Photochemical internalisation, a novel minimally invasive treatment, has shown promising preclinical results in enhancing and site-directing the effect of anticancer drugs by illumination, which initiates localised chemotherapy release. We assessed the safety and tolerability of a newly developed photosensitiser, disulfonated tetraphenyl chlorin (TPCS_2a), in mediating photochemical internalisation of bleomycin in patients with advanced and recurrent solid malignancies.

In this phase 1, dose-escalation, first-in-man trial, we recruited patients (aged ≥18 to <85 years) with local recurrent, advanced, or metastatic cutaneous or subcutaneous malignancies who were clinically assessed as eligible for bleomycin chemotherapy from a single centre in the UK. Patients were given TPCS_2a on day 0 by slow intravenous injection, followed by a fixed dose of 15 000 IU/m² bleomycin by intravenous infusion on day 4. After 3 h, the surface of the target tumour was illuminated with 652 nm laser light (fixed at 60 J/cm²). The TPCS_2a starting dose was 0·25 mg/kg and was then escalated in successive dose cohorts of three patients (0·5, 1·0, and 1·5 mg/kg). The primary endpoints were safety and tolerability of TPCS_2a; other co-primary endpoints were dose-limiting toxicity and maximum tolerated dose. The primary analysis was per protocol. This study is registered with ClinicalTrials.gov, number NCT00993512, and has been completed.

Between Oct 3, 2009, and Jan 14, 2014, we recruited 22 patients into the trial. 12 patients completed the 3-month follow-up period. Adverse events related to photochemical internalisation were either local, resulting from the local inflammatory process, or systemic, mostly as a result of the skin-photosensitising effect of TPCS_2a. The most common grade 3 or worse adverse events were unexpected higher transient pain response (grade 3) localised to the treatment site recorded in nine patients, and respiratory failure (grade 4) noted in two patients. One dose-limiting toxicity was reported in the 1·0 mg/kg cohort (skin photosensitivity [grade 2]). Dose-limiting toxicities were reported in two of three patients at a TPCS_2a dose of 1·5 mg/kg (skin photosensitivity [grade 3] and wound infection [grade 3]); thus, the maximum tolerated dose of TPCS_2a was 1·0 mg/kg. Administration of TPCS_2a was found to be safe and tolerable by all patients. No deaths related to photochemical internalisation treatment occurred.

TPCS_2a-mediated photochemical internalisation of bleomycin is safe and tolerable. We identified TPCS_2a 0·25 mg/kg as the recommended treatment dose for future trials.

PCI Biotech.