The treatment of aneurysmal bone cysts

PURPOSE OF REVIEW

Aneurysmal bone cysts are rare, locally aggressive bone tumors. Optimal treatment of ABCs is still matter of debate as therapies including sclerotherapy, selective arterial embolization and systemic treatment with denosumab are increasingly utilized, in addition to or instead of traditional curettage. The purpose of this review is to discuss current concepts and difficulties in diagnosing and treating primary ABCs, based on latest available literature.

RECENT FINDINGS

In diagnostics, multiple new fusion partners of USP-6 have been described on next-generation sequencing specifically for primary ABCs. In a recent systematic review, failure rates of percutaneous injections and surgery were comparable. In a literature review, the use of denosumab seemed effective but resulted in multiple cases of severe hypercalcemia in children.

SUMMARY

Accurately diagnosing primary ABC is crucial for treatment decisions. Curettage remains a valid treatment option, especially with adjuvant burring, autogenous bone grafting and phenolization. Percutaneous sclerotherapy represents a solid alternative to surgery, with polidocanol showing good results in larger studies. Systematic therapy with denosumab exhibits favorable results but should be reserved in the pediatric population for unresectable lesions, as it may result in severe hypercalcemia in children. When selecting a treatment option, localization, stability and safety should be considered.

Interactions in CSF1-Driven Tenosynovial Giant Cell Tumors

PURPOSE

A major component of cells in tenosynovial giant cell tumor (TGCT) consists of bystander macrophages responding to CSF1 that is overproduced by a small number of neoplastic cells with a chromosomal translocation involving the CSF1 gene. An autocrine loop was postulated where the neoplastic cells would be stimulated through CSF1R expressed on their surface. Here, we use single-cell RNA sequencing (scRNA-seq) to investigate cellular interactions in TGCT.

EXPERIMENTAL DESIGN

A total of 18,788 single cells from three TGCT and two giant cell tumor of bone (GCTB) samples underwent scRNA-seq. The three TGCTs were additionally analyzed using long-read RNA sequencing. Immunofluorescence and IHC for a range of markers were used to validate and extend the scRNA-seq findings.

RESULTS

Two recurrent neoplastic cell populations were identified in TGCT that are highly similar to nonneoplastic synoviocytes. We identified GFPT2 as a marker that highlights the neoplastic cells in TCGT. We show that the neoplastic cells themselves do not express CSF1R. We identified overlapping MAB features between the giant cells in TGCT and GCTB.

CONCLUSIONS

The neoplastic cells in TGCT are highly similar to nonneoplastic synoviocytes. The lack of CSF1R on the neoplastic cells indicates they may be unaffected by current therapies. High expression of GFPT2 in the neoplastic cells is associated with activation of the YAP1/TAZ pathway. In addition, we identified expression of the platelet-derived growth factor receptor in the neoplastic cells. These findings suggest two additional pathways to target in this tumor.

MOTION: A randomized, phase 3, placebo-controlled, double-blind study of vimseltinib (DCC-3014) for the treatment of tenosynovial giant cell tumor

