Pexidartinib for advanced tenosynovial giant cell tumor (TGCT): Long-term efficacy and safety from the phase 3 ENLIVEN and phase 1 PLX108-01 (TGCT cohort) studies

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Background: TGCT is a rare, locally aggressive neoplasm of the joint/tendon sheath linked to colony-stimulating factor 1 (CSF1) overexpression. Pexidartinib (pex), a selective inhibitor of CSF1 receptor, KIT, and FLT3-ITD, had a compelling tumor response rate in the TGCT cohort of a phase 1 study (NCT01004861) and significant tumor response vs placebo by RECIST v1.1 (39% vs 0%, P< 0.0001) and tumor volume score (TVS) (56% vs 0%, P< 0.0001) in the randomized, 2-part, crossover phase 3 ENLIVEN study (NCT02371369). Updated efficacy and safety with longer treatment are reported. Methods: Patients (pts) were ≥18 y with TGCT that was inoperable or for which surgery would likely be associated with worsening functional limitation or severe morbidity. Best overall response (complete or partial [CR/PR]) and duration of response (DOR) by RECIST and TVS were assessed by independent central review. Data cutoff was Jan 31, 2018, 16-67 mo after pts’ first dose. Results: In both studies 130 pts received pex, 61 ongoing at data cutoff. Median treatment duration was 17 mo (1, 60+). CR/PR rates were high and consistent and, together with DOR, improved with prolongation of treatment (Table). Most frequent adverse events were hair color change (75%), fatigue (60%), nausea (45%), arthralgia (38%), AST increase (30%), and diarrhea (30%). In ENLIVEN part 1, 3 of 61 (5%) pts had reversible ALT and AST ≥3 × ULN with TBil and ALP ≥2 × ULN; all started in the first 8 weeks of treatment, and no new cases emerged with continuation of treatment. Conclusions: Tumor response rate increased with continuation of pex treatment. The safety profile remained similar, with no new mixed or cholestatic hepatotoxicity. Clinical trial information: NCT01004861 and NCT02371369. [Table: see text]

Low dose radiotherapy is associated with local complications but not disease control in sacral chordoma

BACKGROUND

We reviewed the disease control and complications of the treatment of sacrococcygeal chordoma from four tertiary cancer centers with emphasis on the effects of radiotherapy in surgically treated patients.

METHODS

A total of 193 patients with primary sacrococcygeal chordoma from 1990 to 2015 were reviewed. There were 124 males, with a mean age of 59 ± 15 years and a mean follow-up of 7 ± 4 years. Eighty-nine patients received radiotherapy with a mean total dose of 61.8 ± 10.9 Gy.

RESULTS

The 10-year disease-free and disease-specific survival was 58% and 72%, respectively. Radiation was not associated with local recurrence (hazard ratio [HR], 1.13; 95% confidence interval [CI], 0.59-2.17; P = 0.71), metastases (HR, 0.93; 95% CI, 0.45-1.91; P = 0.85) or disease-specific survival (HR, 0.96; 95% CI, 0.46-2.00; P = 0.91). Higher doses (≥70 Gy; HR, 0.52; 95% CI, 0.20-1.32; P = 0.17) may be associated with reduced local recurrence. Radiotherapy was associated with wound complications (HR, 2.76; 95% CI, 1.64-4.82;, P < 0.001) and sacral stress fractures (HR, 4.73; 95% CI, 1.88-14.38; P < 0.001).

CONCLUSIONS

In this multicenter review, radiotherapy was not associated with tumor outcome but associated with complications. The routine use of radiotherapy with en-bloc resection of sacrococcygeal chordomas should be reconsidered in favor of a selective, individualized approach with a radiation dose of ≥70 Gy.

The measurement of physical functioning among patients with Tenosynovial Giant Cell Tumor (TGCT) using the Patient-Reported Outcomes Measurement Information System (PROMIS)

Background

Tenosynovial giant cell tumor (TGCT), a rare, locally aggressive neoplasm of the synovium of joints and tendon sheaths, is associated with joint destruction, pain and swelling. Impacts on physical function (PF) vary depending on tumor size and location. The aim of this study was to identify relevant items, and demonstrate the content validity of custom measures of lower extremity PF from the Patient-Reported Outcomes Measurement Information System Physical Function Physical Function (PROMIS-PF) item bank among patients with TGCT.

