RAF inhibitors that evade paradoxical MAPK pathway activation.

Oncogenic activation of BRAF fuels cancer growth by constitutively promoting RAS-independent mitogen-activated protein kinase (MAPK) pathway signalling. Accordingly, RAF inhibitors have brought substantially improved personalized treatment of metastatic melanoma. However, these targeted agents have also revealed an unexpected consequence: stimulated growth of certain cancers. Structurally diverse ATP-competitive RAF inhibitors can either inhibit or paradoxically activate the MAPK pathway, depending whether activation is by BRAF mutation or by an upstream event, such as RAS mutation or receptor tyrosine kinase activation. Here we have identified next-generation RAF inhibitors (dubbed 'paradox breakers') that suppress mutant BRAF cells without activating the MAPK pathway in cells bearing upstream activation. In cells that express the same HRAS mutation prevalent in squamous tumours from patients treated with RAF inhibitors, the first-generation RAF inhibitor vemurafenib stimulated in vitro and in vivo growth and induced expression of MAPK pathway response genes; by contrast the paradox breakers PLX7904 and PLX8394 had no effect. Paradox breakers also overcame several known mechanisms of resistance to first-generation RAF inhibitors. Dissociating MAPK pathway inhibition from paradoxical activation might yield both improved safety and more durable efficacy than first-generation RAF inhibitors, a concept currently undergoing human clinical evaluation with PLX8394.

Pexidartinib versus placebo for advanced tenosynovial giant cell tumour (ENLIVEN): a randomised phase 3 trial.

BACKGROUND: Tenosynovial giant cell tumour (TGCT), a rare, locally aggressive neoplasm, overexpresses colony-stimulating factor 1 (CSF1). Surgery is standard with no approved systemic therapy. We aimed to evaluate pexidartinib, a CSF1 receptor inhibitor, in patients with TGCT to provide them with a viable systemic treatment option, especially in cases that are not amenable to surgical resection. METHODS: This phase 3 randomised trial had two parts. Part one was a double-blind study in which patients with symptomatic, advanced TGCT for whom surgery was not recommended were randomly assigned via an integrated web response system (1:1) to the pexidartinib or placebo group. Individuals in the pexidartinib group received a loading dose of 1000 mg pexidartinib per day orally (400 mg morning; 600 mg evening) for the first 2 weeks, followed by 800 mg per day (400 mg twice a day) for 22 weeks. Part two was an open-label study of pexidartinib for all patients. The primary endpoint, assessed in all intention-to-treat patients, was overall response at week 25, and was centrally reviewed by RECIST, version 1.1. Safety was analysed in all patients who received at least one dose of the study drug. This study is registered with ClinicalTrials.gov, number NCT02371369. FINDINGS: Between May 11, 2015, and Sept 30, 2016, of 174 patients assessed for eligibility, 120 patients were randomly assigned to, and received, pexidartinib (n=61) or placebo (n=59). There were 11 dropouts in the placebo group and nine in the pexidartinib group. Emergence of mixed or cholestatic hepatotoxicity caused the data monitoring committee to stop enrolment six patients short of target. The proportion of patients who achieved overall response was higher for pexidartinib than placebo at week 25 by RECIST (24 [39%] of 61 vs none of 59; absolute difference 39% [95% CI 27-53]; p<0·0001). Serious adverse events occurred in eight (13%) of 61 patients in the pexidartinib group and one (2%) of 59 patients in the placebo group. Hair colour changes (67%), fatigue (54%), aspartate aminotransferase increase (39%), nausea (38%), alanine aminotransferase increase (28%), and dysgeusia (25%) were the most frequent pexidartinib-associated adverse events. Three patients given pexidartinib had aminotransferase elevations three or more times the upper limit of normal with total bilirubin and alkaline phosphatase two or more times the upper limit of normal indicative of mixed or cholestatic hepatotoxicity, one lasting 7 months and confirmed by biopsy. INTERPRETATION: Pexidartinib is the first systemic therapy to show a robust tumour response in TGCT with improved patient symptoms and functional outcomes; mixed or cholestatic hepatotoxicity is an identified risk. Pexidartinib could be considered as a potential treatment for TGCT associated with severe morbidity or functional limitations in cases not amenable to improvement with surgery. FUNDING: Daiichi Sankyo.

Structure-Guided Blockade of CSF1R Kinase in Tenosynovial Giant-Cell Tumor.

