PARP1 expression drives the synergistic antitumor activity of trabectedin and PARP1 inhibitors in sarcoma preclinical models

Background

Enhancing the antitumor activity of the DNA-damaging drugs is an attractive strategy to improve current treatment options. Trabectedin is an isoquinoline alkylating agent with a peculiar mechanism of action. It binds to minor groove of DNA inducing single- and double-strand-breaks. These kinds of damage lead to the activation of PARP1, a first-line enzyme in DNA-damage response pathways. We hypothesized that PARP1 targeting could perpetuate trabectedin-induced DNA damage in tumor cells leading finally to cell death.

Methods

We investigated trabectedin and PARP1 inhibitor synergism in several tumor histotypes both in vitro and in vivo (subcutaneous and orthotopic tumor xenografts in mice). We searched for key determinants of drug synergism by comparative genomic hybridization (aCGH) and gene expression profiling (GEP) and validated their functional role.

Results

Trabectedin activated PARP1 enzyme and the combination with PARP1 inhibitors potentiated DNA damage, cell cycle arrest at G2/M checkpoint and apoptosis, if compared to single agents. Olaparib was the most active PARP1 inhibitor to combine with trabectedin and we confirmed the antitumor and antimetastatic activity of trabectedin/olaparib combination in mice models. However, we observed different degree of trabectedin/olaparib synergism among different cell lines. Namely, in DMR leiomyosarcoma models the combination was significantly more active than single agents, while in SJSA-1 osteosarcoma models no further advantage was obtained if compared to trabectedin alone. aCGH and GEP revealed that key components of DNA-repair pathways were involved in trabectedin/olaparib synergism. In particular, PARP1 expression dictated the degree of the synergism. Indeed, trabectedin/olaparib synergism was increased after PARP1 overexpression and reduced after PARP1 silencing.

Conclusions

PARP1 inhibition potentiated trabectedin activity in a PARP1-dependent manner and PARP1 expression in tumor cells might be a useful predictive biomarker that deserves clinical evaluation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-017-0652-5) contains supplementary material, which is available to authorized users.

Impact of a risk-based follow-up in patients affected by gastrointestinal stromal tumour

BACKGROUND

Follow-up aims to precociously identify recurrences, metastases or treatment-related adverse events so as to undertake the appropriate therapy. Guidelines admit lack of knowledge on optimal surveillance schedule, but suggest follow-up based on experts' opinion and risk stratification. To identify the impact, if any, of regular follow-up, we interrogated our prospectively collected database whether early detection of recurrences affected both clinical management and, likely, the outcome.

PATIENTS AND METHODS

We required information to be available on primary surgery and ≥3°years of follow-up for non-recurring patients. We analysed recurrence characteristics (asymptomatic versus symptomatic, low- versus high tumour burden) and computed tomography (CT) scan counts to detect one recurrence. Kaplan-Meier method estimated recurrence-free survival (RFS), post-recurrence progression-free survival (PR-PFS), and disease-specific overall survival (OS). Comparisons used Hazard ratios (HR) with 95% confidence intervals (CIs). Multivariate analyses employed the Cox proportional hazards model. All tests were two-sided.

RESULTS

Between 01/2001 and 12/2012 we found 233 study-eligible patients. Estimated 5- and 10-year RFS were 61.8% and 50.4%, respectively. After a 68-month median follow-up, we observed 94 (40.3%) recurrences [73/94 (77.7%) asymptomatic versus 21/94 (22.3%) symptomatic and 45/94 (47.9%) low- versus 49/94 (52.1%) high tumour burden]. Multivariate analysis revealed that symptomatic and high tumour burden recurrences were highly predictive of both worse PR-PFS (HR:3.19, P < 0.001; HR:2.80, P = 0.003, respectively) and OS (HR:3.65, P < 0.001; HR:2.38, P = 0.026, respectively). Finally, 29 second (primary) cancers were detected during follow-up.

CONCLUSIONS

Regular follow-up detects recurrences at an earlier stage and may be associated with a better PR-PFS and OS for these patients. In the absence of randomised trials, these evidences support follow-up effort and cost.

Abstract 3709: PARP1 expression (PARP1expr) drives synergy between PARP1 inhibitors (PARP1-Is) and trabectedin (TR)

Purpose of study. An attractive strategy to improve antitumor treatments is to inflict cytotoxic DNA damage with chemotherapy, and then impede DNA repair by molecular targeting. TR is a new drug characterized by a peculiar mechanism of action: TR traps DNA repair machinery leading to DNA damage, particularly in BRCA1/2-deficient tumors. We speculated that TR might activate PARP1, a key player in DNA-repair, and that subsequent PARP1 inhibition perpetuates TR-induced DNA damage leading to cell death.