TPS11590

Background: Tenosynovial giant cell tumor (TGCT) is a rare, locally aggressive neoplasm that occurs in the synovium of joints, bursae, or tendon sheaths. TGCT is caused by upregulation of the colony-stimulating factor 1 (CSF1) gene, resulting in aberrant CSF1 expression and the recruitment of CSF1 receptor (R)-dependent inflammatory cells. Resection is the primary treatment, but nonsurgical treatment options are necessary for patients with symptomatic TGCT not amenable to surgical resection. Vimseltinib is an oral switch control TKI specifically designed to selectively and potently inhibit CSF1R. In a Phase 1/2 study in patients with TGCT, vimseltinib showed encouraging antitumor activity with an overall objective response rate (ORR) of 42% in the cohort receiving 30 mg twice weekly (recommended phase 2 dose; Gelderblom et al, ESMO 2021 Poster). Vimseltinib was also well tolerated, and the majority of the common (≥15%) treatment-emergent adverse events (TEAEs) were Grades 1–2. Among these common TEAEs, the only Grade 3–4 event in the Phase 2, twice-weekly, 30-mg cohort was increased blood creatine phosphokinase (CPK); however, this elevated CPK was not associated with any symptoms (Gelderblom et al, ESMO 2021 Poster). Phase 1/2 efficacy and safety data support further development of vimseltinib; here, we describe the ongoing Phase 3 study for patients with TGCT not amenable to surgical resection. Methods: MOTION (NCT05059262) is a Phase 3, randomized, placebo-controlled, double-blind study that aims to evaluate the efficacy and safety of vimseltinib for the treatment of TGCT not amenable to surgical resection. Participants must be at least 18 years of age and have histologically confirmed and symptomatic TGCT for which surgical resection will potentially cause worsening functional limitation or severe morbidity. Prior CSF1R therapy is not permitted (previous imatinib and nilotinib is allowed). In Part 1 of the study, eligible participants will be randomized 2:1 to receive either vimseltinib 30 mg twice a week or matched placebo for 24 weeks. The primary outcome measure is ORR assessed by central read using Response Evaluation Criteria in Solid Tumors version 1.1 at 25 weeks. Secondary outcome measures include ORR per tumor volume score, range of motion, and patient-reported outcomes. Participants assigned to placebo in Part 1 will have the option to receive vimseltinib in Part 2, a long-term treatment phase in which participants will receive open-label vimseltinib. This international study plans to randomize 120 participants and is currently enrolling. Clinical trial information: NCT05059262.

Biology and technology in the surgical treatment of malignant bone tumours in children and adolescents, with a special note on the very young

PURPOSE

The main challenge in reconstruction after malignant bone tumour resection in young children remains how and when growth-plates can be preserved and which options remain if impossible.

METHODS

We describe different strategies to assure best possible long-term function for young children undergoing resection of malignant bone tumours.

RESULTS

Different resources are available to treat children with malignant bones tumours: a) preoperative planning simulates scenarios for tumour resection and limb reconstruction, facilitating decision-making for surgical and reconstructive techniques in individual patients; b) allograft reconstruction offers bone-stock preservation for future needs. Most allografts are intact at long-term follow-up, but limb-length inequalities and corrective/revision surgery are common in young patients; c) free vascularized fibula can be used as stand-alone reconstruction, vascularized augmentation of structural allograft or devitalized autograft. Longitudinal growth and joint remodelling potential can be preserved, if transferred with vascularized proximal physis; d) epiphysiolysis before resection with continuous physeal distraction provides safe resection margins and maintains growth-plate and epiphysis; e) 3D printing may facilitate joint salvage by reconstruction with patient-specific instruments. Very short stems can be created for fixation in (epi-)metaphysis, preserving native joints; f) growing endoprosthesis can provide for remaining growth after resection of epi-metaphyseal tumours. At ten-year follow-up, limb survival was 89%, but multiple surgeries are often required; g) rotationplasty and amputation should be considered if limb salvage is impossible and/or would result in decreased function and quality of life.

CONCLUSION

Several biological and technological reconstruction options must be merged and used to yield best outcomes when treating young children with malignant bone tumours.

LEVEL OF EVIDENCE

Level V Expert opinion.

Health-related quality of life after isolated limb perfusion compared to extended resection, or amputation for locally advanced extremity sarcoma: Is a limb salvage strategy worth the effort?