Methods

Patients were recruited for qualitative research interviews to identify predominant TGCT symptoms and impacts. Patients completed a checklist to evaluate the relevance of each PROMIS-PF item. The publicly available PROMIS-PF item response theory (IRT) parameters were used to select items representing the range of the latent PF trait.

Results

Participants (n = 20) were 75% female, mean age 42.5 years. TGCTs were located in the knee (n = 15), hip (n = 3), and ankle (n = 2). Fifty-four PROMIS-PF items were identified as relevant by ≥20% of the participants. PF concepts discussed by participants during the qualitative interviews were also used to select relevant items. Selected items (n = 13) were used to create a physical function subscale specific to lower extremity tumors.

Conclusions

We describe a novel method of combining qualitative research and IRT-based item information to select a relevant and content valid subset of PROMIS-PF items to assess heterogeneous impacts on PF in TGCT, a rare disease population.

Electronic supplementary material

The online version of this article (10.1186/s41687-019-0099-0) contains supplementary material, which is available to authorized users.

Discovery of a periosteal stem cell mediating intramembranous bone formation

Bone consists of separate inner endosteal and outer periosteal compartments, each with distinct contributions to bone physiology and each maintaining separate pools of cells owing to physical separation by the bone cortex. The skeletal stem cell that gives rise to endosteal osteoblasts has been extensively studied; however, the identity of periosteal stem cells remains unclear^1-5. Here we identify a periosteal stem cell (PSC) that is present in the long bones and calvarium of mice, displays clonal multipotency and self-renewal, and sits at the apex of a differentiation hierarchy. Single-cell and bulk transcriptional profiling show that PSCs display transcriptional signatures that are distinct from those of other skeletal stem cells and mature mesenchymal cells. Whereas other skeletal stem cells form bone via an initial cartilage template using the endochondral pathway⁴, PSCs form bone via a direct intramembranous route, providing a cellular basis for the divergence between intramembranous versus endochondral developmental pathways. However, there is plasticity in this division, as PSCs acquire endochondral bone formation capacity in response to injury. Genetic blockade of the ability of PSCs to give rise to bone-forming osteoblasts results in selective impairments in cortical bone architecture and defects in fracture healing. A cell analogous to mouse PSCs is present in the human periosteum, raising the possibility that PSCs are attractive targets for drug and cellular therapy for skeletal disorders. The identification of PSCs provides evidence that bone contains multiple pools of stem cells, each with distinct physiologic functions.

Abstract NG03: Chromosomal instability promotes metastasis through a cytosolic DNA response

Chromosomal instability (CIN) is a hallmark of cancer and it results from ongoing errors in chromosome segregation during mitosis. While CIN is a major driver of tumor evolution, its role in metastasis has not been established. Here we show that CIN promotes metastasis by sustaining a tumor-cell autonomous response to cytosolic DNA. Errors in chromosome segregation create a preponderance of micronuclei whose rupture spills genomic DNA into the cytosol. This leads to the activation of the cGAS-STING cytosolic DNA-sensing pathway and downstream noncanonical NF-κB signaling. Genetic suppression of CIN significantly delays metastasis even in highly aneuploid tumor models, whereas inducing continuous chromosome segregation errors promotes cellular invasion and metastasis in a STING-dependent manner. Using single-cell RNA sequencing, we uncover a CIN-induced transcriptional switch from a proliferative and metabolically active state to a mesenchymal phenotype associated with inflammatory pathways, offering an opportunity to target chromosome segregation errors for therapeutic benefit. Our work reveals an unexpected link between CIN, cytosolic DNA sensing pathways, and metastasis. The use of an isogenic system has enabled us to dissect the role of CIN from that of aneuploidy. Importantly, while we do not discount the role of CIN in generating karyotypic heterogeneity that can serve as the substrate for natural selection, our work demonstrates that continuous chromosome missegregation is also required to replenish cytosolic DNA pools leading to chronic upregulation of inflammatory pathways. In non-transformed settings, cytosolic DNA sensing is incompatible with viability. Unlike normal cells, chromosomally unstable cells are awash with cytosolic DNA and have adapted to coexist with a chronically active cGAS-STING pathway by suppressing downstream type I interferon signaling and instead upregulating the alternative NF-κB pathway. Persistent STING activation mediates carcinogen-induced tumor formation and we now show that tumor cells co-opt this otherwise lethal program to spread to distant organs. The evolutionary benefit of the noncanonical pathway might justify the scarcity of inactivating mutations in cGAS and STING among human cancers. The emergence, and subsequent tolerance, of CIN represents an important bottleneck during tumor evolution. Our single-cell analysis revealed that CIN induces a transcriptional switch whereby cells shift from a proliferative and highly metabolic state, ideally suited for primary tumor growth, to a chromosomally unstable and mesenchymal state associated with upregulation of inflammatory pathways. These two largely mutually exclusive states likely account for the reversibility in chromosome missegregation rates seen in primary tumors and metastases, and provide an explanation for the negative effect of aneuploidy during early tumorigenesis. Interestingly, this mutual exclusivity was recently observed in a pan-cancer genomic analysis of metastatic tumors, and it leads us to suggest that CIN underlies the subset of metastases that are characterized by EMT and inflammation. By providing a mechanistic link between CIN and metastasis, our work opens new avenues to target chromosomally unstable tumors for therapeutic benefit.