Experimental procedures and results. We developed a preclinical platform of 31 cell lines from different histotypes to explore the potential synergy between TR and the PARP1-Is olaparib (OL) and veliparib. We demonstrated that, regardless of BRCA1/2 status, PARP1-Is significantly increased TR activity, but a 15-fold range of sensitivity to the combination was observed. OL was proven the best PARP-I to combine with TR, probably due to its PARP1 trapping activity. In selected experiments, whole-genome expression profiling and GSEA analysis comparing cells displaying high vs. low synergism of the combination (HS-C vs. LS-C) revealed that DDR, G2/M cell cycle checkpoint, and DNA repair pathways were mechanistically involved in TR+OL synergy. TR induced PARP1 activation in 3/6 cell lines and PARP1-Is completely blocked both basal and TR-induced PARP1 activation. OL enhanced DNA damage response in 6/6 cell lines, but unrepairable DNA fragmentation was obtained in cells with high PARP1expr only. In two independent cell panels TR+OL synergism was directly related to PARP1expr both at mRNA (Pearson score r: 0.70, p = 0.00079) and protein level (r: 0.71, p = 0.015). Silencing and overexpression experiments validated the functional role of PARP1expr in determining TR+OL synergism: in HS-C the downmodulation of PARP1expr reduced sensitivity to TR+OL while the overexpression of PARP1 in LS-C rose TR+OL activity to levels observed in HS-C. Subcutaneous, intravenous and orthotopic xenografts of one HS-C (DMR) and one LS-C (SJSA-1) in NOD/SCID mice revealed OL significantly increased antitumor and antimetastatic activity of TR in cells with high PARP1expr only. Finally, we demonstrated that basal PARP1expr PARP1 activation by other cytotoxics with a stronger PARP1 activation observed in cells with high vs. low PARP1expr, regardless of the considered drug.

Conclusions. OL enhances and potentially broaden TR cytotoxicity. TR+OL combination is particularly attractive in tumors harboring high PARP1expr and specific DDR-R gene signatures that might become predictive biomarkers of response. Future clinical validation of TR+OL combination may extend the use of PARP1-Is beyond BRCA1/2 defective tumors. Indeed, the crucial role of PARP1expr is confirmed regardless of tumor histotype and BRCA1/2 status. Further studies of combination between PARP1-Is and other cytotoxics should consider basal PARP1expr and activation after drug exposure.

Citation Format: Ymera Pignochino, Federica Capozzi, Lorenzo D’ambrosio, Carmine Dell’aglio, Marco Basiricò, Paola Boccone, Erica Palesandro, Loretta Gammaitoni, Dario Sangiolo, Maria Serena Benassi, Massimo Aglietta, Giovanni Grignani. PARP1 expression (PARP1expr) drives synergy between PARP1 inhibitors (PARP1-Is) and trabectedin (TR). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3709.

Complete remission of paraneoplastic vanishing bile duct syndrome after the successful treatment of Hodgkin's lymphoma: a case report and review of the literature

BACKGROUND

Vanishing bile duct syndrome has been associated with different pathologic conditions (adverse drug reactions, autoimmune diseases, graft versus host disease, and cancer). Though its causes are unknown, an immune-related pathogenesis is the most likely one. Vanishing bile duct syndrome can evolve to hepatic failure and, eventually, to death. The treatment is uncertain, but it needs the resolution of the underlying pathologic condition.

CASE PRESENTATION

We describe the association of Hodgkin's lymphoma with a syndrome characterized by cholestasis, aminotransferase elevation and an histological picture of bile duct loss. All other causes of hepatic function impairment were excluded (in particular, drugs, viral and autoimmune related diseases) eventually leading to the diagnosis of vanishing bile duct syndrome. Despite the fact that the dysfunction is not caused by hepatic Hodgkin's lymphoma involvement, liver impairment can limit the optimal therapy of Hodgkin's lymphoma. A treatment consisting of ursodeoxycholic acid, prednisone, and full dose chemotherapy restored hepatic function and achieved complete and long-lasting remission of Hodgkin's lymphoma.

CONCLUSION

We reviewed all case reports showing that vanishing bile duct syndrome is a dismal paraneoplastic syndrome being fatal in a high proportion of patients if not adequately treated. Indeed, this syndrome requires both an early recognition and an appropriate aggressive treatment consisting of full dose upfront chemotherapy which is the only way to achieve a resolution of the vanishing bile duct syndrome. Delayed or reduced intensity treatments unfavorably correlate with survival.

