Transcription regulators and ultra-rare and other rare translocation-related sarcomas treated with trabectedin: A proof of principle from a post-hoc analysis

Background

Among sarcomas, which are rare cancers with an incidence of <6 per 100.000/year cases, ultra-rare sarcomas have an incidence of approximately ≤1/1,000,000/year cases and altogether account for ~20% of all soft tissue sarcomas (STS) and bone sarcomas. The Italian Sarcoma Group has recently performed a non-interventional, retrospective TrObs study with data from 512 anthracycline-pretreated patients with advanced multiple STS histologies and treated with trabectedin (Palmerini, Cancers 2021; ClinicalTrials.gov Identifier: NCT02793050).

Methods

A post-hoc analysis of case series to evaluate the efficacy and safety of trabectedin on patients with ultra-rare and other rare translocation-related sarcomas included in TrObs study was performed. Main outcomes comprised investigator-assessed overall response rate (ORR), disease control rate (DCR), progression-free survival (PFS) and safety.

Results

Thirty-six patients (18 women) with ultra-rare and other rare sarcoma and a median age of 53.0 years (range: 22-81) were included. Most patients had solitary fibrous tumor (SFT; n=11) followed by epithelioid sarcoma (n=5), malignant peripheral nerve sheath tumor (MPNST; n=4), extraskeletal myxoid chondrosarcoma (EMC; n=3), desmoplastic small round cell tumor (DSRCT; n=3), and alveolar soft part sarcoma (ASPS), rhabdomyosarcoma and clear cell sarcoma (n=2 each). Thirty-five patients had metastatic disease and 23 patients received trabectedin as a second-line treatment. Among 35 patients evaluable for response, two patients with SFT and ASPS had a partial response and one patient with DSRCT obtained a complete response, reaching an ORR of 8.6% (95% CI: 2.8-23.4%). Among patients with an ORR, 6-months PFS was 100% in patients with ASPS, 45.7% in patients with SFT and 33.3% in those with DSRCT. Two patients with epithelioid sarcoma and myoepithelioma had disease stabilization lasting >24 months. Nine patients had at least one grade 3/4 adverse event, mostly being bone marrow toxicity (n=6).

Conclusions

Trabectedin has some anti-tumor activity in some ultra-rare and other rare sarcomas, particularly translocation-related sarcomas, with the well-known manageable safety profile.

Phase II clinical trial of neoadjuvant trabectedin in patients with advanced localized myxoid liposarcoma

BACKGROUND

To evaluate neoadjuvant trabectedin (1.5 mg/m(2) 24-h i.v. infusion every 3 weeks; three to six cycles) in patients with locally advanced myoxid liposarcoma (ML) previously untreated with chemotherapy or radiation.

PATIENTS AND METHODS

Primary efficacy end point was pathological complete response (pCR) or tumoral regression rate. Objective response according to RECIST (v.1.0) was a secondary end point.

RESULTS

Three of 23 assessable patients had pCR [13%; 95% confidence interval (CI), 3% to 34%]. Furthermore, very good and moderate histological responses were observed in another 2 and 10 patients, respectively. Histological decrement in the cellular and vascular tumor component and maturation of tumor cells to lipoblasts were observed in both myoxid and myoxid/round cell variants. Seven patients had partial response according to RECIST (objective response rate of 24%; 95% CI, 10% to 44%). No disease progression was reported. Neoadjuvant trabectedin was usually well tolerated, with a safety profile similar to that described in patients with soft tissue sarcoma or other tumor types.

CONCLUSION

Trabectedin 1.5 mg/m(2) given as a 24-h i.v. infusion every 3 weeks is a therapeutic option in the neoadjuvant setting of ML.

Phase II study of the mammalian target of rapamycin inhibitor ridaforolimus in patients with advanced bone and soft tissue sarcomas

PURPOSE

Ridaforolimus is an inhibitor of mammalian target of rapamycin, an integral component of the phosphatidyl 3-kinase/AKT signaling pathway, with early evidence of activity in sarcomas. This multicenter, open-label, single-arm, phase II trial was conducted to assess the antitumor activity of ridaforolimus in patients with distinct subtypes of advanced sarcomas.

