Clinical development of reovirus for cancer therapy: An oncolytic virus with immune-mediated antitumor activity

Table 1 Phase I trials involving reovirus

Phase	Malignancy	Dosing regimen	Clinical response
I (REO 001)	Various advanced or refractory solid malignancies	1 × 107 PFU to 1 × 1010 PFU intralesional injection once or 3 × weekly (dose escalation)	Out of 19 patients, best overall response ≥ 6 wk was CR in 1 with Klatskin (5.3%), PR in 2 with head and neck cancer (10.5%), SD in 4 1 with head and neck, 1 with melanoma, 1 with breast cancer, 1 with Kaposi's (21.1%)
I/translational (REO 002)	Localized prostate cancer	1 × 107 PFU single intratumoral injection 3 wk prior to planned prostatectomy	Out of 6 patients, all did not exhibit significant fluctuations in PSA from baseline. Five of 6 patients showed staining for reovirus proteins localized to cancer areas but sparing of adjacent benign and remote cancer areas. Pathologic specimens showed peritumoral inflammation in 4 patients, apoptosis in 4 patients, and necrosis in 2 patients
I (REO 003)	Advanced or recurrent malignant gliomas	1 × 107 TCID50 to 1 × 109 TCID50 single stereotactic intralesional injection (dose escalation)	Out of 12 patients, best overall response was SD in 1 patient with oligo-astrocytoma with a TTP of 39 wk. The overall median TTP was 4.3 wk (range 2.6-39 wk), and median OS was 21 wk (range 6-234 wk)
I (REO 004)	Various advanced or refractory solid malignancies	60-min IV infusion from 1 × 108 TCID50 to 3 × 1010 TCID50 once every 28 d (dose escalation)	Out of 18 patients, best overall response was PR > 5 cycles in 1 patient with breast cancer (5.6%) and SD > 1 cycle in 7 (5 with ovarian cancer, 1 with carcinoid, 1 with STS, 38.9%); CBR of about 45%
I (REO 005)	Various advanced or refractory solid malignancies	60-min IV infusion from 1 × 108 TCID50 once every 28 d to 3 × 1010 TCID50 once daily for 5 d every 28 d (dose escalation); IV reovirus 3 × 1010 TCID50 once daily for 5 d every 28 d became recommended phase II dose	Out of 33 enrolled patients, best overall response was SD > 7 wk in 10 patients (2 with colon cancer, 2 with prostate cancer, 2 with STS, 1 with lung cancer, 1 with TCC of the bladder, 1 with melanoma, 1 with endometrial cancer)
I (REO 006)	Various advanced or refractory solid malignancies	1 × 108 TCID50 to 1 × 1010 TCID50 intratumoral injection on days 2 and 4 with 20 Gy local irradiation daily × 5 fractions phase 1b: 1 × 1010 TCID50 intratumoral injection twice weekly from 1-3 wk with 36 Gy local irradiation × 12 fractions over 16 d (two-stage dose escalation); intratumoral 3 × 1010 TCID50× 2 injections with 20 Gy × 5 fractions and intratumoral 1 × 1010 TCID50 × 6 injections with 36 Gy × 12 fractions became recommended phase II doses for short and prolonged palliative regimens, respectively	Out of 7 patients in phase 1a, best overall response was PR in 2 (esophageal adenocarcinoma and SCC of skin), SD in 5 (melanoma, pancreatic adenocarcinoma, SCC of larynx, and 2 with SCC of skin); out of 7 patients in phase 1b, 5 had PR (lung adenocarcinoma, colorectal cancer, ovarian adenocarcinoma, 2 with melanoma) and 2 had SD (melanoma) up to 3 mo post-treatment
I (REO 007)	Recurrent malignant gliomas	72-h intratumoral infusion from 1 × 108 TCID50 to 1 × 1010 TCID50 (dose escalation)	Out of 15 patients enrolled, best overall response was SD in 10 patients during the study period of 24 wk. The median TTP was 61 d (range 29-150 d), and median survival was 140 d (range 97-989)
I (REO 009)	Various advanced or refractory solid malignancies	60-min IV infusion from 1 × 109 TCID50 to 3 × 1010 TCID50 on day 1 (dose escalation) with 30-min IV infusion of gemcitabine 1000 mg/m2 days 1 and 8 every 21 d (1 × 1010 TCID50 reovirus on day 1 became recommended phase II dose with gemcitabine)	Out of 10 patients, best overall response was PR after 4 cycles in 2 patients (1 with nasopharyngeal carcinoma, 1 with breast cancer) and SD for 4-8 cycles in 5 patients (median SD 72 d, range 36-112 d); CBR of 80%
I (REO 010)	Various advanced or refractory solid malignancies	60-min IV infusion from 3 × 109 TCID50 to 3 × 1010 TCID50 days 1-5 (dose escalation) with 60-min IV infusion of docetaxel 75 mg/m2 day 1 every 21 d (3 × 1010 TCID50 reovirus days 1-5 every 21 d became recommended phase II dose with docetaxel)	Out of 16 patients, best overall response was PR ≥ 2 cycles in 4 patients (1 with breast cancer who experienced CR in liver lesion, 1 with gastric cancer, 1 with gastroesophageal cancer, 1 with ocular melanoma) and SD ≥ 2 cycles in 10 patients (cancers included prostate, mesothelioma, SCC of head and neck, unknown primary, melanoma, esophageal cancer, pancreatic cancer); CBR of 88%
I/translational (REO 013)	Colorectal cancer metastatic to the liver	60-min IV infusion of 1 × 1010 TCID50 daily × 5 d between 6-28 d prior to planned radical resection of liver metastases	Out of 10 patients, 9 patients with resected tumor specimens demonstrated positive staining for reovirus that was greatest in tumor metastases compared to surrounding tumor stroma or adjacent normal liver. In addition, tissue analysis in 4 patients showed findings consistent with reovirus-associated apoptosis
I (REO 022)	Metastatic colorectal cancer	60-min IV infusion from 1 × 1010 TCID50 to 3 × 1010 TCID50 days 1-5 every 28 d (dose escalation) with standard FOLFIRI doses (recommended phase II dose was irinotecan 150 mg/m2 with 3 × 1010 TCID50IV reovirus days 1-5 every 28 d)	Out of 18 patients, best overall response was PR in 1 patient (5%) and SD in 9 (50%) with median PFS in FOLFIRI-naïve patients of 7.4 mo (95%CI: 1.9-12.9 mo) and overall median PFS of 7.4 mo (95%CI: 0.6-14.1 mo)
I (OSU-11148, NCI trial)	Refractory or relapsed multiple myeloma	60-min IV infusion from 3 × 109 TCID50 to 3 × 1010 TCID50 days 1-5 every 28 d (dose escalation)	Out of 12 patients, best overall response was SD with longest duration being 8 cycles. During cycle 1, 5 patients had decreased myeloma proteins, 3 had minimal increases, and 4 had progressive disease