e23539

Background: Induction isolated limb perfusion (ILP) followed by limb-sparing resection or extended resection are frequently used limb salvation strategies (LSS) in locally advanced extremity soft tissue sarcoma (eSTS) to prevent amputation. However little is known about the long term health-related quality of life (HRQoL) in these patients. The aim of this study was to compare long-term patient reported outcomes (PROs) such as HRQoL after ILP compared to extended resection or amputation. Methods: Patients treated with an ILP, extended resection, or amputation were selected from the respondents of a multi-institutional cross-sectional cohort survivorship study (SURVSARC) conducted 2-10 years after diagnosis among sarcoma survivors registered in the Netherlands Cancer Registry (NCR). Extended resection was defined as resection for stage III eSTS, details regarding amputation levels other than upper or lower extremity are unknown. Used PROs were the EORTC QLQ-C30, Cancer worry scale (CWS), the Hospital Anxiety and Depression Scale (HADS), and the Toronto Extremity Salvage Score (TESS). Results: We identified 96 eSTS survivors and assigned them into four groups: ILP (N = 20), extended resection (N = 48), primary amputation (N = 20), and amputation after ILP (N = 8). While there were no differences in PROs between ILP and extended resections, results showed better functioning and functionality after these two LSS groups versus the amputation groups. The amputation groups scored significantly lower on the EORTC QLQ-C30 physical functioning scale (p < 0.001, 62.7 and 65.7 versus 78.0 and 84.1) and role functioning scale (p = 0.038, 67.5 and 52.8 versus 79.2 and 80.9), which both account for a difference with ‘medium’ clinical relevance. Also for the TESS, the scores were significantly lower for the amputation groups compared to the LSS groups (upper extremity p = 0.007 with 68.9 and 71.6 versus 93.3 and 91.1; lower extremity p < 0.001 with 72.2 and 50.9 versus 84.5 and 85.5). There were no significant differences on cancer worry, anxiety and depression were found between all groups. Conclusions: Based on this survivorship study, HRQoL in eSTS survivors treated with ILP followed by limb-sparing resection is not inferior to extended resections, however it is superior in maintenance of physical functioning and functionality compared to an amputation.[Table: see text]

Regression of fibrous dysplasia in response to denosumab therapy: A report of two cases

We present two patients with fibrous dysplasia who showed a decrease in lesional size and activity after denosumab therapy. Both patients also experienced a reduction in pain and bone turnover markers, which had not been accomplished during previous bisphosphonate therapy. These cases highlight the potential of denosumab to decrease lesional size in fibrous dysplasia. This finding has been reported in mice, but not in humans. Denosumab may be considered when bisphosphonates are not tolerated or not effective (enough), or in severe cases as neoadjuvant therapy to improve surgical possibilities and outcome. In addition, these results show that Na[¹⁸F]F PET-CT is suitable for detecting change in each fibrous dysplasia lesion distinctively.

Single-Center Experience with Ifosfamide Monotherapy as Second-Line Treatment of Recurrent/Metastatic Osteosarcoma

Background

The effectiveness of second‐line palliative chemotherapy in patients with recurrent/metastatic osteosarcoma is not well defined. Several small studies (6–19 patients) have reported on ifosfamide as second‐line treatment. In this study we report our single‐center experience with second‐line ifosfamide monotherapy in patients treated for recurrent/metastatic osteosarcoma.

Methods

A chart review was conducted of all patients with osteosarcoma treated with ifosfamide from 1978 until 2017. Until 1997 a 5 g/m² regimen was used, and from 1997 onwards a 9 g/m² regimen was used. Overall survival (OS) from start of ifosfamide was the primary endpoint. Progression‐free survival (PFS) from start of treatment was also studied. To assess difference in survival between groups the log rank test was applied. To investigate the effect of ifosfamide dose and World Health Organization performance status (PS) a Cox proportional hazard regression model was estimated.

Results

Sixty‐two patients were selected with recurrent/metastatic osteosarcoma treated with second‐line ifosfamide monotherapy (dose of 5 g/m², n = 26; 9 g/m², n = 36). OS was significantly better in univariate analysis for 9 g/m² compared with 5 g/m² (10.9 months [95% confidence interval (CI), 9.3–12.6] vs. 6.7 months [95% CI, 5.9–7.6], respectively) and for PS (median OS PS 0, 13.0 months [95% CI, 2.3–23.8]; PS 1, 8.2 months [95% CI, 5.4–11.1]; PS ≥2, 6.2 months [95% CI, 2.2–10.3]; and unknown PS, 5.4 months [95% CI, 2.2–8.5]). In multivariate analysis only PS showed a significant difference. No difference in PFS was found between 5 and 9 g/m² ifosfamide treatment or PS.

