Survival and Local Recurrence Risk in Patients with High-Risk Neuroblastoma Treated with Proton Therapy over a 10 Year Interval

PURPOSE/OBJECTIVE(S)

Patients (pts) with high-risk neuroblastoma (HR-NBL) require radiation (RT) to the primary tumor site (PS); approach is standardized within North American paradigms but remains a subject of global study. Long-term experience using proton therapy (PRT) in this population is lacking. We hypothesized that PRT would be associated with low risk of local recurrence (LR) in a large population of pts with HR-NBL spanning > 10 years.

MATERIALS/METHODS

Sequential pts with HR-NBL at a single institution received RT to PS and persistent metastatic sites (MS). Dose to PS after subtotal resection (STR) was reduced from 36 Gy to 21.6 Gy in 2019 based on results from the Children's Oncology Group ANBL0532 trial (Liu K, 2019). Analysis using Kaplan Meier method and log rank test was performed with IRB approval.

RESULTS

From 9/2010 - 12/2021, 99 pts with HR-NBL received PS RT during first-line therapy; most [78, (79%)] had adrenal primary tumors and 26 (26%) received MS RT. Median age was 48m at RT (R 11m to 17.5y) and 52 (53%) were female. All pts had multi-agent induction chemotherapy (CT) [+ dinutuximab [12 (13%)] and/ or therapeutic 131MIBG [19 (19%)] and resection of primary tumor prior to RT; 34 (34%) patients had STR with residual disease (RD) on post-op imaging, 65 (66%) had gross total resection (GTR). Dose to PS was 21.6 Gy for 78 (79%) pts and 36 Gy for 21 (21%) based on RD and treatment era; PRT was pencil beam [78 (79%)] or double scattered [22 (22%)], combined with IMRT in 2 (2%). With median FU of 4.2 yrs (R 0.5y - 12y), 80 pts (81%) are alive [66 (67%) disease-free, 14 (14%) with disease], 19 (19%) have died. Progressive disease (PD) occurred in 33 (33%), with median time to PD 24m (R 8-116m); two pts (2%) had isolated LR, 25 (25%) distant PD, and 6 (6%) concurrent LR and distant PD. Risk of LR at 10 years was 8%; absolute risk of any LR was 8% (6/78) in 21.6 Gy cohort and 9% (2/21) in 36 Gy cohort (p = NS). After induction CT, 34 (34%) pts had STR with > 1cm3 RD on axial imaging; 18/ 34 (53%) also had MIBG uptake (MIBG+) at PS. Based on treatment era, 21 pts (62%) after STR received 21.6 Gy + boost to RD (36 Gy), and 13 (38%) 21.6 alone. Of those who received 36 Gy (median FU 5.7y), 2/21 (9.5%) had LR with concurrent distant PD; of those who received 21.6 Gy (median FU 3.2y) 4/13 (31%) had LR (2 with concurrent distant PD and 2 LR only) (p = 0.03). In the 21.6 Gy GTR cohort, 2/65 (3%) had LR + distant PD. Of 8 total patients who experienced LR, 5 had MIBG + RD, 1 MIBG- RD, and 2 GTR.

CONCLUSION

We observed excellent outcomes in 99 pts treated with proton radiotherapy for HR-NBL from 2010 through 2021, with 81% of patients alive and 92% free of LR. Our data suggest that LR is rare after GTR and 21.6 Gy, and uncommon among pts with STR treated with 36 Gy. A small number of pts received 21.6 Gy after STR, however, this experience suggests that a subset of pts with RD may require RT dose > 21.6 Gy. Further work is required to further characterize individual management of PS in pts with HR-NBL with regard to extent of RD and biologic disease features.

Phase 1 trial of temsirolimus in combination with irinotecan and temozolomide in children, adolescents and young adults with relapsed or refractory solid tumors: a Children's Oncology Group Study

BACKGROUND

mTOR inhibitors have activity in pediatric tumor models. A phase I trial of the mTOR inhibitor temsirolimus (TEM) with irinotecan (IRN) and temozolomide (TMZ) was conducted in children with recurrent/refractory solid tumors, including central nervous system (CNS) tumors.