Preoperative Tru-Cut biopsy (POB) for the diagnosis of retroperitoneal soft tissue sarcomas (RPS) and risk of local recurrence (LR) compared to primary surgery of the tumor

10583

Background: Regardless optimal surgery LR is still a major challenge in RPS affecting 60% of the patients (pts). To improve these results pre-operative radiotherapy +/- chemotherapy are under investigation. This strategy requires to perform a POB. The surgical removal of the whole needle track is mandatory for limb sarcomas, but it can hardly ever be achieved in RPS. We explored whether POB did increase the risk of LR in terms of tumor cell seeding (along the needle track) or in the tumor mass area. Methods: We scanned our prospectively (01/2000 to 12/2010) collected RPS database including 176 pts. Complete information (records, CT scans, biopsy-track, follow up data) were available and retrospectively examined in 100 pts. Pts were divided into: group A (POB), group B (direct surgery). The 7 year probability of disease free survival (DFS) was estimated for each pt (ASCO 2012 abs 10000). T student test and Fisher's exact test were used to compare the estimated DFS and the incidence of LR in the 2 groups, respectively. Kaplan-Meier method was used to estimate DFS and overall survival (OS). Results: In 51 male, 49 female, median age 58 years (22-81) RPS histotype distribution was: lipo 43, leio 28, pleomorphic 9 and other 20. RPS grades were: G1 29%, G2 32%, G3 39%. POB was performed in 25 pts (25%) without major complications. The baseline probability of 7 year DFS was 0.43 and 0.51 (p= .24) for group A and B, respectively. After a median follow up of 71 mos, LR was 8% and 23% (p> .05) for group A and B, respectively. No relapse along the needle track was detected. As expected, liposarcoma was associated with a higher rate of LR (Odds Ratio 5.6 CI 95% 2-13). Median DFS, local DFS and OS were 24, 88 and 71 months, respectively. Conclusions: With the limit of the retrospective nature of our data, we didn’t find any increased risk of LR for POB in RPS. Although surgery is still the standard therapy in RPS, knowledge of histotype and differential diagnosis might encourage to consider inclusion of pts into pre-operative clinical trials and to avoid surgery for other retroperitoneal tumors (e.g. lymphomas, germinal cell tumors, IgG4-related sclerosing disease).

A risk-based individualized follow-up after complete surgery as an effective procedure to reduce the relapse (R) impact in GIST patients (pts)

10552

Background: FU care poses a burden on both pts and health system. FU aims to precociously identify recurrences, metastases or treatment-related adverse events so to undertake the appropriate therapy as soon as possible. Guidelines (NCCN, ESMO) admit lack of knowledge on optimal surveillance, but suggest FU based on experts’ opinion and risk stratification. Moreover, tumor burden (TB) is a well known negative prognostic factor (Van Glabbeke 2005). Therefore, low-TB at R might affect final outcome. To identify the impact, if any, of regular FU, we examined our prospectively collected database looking for Rs in which the early detection affected both clinical management and, likely, the outcome. Methods: 140 pts were stratified (AFIP classification). High risk (HR) pts had complete history + physical examination (H&P) and CT every 3 mos for 2 years, 4 mos in 3rd year, 6 mos in the 4th and 5th yrs, yearly thereafter; intermediate (IR), low (LR) and very low risk (VLR) pts had H&P + CT every 4 mos for 2 years, every 6 mos up to the 5th year, then yearly. Rs were divided in: low-TB + completely resectable R (Group 1) and high-TB + disseminated R (Group 2). The number of CT needed to detect (NND) one R and the incidence of early (<6 mos) R was calculated. Overall survival (OS) was estimated by Kaplan-Meier method. Results: In 73 male and 67 female, median age 63 (23-82), risk stratification was: HR 73, IR 31, LR 28, VLR 8. After a median FU of 63 mos we observed 58 Rs: 25 (43%) and 33 (57%) in group 2 and 1, respectively. Relapsed pts genotype was KIT Ex11 72%; Ex9 10%; Ex13 3%; wild-type 15%. Median time to R was 16 mos (1-120). 21 pts underwent surgical resection of their R. 16 pts remained free from progression for a median of 90 mos. We detected 15 (26%) early Rs. NND was 17 and 32 CT for HR and non-HR pts, respectively. Group 1 and 2 median estimated OS was 112 and 87 mos (p=.05), respectively. Conclusions: Though retrospective, this series shows that FU may detect low-TB Rs. In principle, this might affect pts final outcome and, therefore, justify this costly effort. Since it is difficult to foresee a prospective randomized trial, a confirmation of these data in a different series might increase their reliability.

