Current and future targeted alpha particle therapies for osteosarcoma: Radium-223, actinium-225, and thorium-227

Osteosarcoma is a high-grade sarcoma characterized by osteoid formation, nearly universal expression of IGF1R and with a subset expressing HER-2. These qualities provide opportunities for the use of the alpha particle-emitting isotopes to provide targeted radiation therapy via alpha particles precisely to bone-forming tumors in addition to IFG1R or Her-2 expressing metastases. This review will detail experience using the alpha emitter radium-223 (²²³Ra, tradename Xofigo), that targets bone formation, in osteosarcoma, specifically related to patient selection, use of gemcitabine for radio-sensitization, and using denosumab to increasing the osteoblastic phenotype of these cancers. A case of an inoperable left upper lobe vertebral-paraspinal-mediastinal osteoblastic lesion treated successfully with ²²³Ra combined with gemcitabine is described. Because not all areas of osteosarcoma lesions are osteoblastic, but nearly all osteosarcoma cells overexpress IGF1R, and some subsets expressing Her-2, the anti-IGF1R antibody FPI-1434 linked to actinium-225 (²²⁵Ac) or the Her-2 antibody linked to thorium-227 (²²⁷Th) may become other means to provide targeted alpha particle therapy against osteosarcoma (NCT03746431 and NCT04147819).

Phase II trial of gemcitabine and nab-paclitaxel for recurrent osteosarcoma: A report from the National Pediatric Cancer Foundation

10042

Background: The combination of gemcitabine and docetaxel is often used to treat patients with recurrent osteosarcoma. A retrospective study of 35 such patients has reported an objective response rate of 17% and 4-month progression-free survival (PFS) of 56% with this combination (BMC Cancer 2016;16:280). Nab-paclitaxel is a nanoparticle taxane that has activity against osteosarcoma xenografts and may have less myelosuppression than docetaxel. The combination of gemcitabine and nab-paclitaxel is now frontline therapy for pancreatic cancer. We conducted a prospective multi-institutional phase II trial of this drug combination for patients with recurrent osteosarcoma. Methods: Patients with relapsed/refractory osteosarcoma with measurable disease and age ≥ 12 years and adequate organ function were included. A Simon’s two-stage design was used to identify a 4-month progression-free survival (PFS) of > 35%. Patients received nab-paclitaxel 125 mg/m2 and gemcitabine 1000 mg/m2 weekly x 3 in 4-week cycles. Results: Eighteen patients with a median age 16 years (range 12- 26) received a total of 56 total cycles.(median 2, range 1 - 12). The median number of prior treatment regimens was 3 (range 1-7). Two patients (11%) experienced a partial response, and 6 (33%) received more than 2 cycles. The 4-month PFS was 30% (95% CI 14-62 %). Six patients required dose reductions for neutropenia (n = 4), pleural effusion (1), or neuropathy (1). Two patients were removed from study secondary to neutropenia despite dose reduction and myeloid growth factor support, and one patient came off study due to severe peripheral edema. Conclusions: In this prospective study, the combination of gemcitabine and nab-paclitaxel administered on this schedule showed only limited activity for patients with heavily pretreated recurrent osteosarcoma. Toxicity led to dose modifications in 33% and discontinuation in 17% of patients. When compared to a historical retrospective study, the substitution of nab-paclitaxel for docetaxel did not appear to increase activity or decrease toxicity for this patient population. Clinical trial information: NCT02945800.

Phase 1/2 study of devimistat in combination with hydroxychloroquine (HCQ) in patients with relapsed or refractory (R/R) clear cell sarcoma (CCS)

