161), epidermal proliferation (Ki67) and differentiation (K10), which were quantified using manual and digital image analysis. Alefacept monotherapy resulted in statistically significant improvement in plaque severity. Subsequently, immunohistochemical assessments on T-cell subsets, epidermal proliferation (Ki67) and keratinization (K10) revealed marked time-related improvements with respect to the mentioned parameters, without significant differences between both treatment regimens. Alefacept monotherapy induces improvement of plaque severity, which is accompanied by a reduction in activated (CD2+, CD25+, CD45RO+) dermal CD4+ and activated epidermal CD8+ T cells, epidermal proliferation and differentiation. Once daily treatment with betamethasone dipropionate cream during the first 4 weeks of an intramuscular alefacept course did not provide substantial additional clinical and immunohistochemical improvement.

Inhibition of platelet function by abciximab or high-dose tirofiban in patients with STEMI undergoing primary PCI: a randomised trial.

BACKGROUND: In patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary PCI, few data exist on the magnitude of platelet activation, aggregation and dosing of glycoprotein (GP) IIb/IIIa receptor inhibitors. METHODS: Sixty STEMI patients were randomised to abciximab, to high-dose tirofiban or to no additional GP IIb/IIIa inhibitor treatment. Platelet activation (P-selectin expression) was measured using flow cytometry and the level of inhibition of platelet aggregation was assessed using the Plateletworks assay. Additionally, the PFA-100 with the collagen/adenosine-diphosphate cartridge (CADP) was used to compare the levels of platelet inhibition. All measurements were performed at baseline (T(0)), immediately after (T(1)), 30 minutes (T(2)), 60 minutes (T(3)) and 120 minutes (T(4)) after primary PCI. RESULTS: The level of platelet activation in both GP IIb/IIIa receptor inhibitor treated groups was significantly lower compared with the control group at all time points after primary PCI (p=0.04). Also the administration of the currently recommended dose of abciximab resulted in significantly lower levels of inhibition of aggregation compared with high-dose tirofiban (p<0.0001). In addition, the CADP closure times were significantly prolonged in both GP IIb/IIIa inhibitor treated groups compared with the control group at time points T(1) (p=0.006) and T(4) (p<0.0001). CONCLUSION: The administration of high-dose tirofiban resulted in a significantly higher inhibition of platelet aggregation compared with the currently recommended dose of abciximab. Large clinical trials are needed to assess whether this laboratory superiority of high-dose tirofiban translates into higher clinical efficacy. (Neth Heart J 2007;15:375-81.).

Evaluation of adenoviral oncolytic effect on glioma spheroids by 18F-DG positron-emission tomography.

Multicellular tumor spheroids are used as a model to assess the efficacy of replicating oncolytic adenoviruses. As most assays used to assess cellular viability are unsuitable for oncolytic viruses because of ongoing viral replication, we have used positron emission tomography (PET) to sequentially determine the incorporation of 18F-labeled deoxyglucose (18F-DG) as a measure of viability and compared the results to more commonly used assays for measuring the effect of oncolytic therapy. Glioma monolayer cultures and spheroids were infected with wild-type replicating adenovirus and viability was measured by 18F-DG incorporation, WST-1 assay, crystal violet assay, and spheroid volume 2 to 10 days following infection. Results show that volume measurements in adenovirus-infected spheroids are confounded by the cytopathic effect occurring in infected cells. 18F-DG PET provides a useful method to assess small differences in cell number and viability following oncolytic viral therapy in glioma monolayer cultures and spheroids without the need for disintegration of these cultures. Moreover, using 18F-DG PET, repeated sequential measurements of spheroid viability can be made, decreasing the required number of spheroids per experiment. This is a valuable feature when using spheroids derived from limited amounts of patient material.

[The unicorn and the pharmacists. Early modern views on the presumed anti-toxic effects of unicorn horn]. / De eenhoorn en de apothekers. Opvattingen omtrent de antitoxische werking van 'eenhoornhoorn' in het laatste kwart van de 16e en het eerste kwart van de 17e eeuw.