Citation Format: Samuel F. Bakhoum, Bryon Ngo, Ashley L. Bakhoum, Julie-Ann Cavallo, Charles J. Murphy, Peter Ly, Pragya Shah, Roshan K. Sriram, Thomas B.k. Watkins, Neil K. Taunk, Mercedes Duran, Chantal Pauli, Christine Shaw, Kalyani Chadalavada, Vinagolu K. Rajasekhar, Giulio Genovese, Subramanian Venkatesan, Nicolai J. Birkbak, Nicholas McGranahan, Mark Lundquist, Quincy LaPlant, John H. Healey, Olivier Elemento, Christine H. Chung, Nancy Y. Lee, Marcin Imielinski, Gouri Nanjangud, Dana Pe'er, Don W. Cleveland, Simon N. Powell, Jan Lammerding, Charles Swanton, Lewis C. Cantley. Chromosomal instability promotes metastasis through a cytosolic DNA response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr NG03.

Chromosomal instability drives metastasis through a cytosolic DNA response

Chromosomal instability is a hallmark of cancer that results from ongoing errors in chromosome segregation during mitosis. Although chromosomal instability is a major driver of tumour evolution, its role in metastasis has not been established. Here we show that chromosomal instability promotes metastasis by sustaining a tumour cell-autonomous response to cytosolic DNA. Errors in chromosome segregation create a preponderance of micronuclei whose rupture spills genomic DNA into the cytosol. This leads to the activation of the cGAS-STING (cyclic GMP-AMP synthase-stimulator of interferon genes) cytosolic DNA-sensing pathway and downstream noncanonical NF-κB signalling. Genetic suppression of chromosomal instability markedly delays metastasis even in highly aneuploid tumour models, whereas continuous chromosome segregation errors promote cellular invasion and metastasis in a STING-dependent manner. By subverting lethal epithelial responses to cytosolic DNA, chromosomally unstable tumour cells co-opt chronic activation of innate immune pathways to spread to distant organs.

Tumor Xenografts of Human Clear Cell Renal Cell Carcinoma But Not Corresponding Cell Lines Recapitulate Clinical Response to Sunitinib: Feasibility of Using Biopsy Samples

BACKGROUND

Parallel development of preclinical models that recapitulate treatment response observed in patients is central to the advancement of personalized medicine.

OBJECTIVE

To evaluate the use of biopsy specimens to develop patient-derived xenografts and the use of corresponding cell lines from renal cell carcinoma (RCC) tumors for the assessment of histopathology, genomics, and treatment response.

DESIGN, SETTING, AND PARTICIPANTS

A total of 74 tumor specimens from 66 patients with RCC were implanted into immunocompromised NOD-SCID IL2Rg-/- mice. Four cell lines generated from patients' specimens with clear cell pathology were used for comparative studies.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Preclinical models were established and assessed. Engraftment rates were analyzed using chi-square testing. Analysis of variance (two-way analysis of variance) was conducted to assess tumor growth.

RESULTS AND LIMITATIONS

Overall, 33 RCC mouse xenograft models were generated with an overall engraftment rate of 45% (33 of 74). Tumor biopsies engrafted comparably with surgically resected tumors (58% vs 41%; p=0.3). Xenograft tumors and their original tumors showed high fidelity in regard to histology, mutation status, copy number change, and targeted therapy response. Engraftment rates from metastatic tumors were higher but not more significant than primary tumors (54% vs 34%; p=0.091). Our engraftment rate using metastases or biopsies was comparable with recent reports using resected primary tumors. In stark contrast to corresponding cell lines, all tested xenografts recapitulated patients' clinical response to sunitinib.