TPS11595

Background: CCS of the soft tissues is a rare and aggressive subtype of sarcoma that often starts in the tendons of the arms or legs. It is molecularly characterized by t(12;22)(q13;q12) translocation, resulting in EWSR1-ATF1 or EWSR1-CREB1 gene fusion. Despite reports of occasional responses to systemic therapies, currently available therapies have shown limited efficacy in advanced CCS. Therefore, there is a significant unmet medical need for more active agents in CCS. Devimistat is a stable intermediate of a lipoate analog that inhibits pyruvate dehydrogenase and α-ketoglutarate dehydrogenase enzymes of the tricarboxylic acid (TCA) cycle preferentially within the mitochondria of cancer cells. Devimistat induces autophagy in cancer cells. In a metastatic mouse model of CCS, treatment with devimistat in combination with chloroquine significantly suppressed tumor growth (Egawa et al, 2018). Based on this data, we hypothesized that inhibition of autophagy with HCQ may sensitize cancer cells to devimistat with increased efficacy and acceptable toxicity. Given its expected synergy, we have initiated a single-arm phase I/II prospective, multicenter, open-label, non-randomized study to evaluate maximally tolerated dose (MTD), safety, and efficacy of devimistat in combination with HCQ in patients with R/R CCS. Methods: In the phase 1 portion of the study, patients with R/R CCS and other fusion-positive R/R sarcomas will be enrolled and a standard 3+3 design will be followed to evaluate toxicity, MTD, and recommended phase 2 dose. There will be two patient groups based on weight, and dose escalation will be conducted separately for each group. Starting dose of HCQ will be 5mg/kg PO BID for patients < 45 kg and 200 mg PO BID for patients ≥45 kg on days 1 through 5 of every 28 days. The first dose of HCQ each day will be followed 2 hours later by 1,000 mg/m2 devimistat (for patients < 45 kg) and 2,000 mg/m2 of devimistat (for patients ≥ 45 kg) administered over 2 hours. A maximum of 36 patients will be enrolled for the phase I portion, 18 for each patient group. In the phase 2 portion of the study, only relapsed or refractory CCS patients will be enrolled, and the response rate will be determined using RECIST 1.1. In phase 2, pharmacokinetics, duration of response, clinical benefit rate, progression-free survival, overall survival, safety, and patient-reported outcomes will also be assessed. This portion of the study will utilize Simon’s admissible two-stage design with 29 patients. This study started enrolling participants in November 2021 and has dosed six patients to date. The first two dose-escalation cohorts for patients ≥45 kg have been completed without DLT and the third dose level will be opening shortly. Clinical trial information: NCT04593758.

Phase II Study of ONC201 in Neuroendocrine Tumors including Pheochromocytoma-Paraganglioma and Desmoplastic Small Round Cell Tumor

PURPOSE

Tumor dopamine-like DRD2 receptor expression is higher in pheochromocytoma-paraganglioma (PC-PG) compared with other cancers. ONC201 is a bitopic DRD2 antagonist with preclinical ONC201 activity in desmoplastic small round cell tumor (DSRCT).

PATIENTS AND METHODS

Patients (N = 30) with neuroendocrine tumors were treated on this investigator-initiated trial (NCT03034200). ONC201 dose and schedule were 625 mg orally weekly in cohorts A (PC-PG) + B (other neuroendocrine tumors) and 625 mg orally on 2 consecutive days each week in cohort C, which included 5 responding patients. The primary endpoint was radiographic response measured using RECIST. Secondary endpoints included progression-free survival, overall survival, and safety.

RESULTS

In arm A (n = 10; all PC-PG), 50% (5/10) exhibited a partial response (PR) and 2 additional patients had stable disease (SD) >3 months. Median duration of therapy for arm A patients was 9 months (range: 1.5-33 months) with 5 patients treated >1 year. In arm B (n = 12), there were 1 PR (DSRCT) and 2 SD (DSRCT; neuroblastoma) >3 months. Median duration of therapy in arm A was 18 months (range: 1-33 months) and arm B was 3 months (range: 1.5-33 months). Arm C PC-PG (N = 8) showed 1 PR and 7 SD at 3 months, with median duration of therapy >10 months. There was no decline in Karnofsky performance status at week 12 for 28 of 30 patients and no dose modification due to treatment-related adverse events.

CONCLUSIONS

Oral ONC201 was well tolerated in patients with metastatic neuroendocrine tumors and associated with clinical benefit, including tumor responses, particularly in some patients with DSRCT and the majority of patients with PC-PG. See related commentary by Owen and Trikalinos, p. 1748.