METHODS

Escalating doses of intravenous (IV) TEM were administered on days 1 and 8 of 21-day cycles. IRN (50 mg/m(2)/dose escalated to a maximum of 90 mg/m(2)/dose) and TMZ (100 mg/m(2)/dose escalated to a maximum of 150 mg/m(2)/dose) were administered orally (PO) on days 1-5. When maximum tolerated doses (MTD) were identified, TEM frequency was increased to weekly.

RESULTS

Seventy-one eligible pts (median age 10.9 years, range 1.0-21.5) with neuroblastoma (16), osteosarcoma (7), Ewing sarcoma (7), rhabdomyosarcoma (4), CNS (22) or other (15) tumors were enrolled. Dose-limiting hyperlipidemia occurred in two patients receiving oral corticosteroids. The protocol was subsequently amended to preclude chronic steroid use. The MTD was identified as TEM 35 mg/m(2) IV weekly, with IRN 90 mg/m(2) and TMZ 125 mg/m(2) PO on days 1-5. At higher dose levels, elevated serum alanine aminotransferase and triglycerides, anorexia, and thrombocytopenia were dose limiting. Additional ≥ grade 3 regimen-related toxicities included leukopenia, neutropenia, lymphopenia, anemia, and nausea/vomiting. Six patients had objective responses confirmed by central review; three of these had sustained responses through ≥ 14 cycles of therapy.

CONCLUSION

The combination of TEM (35 mg/m(2)/dose IV weekly), IRN (90 mg/m(2)/dose days 1-5) and TMZ (125 mg/m(2)/dose days 1-5) administered PO every 21 days is well tolerated in children. Phase 2 trials of this combination are ongoing.

fdg-pet in two cases of neurofibromatosis type 1 and atypical malignancies

Patients with neurofibromatosis type 1 (nf1) are at increased risk for both benign and malignant tumours, and distinguishing the malignant potential of an individual tumour is a common clinical problem in these patients. Here, we review two cases of uncommon malignancies (Hodgkin lymphoma and mediastinal germ-cell tumour) in patients with nf1. Although (18)F-fluorodeoxyglucose positron-emission tomography (fdg-pet) has been used to differentiate benign neurofibromas from malignant peripheral nerve sheath tumours, fdg-pet characteristics for more rare tumours have been poorly described in children with nf1. Here, we report the role of pet imaging in clinical decision-making in each case. In nf1, fdg-pet might be useful in the clinical management of unusual tumour presentations and might help to provide information about the malignant potential of uncommon tumours.

Pharmacokinetically guided phase 1 trial of the IGF-1 receptor antagonist RG1507 in children with recurrent or refractory solid tumors

PURPOSE

This pediatric phase I study was designed to identify the doses of RG1507, a monoclonal antibody against the Type 1 Insulin-like Growth Factor Receptor (IGF1R), that achieves exposures equivalent to those achieved in adults at recommended doses.

EXPERIMENTAL DESIGN

Children with relapsed or refractory solid tumors were treated using the same doses and administration schedules of RG1507 (3 and 9 mg/kg/wk, and 16 mg/kg every 3 weeks [q3W]) as those studied in adults. Detailed pharmacokinetic (PK) sampling was performed after the first dose; selected peak and trough levels were subsequently obtained. Target exposures were ≥85% of mean areas under concentration x time curves (AUCs) in adults at doses of 9 mg/kg/wk and 16 mg/kg q3W. A maximum tolerated dose could be identified if dose-limiting toxicities (DLT) occurred.

RESULTS

Thirty-one evaluable patients aged 3-17 years were enrolled at 3 mg/kg/wk (n = 3), 9 mg/kg/wk (n = 18), or 16 mg/kg q3W (n = 10). There were no DLTs. At 9 mg/kg/wk the mean AUC(0-7d) (21,000 μg h/mL) exceeded the target (16,000 μg h/mL). At 16 mg/kg q3W, the mean AUC(021d) (70,000 μg h/mL) exceeded the target (59,400 μg h/mL). Clearance normalized to body weight was age dependent. There were no objective responses. Seven patients had stable disease for >12 weeks, including two patients with osteosarcoma with stable disease for 52+ and 78+ weeks.