Around 1600, the age-old belief in the anti-toxic effect of unicorn horn began to be called into question. This is evidenced by the views of two well-known French pharmaceutic authorities whose publications are discussed in this paper: the surgeon Ambroise Paré (1510-1590), court physician to four French kings, and the Montpellier pharmacist Laurent Catelan (1568-1647), who owned a famous cabinet de curiosités. Although Paré had to accept, however reluctantly, the existence of the unicorn (since it is mentioned in the Bible), he vehemently denied the supposed medicinal effect of unicorn products. He defended his position by an appeal to ancient and contemporary authorities, by rational argumentation, and by experiment. Paré's arguments failed to convince Catelan, who adhered to an alternative, so-called spagyric, medical theory of neoplatonic inspiration, as propagated by Paracelsus and Ficino. Catelan remained convinced of the efficacity of unicorn horn, which in his view could drain the human body from any poisonous substance. The medical establishment being reluctant to give up a rewarding source of income,'unicorn' remained much in demand as a prescription.

Significant reduction in blood loss in patients undergoing minimal extracorporeal circulation.

Several recent studies have shown differences in blood loss and allogeneic transfusion requirements between on-pump and off-pump coronary artery bypass grafting (CABG). Recently a new concept, the mini-extracorporeal circulation, was introduced to minimize the side effects of extracorporeal circulation. Therefore, there are no data comparing the three techniques with special emphasis to blood loss and transfusion requirements. Two hundred and eighty-five patients undergoing first-time coronary artery bypass grafting were retrospectively matched for number of grafts, age and sex. Ninety-five patients underwent surgery with the off-pump CABG (OPCAB) technique, 97 patients using conventional CABG with cold cardioplegia (CCABG) and 93 patients with the mini-extracorporeal circuit with warm blood cardioplegia (MCABG). Blood loss for the CCABG group with a mean loss of 819 +/- 557 mL and the OPCAB group with a mean loss of 870 +/- 768 mL was significant different compared to the MCABG group with a mean loss of 679 +/- 290 mL. The use of units red blood cell units was significantly higher for CCABG group and OPCAB group compared to the MCABG group. On the day of operation the use of platelet concentrate was significantly higher for the CCABG group compared to MCABG group. As a consequence of improvements of several components of the mini heart lung machine, significantly less blood products are needed in MCABG patients. The expected reduced need for transfusion when the pump was completely avoided could not be confirmed in this single retrospective cohort study.

Different susceptibility of osteosarcoma cell lines and primary cells to treatment with oncolytic adenovirus and doxorubicin or cisplatin.

Despite improvements in treatment regimens for osteosarcoma (OS) patients, survival rate has not increased over the last two decades. New treatment modalities are therefore warranted. Preclinical results with conditionally replicative adenoviruses (CRAds) to treat OS are promising. One type of CRAd that was effective against OS cells is Ad5-Delta24RGD. In other types of cancer, CRAds have been shown to interact synergistically with chemotherapeutic agents. Chemotherapy for OS often includes doxorubicin and cisplatin. Therefore, we explored combination treatment of OS cell lines and primary OS cell cultures with Ad5-Delta24RGD and doxorubicin or cisplatin. On OS cell lines, combination treatment was additive to synergistic. Surprisingly, however, on seven of eight primary OS samples no such combination effects were observed. In contrast, in many cases chemotherapy even inhibited CRAd-mediated cell killing. The inhibitory effect of doxorubicin on Ad5-Delta24RGD in primary OS cells appeared to correlate with slow cell growth rate; reduced viral replication and absence of chemotherapy-induced G2 cell cycle arrest. Our results point to the possibility that, at least for OS, virotherapy and chemotherapy should best not be performed simultaneously. In general, our work underscores the importance of testing new genetic anticancer agents and treatment regimens on primary cancer specimens.