CONCLUSIONS

Patient-derived xenograft models can be effectively established from tumor biopsies. Preclinical xenograft models but not matched cell lines reflected clinical responses to sunitinib.

PATIENT SUMMARY

Matched patient-derived clear cell renal cell carcinoma xenografts and cell lines from responsive and refractory patients treated with sunitinib were established and evaluated for pharmacologic response to anti-vascular endothelial growth factor treatment. Both models accurately reflected the genetic characteristics of original tumors, but only xenografts recapitulated drug responses observed in patients. These models could serve as a powerful platform for precision medicine.

HPMA-Copolymer Nanocarrier Targets Tumor-Associated Macrophages in Primary and Metastatic Breast Cancer

Polymeric nanocarriers such as N-(2-hydroxypropyl) methacrylamide (HPMA) copolymers deliver drugs to solid tumors and avoid the systemic toxicity of conventional chemotherapy. Because HPMA copolymers can target sites of inflammation and accumulate within innate immune cells, we hypothesized that HPMA copolymers could target tumor-associated macrophages (TAM) in both primary and metastatic tumor microenvironments. We verified this hypothesis, first in preliminary experiments with isolated bone marrow macrophage cultures in vitro and subsequently in a spontaneously metastatic murine breast cancer model generated from a well-established, cytogenetically characterized 4T1 breast cancer cell line. Using our standardized experimental conditions, we detected primary orthotopic tumor growth at 7 days and metastatic tumors at 28 days after orthotopic transplantation of 4T1 cells into the mammary fat pad. We investigated the uptake of HPMA copolymer conjugated with Alexa Fluor 647 and folic acid (P-Alexa647-FA) and HPMA copolymer conjugated with IRDye 800CW (P-IRDye), following their retroorbital injection into the primary and metastatic tumor-bearing mice. A significant uptake of P-IRDye was observed at all primary and metastatic tumor sites in these mice, and the P-Alexa647-FA signal was found specifically within CD11b⁺ TAMs costained with pan-macrophage marker CD68. These findings demonstrate, for the first time, a novel capacity of a P-Alexa647-FA conjugate to colocalize to CD11b⁺CD68⁺ TAMs in both primary and metastatic breast tumors. This underscores the potential of this HPMA nanocarrier to deliver functional therapeutics that specifically target tumor-promoting macrophage activation and/or polarization during tumor development. Mol Cancer Ther; 16(12); 2701-10. ©2017 AACR.

Tumor volume score (TVS), modified recist, and tissue damage score (TDS) as novel methods for assessing response in tenosynovial giant cell tumors (TGCT) treated with pexidartinib: Relationship with patient-reported outcomes (PROs)

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Background: TGCT is a locally aggressive neoplasm of joint and tendon sheath synovia that may cause pain, limit joint function and destroy bone and local tissues. Measuring TGCT with RECIST is a challenge due to irregular shape and asymmetrical growth, and local tissue damage is not assessed. We reported earlier results of a longitudinal trial of pexidartinib, a selective CSF1R kinase inhibitor, using RECIST as well as novel TVS, modified RECIST and TDS. Here we examine concordance of these MRI measures with PROs. Methods: Patients (pts) with progressive TGCT in a single-arm, multi-center trial of pexidartinib (1000 mg po daily) were assessed by MRI every 2 months by 2 central radiologists (blind to visit order). For RECIST, longest measurable dimensions of up to 2 tumors per joint or tendon sheath were summed (SLD). Modified RECIST summed short axis dimensions (SSD). TVS was based on 10% increments of the estimated maximally distended normal synovial cavity or tendon sheath. TDS scored bone erosion (ERO), cartilage loss (CAR) and bone marrow edema (BME) in multiple regions of each joint. The relationship with PROs (Worst Pain numerical rating scale [NRS] and Worst Stiffness NRS) was assessed. Results: 15 pts (7 knees, 3 hips, 2 ankles, 1 elbow, 1 wrist, 1 thigh) with PRO data and evaluable MRI scans at baseline and Month 7 were assessed. All SLD, SSD and TVS scores improved with respective median changes of -25%, -39% and -50%. Baseline ERO, CAR, and BME ranged 0-19, 0-34, and 0-15, respectively. Median change for each was 0%: ERO worsened in 1 pt, CAR did not change, and BME improved in 4 and worsened in 2. Worst Pain NRS and Worst Stiffness NRS improved in 11 and 9 pts, respectively. Conclusions: TVS demonstrated the greatest pexidartinib effect size, followed by SSD and then conventional RECIST. All had good concordance with PROs. Clinical trial information: NCT01004861. [Table: see text]