Phase 1 trial of autologous dendritic cell vaccination with imiquimod immunomodulation in children and adults with refractory sarcoma

11542

Background: Sarcomas are rare, heterogeneous, and aggressive neoplasms that often affect otherwise healthy individuals. Patients with advanced or metastatic sarcomas have dismal outcomes. Immunotherapy presents promising new modalities to help treat sarcomas. One such therapy, autologous dendritic cell (DC) vaccines, using antigen-loaded DCs, intensify the adaptive immune response by enhancing T-cell activity and inducing tumor cell death through apoptosis and cytolysis. We present the results of a phase 1 study of DC vaccine for refractory sarcomas. Methods: A phase 1 dose-escalation study of autologous DC vaccination was conducted in children and adults with recurrent/refractory sarcomas who underwent surgical resection of a primary or metastatic tumor between 2014-2019. A 5+3 dose-escalation schema was chosen to determine safety and recommended phase 2 dose. Patient monocytes were collected by pheresis and incubated with GM-CSF plus IL-4 to generate immature DCs which were then loaded with autologous tumor lysates from the patient’s surgical resection. Three dose levels, 3, 6, and 12 million DCs per treatment were tested. The DC product was administered intradermally in imiquimod-treated skin to complete in situ maturation. Treatment consisted of four weekly injections of the DC product, followed by four monthly “boosters” of tumor lysate. The primary and secondary endpoints included safety/feasibility and preliminary clinical efficacy, respectively. Results: Nineteen patients were enrolled with a median age 50 years (13-75 years) and 47% female. Seven patients were treated on dose level 1 and six each on dose level 2 and 3. Thirteen patients received all planned injections while the remaining six patients progressed during treatment. There was no treatment related dose limiting toxicity. Grade 1-2 fever, headache, arthralgia, injection site reaction attributable to treatment were noted in four patients. There were no adverse events > grade 2. Disease progression before or after completion of study treatment was noted in 15 patients with a median PFS of 9.5 months (95%CI 5.6-28.7). The two-year PFS and OS was 36.8% and 68.1%, respectively. There were seven deaths due to disease, one patient was discharged to hospice and two patients have been lost to follow up. Five patients are currently receiving alternative therapy. Four patients remain in follow up without evidence of disease progression including three patients (pleomorphic myxofibrosarcoma, pleomorphic myosarcoma, and leiomyosarcoma) who are disease free over two years from initiating study therapy and one pediatric patient (Ewing sarcoma) disease free for over one year. Conclusions: Autologous DC vaccine with imiquimod immunomodulation for patients with relapsed/refractory sarcomas is feasible and well-tolerated. Refinement to augment initial and sustained antitumor activity is needed. Clinical trial information: NCT01803152.

Axitinib plus pembrolizumab in patients with advanced sarcomas including alveolar soft-part sarcoma: a single-centre, single-arm, phase 2 trial

BACKGROUND

VEGF promotes an immunosuppressive microenvironment and contributes to immune checkpoint inhibitor resistance in cancer. We aimed to assess the activity of the VEGF receptor tyrosine-kinase inhibitor axitinib plus the anti-PD-1 immune checkpoint inhibitor pembrolizumab in patients with sarcoma.

METHODS

This single-centre, single-arm, phase 2 trial was undertaken at a tertiary care academic medical centre in Miami, FL, USA, and participants were recruited from all over the USA and internationally. Patients were eligible if they were aged 16 years or older, and had histologically confirmed advanced or metastatic sarcomas, including alveolar soft-part sarcoma (ASPS); measurable disease with one site amenable to repeated biopsies; an ECOG performance status of 0-1; and progressive disease after previous treatment with at least one line of systemic therapy (unless no standard treatment existed or the patient declined therapy). The first five patients were enrolled in a lead-in cohort and were given axitinib 5 mg orally twice daily and pembrolizumab 200 mg intravenously for 30 min on day 8 and every 3 weeks for cycles of 6 weeks for up to 2 years. Thereafter, patients received escalating doses of axitinib (2-10 mg) plus flat dose pembrolizumab according to the schedule above. The primary endpoint was 3-month progression-free survival. All patients were evaluable for survival and safety analyses. This study is registered with ClinicalTrials.gov, number NCT02636725, and is closed to accrual.

