Early safety from a phase I, multicenter, open-label clinical trial of talimogene laherparepvec (T-VEC) injected (inj) into liver tumors in combination with pembrolizumab (pem).

Abstract

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Background: T-VEC is a genetically modified, oncolytic HSV-1 designed to selectively replicate within tumors and produce GM-CSF to enhance systemic antitumor immunity. The safety and efficacy of T-VEC in treatment of advanced melanoma has been demonstrated as monotherapy and in combination with checkpoint inhibitors (Andtbacka JCO 2015, Chesney JCO 2017, Ribas Cell 2017). T-VEC has also demonstrated tolerable safety for intrahepatic inj (Hecht JCO 2018). This phase 1b, multicenter, open-label, dose escalation study (NCT02509507) evaluates the safety of intrahepatic inj of T-VEC in combination with intravenous (IV) pem in patients (pts) with hepatocellular carcinoma (HCC) or liver metastases (mets). Methods: The primary objective is to assess the maximum tolerated concentration (MTC) of T-VEC inj into liver tumors based on the incidence of dose-limiting toxicities (DLTs). DLT rate was evaluated with the mTPI up-and-down design. Eligible pts were ≥ 18 years, had progressive HCC or breast cancer, colorectal cancer, gastroesophageal cancer, melanoma, non-small cell lung cancer, or renal cell cancer liver mets, with measurable liver tumors suitable for inj. This dose escalation study comprised 2 groups: A (non-HCC) and B (HCC). T-VEC was given initially at 10 ⁶ plaque-forming units (PFU)/mL followed by up to 4 mL of 10 ⁷ PFU/mL (cohort 5) or 10 ⁸ PFU/mL (cohort 6) every 21 (±3) days (Q21D). Inj volume was based on lesion size. Pem (200 mg) was given IV Q21D. Results: Here we report on three cohorts: A5 (10 ⁷ PFU/mL T-VEC + pem), A6 (10 ⁸ PFU/mL T-VEC + pem), and B5 (10 ⁷ PFU/mL T-VEC + pem). Twenty-nine pts were treated: 7 in A5, 17 in A6, 5 in B5. Median age was 61 years (range: 30, 76). Median number of inj was 4 and median treatment duration was 88 days. One DLT of cholestatic hepatitis was observed out of 6 DLT evaluable pts in cohort A5. No DLTs were observed in cohort A6 and B5. MTC was 10 ⁸ PFU/mL in non-HCC patients; exploration of MTC in the HCC population is ongoing. Treatment-emergent adverse events (TEAEs) were consistent across cohorts. The most common treatment-emergent treatment-related adverse events (TETRAE) were pyrexia (79.3%), chills (37.9%), and nausea (37.9%). Eight pts (27.6%) had grade 3/4 TEAEs: 2pts (6.9%) related to the combination therapy and the rest not related to treatment. No fatal AEs were observed. Conclusions: T-VEC intrahepatic inj in combination with IV pem at standard doses has thus far been demonstrated as feasible and tolerable to continue further investigation. Clinical trial information: NCT02509507 .