What questionnaires to use when measuring quality of life in sacral tumor patients: the updated sacral tumor survey

BACKGROUND CONTEXT

Patient-reported outcomes are becoming increasingly important when investigating results of patient and disease management. In sacral tumor, the symptoms of patients can vary substantially; therefore, no single questionnaire can adequately account for the full spectrum of symptoms and disability.

PURPOSE

The purpose of this study is to analyze redundancy within the current sacral tumor survey and make a recommendation for an updated version based on the results and patient and expert opinions.

STUDY DESIGN/SETTING

A survey study from a tertiary care orthopedic oncology referral center was used.

PATIENT SAMPLE

The patient sample included 70 patients with sacral tumors (78% chordoma).

OUTCOME MEASURES

The following 10 questionnaires included in the current sacral tumor survey were evaluated: the Patient-Reported Outcomes Measurement Information System (PROMIS) Global Item short form, PROMIS Pain Intensity short form, PROMIS Pain Interference short form, PROMIS Neuro-QOL v1.0 Lower Extremity Function short form, PROMIS v1.0 Anxiety short form, the PROMIS v1.0 Depression short form, the International Continence Society Male short form, the Modified Obstruction-Defecation Syndrome questionnaire, the PROMIS Sexual Function Profile v1.0, and the Stoma Quality of Life tool.

METHODS

We performed an exploratory factor analysis to calculate the possible underlying latent traits. Spearman rank correlation coefficients were used to measure to what extent the questionnaires converged. We hypothesized the existence of six domains based on current literature: mental health, physical health, pain, gastrointestinal symptoms, sexual function, and urinary incontinence. To assess content validity, we surveyed 32 patients, 9 orthopedic oncologists, 1 medical oncologist, 1 radiation oncologist, and 1 orthopedic oncology nurse practitioner with experience in treating sacral tumor patients on the relevance of the domains.

RESULTS

Reliability as measured by Cronbach alpha ranged from 0.65 to 0.96. Coverage measured by floor and ceiling effects ranged from 0% to 52% and from 0% to 30%, respectively. Explanatory factor analysis identified three traits to which the questionnaires that were expected to measure a similar construct correlated the most: mental health, physical function, and pain. Content validity index demonstrated low disagreement among patients (range: 0.10-0.18) and high agreement among physicians (range: 0.91-1.0) on the relevance of the proposed domains. Social health was identified by 50% of the commenting patients as an important yet missing domain.

CONCLUSIONS

The current sacral tumor survey is incomplete and time-consuming, and not all surveys are appropriate for the sacral tumor population. Our recommended survey contains less than half the questions and includes the newly recognized social health domain.

Has the Level of Evidence of Podium Presentations at the Musculoskeletal Tumor Society Annual Meeting Changed Over Time?

BACKGROUND

Level of evidence (LOE) framework is a tool with which to categorize clinical studies based on their likelihood to be influenced by bias. Improvements in LOE have been demonstrated throughout orthopaedics, prompting our evaluation of orthopaedic oncology research LOE to determine if it has changed in kind.

QUESTIONS/PURPOSES

(1) Has the LOE presented at the Musculoskeletal Tumor Society (MSTS) annual meeting improved over time? (2) Over the past decade, how do the MSTS and Orthopaedic Trauma Association (OTA) annual meetings compare regarding LOE overall and for the subset of therapeutic studies?

METHODS

We reviewed abstracts from MSTS and OTA annual meeting podium presentations from 2005 to 2014. Three independent reviewers evaluated a total of 1222 abstracts for study type and LOE; there were 577 abstracts from MSTS and 645 from OTA. Changes in the distributions of study type and LOE over time were evaluated by Pearson chi-square test.

RESULTS

There was no change over time in MSTS LOE for all study types (p = 0.13) and therapeutic (p = 0.36) study types during the reviewed decade. In contrast, OTA LOE increased over this time for all study types (p < 0.01). The proportion of Level I therapeutic studies was higher at the OTA than the MSTS (3% [14 of 413] versus 0.5% [two of 387], respectively), whereas the proportion of Level IV studies was lower at the OTA than the MSTS (32% [134 of 413] versus 75% [292 of 387], respectively) during the reviewed decade. The proportion of controlled therapeutic studies (LOE I through III) versus uncontrolled studies (LOE IV) increased over time at OTA (p < 0.021), but not at MSTS (p = 0.10).