FINDINGS

Between April 19, 2016, and Feb 7, 2018, of 36 patients assessed for eligibility, 33 (92%) were enrolled and given study treatment (intention-to-treat population and safety population), 12 (36%) of whom had ASPS. With a median follow-up of 14·7 months (IQR 10·1-19·1), 3-month progression-free survival for all evaluable patients was 65·6% (95% CI 46·6-79·3). For patients with ASPS, 3-month progression-free survival was 72·7% (95% CI 37·1-90·3). The most common grade 3 or 4 treatment-related adverse events included hypertension (five [15%] of 33 patients), autoimmune toxicities (five [15%]), nausea or vomiting (two [6%]), and seizures (two [6%]). Serious treatment-related adverse events occurred in seven (21%) patients, including autoimmune colitis, transaminitis, pneumothorax, haemoptysis, seizures, and hypertriglyceridemia. There were no treatment-related deaths.

INTERPRETATION

Axitinib plus pembrolizumab has manageable toxicity and preliminary activity in patients with advanced sarcomas, particularly patients with ASPS, warranting further investigation in randomised controlled trials.

FUNDING

Merck, Pfizer, American Cancer Society, and Sylvester Comprehensive Cancer Center.

A phase II study of temsirolimus and liposomal doxorubicin for patients with recurrent and refractory bone and soft tissue sarcomas

Background

Relapsed and refractory sarcomas continue to have poor survival rates. The cancer stem cell (CSC) theory provides a tractable explanation for the observation that recurrences occur despite dramatic responses to upfront chemotherapy. Preclinical studies demonstrated that inhibition of the mechanistic target of rapamycin (mTOR) sensitizes the CSC population to chemotherapy.

Methods

Here we present the results of the Phase II portion of a Phase I/II clinical trial that aimed to overcome the chemoresistance of sarcoma CSC by combining the mTOR inhibitor temsirolimus (20 mg/m² weekly) with the chemotherapeutic agent liposomal doxorubicin (30 mg/m² monthly).

Results

Fifteen patients with relapsed/refractory sarcoma were evaluable at this recommended Phase 2 dose level. The median progression free survival was 315 days (range 27–799). Response rate, defined as stable disease or better for 60 days, was 53%. Nine of the patients had been previously treated with doxorubicin. Therapy was well tolerated. In a small number of patients, pre- and post- treatment tumor biopsies were available for assessment of ALDH expression as a marker of CSCs and showed a correlation between response and decreased ALDH expression. We also found a correlation between biopsy-proven inhibition of mTOR and response.

Conclusions

Our study adds to the literature supporting the addition of mTOR inhibition to chemotherapy agents for the treatment of sarcomas, and proposes that a mechanism by which mTOR inhibition enhances the efficacy of chemotherapy may be through sensitizing the chemoresistant CSC population. Further study, ideally with pre- and post-therapy assessment of ALDH expression in tumor cells, is warranted.

Trial registration The trial was registered on clinicaltrials.gov (NCT00949325) on 30 July 2009. http://www.editorialmanager.com/csrj/default.aspx

A novel chordoma xenograft allows in vivo drug testing and reveals the importance of NF-κB signaling in chordoma biology

Chordoma is a rare primary bone malignancy that arises in the skull base, spine and sacrum and originates from remnants of the notochord. These tumors are typically resistant to conventional chemotherapy, and to date there are no FDA-approved agents to treat chordoma. The lack of in vivo models of chordoma has impeded the development of new therapies for this tumor. Primary tumor from a sacral chordoma was xenografted into NOD/SCID/IL-2R γ-null mice. The xenograft is serially transplantable and was characterized by both gene expression analysis and whole genome SNP genotyping. The NIH Chemical Genomics Center performed high-throughput screening of 2,816 compounds using two established chordoma cell lines, U-CH1 and U-CH2B. The screen yielded several compounds that showed activity and two, sunitinib and bortezomib, were tested in the xenograft. Both agents slowed the growth of the xenograft tumor. Sensitivity to an inhibitor of IκB, as well as inhibition of an NF-κB gene expression signature demonstrated the importance of NF-κB signaling for chordoma growth. This serially transplantable chordoma xenograft is thus a practical model to study chordomas and perform in vivo preclinical drug testing.