BACKGROUND: Expression of the colony-stimulating factor 1 (CSF1) gene is elevated in most tenosynovial giant-cell tumors. This observation has led to the discovery and clinical development of therapy targeting the CSF1 receptor (CSF1R). METHODS: Using x-ray co-crystallography to guide our drug-discovery research, we generated a potent, selective CSF1R inhibitor, PLX3397, that traps the kinase in the autoinhibited conformation. We then conducted a multicenter, phase 1 trial in two parts to analyze this compound. In the first part, we evaluated escalations in the dose of PLX3397 that was administered orally in patients with solid tumors (dose-escalation study). In the second part, we evaluated PLX3397 at the chosen phase 2 dose in an extension cohort of patients with tenosynovial giant-cell tumors (extension study). Pharmacokinetic and tumor responses in the enrolled patients were assessed, and CSF1 in situ hybridization was performed to confirm the mechanism of action of PLX3397 and that the pattern of CSF1 expression was consistent with the pathological features of tenosynovial giant-cell tumor. RESULTS: A total of 41 patients were enrolled in the dose-escalation study, and an additional 23 patients were enrolled in the extension study. The chosen phase 2 dose of PLX3397 was 1000 mg per day. In the extension study, 12 patients with tenosynovial giant-cell tumors had a partial response and 7 patients had stable disease. Responses usually occurred within the first 4 months of treatment, and the median duration of response exceeded 8 months. The most common adverse events included fatigue, change in hair color, nausea, dysgeusia, and periorbital edema; adverse events rarely led to discontinuation of treatment. CONCLUSIONS: Treatment of tenosynovial giant-cell tumors with PLX3397 resulted in a prolonged regression in tumor volume in most patients. (Funded by Plexxikon; ClinicalTrials.gov number, NCT01004861.).

Clinical efficacy of a RAF inhibitor needs broad target blockade in BRAF-mutant melanoma.

B-RAF is the most frequently mutated protein kinase in human cancers. The finding that oncogenic mutations in BRAF are common in melanoma, followed by the demonstration that these tumours are dependent on the RAF/MEK/ERK pathway, offered hope that inhibition of B-RAF kinase activity could benefit melanoma patients. Herein, we describe the structure-guided discovery of PLX4032 (RG7204), a potent inhibitor of oncogenic B-RAF kinase activity. Preclinical experiments demonstrated that PLX4032 selectively blocked the RAF/MEK/ERK pathway in BRAF mutant cells and caused regression of BRAF mutant xenografts. Toxicology studies confirmed a wide safety margin consistent with the high degree of selectivity, enabling Phase 1 clinical trials using a crystalline formulation of PLX4032 (ref. 5). In a subset of melanoma patients, pathway inhibition was monitored in paired biopsy specimens collected before treatment initiation and following two weeks of treatment. This analysis revealed substantial inhibition of ERK phosphorylation, yet clinical evaluation did not show tumour regressions. At higher drug exposures afforded by a new amorphous drug formulation, greater than 80% inhibition of ERK phosphorylation in the tumours of patients correlated with clinical response. Indeed, the Phase 1 clinical data revealed a remarkably high 81% response rate in metastatic melanoma patients treated at an oral dose of 960 mg twice daily. These data demonstrate that BRAF-mutant melanomas are highly dependent on B-RAF kinase activity.

A Novel Motion-Preservation Technique for Intra and Intra-Intersegmental Repair of Spondylolysis and Spondylolisthesis: The Lin Technique.

OBJECTIVE: A novel motion-preserving technique to directly repair pars defects. Moreover, the indications for repair are expanded to include those with disc disease and associated spondylolisthesis. SUMMARY OF BACKGROUND DATA: The challenge in treating pars defects has been that there are few techniques available to stabilize them adequately. Treatment has focused on fusion across the inter-space versus grafting and instrumentation of the defect itself. We hypothesize that direct repair of the defect favors maintenance of normal motion characteristics by preserving the functional unit of the disc. This paper describes a motion-preserving technique to repair bilateral pars defects and its early clinical outcomes. MATERIALS AND METHODS: A retrospective review of 20 patients with symptomatic bilateral pars defects treated with either intra-segmental or intra-intersegmental motion-preserving repair with two years of follow-up. Fifteen patients met the criteria for single level fixation. Five patients required additional fixation of flexible posterolateral fusion involving the inferior segment. Rh-BMP and autologous bone graft were placed within the defect. Plain film X-rays were used to determine stability, and thin-section CT was used to assess healing of the defect. RESULTS: The procedure arrested any further slippage in 100% of cases, with bony healing in 95% of cases as demonstrated by CT scan. Clinical outcomes for the entire series were: excellent n=14, good n=3, no significant help n=3. For all cases there was a 5% rate of non-union. CONCLUSION: Further study and development of the technique via biomechanical testing is ongoing; however, the initial results are encouraging. Bone formation appears to be linked to decreasing symptoms in patients with bilateral pars fractures who have failed conservative treatment.

