4703 - Updated results of a phase II study evaluating accelerator-based boron neutron capture therapy (AB-BNCT) with borofalan(10B) (SPM-011) in recurrent squamous cell carcinoma (R-SCC-HN) and recurrent and locally advanced non-SCC (R/LA-nSCC-HN) of the head and neck

Background

BNCT is a unique cancer treatment technique in which tumor cells are irradiated from the inside with heavy particles produced by ¹⁰B(n,α)⁷Li nuclear transmutation reaction of boron atom and neutron. A next-generation AB-BNCT system that does not require a nuclear reactor has been developed, and it has become possible to perform BNCT in urban hospitals along with stable supply of borofalan (¹⁰B) supported by high ¹⁰B concentration technology.

Methods

In this world-first, open-label phase II trial of AB-BNCT, patients (pts) with previously irradiated, platinum-resistant R-SCC-HN or with R/LA-nSCC-HN were administered with borofalan(¹⁰B) at 200 mg/kg/h intravenously for 2 hours, followed by neutron irradiation with continuous infusion at 100 mg/kg/h. The irradiated dose for tumor was determined passively as a mucosal maximum dose was given 12 Gy-Eq. Primary endpoint was objective response rate (ORR) by central review. Updated efficacy and safety analysis are presented here (data cut off: 5 April 2019).

Results

Eight R-SCC-HN and thirteen R/LA-nSCC-HN pts were enrolled. All R-SCC-HN pts had prior radiotherapy with a dose of 65.5 Gy (range, 59.4–76.0). The tumor minimum dose was 31.0 Gy-Eq (range, 16.1–42.6). ORR for all pts were 71.4%, and CR/PR were 50.0%/25.0% in R-SCC-HN and 7.7%/61.5% in R/LA-nSCC-HN. With a median follow up of 21.3 months (range 9.2–30.6), 1-year PFS by investigator review were 70.6%. Other ecacy data are shown in the table. For adverse event, nausea (81%), dysgeusia (71%), acute parotitis (67%) were observed frequently.Table: 1135P

NR, Not reached.

Conclusions

These data suggest that AB-BNCT with borofalan(¹⁰B) emerges as a promising treatment option for pts with R –SCC- HN or R/LA-nSCC-HN with no other treatment option.

Clinical trial identification

JapicCTI-194640.

Editorial acknowledgement

Legal entity responsible for the study

Sumitomo Heavy Industries, Ltd, Stella Pharma Corporation.

Funding

Fukushima prefectural subsidy for development and testing of global cutting-edge medical devices.

Disclosure

K. Hirose: Research grant / Funding (self), Travel / Accommodation / Expenses: Sumitomo Heavy Industries, Ltd; Travel / Accommodation / Expenses: Stella Pharma Corporation. K. Ono: Advisory / Consultancy: Stella Pharma Corporation; Advisory / Consultancy: Sumitomo Heavy Industries, Ltd. Y. Takai: Travel / Accommodation / Expenses: Stella Pharma Corporation; Travel / Accommodation / Expenses: Sumitomo Heavy Industries, Ltd. All other authors have declared no conflicts of interest.