Analysis of Hohn (HC) and porth-a-cath (PAC) central venous catheters (CVC) adverse events (AEs) and related costs in advanced soft tissue sarcomas (STS) treated with trabectedin (TR) 24-hour (24-h) infusion therapy

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Background: TR is registered as second line in STS. The 24-h infusion schedule showed a better activity profile but a CVC is mandatory to administer TR with related costs and possible complications. The HC (Bard Access System, USA) is a silicone, open-ended, non-tunneled CVC characterized by low cost and easy placement and removal. We performed a retrospective analysis of STS patients (pts) treated with TR through a CVC to evaluate the incidence of CVC AEs (malfunctioning, thrombosis, infection or extravasation) in pts carrying HC or PAC. Methods: Eligible criteria were: at least 1 course of TR via CVC, adequate premedication (steroid and 4000 units/die of low molecular weight heparin), absence of previous CVC alterations or any underlying coagulation disorder. All CVC were placed in our Institution under radiological control and full medical history was available for all pts included into the study. Average total costs (placement, hospital admission, device, and medications) are 255 and 560 $ for HC and PAC, respectively. Results: Between March 2008 and October 2011 42 pts, median age 58 (20-74) yrs, received TR after placement of a CVC: 14 (33%) HC and 28 (67%) PAC. At the time of TR administration, pts had received a median of 2 (range 1-4) chemotherapeutic lines. A total of 185 courses of TR (44 via HC / 141 via PAC) were administered at a median dose of 1.3 mg/m2 with a median of 3 (1-22) courses per pts. AEs occurred after a median of 2 (range 1-6) TR courses. We recorded 13 CVC-related AEs: 7 infection (2 HC / 5 PAC), 4 thrombosis (2 HC / 2 PAC), 2 malfunctioning (1 HC / 1 PAC,) no extravasation. CVC had to be removed and substituted in 10 pts (5 HC/5 PAC) with an estimated total cost of 280 and 680 $ for HC and PAC, respectively. In PAC pts, AEs determined 5 dose delays, only. Conclusions: CVC AEs should be considered in the management of pts treated with TR. HC showed a favorable safety profile and its AEs management is easier compared to implanted CVC. If disease does not progress after 2 cycles, HC can be converted in an implanted CVC. However, HC is also an adequate and cheaper device when best supportive care is the only useful therapy left.

Risk of adverse cardiovascular events (CVE) and incident diabetes mellitus (DM) in patients (pts) with prostate cancer (PC) treated with androgen deprivation therapy (ADT): A meta-analysis of adjusted observational results

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Background: ADT is a mainstay treatment in pts with PC and is supposedly associated to an unfavorable metabolic and cardiovascular profile. Recently, a meta-analysis of randomized controlled trials (RCT) found no association between ADT and increased risk of CVE (JAMA 2011). However, no conclusive data were available about ADT association with metabolic changes and adverse CVE or DM because of pts selection in RCT. Therefore, we performed a meta-analysis of adjusted observational results in order to look for DM and CVE onset in an ADT unselected population. Methods: Medline, Cochrane Library and Biomed Central were searched for articles addressing adverse events related to ADT in patients with PC. Selection criteria were: not RCT, pts assigned to ADT or not, adjusted risk of CVE and DM according to ADT. Exclusion criteria were: duplicate publication, comparison of two different strategies of ADT (different drugs or duration). Cardiovascular death was the primary endpoint; non-fatal myocardial infarction (MI), stroke/transient ischemic attack (TIA) and new DM onset were secondary endpoints. Random effects model with generic inverse variance weighting was used to estimate adjusted risks as odds ratios (OR) with 99% confidence interval (CI). Results: We selected 12/2100 screened studies. We included 208643 pts of which 102177 received ADT. At a follow up of 5 years (4-7.5), ADT did not result as an independent risk factor for cardiovascular death (OR= 1.04; 99% CI= 0.94-1.14). No increased risk of MI (OR= 1.13; CI= 0.86-1.48) or of stroke/TIA (OR= 1.11; CI= 0.78-1.57) were detected. Incident DM was more frequent among ADT pts (OR= 1.32; CI= 1.14-1-53). Even in 7205 pts with previous CVE (2450 received ADT), ADT was not associated with an increased risk of overall death (OR= 1.23; CI= 0.87-1.75). Meta-regression analysis showed no significant interactions between duration of ADT and cardiovascular death or incident DM. Conclusions: In non-selected pts,ADT appears to increase the risk of incident DM, but not of CVE or stroke/TIA. Moreover, overall mortality is not increased in pts with a history of CVE.