Cervical conization of adenocarcinoma in situ: a predicting model of residual disease.

OBJECTIVE: To determine factors associated with the presence of residual disease in women who have undergone cervical conization for adenocarcinoma in situ (ACIS) of the cervix. STUDY DESIGN: We identified women who underwent a cervical conization for a diagnosis of ACIS followed by repeat conization or hysterectomy between Jan. 1, 1995, and April 30, 2010. Data were summarized using standard descriptive statistics. RESULTS: Seventy-eight patients met study criteria. The presence of ACIS at the internal conization margin or in the postconization endocervical curettage (ECC) correlated with residual ACIS (P < .001). A margin positive for ACIS was associated with residual glandular neoplasia in 68% of cases. An endocervical curettage positive for ACIS was associated with residual ACIS in 95% of cases. If both the margins and the endocervical curettage were positive for the presence of ACIS, 8% did not have residual disease, 77% had residual ACIS, and 15% had invasive adenocarcinoma. If both the internal conization margin and the postconization ECC were negative for the presence of ACIS, 14% of the final specimens had residual ACIS and none had invasive cancer. CONCLUSION: The addition of postconization ECC to cone biopsy for ACIS of the cervix provides valuable prognostic information regarding the risk of residual ACIS. Women with ACIS who have both a negative postconization ECC and a negative conization margin have a 14% risk for residual ACIS and can be treated conservatively if desiring fertility. A positive postconization ECC or internal margin incurs significant risk of residual disease and 12-17% will have cancer.

Results from Phase I Extension Study Assessing Pexidartinib Treatment in Six Cohorts with Solid Tumors including TGCT, and Abnormal CSF1 Transcripts in TGCT.

PURPOSE: To assess the response to pexidartinib treatment in six cohorts of adult patients with advanced, incurable solid tumors associated with colony-stimulating factor 1 receptor (CSF1R) and/or KIT proto-oncogene receptor tyrosine kinase activity. PATIENTS AND METHODS: From this two-part phase I, multicenter study, pexidartinib, a small-molecule tyrosine kinase inhibitor that targets CSF1R, KIT, and FMS-like tyrosine kinase 3 (FLT3), was evaluated in six adult patient cohorts (part 2, extension) with advanced solid tumors associated with dysregulated CSF1R. Adverse events, pharmacokinetics, and tumor responses were assessed for all patients; patients with tenosynovial giant cell tumor (TGCT) were also evaluated for tumor volume score (TVS) and patient-reported outcomes (PRO). CSF1 transcripts and gene expression were explored in TGCT biopsies. RESULTS: Ninety-one patients were treated: TGCT patients (n = 39) had a median treatment duration of 511 days, while other solid tumor patients (n = 52) had a median treatment duration of 56 days. TGCT patients had response rates of 62% (RECIST 1.1) and 56% (TVS) for the full analysis set. PRO assessments for pain showed improvement in patient symptoms, and 76% (19/25) of TGCT tissue biopsy specimens showed evidence of abnormal CSF1 transcripts. Pexidartinib treatment of TGCT resulted in tumor regression and symptomatic benefit in most patients. Pexidartinib toxicity was manageable over the entire study. CONCLUSIONS: These results offer insight into outcome patterns in cancers whose biology suggests use of a CSF1R inhibitor. Pexidartinib results in tumor regression in TGCT patients, providing prolonged control with an acceptable safety profile.

Targeting BRAFV600E with PLX4720 displays potent antimigratory and anti-invasive activity in preclinical models of human thyroid cancer.