CONCLUSIONS

Uncontrolled case series continue to dominate the MSTS scientific program, limiting progress in evidence-based clinical care. Techniques used by the OTA to improve LOE may be emulated by the MSTS. These techniques focus on broad participation in multicenter collaborations that are designed in a comprehensive manner and answer a pragmatic clinical question.

Evolution of Cancer Stem-like Cells in Endocrine-Resistant Metastatic Breast Cancers Is Mediated by Stromal Microvesicles

The hypothesis that microvesicle-mediated miRNA transfer converts noncancer stem cells into cancer stem cells (CSC) leading to therapy resistance remains poorly investigated. Here we provide direct evidence supporting this hypothesis, by demonstrating how microvesicles derived from cancer-associated fibroblasts (CAF) transfer miR-221 to promote hormonal therapy resistance (HTR) in models of luminal breast cancer. We determined that CAF-derived microvesicles horizontally transferred miR-221 to tumor cells and, in combination with hormone therapy, activated an ER^lo/Notch^hi feed-forward loop responsible for the generation of CD133^hi CSCs. Importantly, microvesicles from patients with HTR metastatic disease expressed high levels of miR-221. We further determined that the IL6-pStat3 pathway promoted the biogenesis of onco-miR-221^hi CAF microvesicles and established stromal CSC niches in experimental and patient-derived breast cancer models. Coinjection of patient-derived CAFs from bone metastases led to de novo HTR tumors, which was reversed with IL6R blockade. Finally, we generated patient-derived xenograft (PDX) models from patient-derived HTR bone metastases and analyzed tumor cells, stroma, and microvesicles. Murine and human CAFs were enriched in HTR tumors expressing high levels of CD133^hi cells. Depletion of murine CAFs from PDX restored sensitivity to HT, with a concurrent reduction of CD133^hi CSCs. Conversely, in models of CD133^neg, HT-sensitive cancer cells, both murine and human CAFs promoted de novo HT resistance via the generation of CD133^hi CSCs that expressed low levels of estrogen receptor alpha. Overall, our results illuminate how microvesicle-mediated horizontal transfer of genetic material from host stromal cells to cancer cells triggers the evolution of therapy-resistant metastases, with potentially broad implications for their control. Cancer Res; 77(8); 1927-41. ©2017 AACR.

Direct Repair of the Superior Band of Bigelow's Ligament After Hip Arthroplasty: a Surgical Technique

BACKGROUND

The posterolateral approach is one of the most common approaches used during hip arthroplasty. A posterior soft tissue repair is necessary to limit the risk of postoperative dislocation. For a trapezoidal capsulotomy, the proximal limb divides the superior band of the iliofemoral ligament (Bigelow's ligament). A transosseous repair frequently leaves a defect in this region, which may elevate the risk for dislocation. The purpose of this article is to describe a simple, rational technique for reinforcing the posterior capsular repair.

DESCRIPTION OF TECHNIQUE

A meticulous exposure of the hip capsule is performed during the posterolateral surgical approach. A trapezoidal capsulotomy is performed. After implantation of the arthroplasty implants, retractors are placed to expose the superior capsule. Prior to transosseous repair of the capsule and short external rotator tendons, the proximal limb of the capsulotomy is reapproximated anatomically and repaired with non-absorbable sutures. If anatomical repair is not possible, leg length and femoral offset should be reassessed carefully.

DISCUSSION

The described modification may further minimize the risk of dislocation following hip arthroplasty, as the superior band of Bigelow's ligament is an additional checkrein to internal and external rotation. This repair provides a secondary intraoperative assessment of leg length and femoral offset to ensure proper biomechanical reconstruction of the hip joint. It is the authors' preferred technique of all hip hemiarthroplasties and total hip arthroplasties, whenever possible.

Local Control Modality and Outcome for Ewing Sarcoma of the Femur: A Report From the Children's Oncology Group

BACKGROUND

The choice of a local control (LC) modality for Ewing sarcoma (EWS) of the femur is controversial. This study aimed to determine the effect of LC modality on tumor LC and patient outcomes.

