Case report: Treatment of metastatic dedifferentiated chondrosarcoma with pembrolizumab yields sustained complete response

Genomic Characterization of Chondrosarcoma Reveals Potential Therapeutic Targets

PURPOSE

Chondrosarcomas are rare cancers of cartilage with limited systemic therapy options. To identify potential therapeutic targets, this study investigated the molecular and immune landscape of three chondrosarcoma subtypes using a large database of clinical-grade sequencing results.

METHODS

Deidentified records from patients with a histologic diagnosis of conventional, dedifferentiated, or mesenchymal chondrosarcoma sequenced by the Tempus xT DNA assay were included. Microsatellite instability (MSI) and tumor mutational burden (TMB) were determined from sequencing data. The expression of PD-L1 and mismatch repair enzymes was evaluated in cases with available immunohistochemistry (IHC) data.

RESULTS

Of the 149 patients, 103 had conventional chondrosarcoma, 31 dedifferentiated chondrosarcoma, and 15 mesenchymal chondrosarcoma. Across the cohort, 44% (n = 65) had an IDH1 or IDH2 mutation. No cases were MSI high. One conventional chondrosarcoma patient had a TMB >10 mut/Mb. Among 112 patients with available PD-L1 IHC, 10% of conventional (n = 7), 45% of dedifferentiated (n = 13), and 17% of mesenchymal cases (n = 2) were PD-L1-positive. The most common somatic alterations were in IDH1 (34%) and TP53 (28%) in conventional chondrosarcoma; TP53 (68%), TERT (65%), IDH1 (39%), IDH2 (39%), CDKN2A (35%), and CDKN2B (35%) in dedifferentiated chondrosarcoma; and HEY1-NCOA2 fusions (87%) and CDKN2A (20%) in mesenchymal chondrosarcoma. MTAP was deleted in >10% of each subtype, and potentially actionable PDGFRB mutations were identified in 13% of dedifferentiated chondrosarcomas.

CONCLUSION

These findings reinforce therapeutic efforts to target IDH signaling in chondrosarcoma, provide insight into varied subpopulation response to immune checkpoint inhibitors, and identify new potential therapeutic targets for clinical development in chondrosarcoma.

Emerging Treatments Targeting the Tumor Microenvironment for Advanced Chondrosarcoma

Chondrosarcoma (ChS), a malignant cartilage-producing tumor, is the second most frequently diagnosed osseous sarcoma after osteosarcoma. It represents a very heterogeneous group of malignant chemo- and radiation-resistant neoplasms, accounting for approximately 20% of all bone sarcomas. The majority of ChS patients have a good prognosis after a complete surgical resection, as these tumors grow slowly and rarely metastasize. Conversely, patients with inoperable disease, due to the tumor location, size, or metastases, represent a great clinical challenge. Despite several genetic and epigenetic alterations that have been described in distinct ChS subtypes, very few therapeutic options are currently available for ChS patients. Therefore, new prognostic factors for tumor progression as well as new treatment options have to be explored, especially for patients with unresectable or metastatic disease. Recent studies have shown that a correlation between immune infiltrate composition, tumor aggressiveness, and survival does exist in ChS patients. In addition, the intra-tumor microvessel density has been proven to be associated with aggressive clinical behavior and a high metastatic potential in ChS. This review will provide an insight into the ChS microenvironment, since immunotherapy and antiangiogenic agents are emerging as interesting therapeutic options for ChS patients.