PURPOSE: B-Raf(V600E) may play a role in the progression from papillary thyroid cancer to anaplastic thyroid cancer (ATC). We tested the effects of a highly selective B-Raf(V600E) inhibitor, PLX4720, on proliferation, migration, and invasion both in human thyroid cancer cell lines (8505c(B-RafV600E) and TPC-1(RET/PTC-1 and wild-type B-Raf)) and in primary human normal thyroid (NT) follicular cells engineered with or without B-Raf(V600E). EXPERIMENTAL DESIGN: Large-scale genotyping analysis by mass spectrometry was performed in order to analyze >900 gene mutations. Cell proliferation and migration/invasion were performed upon PLX4720 treatment in 8505c, TPC-1, and NT cells. Orthotopic implantation of either 8505c or TPC-1 cells into the thyroid of severe combined immunodeficient mice was performed. Gene validations were performed by quantitative polymerase chain reaction and immunohistochemistry. RESULTS: We found that PLX4720 reduced in vitro cell proliferation and migration and invasion of 8505c cells, causing early downregulation of genes involved in tumor progression. PLX4720-treated NT cells overexpressing B-Raf(V600E) (heterozygous wild-type B-Raf/B-Raf(V600E)) showed significantly lower cell proliferation, migration, and invasion. PLX4720 treatment did not block cell invasion in TPC-1 cells with wild-type B-Raf, which showed very low and delayed in vivo tumor growth. In vivo, PLX4720 treatment of 8505c orthotopic thyroid tumors inhibited tumor aggressiveness and significantly upregulated the thyroid differentiation markers thyroid transcription factor 1 and paired box gene 8. CONCLUSIONS: Here, we have shown that PLX4720 preferentially inhibits migration and invasion of B-Raf(V600E) thyroid cancer cells and tumor aggressiveness. Normal thyroid cells were generated to be heterozygous for wild-type B-Raf/B-Raf(V600E), mimicking the condition found in most human thyroid cancers. PLX4720 was effective in reducing cell proliferation, migration, and invasion in this heterozygous model. PLX4720 therapy should be tested and considered for a phase I study for the treatment of patients with B-Raf(V600E) ATC.

Role of robotic surgery in endometrial cancer.

OPINION STATEMENT: Uterine cancer is the most common gynecologic cancer in women in the United States with an estimated number of 40,100 women diagnosed in 2008, the great majority of which belongs to endometrial classification. The traditional approach to treatment of endometrial cancer has been primarily surgery via an open, laparotomy incision. Minimally invasive approaches with smaller incisions, i.e., laparoscopy for the management of endometrial cancer was initially reported in 1992; however, its adoption has been slow due to the prolonged learning curve needed to become proficient in such a technique. Robotic-assisted surgery, a further advancement of traditional laparoscopy, using computer-based controls has been developed enabling the performance of complex procedures that otherwise had been too difficult to accomplish in a minimally invasive fashion. Robotic-assisted laparoscopic radical prostatectomy is one such example that has gained rapid acceptance in recent years. Although the use of robotic-assisted laparoscopy for endometrial cancer is still in its early phase, this approach is anticipated to become similarly, a common approach to the management of endometrial cancer in the future.

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.

Indications and efficacy of the human papillomavirus vaccine.

In the United States, there are 11,150 cases and 3670 deaths projected due to invasive cervical cancer for 2007. Approximately 500,000 new cases and 274,000 deaths will occur in women throughout the world. Human papillomavirus (HPV) has been designated by the World Health Organization (WHO) as a "necessary cause" of cervical cancer. There are 6.2 million new cases of HPV diagnosed each year. In addition to cervical cancer, the virus has also been implicated in vaginal, vulvar, penile, anal, and head and neck cancers. Current methods for prevention of cervical cancer include Pap smears, HPV testing, ablative procedures, cervical conization, and hysterectomy. These are costly as well as invasive. The HPV vaccine is the most recent breakthrough for the prevention of cervical cancer. The quadrivalent HPV vaccine (Gardasil) covers types 6, 11, 16, & 18. The bivalent vaccine (Cervarix) covers types 16 & 18, and is expected to come out in the early part of 2007. Approximately 70% of cervical cancer is caused by HPV types 16 & 18. HPV types 6 &11 are responsible for 90% of anogenital warts. Females of ages 11-12 and those prior to their sexual debut should be vaccinated, with all females in the age range of 9-26 also eligible. This vaccination strategy can prevent the above HPV infections, cervical dysplasia, and possibly cervical cancer.

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).

