Replimune : Uveal Melanoma Biomarker Poster at AACR 2024

Enhanced CD8+ T-cell infiltration, PD-L1 expression, and T-cell repertoire expansion in patients with metastatic uveal melanoma responding to treatment with RP2 alone or in combination with nivolumab

Praveen K. Bommareddy1, Alireza Kalbasi1, Kevin J. Harrington2, Anna Olsson-Brown3, Tze Y. Chan3, Pablo Nenclares2, Isla Leslie2, Mark R. Middleton4, Aglaia Skolariki4, David M. Cohan1, Konstantinos Xynos1, Robert Coffin1, Joseph J. Sacco3

1Replimune, Inc., Woburn, MA, USA; 2The Institute of Cancer Research, London, UK; 3The Clatterbridge Cancer Centre, Wirral, UK and University of Liverpool, Liverpool, UK; 4Churchill Hospital and University of Oxford, Oxford, UK

Background

• RP2 is a genetically modified herpes simplex virus type 1 that encodes granulocyte- macrophage colony-stimulating factor, the fusogenic gibbon ape leukemia virus glycoprotein with the R sequence deleted (GALV-GP-R-), and a human anti-CTLA-4antibody-like molecule1
• RP2 ± nivolumab is currently being tested in clinical trials in a range of solid tumors including in patients with metastatic uveal melanoma (mUM)
• Uveal melanoma is the most common form of intraocular primary malignancy and accounts for ~90% of all cases of ocular melanoma and up to 5% of all melanomas2-5
• Approximately 50% of patients with uveal melanoma will develop distant metastases, with the liver representing the most frequent site of metastatic disease (~90%). Following metastasis, median overall survival is <1 year2,3
• As of November 20, 2023, 17 patients with uveal melanoma were enrolled (RP2 monotherapy, n = 3; RP2 + nivolumab, n = 14)
• Here, we present the biomarker data from patients with mUM treated with RP2 in combination with nivolumab

Patient demographics and baseline characteristics

	RP2 monotherapy (n = 3)	RP2 + nivolumab (n = 14)
Age, median (range), years	55 (48-64)	65 (38-82)
Sex, n (%)
Female	0	5	(35.7)
Male	3 (100.0)	9	(64.3)
ECOG PS, n (%)
0	3 (100.0)	11 (78.6)
1	0	3 (21.4)
Prior lines of treatment, n (%)
0	0	2 (14.3)
1	1 (33.3)	5	(35.7)
2	1 (33.3)	5	(35.7)
3	0	1	(7.1)
4	1 (33.3)	1	(7.1)
Prior therapies, n (%)	3 (100.0)	10	(71.4)
Anti-PD-1a
Anti-CTLA-4b	3 (100.0)	10	(71.4)
Anti-PD-1 and anti-CTLA-4	3 (100.0)	9 (64.3)

aAlone or combined with anti-CTLA-4.bAlone or combined with anti-PD-1.

CTLA-4, cytotoxic T-lymphocyte antigen 4; ECOG PS, Eastern Cooperative Oncology Group performance status; PD-1, programmed cell death protein 1.

Increase in CD8+ T cells influx and PD-L1 expression are observed in patients

treated with RP2 combined with nivolumab

RP2 ± nivolumab in patients who progressed on prior immunotherapy

201-4402-0014 PR

201-4401-0003 PR

 RP2 + nivolumab combination	 RP2 monotherapy
 More than 50% tumor reduction was observed	 Extensive liver metastases
 Prior therapies: ipilimumab, pembrolizumab	 Prior therapies: ipilimumab + nivolumab
 Patient progressed at 21.5 months after	 Patient progressed at 14.3 months after
initiating treatment with RP2	initiating treatment with RP2

Responses were observed in both HLA-A2*02:01-positive and HLA-A2*02:01-

negative patients

RP2 - A fusion-enhanced oncolytic HSV expressing anti-CTLA-4

αCTLA-4,anti-cytotoxicT-lymphocyte antigen 4; GALV-GP-R−, gibbon ape leukemia virus glycoprotein with the R sequence deleted; hGM-CSF, human granulocyte- macrophage colony-stimulating factor; HSV, herpes simplex virus; ICP, infected cell protein; P, promoter; pA, polyA signal; US11, unique short 11; X, denotes inactivation of viral protein.

Objectives

 To evaluate the efficacy of RP2 alone and in combination with nivolumab and the impact

on tumor biopsies and peripheral blood mononuclear cell (PBMC) samples collected from

Screening

Day 43

Screening

	201-3412-0001 PR			201-4402-0014 PR
CD8			PD-L1		CD8			PD-L1
				Screening

Day 43

	201-4401-0021 SD			201-4403-0015 SD
CD8			PD-L1		CD8		PD-L1
				Screening

• IHC of the day 43 biopsy demonstrates an increase in intratumoral CD8 T-cell infiltration and PD-L1 expression in patients achieving partial response (PR) and stable disease (SD)

HLA-A*02:01	Positive	Negative	Total
status	(n = 6)	(n = 11)	(n = 17)
PR	1 (16.7%)	4 (36.4%)	5 (29.4%)
SD	2 (33.3%)	3 (27.3%)	5 (29.4%)
PD/NE	3 (50.0%)	4 (36.4%)	7 (41.2%)