Conclusion

This study suggests that ifosfamide is an effective second‐line treatment for patients with recurrent/metastatic osteosarcoma.

Implications for Practice

Ifosfamide monotherapy is commonly used as second‐line treatment in osteosarcoma, although large series to support this are lacking. This retrospective study reports overall and progression‐free survival for regimens with 5 g/m² and with 9 g/m². This study was unable to show a significant difference in survival between 5 and 9 g/m² but showed an important impact of World Health Organization performance status on overall survival. This study sets a standard and reference for comparison with the multiple phase II studies under development.

The effectiveness of second‐line palliative chemotherapy for recurrent or metastatic osteosarcoma has not been determined. This article reports the Leiden University Medical Center experience with ifosfamide monotherapy as palliative treatment in patients with osteosarcoma.

Development and external validation of a dynamic prognostic nomogram for primary extremity soft tissue sarcoma survivors

BACKGROUND

Prognostic nomograms for patients with extremity soft tissue sarcoma (eSTS) typically predict survival or the occurrence of local recurrence or distant metastasis at time of surgery. Our aim was to develop and externally validate a dynamic prognostic nomogram for overall survival in eSTS survivors for use during follow-up.

METHODS

All primary eSTS patients operated with curative intent between 1994 and 2013 at three European and one Canadian sarcoma centers formed the development cohort. Patients with Fédération Française des Centres de Lutte Contre le Cancer (FNCLCC) grade II and grade III eSTS operated between 2000 and 2016 at seven other European reference centers formed the external validation cohort. We used a landmark analysis approach and a multivariable Cox model to create a dynamic nomogram; the prediction window was fixed at five years. A backward procedure based on the Akaike Information Criterion was adopted for variable selection. We tested the nomogram performance in terms of calibration and discrimination.

FINDINGS

The development and validation cohorts included 3740 and 893 patients, respectively. The variables selected applying the backward procedure were patient's age, tumor size and its interaction with landmark time, tumor FNCLCC grade and its interaction with landmark time, histology, and both local recurrence and distant metastasis (as first event) indicator variables. The nomogram showed good calibration and discrimination. Harrell C indexes at different landmark times were between 0.776 (0.761-0.790) and 0.845 (0.823-0.862) in the development series and between 0.675 (0.643-0.704) and 0.810 (0.775-0.844) in the validation series.

INTERPRETATION

A new dynamic nomogram is available to predict 5-year overall survival at different times during the first three years of follow-up in patients operated for primary eSTS. This nomogram allows physicians to update the individual survival prediction during follow-up on the basis of baseline variables, time elapsed from surgery and first-event history.

Perioperative Management of Extremity Soft Tissue Sarcomas

Surgery is potentially curative for primary nonmetastatic extremity soft tissue sarcomas. After surgery alone, patients may remain at risk for local recurrences and/or metastatic disease. To reduce the likelihood of a local relapse, the addition of radiotherapy (RT) to limb-sparing surgery may result in higher local control rates of at least 85%. Generally, it can be stated that local control after both preoperative and postoperative RT is comparable, but that preoperative RT comes with a more favorable toxicity profile after prolonged follow-up, albeit at the cost of a higher wound complication rate. Furthermore, recent data suggest that preoperative RT is more cost effective. To reduce the risk of subsequent metastatic disease, systemic chemotherapy can be introduced early during the primary management of these patients. These systemic chemotherapy regimens can also be applied both preoperatively and postoperatively. Finally, with the aim of increasing the antitumor response of perioperative RT, these agents may even be combined with RT, concurrently and sequentially. While designing new preoperative combination regimens, responses should be carefully monitored by both sophisticated radiologic and pathologic evaluations. This article reviews all these aspects, in addition to limb-sparing surgery.