A Systematic Review of Adjuvant Chemotherapy in Localized Dedifferentiated Chondrosarcoma

Dedifferentiated chondrosarcoma (DDCS) is a high-grade subtype of chondrosarcoma with the bimorphic histological appearance of a conventional chondrosarcoma component with abrupt transition to a high-grade, non-cartilaginous sarcoma. DDCS can be radiographically divided into central and peripheral types. Wide resection is currently the main therapeutic option for localized DDCS. Moreover, the effectiveness of adjuvant chemotherapy remains controversial. Therefore, we performed a systematic review of available evidence to evaluate the effect of adjuvant chemotherapy on localized DDCS. The purpose was to compare the 5-year survival rate among patients treated with surgery plus adjuvant chemotherapy or surgery alone for localized DDCS. The search was conducted in PubMed, Embase, and Cochrane Central Register of Controlled Trials (CENTRAL) databases. Of the 217 studies shortlisted, 11 retrospective non-randomized studies (comprising 556 patients with localized DDCS) were selected. The 5-year survival rates were similar between the two treatment groups (28.2% (51/181) vs. 24.0% (90/375), respectively). The overall pooled odds ratio was 1.25 (95% confidence interval: 0.80-1.94; p = 0.324), and heterogeneity I2 was 2%. However, when limited to peripheral DDCS, adjuvant chemotherapy was associated with prolonged survival (p = 0.03). Due to the paucity of included studies and the absence of prospective comparative studies, no conclusions can be drawn regarding the effectiveness or ineffectiveness of adjuvant chemotherapy for localized DDCS.

Dedifferentiated Chondrosarcoma from Molecular Pathology to Current Treatment and Clinical Trials

Dedifferentiated chondrosarcoma (DDCS) is a rare subtype of chondrosarcoma, a primary cartilaginous malignant neoplasm. It accounts for up to 1-2% of all chondrosarcomas and is generally associated with one of the poorest prognoses among all chondrosarcomas with the highest risk of metastasis. The 5-year survival rates range from 7% to 24%. DDCS may develop at any age, but the average presentation age is over 50. The most common locations are the femur, pelvis humerus, scapula, rib, and tibia. The standard treatment for localised disease is surgical resection. Most patients are diagnosed in unresectable and advanced stages, and chemotherapy for localised and metastatic dedifferentiated DDCS follows protocols used for osteosarcoma.

Primary dedifferentiated chondrosarcoma of the lung with a 4-year history of breast cancer: A case report

BACKGROUND

Primary dedifferentiated chondrosarcoma (DDCS) of the lung is extremely rare and has a poor prognosis, especially in patients with a history of carcinomas and related treatment. Herein, we report a case of primary DDCS of the lung in a patient with a 4-year history of breast cancer and related treatment.

CASE SUMMARY

A 49-year-old woman was admitted to our hospital with complaints of headache, dizziness, slurred speech, and dyskinesia in May 2021. Computed tomography (CT) examinations showed multiple nodules in the brain, vertebral body, and both lungs with multiple enlarged lymph nodes in the right hilum and mediastinum, which were considered metastases of breast cancer. No obvious mass was discovered in the right hilum. After several months of related administration, the patient's headache disappeared, and her condition improved. However, new problems of asthma, dyspnea, cough, and restricted activity appeared in late November 2021. Although the CT scan indicated that the lesions in the brain, lung, and vertebral body had shrunk or disappeared, a soft tissue density lesion appeared in her right hilum and blocked the bronchial lumen. To relieve her dyspnea, part of the mass was resected, and a stent was placed via fiberoptic bronchoscopy. Following a complete pathological examination of the tumor, it was confirmed to be a primary DDCS of the lung. The patient then received two rounds of systemic chemotherapy with a regimen of cisplatin + ifosfamide + doxorubicin hydrochloride liposome, palliative radiotherapy for the tumor in her right lung, and four cycles of systemic chemotherapy and targeted therapy with a regimen of temozolomide combined with bevacizumab successively. She was in stable condition after the completion of the systemic chemotherapy and targeted therapy but underwent rapid progression after lung radiotherapy. The CT examinations showed multiple nodules in the brain and in both lungs, and the tumor in the right hilum was increased in size.

CONCLUSION

This case revealed a rare primary DDCS of the lung with a medical history of breast cancer, meaning a worse prognosis and making it more difficult to treat.