METHODS

The study reviewed the treatment and outcomes for 115 patients who had EWS of the femur treated with similar chemotherapy in three cooperative group trials. Patient outcomes were analyzed according to the LC modality using the log-rank test and the cumulative incidence of local or distant failure using competing risks regression.

RESULTS

The median age of the patients was 13 years. The most common tumor location was the proximal femur followed by the mid femur. For 55 patients with available data, the tumor was larger than 8 cm in 29 patients and 8 cm or smaller in 26 patients. For 84 patients (73 %), surgery only was performed, whereas 17 patients (15 %) had surgery plus radiation, and 14 patients (12 %) had radiation only. The 5-year event-free survival (EFS) rate was 65 % (95 % confidence interval [CI], 55-73 %), and the 5-year overall survival (OS) rate was 70 % (95 % CI, 61-78 %). Patient outcomes did not differ significantly according to tumor location within the femur (proximal, mid or distal) or tumor size (<8 vs ≥8 cm). The findings showed no statistically significant differences in EFS, OS, cumulative incidence of local failure, or cumulative incidence of distant failure according to LC modality (surgery, surgery plus radiation, or radiation).

CONCLUSIONS

The LC modality did not significantly affect disease outcome for EWS of the femur. Further study of treatment complications and functional outcome may help to define the optimal LC modality.

Ga-68 DOTATOC PET/CT-Guided Biopsy and Cryoablation with Autoradiography of Biopsy Specimen for Treatment of Tumor-Induced Osteomalacia

Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome caused by small benign tumors of mesenchymal origin also known as phosphaturic mesenchymal tumors mixed connective tissue variant. Excellent prognosis is expected with eradication of the culprit tumor. These small tumors are notoriously difficult to localize with conventional imaging studies; this often leads to an extensive work up and prolonged morbidity. We report a patient with clinical diagnosis of TIO whose culprit tumor was localized with Ga-68 DOTATOC PET/CT and MRI. Biopsy and cryoablation were performed under Ga-68 DOTATOC PET/CT guidance. Autoradiography of the biopsy specimen was performed and showed in situ correlation between Ga-68 DOTATOC uptake and histopathology with millimeter resolution.

Patient-reported Symptoms of Tenosynovial Giant Cell Tumors

Purpose

Tenosynovial giant cell tumor (TGCT), a rare locally aggressive neoplasm of the synovium of joints and tendon sheaths, is associated with joint destruction, inflammation, pain, and swelling, in part due to colony-stimulating factor 1 receptor–bearing macrophages recruited to the tumor by genetic elevation of colony-stimulating factor 1 activity. The most common treatment is surgery, although promising pharmacologic treatments are in development. Patient-reported outcome (PRO) instruments are critical end points in demonstrating the clinical relevance of standard oncologic outcome measures and the overall impact of novel pharmacologic therapies in nonmalignant neoplastic conditions such as TGCT. The content validity of PROs relevant to patients with TGCT has not been formally investigated, and instruments to evaluate such outcomes do not exist for this condition.

Methods

PRO instruments of potential relevance were evaluated by using a literature review and by clinical and PRO experts. Patients with TGCT were recruited through clinical sites and the Internet for participation in qualitative research interviews to identify predominant symptoms and to test the relevance and content validity of several PRO measures. Select PRO measures were included in a Phase I clinical trial, and preliminary results of the PRO end points are reported descriptively.

Findings

Of the 22 subjects who participated in qualitative interviews, 73% were female, and their mean age was 42.5 years (range, 27–56 years). The TGCTs (19 diffuse and 3 localized) were located in the knee (n = 15), hip (n = 3), ankle (n = 2), elbow (n= 1), and forearm (n = 1). The most common symptoms cited were pain (82%), swelling (86%), stiffness (73%), reduced range of motion (64%), and joint instability (64%), which were consistent with clinical expert input and with the content of instruments chosen by PRO experts. The worst pain numeric rating scale, Patient Reported Outcomes Measurement Information System physical functioning items, and the Western Ontario and McMaster Universities Osteoarthritis Index, as well as a worst stiffness numeric rating scale developed for TGCT, were confirmed as meaningful measures of TGCT patient symptoms and were well understood in qualitative interviews. Results from the Phase I trial showed trends of improvement in both pain and stiffness over time.

Implications

This study is the first to gather information directly from patients with TGCT regarding their symptom experiences. Pain, stiffness, and physical functioning are important treatment outcomes in patients with TGCT. We have identified content-valid PRO measures of these concepts, which are included in an ongoing Phase III TGCT clinical trial with pexidartinib (PLX3397) (NCT02371369).