Targeting cells of the myeloid lineage attenuates pain and disease progression in a prostate model of bone cancer.

Tumor cells frequently metastasize to bone where they can generate cancer-induced bone pain (CIBP) that can be difficult to fully control using available therapies. Here, we explored whether PLX3397, a high-affinity small molecular antagonist that binds to and inhibits phosphorylation of colony-stimulating factor-1 receptor, the tyrosine-protein kinase c-Kit, and the FMS-like tyrosine kinase 3, can reduce CIBP. These 3 targets all regulate the proliferation and function of a subset of the myeloid cells including macrophages, osteoclasts, and mast cells. Preliminary experiments show that PLX3397 attenuated inflammatory pain after formalin injection into the hind paw of the rat. As there is an inflammatory component in CIBP, involving macrophages and osteoclasts, the effect of PLX3397 was explored in a prostate model of CIBP where skeletal pain, cancer cell proliferation, tumor metastasis, and bone remodeling could be monitored in the same animal. Administration of PLX3397 was initiated on day 14 after prostate cancer cell injection when the tumor was well established, and tumor-induced bone remodeling was first evident. Over the next 6 weeks, sustained administration of PLX3397 attenuated CIBP behaviors by approximately 50% and was equally efficacious in reducing tumor cell growth, formation of new tumor colonies in bone, and pathological tumor-induced bone remodeling. Developing a better understanding of potential effects that analgesic therapies have on the tumor itself may allow the development of therapies that not only better control the pain but also positively impact disease progression and overall survival in patients with bone cancer.

Long-term outcome in BRAF(V600E) melanoma patients treated with vemurafenib: Patterns of disease progression and clinical management of limited progression.

INTRODUCTION: Vemurafenib induces tumour regression in most patients with BRAF(V600E)-mutant melanoma; eventually, most experience progressive disease (PD). Long-term follow-up of patients with BRAF(V600E) melanoma treated in the phase 1 vemurafenib trial is reported. METHODS: Patients received vemurafenib 240-1120 mg (dose escalation cohort) or 960 mg (extension cohort) orally twice daily. Clinical response was evaluated every 8 weeks by Response Evaluation Criteria In Solid Tumors (RECIST). Patients with PD amenable to local therapy (surgery or radiotherapy) were allowed to continue vemurafenib after progression. Overall survival (OS) from time of treatment initiation and from PD was estimated. Sites of PD were recorded. RESULTS: Forty-eight patients (escalation cohort, n = 16; extension cohort, n = 32) received therapeutic doses of vemurafenib (⩾ 240 mg twice daily). Forty-four patients had PD by the time of this analysis and four remained progression free (follow-up time, 1.2-56.1 months). Median OS was 14 months (range, 1.2-56.1); 3- and 4-year melanoma-specific survival rate in the extension cohort was 26% and 19%, respectively. Median OS was 26.0 months (range, 7.7-56.1) among 20 patients who continued vemurafenib after local therapy. Median treatment duration beyond initial PD was 3.8 months (range, 1.1-26.6). In the extension cohort, six and five patients were alive after 3 and 4 years, respectively, on vemurafenib monotherapy. CONCLUSIONS: Some patients with melanoma achieved long-term survival with vemurafenib monotherapy. Continuation of vemurafenib after PD might be beneficial in some patients because remaining disease might continue to respond to BRAF inhibition.

The role of cytoreductive/debulking surgery in ovarian cancer.

Ovarian cancer is the fifth most common cause of cancer-related death among women in the United States, although the median survival of patients has been increasing over the past few decades. In patients with epithelial ovarian cancer, chemotherapy has increased survival. Platinum agents combined with taxanes have become standard treatment. Intraperitoneal chemotherapy has also increased survival. Cytoreductive surgery to optimally debulk a tumor or, ideally, remove any gross disease has also been shown to increase survival. Each 10% increase in cytoreduction correlates with a 5.5% increase in median survival. The ability to successfully perform optimal cytoreduction ranges from 20% to 90%. Many institutions have recently begun to perform aggressive/ultraradical procedures to achieve this result. Interval cytoreduction may also benefit patients whose initial surgery is suboptimal, especially if the first procedure was performed by a surgeon unfamiliar with the disease. Secondary cytoreduction can increase survival in patients with low-volume disease and a long disease-free interval. All of these procedures should be performed by a specialist trained in ovarian cancer surgery.