CONCLUSIONS

The recommended doses of RG1507 in children with solid tumors are 9 mg/kg/wk and 16 mg/kg q3W. This flexible design is well suited for trials of agents associated with limited toxicity.

Irinotecan plus temozolomide in children with recurrent or refractory neuroblastoma: A phase II Children's Oncology Group study

10011

Background: Treatment of children with relapsed or refractory neuroblastoma (NB) remains a challenge. Responses to irinotecan (IRN) + temozolomide (TEM) were seen in NB xenograft-bearing mice, and objective responses were observed in patients with NB treated on a phase I study of this combination. Methods: A phase II study of IRN (10 mg/m2/dose IV daily × 5 days times; 2 weeks) + TEM (100 mg/m2/dose PO daily × 5 days) for children with relapsed or refractory NB was conducted. A one-stage design (endpoint: best overall response) required 5 or more responders out of the first 25 evaluable patients on each of two strata: 1) patients with disease measurable by CT or MRI; and 2) patients with disease detected only by bone marrow aspirate/biopsy and/or MIBG scan. Patients with stable disease or better after 3 cycles could receive an additional 3 cycles of study therapy. International Neuroblastoma Response Criteria were used for response assessment. Radiographic responses were centrally reviewed. Results: Fifty-five eligible and evaluable patients were enrolled, 28 on stratum 1 and 27 on stratum 2. Four responses were observed in the first 25 evaluable stratum 1 patients, and five responses were observed in the first 25 evaluable stratum 2 patients. Three patients had complete responses, but the overall objective response rate (CR+PR) was 16% (9/55). Eleven (stratum 1) and 13 (stratum 2) patients had stable disease. Less than 5% of patients experienced Grade 3 or 4 diarrhea. Although 18% of patients on stratum 1 and 35% of patients on stratum 2 experienced Grade 3 or 4 neutropenia during the first 3 cycles of therapy, <10% of all patients developed evidence of infection while neutropenic. Thrombocytopenia (Grade 3 or 4) was observed in only 7% of patients on stratum 1 and 12% on stratum 2. Conclusions: The combination of IRN+TEM was well tolerated in patients with recurrent or refractory NB. There were 9 objective responses, including 3 complete responses. The minimum desired response rate was attained within stratum 2, but not stratum 1. IRN+TEM may be an appropriate backbone for further study in the relapse setting in combination with novel, targeted agents.

No significant financial relationships to disclose.

A phase I study of cetuximab and irinotecan in pediatric patients (pts) with refractory solid tumors

9547

Background: Irinotecan has shown antitumor activity in a number of pediatric tumors. In adults with colorectal cancer, combining irinotecan with cetuximab enhances clinical activity as compared to treatment with irinotecan alone. We implemented this first-in- pediatrics phase I study to determine the maximum tolerated dose (MTD) and recommended Phase II dose (RP2D) of cetuximab and irinotecan in pediatric patients. Methods: 35 heavily pre-treated pts with refractory solid tumors were enrolled: brainstem glioma/astrocytoma (16), hepatoblastoma (4), neuroblastoma (2), other (13). Weekly cetuximab was escalated in 3 sequential dose levels: 75, 150 or 250mg/m2; Irinotecan was given at 16 or 20 mg/m2/day over 1 hour [daily × 5] for two weeks, every 21 days. Correlative EGFR expression (immunohistochemistry and FISH) and/or mutations, pharmacokinetics (PK) of and immune response to cetuximab were performed. Results: Pts were treated in two age cohorts (ages 1–12 yrs = Group A, and 13–18 yrs = Group B). PK analyses show linearity, with similar t1/2, clearance, and volume of distribution between groups. Irinotecan-related DLT in 2/6 pts in Group A/dose 2 necessitated dose de-escalation. Three pts experienced Grade 3 hypersensitivity infusion reaction and were discontinued. A pt with an EGFR-negative high-grade glioma (dose level 1) achieved a >70% reduction in tumor size and remains on study for 16+ months (24 cycles). A pt with ependymoma experienced a partial response (PR) and continues on cycle 12+. 9 pts received ≥4 cycles of therapy. 16 pts had a best response of stable disease or PR (mean 17 wks, range 5–66+ wks) for a clinical benefit rate of 45%. Conclusions: The combination of cetuximab and irinotecan is well-tolerated over multiple repeat cycles without cumulative toxicity in children with refractory CNS and non-CNS solid tumors. Promising preliminary anti-cancer activity was observed in a variety of pediatric solid tumors. Detailed biologic correlative and PK data will be presented.