PFU: Plaque forming units; CR: Complete response; PR: Partial response; SD: Stable disease; PSA: Prostate-specific antigen; TCID₅₀: Tissue culture infectious dose-50; TTP: Time to disease progression; OS: Overall survival; IV: Intravenous; STS: Soft tissue sarcoma; CBR: Clinical benefit rate; TCC: Transitional cell carcinoma; Gy: Gray; SCC: Squamous cell carcinoma; FOLFIRI: Irinotecan/fluorouracil/leucovorin; PFS: Progression-free survival.

Table 2 Phase I/II, II, and III trials involving reovirus

Phase	Malignancy	Dosing regimen	Clinical response
I/II (REO 011)	Various advanced or refractory solid malignancies	60-min IV infusion from 3 × 109 TCID50 to 3 × 1010 TCID50 days 1-5 (dose escalation) with IV paclitaxel 175 mg/m2 over 3 h and IV carboplatin AUC5 (over 30 min) on day 1 every 21 d (3 × 1010 TCID50IV reovirus days 1-5 every 21 d became recommended phase II dose with paclitaxel and carboplatin)	Out of 26 patients, best overall response was CR in 1 patient (3.8%,head and neck cancer), PR in 6 patients (23.1%, 3 each with SCC of head and neck and head and neck cancer), major clinical response not evaluable by RECIST criteria in 2 patients (7.7%, SCC of head and neck), and SD in 9 patients (34.6%, 3 with SCC of head and neck, 3 with head and neck cancer, 1 with gynecological cancer, 1 with melanoma, 1 with sarcoma) with median duration of SD and PR of 6 mo (range 3-10 mo). Of the 24 patients with head and neck cancer, median OS was 7.1 mo (CI: 4.2-11.5 mo)
I/II (OSU-07022, NCI trial)	Recurrent or refractory ovarian, peritoneal, and fallopian tube carcinomas	60-min IV infusion 3 × 1010 TCID50 days 1-5 with daily IP administration days 2-3 beginning cycle 2 every 28 d (dose escalation with IP dosing)	Thus far 8 patients have received treatment. Biopsied ovarian and peritoneal tumor samples reveal detection of viral proteins in tumor tissues compared to control after systemic (IV) administration of reovirus and presence of reovirus replication in tumors due to overlap of reovirus protein and microtubules
II (REO 008)	Various advanced or refractory solid malignancies	Open-label, single-arm, multicenter: 1 × 1010 TCID50 intratumoral injection on days 2 and 4 with 4 Gy local irradiation daily × 5 (total 20 Gy) every cycle	Out of 16 patients enrolled (5 with melanoma, 4 colorectal, 1 gastric, 1 ovarian, 1 pancreatic, 1 lung, 1 cholangiocarcinoma, 1 sinus, 1 thyroid), 14 were evaluable and best overall response was SD or better in 13 patients (93%). Of these patients, 4 had PR (2 with melanoma, 1 lung, 1 gastric) and 2 had minor responses (1 thyroid and 1 ovarian)
II (MAYO-MC0672, NCI trial)	Metastatic melanoma	Open-label, single-arm, multicenter: 60-min IV infusion 3 × 1010 TCID50 days 1-5 every 28 d	Out of 21 evaluable patients, best overall response was SD > 8 wk in 6 patients. The median TTP was 45 d (range 13-96 d) and median OS was 165 d (range 15 d-15.8 mo). Trial was closed as did not meet previously defined efficacy criteria to proceed to second stage of accrual
II (REO 014)	Advanced or refractory sarcomas metastatic to lung	Open-label, single-arm, multicenter: 60-min IV infusion 3 × 1010 TCID50 days 1-5 every 28 d	Out of 53 enrolled patients, best overall response was SD ≥ 12 wk in 18 patients (34%) with a subgroup of 12 patients (3 with synovial sarcoma, 2 with leiomyosarcoma, 2 with MFH, 1 with ES, 1 with non-specified spindle cell sarcoma, 1 with chordoma, 1 with ASPS), 1 with myxoid liposarcoma) having prolonged SD > 16 wk. Three of these patients demonstrated SD > 1 yr (1 with MFH, 1 with synovial sarcoma, 1 with ES). The median TTP was 58.0 d (95%CI, 54-110, range 8-726 d). The prolonged SD demonstrated fulfilled the study criteria for consideration as an active agent