Self-renewal of CD133(hi) cells by IL6/Notch3 signalling regulates endocrine resistance in metastatic breast cancer

The mechanisms of metastatic progression from hormonal therapy (HT) are largely unknown in luminal breast cancer. Here we demonstrate the enrichment of CD133^hi/ER^lo cancer cells in clinical specimens following neoadjuvant endocrine therapy and in HT refractory metastatic disease. We develop experimental models of metastatic luminal breast cancer and demonstrate that HT can promote the generation of HT-resistant, self-renewing CD133^hi/ER^lo/IL6^hi cancer stem cells (CSCs). HT initially abrogates oxidative phosphorylation (OXPHOS) generating self-renewal-deficient cancer cells, CD133^hi/ER^lo/OXPHOS^lo. These cells exit metabolic dormancy via an IL6-driven feed-forward ER^lo-IL6^hi-Notch^hi loop, activating OXPHOS, in the absence of ER activity. The inhibition of IL6R/IL6-Notch pathways switches the self-renewal of CD133^hi CSCs, from an IL6/Notch-dependent one to an ER-dependent one, through the re-expression of ER. Thus, HT induces an OXPHOS metabolic editing of luminal breast cancers, paradoxically establishing HT-driven self-renewal of dormant CD133^hi/ER^lo cells mediating metastatic progression, which is sensitive to dual targeted therapy.

ER⁺ breast cancer patients treated with endocrine therapies often acquire resistance and develop metastasis. In this study, the authors demonstrate that endocrine therapies can promote the self-renewal of CD133^hi/ER^lo drug resistant cells with metastatic potential driven through the IL6-Notch3 axis activation.

Revision Distal Femoral Arthroplasty With the Compress(®) Prosthesis Has a Low Rate of Mechanical Failure at 10 Years

BACKGROUND

Patients with failed distal femoral megaprostheses often have bone loss that limits reconstructive options and contributes to the high failure rate of revision surgery. The Compress(®) Compliant Pre-stress (CPS) implant can reconstruct the femur even when there is little remaining bone. It differs from traditional stemmed prostheses because it requires only 4 to 8 cm of residual bone for fixation. Given the poor long-term results of stemmed revision constructs, we sought to determine the failure rate and functional outcomes of the CPS implant in revision surgery.

QUESTIONS/PURPOSES

(1) What is the cumulative incidence of mechanical and other types of implant failure when used to revise failed distal femoral arthroplasties placed after oncologic resection? (2) What complications are characteristic of this prosthesis? (3) What function do patients achieve after receiving this prosthesis?

METHODS

We retrospectively reviewed 27 patients who experienced failure of a distal femoral prosthesis and were revised to a CPS implant from April 2000 to February 2013. Indications for use included a minimum 2.5 mm cortical thickness of the remaining proximal femur, no prior radiation, life expectancy > 10 years, and compliance with protected weightbearing for 3 months. The cumulative incidence of failure was calculated for both mechanical (loss of compression between the implant anchor plug and spindle) and other failure modes using a competing risk analysis. Failure was defined as removal of the CPS implant. Followup was a minimum of 2 years or until implant removal. Median followup for patients with successful revision arthroplasty was 90 months (range, 24-181 months). Functional outcomes were measured with the Musculoskeletal Tumor Society (MSTS) functional assessment score.

RESULTS

The cumulative incidence of mechanical failure was 11% (95% confidence interval [CI], 4%-33%) at both 5 and 10 years. These failures occurred early at a median of 5 months. The cumulative incidence of other failures was 18% (95% CI, 7%-45%) at 5 and 10 years, all of which were deep infection. Three patients required secondary operations for cortical insufficiency proximal to the anchor plug in bone not spanned by the CPS implant and unrelated to the prosthesis. Median MSTS score was 27 (range, 24-30).

CONCLUSIONS

Revision distal femoral replacement arthroplasty after a failed megaprosthesis is often difficult as a result of a lack of adequate bone. Reconstruction with the CPS implant has an 11% failure rate at 10 years. Our results are promising and demonstrate the durable fixation provided by the CPS implant. Further studies to compare the CPS prosthesis and other reconstruction options with respect to survival and functional outcomes are warranted.

LEVEL OF EVIDENCE

Level IV, therapeutic study.