[Table: see text]

No significant financial relationships to disclose.

A phase I study of 17-AAG in relapsed/refractory pediatric patients with solid tumors: A Children’s Oncology Groups study

9018

Background: A pediatric phase I study of 17-allylaminogeldanamycin (17-AAG), an Hsp90 inhibitor, was conducted to determine the dose limiting toxicities (DLTs), the recommended phase II dose, the pharmacokinetics (PK), and to evaluate a surrogate marker for Hsp90 inhibition in peripheral blood mononuclear cells (PBMCs). Methods: Cohorts of 3–6 pts were enrolled at dose levels of 150, 200, 270 and 360 mg/m2/dose, administered as a 60 min infusion, on days 1, 4, 8 and 11 of a 21-day cycle. PK and PBMC evaluations were done during the first course of therapy. Results: 17 pts (7 male), median 7 yrs of age (range 1–19), were enrolled. 5 pts who developed PD prior to completing a full cycle of therapy were not considered evaluable for toxicity. No DLTs occurred. Non-DLTs included elevated transaminases (n=6), anemia (n=3), and vomiting (n=3). Based on the adult recommended dose and challenges posed by infusing the large volumes of DMSO, dose escalation was stopped at dose level 4. No CRs or PRs were observed; 3 patients remain on therapy at 6, 7 and 9 months with SD. One patient with hepatoblastoma had a reduction in AFP and SD over 3 cycles. PK data is available from the initial 3 dose levels. Drug exposure increases in proportion to dose for both17-AAG and its metabolite 17-AG. At 270 mg/m2/dose the Cmax and AUC of 17-AAG were 5,303 ± 1,591 ng/ml and 13,150 ± 5,086 ng/ml*hr, respectively, similar to the exposure in adults. The mean terminal half-life for 17-AAG was 3.0 ± 0.5 hrs. Induction of Hsp72, a surrogate marker for inhibition of Hsp90 was detected at all dose levels. Conclusions: The recommended phase II dose of 17AAG is 360mg/m2/day. Non-DMSO formulations may allow for further dose escalation in children and should be studied.

No significant financial relationships to disclose.

Phase I pharmacokinetic (PK) and pharmacodynamic (PD) study of 17-Allylamino-17-demethoxygeldanamycin (17AAG) in children with solid tumors

9022

Background: 17AAG is a benzoquinone ansamycin that binds to heat shock protein 90 (Hsp90) and alters levels of cancer-associated proteins that are regulated by Hsp90. 17AAG has been well-tolerated in adults, but has not previously been administered to children. Methods: A Phase I study of 17AAG was initiated to define the maximally tolerated dose and toxicity profile of this drug in children. PK and PD were also studied. Cohorts of 3–6 patients with recurrent or refractory solid tumors were treated every 21 days with escalating doses of 17AAG twice weekly for two weeks. Plasma PK of 17AAG and its major metabolite, 17AG, were measured on day 1 by HPLC. Changes in levels of the inducible isoform of Hsp70 were assessed by Western blot using peripheral blood mononuclear cells (PBMCs) obtained 24 h after the 17AAG infusion. Actin was measured for comparison. Because 17AAG is a substrate for CYP3A4/5 and MDR1, pharmacogenetic analyses have been undertaken to determine if genotypes including CYP3A4*1B, CYP3A5*3, and MDR1 G2677T/A and C3435T influence 17AAG disposition. Results: 12 pts (median age 11 years, range 5–18) with neuroblastoma (5), osteosarcoma (4), Ewing’s family tumors (2), and desmoplastic small round cell tumor (1) have been treated with 17AAG. An MTD has yet to be defined though one dose limiting toxicity (Grade 3 hypoxia) was observed at Dose Level 4 (360 mg/m2). The AUC of 17AAG increased with dose, with a linear relationship between end of infusion 17AAG plasma concentration and AUC. The AUC of 17AAG increased with dose, with a linear relationship between end of infusion 17AAG plasma concentration and AUC. Clearance ranged between 12.5 and 29.6 l/hr/m2 (median, 21.6 l/h/m2) and did not change with increasing doses. Post-treatment increases in Hsp70 in PBMCs have been observed in pts treated with 17AAG doses at or above 150 mg/m2. Declines in Akt and IGF1R in PBMCs have been seen in some but not all pts following treatment. Conclusions: 17AAG is well tolerated in children at dose levels studied to date. 17AAG dose escalation continues and at the time of the meeting, updated data will be reported.

