Source: Sanofi (EURONEXT: SAN) (NASDAQ: SNY) Libtayo (cemiplimab) shows clinically meaningful and durable responses in second-line advanced basal cell carcinoma * Objective responses seen in 29% of patients

Libtayo (cemiplimab) shows clinically meaningful and durable

responses in second-line advanced basal cell carcinoma

Paris and Tarrytown, NY May 5, 2020 - Topline data for a pivotal, single-arm,

open-label trial for Sanofi and Regeneron s PD-1 inhibitor Libtayo (cemiplimab) in patients with advanced basal cell carcinoma (BCC) who had

progressed on or were intolerant to prior hedgehog pathway inhibitor (HHI) therapy were announced today. Libtayo demonstrated clinically meaningful and durable responses in this group of patients for whom there are no approved treatments. Sanofi and

Regeneron plan regulatory submissions in 2020.

BCC is a skin cancer and is the most common cancer worldwide, with approximately two million new cases

diagnosed every year in the U.S. alone. While the vast majority of BCCs are caught early and cured with surgery or radiation, a small proportion of tumors can become advanced and penetrate deeper into surrounding tissues (locally advanced), which is

more difficult to treat. Approximately 20,000 U.S. patients have advanced BCC and it is estimated that about 3,000 die each year. BCC marks the second non-melanoma skin cancer for which Libtayo has

demonstrated first-in-class data and follows its initial U.S. approval in advanced cutaneous squamous cell carcinoma (CSCC) in 2018.

In the trial, the objective response rate (ORR) for patients (n=84) with locally advanced disease was 29% (95% CI:

19%-40%), with an estimated duration of response (DOR) exceeding one year in 85% of responders. The durable disease control rate (DCR response or stable disease lasting at least 6 months) was 60% (95%

CI: 48%-70%). In a preliminary analysis of patients (n=28) with metastatic disease, the ORR was 21% (95% CI: 8%-41%), with an estimated DOR exceeding one year in 83% of

responders. The durable DCR was 46% (95% CI: 28%-66%). All data were assessed by an independent central review. Data are expected to continue to evolve with further

follow-up across both patient groups.

While PD-1 inhibitors have transformed the

outlook for many patients with melanoma, progress for patients with non-melanoma skin cancers has not been as rapid, said Peter C. Adamson, M.D, Global Head of Oncology Development at Sanofi.

We are continuing to address this unmet need by first bringing Libtayo to patients with advanced cutaneous squamous cell carcinoma, and now, with this second trial, as a potential therapy for patients with advanced basal cell carcinoma. These

important new results further demonstrate Libtayo s potential in patients with difficult-to-treat, non-melanoma skin

There were no new safety signals in this trial. Among the 132 patients assessed for safety (84 locally advanced and 48 metastatic),

95% of patients experienced an adverse event (AE), 32% had a serious AE and 13% discontinued due to an AE. There were 10 deaths in the locally advanced group and nine deaths in the metastatic group; none of the deaths were considered

treatment-related. Sanofi and Regeneron will present additional trial findings at an upcoming medical meeting.

investigated as a monotherapy treatment and as a foundation therapy for combinations with novel therapeutic approaches being developed by Regeneron and our collaborators, Israel Lowy, M.D., Ph.D., Senior Vice President, Translational and

Clinical Sciences, Oncology at Regeneron. These data in advanced BCC provide the third instance where Libtayo monotherapy has demonstrated robust and clinically meaningful outcomes in advanced cancer, and follows last week s

announcement in advanced non-small cell lung cancer where the pivotal trial was stopped early for positive overall survival.

In this ongoing global Phase 2 trial, patients received Libtayo 350 mg intravenously every three weeks for up to 93 weeks or until disease progression,

unacceptable toxicity, withdrawal of consent or confirmed complete response. ORR is the primary endpoint and key secondary endpoints include overall survival, progression-free survival, duration of response, safety and quality of life.

Libtayo is being jointly developed and commercialized by Sanofi and Regeneron under a global collaboration agreement.

The use of Libtayo to treat advanced BCC is investigational and the safety and efficacy have not been evaluated by any regulatory authority.

Libtayo is a fully-human monoclonal

antibody targeting the immune checkpoint receptor PD-1 on T-cells. By binding to PD-1, Libtayo has been shown to block cancer

cells from using the PD-1 pathway to suppress T-cell activation.

is the first and only immunotherapy approved in the U.S., EU, and other countries for adults with metastatic cutaneous squamous cell carcinoma (CSCC) or locally advanced CSCC who are not candidates for curative surgery or curative radiation. In the

U.S., the generic name for Libtayo in its approved indication is cemiplimab-rwlc, with rwlc as the suffix designated in accordance with Nonproprietary Naming of Biological Products Guidance for Industry issued by the U.S. Food and Drug

The extensive clinical program for Libtayo is focused on difficult-to-treat cancers. In skin cancer, this includes trials in adjuvant and neoadjuvant CSCC. Libtayo is also being investigated in potentially registrational Phase 3 trials in non-small lung cancer and cervical cancer, as well as in trials combining Libtayo with novel therapeutic approaches for both solid tumors and blood cancers. These potential uses are investigational, and their safety

and efficacy have not been evaluated by any regulatory authority.

About Regeneron Pharmaceuticals, Inc.

Regeneron (NASDAQ: REGN) is a leading biotechnology company that invents life-transforming medicines for people with serious diseases. Founded and led for over

30 years by physician-scientists, our unique ability to repeatedly and consistently translate science into medicine has led to seven FDA-approved treatments and numerous product candidates in development, all

of which were homegrown in our laboratories. Our medicines and pipeline are designed to help patients with eye diseases, allergic and inflammatory diseases, cancer, cardiovascular and metabolic diseases, pain, infectious diseases and rare diseases.

Regeneron is accelerating and improving the traditional drug development process through our proprietary VelociSuite technologies, such as VelocImmune which uses unique genetically-humanized mice to produce optimized fully-human antibodies and bispecific antibodies, and through ambitious research initiatives

such as the Regeneron Genetics Center, which is conducting one of the largest genetics sequencing efforts in the world.

For additional information about

the company, please visit www.regeneron.com or follow @Regeneron on Twitter.

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