TCR sequencing of PBMCs demonstrated expansion of existing T cell clones

along with the generation of new tumor-specific T cell clones

mUM patients enrolled in the NCT04336241 clinical trial

Methods

Day 43

Day 43

201-3412-0001 PR

201-4401-0021 SD

201-4402-0007 PR

201-4402-0014 PR

201-4403-0018 SD

MART-1 clone

Part 1

Dose	RP2D	(28 days)
escalation	selected	Screening

• The RP2D was identified as
  1 × 106 PFU/mL once, followed by up to 7 doses of 1 × 107 PFU/mL per dosing day
• Re-initiationof up to 8 additional RP2 doses is permitted if prespecified criteria are met

	Part 2
Cohort 2a (completed)	Cohort 2b
Combination treatment (N = 30)	Expansion cohort (N = 30)
All-comers solid tumors	Specified solid tumors
RP2 (Q2W × 8 doses) + nivo (240 mg	RP2 (Q2W × 4 doses) followed by RP2 (Q4W × 4 doses) up to 8
Q2W × 4 mo; 480 mg Q4W × 20 mo)	doses + nivo starting at week 6 (240 mg Q2W or 480 mg Q4W ×
	22 mo)
	Part 3
	RP2 monotherapy (N = 15)
	Specified solid tumors
	RP2 (Q2W × 4 doses) followed by RP2 (Q4W × 4
	doses) up to 8 doses

Treatment period (24 mo)

Overall survival (up to 3 y from C1D1)

RP2 is administered via direct intratumoral injection into superficial/subcutaneous lesions or into deep/visceral lesions using image guidance (eg, ultrasound or CT)

EOT + safety follow-up

Screening

Day 43

201-4403-0014 PD

201-4402-0019 PD

201-4401-0002 PD

CD8

PD-L1

CD8

PD-L1

CD8

PD-L1

Screening

Screening

Day 43

Day 43

Duration of benefit; objective response rate and disease control rate

Day 43

Day 1

 TCR sequencing of PBMCs demonstrated expansion of pre-existing and generation of new T cell

clones following treatment with RP2 with nivolumab

 Numerous clones that exhibited expansion were first identified on day 43, suggesting that the

treatment contributed not only to the proliferation of pre-existing T cell clones but also to the de novo

generation of new T cell clones

 The expansion of new or pre-existing clones in the peripheral blood did not show correlation with

clinical response

C1D1, cycle 1 day 1; CT, computed tomography; EOT, end of treatment; nivo, nivolumab; PFU, plaque-forming unit; RP2D, recommended phase 2 dose; Q2W, every 2 weeks; Q4W, every 4 weeks.

RP2 ± nivolumab

Screening

Day 1

Day 15

Day 43

 In this pretreated population, the ORR was 29.4% (5/17; all PRs; RP2 monotherapy, 1/3; RP2 + nivolumab, 4/17)

RP2 monotherapy

Summary and conclusions

 Biomarker analysis shows that RP2 treatment in combination with nivolumab leads to significant immune

Archival/fresh biopsy

Peripheral blood mononuclear cells

 Tumor biopsies and PBMCs were collected at screening and at day 43

Tumor immune microenvironment was analyzed by immunohistochemistry (IHC) to detect

RP2 monotherapy

 The disease control rate (complete response + PR + SD) was 58.8% (10/17; 5 patients with SD in RP2 + nivolumab cohort)

 The median (range) duration of response at

activation. This is evidenced by the expansion of pre-existing T cell clones and the emergence of new T cell

clones in the peripheral blood, as well as increased PD-L1 expression and enhanced CD8+ T-cell infiltration in

tumors form mUM patients achieving PR and SD

 RP2 monotherapy and RP2 + nivolumab demonstrate a meaningful antitumor activity with durable responses in

patients with mUM, including in patients with liver metastases. These responses were observed in both HLA-



CD8 (SP57 clone, Ventana) and PD-L1(PD-L1 IHC 28-8 pharmDx by Agilent)

 Systemic antitumor immunity was assessed using PBMCs by sequencing the CDR3

regions of human TCRβ chains using the immunoSEQ assay.

RP2 monotherapythe data cutoff was 11.47 (2.78-21.22) months

Duration on study (days)

A2*02:01-positive and HLA-A2*02:01-negative patients

 Based on data in this population, planning is underway for a potentially registrational clinical trial with RP2

in advanced uveal melanoma

Acknowledgements:	References:	2.	Jager MJ, et al. Nat Rev Dis Primers. 2020;6(1):24.	4. Mahendraraj K, et al. Clin Ophthalmol. 2017;11:153-60.	Study Sponsor:
The authors would like to thank the patients for their participation in the trial. The authors would also like to acknowledge the contributions of Moran Mishal,	1. Thomas S, et al. J Immunother Cancer. 2019;7(1):214.	3.	National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology (NCCN
5. Branisteanu DC, et al. Exp Ther Med. 2021;22(6):1428.	The study is sponsored by Replimune Inc., Woburn, MA, USA.
Vineetha Edavana, and Mary Kate Cronin.			Guidelines®). Melanoma: Uveal. Version 2.2022.