A dose-finding study of temsirolimus and liposomal doxorubicin for patients with recurrent and refractory bone and soft tissue sarcoma

There are few effective therapies for high-risk sarcomas. Initial chemosensitivity is often followed by relapse. In vitro, mammalian target of rapamycin (mTOR) inhibition potentiates the efficacy of chemotherapy on resistant sarcoma cells. Although sarcoma trials using mTOR inhibitors have been disappointing, these drugs were used as maintenance. We conducted a Phase I/II clinical trial to test the ability of temsirolimus to potentiate the cytotoxic effect of liposomal doxorubicin and present here the dose-finding portion of this study. Adult and pediatric patients with recurrent or refractory sarcomas were treated with increasing doses of liposomal doxorubicin and temsirolimus using a continual reassessment method for escalation, targeting a dose-limiting toxicity rate of 20%. Blood samples were drawn before and after the first dose of temsirolimus in Cycles 1 and 2 for pharmacokinetic analysis. The maximally tolerated dose combination was liposomal doxorubicin 30 mg/m(2) monthly with temsirolimus 20 mg/m(2) weekly. Hematologic toxicity was common but manageable. Dose-limiting toxicities were primarily renal. Concurrent administration of liposomal doxorubicin resulted in increased exposure to sirolimus, the active metabolite of temsirolimus. Thus, the combination of liposomal doxorubicin and temsirolimus is safe for heavily pretreated sarcoma patients. Co-administration with liposomal doxorubicin did not alter temsirolimus pharmacokinetics, but increased exposure to its active metabolite.

Protein kinase A translocation and insulin secretion in pancreatic beta-cells: studies with adenylate cyclase toxin from Bordetella pertussis

Activation of protein kinase A (cAMP-dependent protein kinase; PKA) triggers insulin secretion in the beta-cell. Adenylate cyclase toxin (ACT), a bacterial exotoxin with adenylate cyclase activity, and forskolin, an activator of adenylate cyclase, both dose-dependently increased insulin secretion in the presence, but not the absence, of glucose in insulin-secreting betaTC3 cells. The stimulation of cAMP release by either agent was dose-dependent but glucose-independent. Omission of extracellular Ca(2+) totally abolished the effects of ACT on insulin secretion and cytosolic cAMP accumulation. ACT and forskolin caused rapid and dramatic increases in cytosolic Ca(2+), which were blocked by nifedipine and the omission of extracellular Ca(2+). Omission of glucose completely blocked the effects of forskolin and partially blocked the effects of ACT on cytosolic Ca(2+). PKA alpha, beta and gamma catalytic subunits (Calpha, Cbeta and Cgamma respectively) were identified in betaTC6 cells by confocal microscopy. Glucose and glucagon-like polypeptide-1 (GLP-1) caused translocation of Calpha to the nucleus and of Cbeta to the plasma membrane and the nucleus, but did not affect the distribution of Cgamma. In conclusion, glucose and GLP-1 amplify insulin secretion via cAMP production and PKAbeta activation.

Sex differences in secondary attack rate of IDDM to siblings of probands through older ages. Pittsburgh Etiology of IDDM Study

OBJECTIVE

To determine the descriptive epidemiological patterns of the secondary attack rate of insulin-dependent diabetes mellitus (IDDM) among siblings of probands through older ages.

RESEARCH DESIGN AND METHODS

A family history analysis was performed on 1774 IDDM probands who were diagnosed or seen within 1 yr of diagnosis at Children's Hospital of Pittsburgh from 1 January 1950 through 31 December 1981. The probands were discharged on insulin and were diagnosed at less than 17 yr of age. The time frame permitted the risk of IDDM for siblings of probands to be calculated over a broad spectrum of age.

RESULTS

Risk estimates for the 3966 full natural siblings through 10, 20, and 30 yr of age were 1.6, 4.1, and 6.3%, respectively. Secondary attack rates were equivalent for male and female siblings through 15 yr of age (3%); however, the risk to males increased an additional 4% between 16 and 30 yr of age compared with 2.5% for females (P = 0.01). There was no evidence of an excess sex concordance among affected sibling pairs.

CONCLUSIONS

Males have a greater secondary attack rate of IDDM at older ages than females. This may be due to an increased exposure to environmental agents among males or protective influences operating among females.