No significant financial relationships to disclose.

Destabilization of steroid receptors by heat shock protein 90-binding drugs: a ligand-independent approach to hormonal therapy of breast cancer

Steroid hormone receptors have become an important target in the management of breast cancers. Despite a good initial response rate, however, most tumors become refractory to current hormonal therapies within a year of starting treatment. To address this problem, we evaluated the effects of agents that bind the molecular chaperone heat shock protein 90 (Hsp90) on estrogen receptor function in breast cancer. Unstimulated estrogen and progesterone receptors exist as multimolecular complexes consisting of the hormone-binding protein itself and several essential molecular chaperones including Hsp90. We found that interaction of the Hsp90-binding drugs geldanamycin and radicicol with the chaperone destabilizes these hormone receptors in a ligand-independent manner, leading to profound and prolonged depletion of their levels in breast cancer cells cultured in vitro. Consistent with these findings, in vivo administration of the geldanamycin derivative 17-allylaminogeldanamycin (17AAG; NSC330507) to estrogen-supplemented, tumor-bearing SCID mice resulted in marked depletion of progesterone receptor levels in both uterus and tumor. Drug administration also delayed the growth of established, hormone-responsive MCF-7 and T47D human tumor xenografts for up to 3 weeks after the initiation of therapy. We conclude that in light of their novel mechanism of anti-hormone action, consideration should be given to examining the activity of 17AAG and other Hsp90-binding agents in patients with refractory breast cancer in future clinical trials, either alone or in combination with conventional hormone antagonists.

Induction of a heat shock factor 1-dependent stress response alters the cytotoxic activity of hsp90-binding agents

In addition to its classic role in the cellular stress response, heat shock protein 90 (Hsp90) plays a critical but less well appreciated role in regulating signal transduction pathways that control cell growth and survival under basal, nonstress conditions. Over the past 5 years, the antitumor antibiotics geldanamycin and radicicol have become recognized as selective Hsp90-binding agents (HBA) with a novel ability to alter the activity of many of the receptors, kinases, and transcription factors involved in these cancer-associated pathways. As a consequence of their interaction with Hsp90, however, these agents also induce a marked cellular heat shock response. To study the mechanism of this response and assess its relevance to the anticancer action of the HBA, we verified that the compounds could activate a reporter construct containing consensus binding sites for heat shock factor 1 (HSF1), the major transcriptional regulator of the vertebrate heat shock response. We then used transformed fibroblasts derived from HSF1 knock-out mice to show that unlike conventional chemotherapeutics, HBA increased the synthesis and cellular levels of heat shock proteins in an HSF1-dependent manner. Compared with transformed fibroblasts derived from wild-type mice, HSF1 knock-out cells were significantly more sensitive to the cytotoxic effects of HBA but not to doxorubicin or cisplatin. Consistent with these in vitro data, we found that systemic administration of an HBA led to marked increases in the level of Hsp72 in both normal mouse tissues and human tumor xenografts. We conclude that HBA are useful probes for studying molecular mechanisms regulating the heat shock response both in cells and in whole animals. Moreover, induction of the heat shock response by HBA will be an important consideration in the clinical application of these drugs, both in terms of modulating their cytotoxic activity as well as monitoring their biological activity in individual patients.

Inhibition of oncogene expression using vector-generated RNA antisense

Antisense RNA expression vectors have been developed relatively recently as a means to study the role of specific oncogenes in malignant transformation. In this paper, strategies for the construction of antisense plasmid vectors from commercially available reagents are described. Techniques for the introduction of these vectors into cell lines and tumors are also described and preferred methods for the evaluation of biological effects are presented. Lastly, using specific examples, the limitations and potential artifacts associated with antisense vector use in the study of tumorigenesis are discussed.