PATIENTS AND METHODS

Patients with metastatic or unresectable soft tissue or bone sarcomas received ridaforolimus 12.5 mg administered as a 30-minute intravenous infusion once daily for 5 days every 2 weeks. The primary end point was clinical benefit response (CBR) rate (complete response or partial response [PR] or stable disease ≥ 16 weeks). Safety, progression-free survival (PFS), overall survival (OS), time to progression, and duration of response were also evaluated.

RESULTS

A total of 212 patients were treated in four separate histologic cohorts. In this heavily pretreated population, 61 patients (28.8%) achieved CBR. Median PFS was 15.3 weeks; median OS was 40 weeks. Response Evaluation Criteria in Solid Tumors (RECIST) confirmed response rate was 1.9%, with four patients achieving confirmed PR (two with osteosarcoma, one with spindle cell sarcoma, and one with malignant fibrous histiocytoma). Archival tumor protein markers analyzed were not correlated with CBR. Related adverse events were generally mild or moderate and consisted primarily of stomatitis, mucosal inflammation, mouth ulceration, rash, and fatigue.

CONCLUSION

Single-agent ridaforolimus in patients with advanced and pretreated sarcomas led to PFS results that compare favorably with historical metrics. A phase III trial based on these data will further define ridaforolimus activity in sarcomas.

Clinical impact of trabectedin (ecteinascidin-743) in advanced/metastatic soft tissue sarcoma

BACKGROUND

Patients with advanced or metastatic non-gastrointestinal stromal tumour soft tissue sarcoma (STS) whose disease progresses during or after chemotherapy with doxorubicin or ifosfamide have few options and very limited life expectancy. In this setting, the DNA and transcription interacting agent trabectedin (ecteinascidin-743), isolated originally from the tunicate Ecteinascidia turbinata, has encouraging activity and is now approved in the European Union.

OBJECTIVE

To review evidence for the efficacy of trabectedin in STSs.

METHODS

This review includes material known to the authors through preclinical and clinical work with trabectedin, and information from relevant papers and abstracts.

RESULTS

Pooled analysis of Phase II studies suggests that around 50% of STS patients, failing conventional chemotherapy, experienced long lasting tumour control (either objective response or stabilization of disease) when treated with trabectedin. Twenty-nine per cent of patients were alive at 2 years, and median overall survival was 10.3 months. Leiomyosarcomas and liposarcomas appear particularly sensitive to the drug. In myxoid and round-cell liposarcomas trabectedin seems exceptionally active. A link between specific translocations underlying this disease and the drug's mechanism of action is being explored. Trabectedin is also active in synovial, ewing sarcoma and other translocation-related STSs. Trabectedin is not cardio- or neurotoxic. The neutropenia and hepatic toxicity that occur are non-cumulative, reversible, and lessened by steroid premedication. The lack of cumulative toxicities could make trabectedin appropriate for prolonged treatment.

CONCLUSION

The potential of trabectedin should be further explored in STSs in general and in specific subtypes, both in combination with other cytotoxic agents and with modulators of intracellular signalling.

Role of homologous recombination in trabectedin-induced DNA damage

Trabectedin (ET-743, Yondelis) is a natural marine compound with antitumour activity currently undergoing phase II/III clinical trials. The mechanism of the drug's action is still to be defined, even though it has been clearly demonstrated the key role of Nucleotide Excision Repair (NER). To get further insights into the drug's mode of action, we studied the involvement of the DNA-double strand break repair (DNA-DSB) pathways: homologous and non-homologous recombination, both in budding yeasts and in mammalian cells and the possible cross-talk between NER and these repair pathways. Budding yeasts and mammalian cells deficient in the non-homologous end-joining pathway were moderately sensitive to trabectedin, while systems deficient in the homologous recombination pathway were extremely sensitive to the drug, with a 100-fold decrease in the IC50, suggesting that trabectedin-induced lesions are repaired by this pathway. The induction of Rad51 foci and the appearance of gamma-H2AX were chosen as putative markers for DNA-DSBs and were studied at different time points after trabectedin treatment in NER proficient and deficient systems. Both were clearly detected only in the presence of an active NER, suggesting that the DSBs are not directly caused by the drug, but are formed during the processing/repair of the drug- induced lesions.