II (REO 015)	Refractory, recurrent, or metastatic SCC of the head and neck	Open-label, single-arm: 60-min IV infusion 3 × 1010 TCID50 days 1-5 with IV paclitaxel 175 mg/m2 over 3 h and IV carboplatin AUC5 (over 30 min) on day 1 every 21 d	Out of 13 evaluable patients (sites included 3 larynx, 6 oral cavity, 4 pharynx, 1 other), 4 had PR (31%) and 2 had SD ≥ 12 wk for a CBR of 46%
II (REO 016)	Recurrent or metastatic NSCLC	60-min IV infusion 3 × 1010 TCID50 days 1-5 with IV paclitaxel 175 mg/m2 over 3 h and IV carboplatin AUC5 (over 30 min) on day 1 every 21 d	Out of 37 patients enrolled, 20 patients had detected K-Ras mutations, 3 patients had EGFR mutations, 10 patients had EGFR amplifications alone, and 4 patients had BRAF V600E mutations. Median PFS was 4 mo (95%CI: 2.9-6.1), median OS was 13.1 mo (95%CI: 9.2-21.6), and 1-yr OS rate was 57% (95%CI: 39%-72%)
II (REO 017)	Advanced or unresectable pancreatic cancer	60-min IV infusion 1 × 1010 TCID50 on days 1, 2, 8 and 9 with IV infusion of gemcitabine 800 mg/m2 days 1 and 8 every 21 d	Out of 34 enrolled patients, median PFS was 4 mo and OS was 10.2 mo. One- and 2-yr survival rates were 45% and 24%, respectively
II (REO 021)	Recurrent or metastatic SCC of the lung	Open-label, single-arm: 60-min IV infusion 3 × 1010 TCID50 days 1-5 with IV paclitaxel 200 mg/m2 over 3 h and IV carboplatin AUC6 every 21 d	Out of 25 patients who received more than 1 cycle of therapy, best overall response was PR in 12 patients (48%) and SD in 10 patients (40%) for a CBR of 88%. Of 21 patients with > 6 mo follow-up 7 had PFS ≥ 6 mo (33.3%)
III (REO 018)	Advanced or metastatic head and neck cancer	Randomized, double-arm, double-blinded, multicenter: 60-min IV infusion 3 × 1010 TCID50 days 1-5 with standard doses of IV paclitaxel and IV carboplatin on day 1 only every 21 d (treatment arm) vs standard doses of IV paclitaxel and IV carboplatin alone (control arm)	Out of 167 enrolled patients, 118 patients were segregated into an intent-to-treat basis group with loco-regional head and neck cancer (with or without metastases). In this group, median PFS was 94 d (13.4 wk, n = 62) in the test arm vs 50 d (7.1 wk, n = 56) in control arm maintained through 5 cycles. In the 88 patients discontinued from the study from this group, median OS was 150 d (21.4 wk, n = 50) in the test arm vs 115 d (16.4 wk, n = 38) in the control arm. Survival analysis in the other group (distal metastases-only) has not been conducted

IV: Intravenous; TCID₅₀: Tissue culture infectious dose-50; AUC_5/6: Area under curve-5/-6; CR: Complete response; PR: Partial response; SCC: Squamous cell carcinoma; RECIST: Response evaluation criteria in solid tumors; SD: Stable disease; OS: Overall survival; IP: Intraperitoneal; Gy: Gray; TTP: Time to disease progression; PFS: Progression-free survival; MFH: Malignant fibrous histiocytoma; ES: Ewing sarcoma; ASPS: Alveolar soft part sarcoma; CBR: Clinical benefit rate; NSCLC: Non-small cell lung cancer; EGFR: Epidermal growth factor receptor.