Menlo Therapeutics Inc.June 2019

Developing Serlopitant, a Once-Daily Oral NK1 Receptor Antagonist for Pruritus

Special Note Regarding Forward-Looking StatementsThis presentation contains forward-looking statements, including statements about our plans to develop and commercialize our product candidates, our planned clinical trials for serlopitant, the timing of the availability of data from our clinical trials, the timing of our planned regulatory filings, the timing of and our ability to obtain and maintain regulatory approvals for serlopitant and the clinical utility of serlopitant, alone and as compared to other treatment options, the duration of patent protection, and other statements regarding strategy, future operations and plans, as well as assumptions underlying such statements. These statements involve substantial known and unknown risks, uncertainties and other factors, some of which are outside of our control, that may cause our actual results, levels of activity, performance or achievements to be materially different from the information expressed or implied by these forward-looking statements, including risks related to the clinical drug development process, the regulatory approval process, our reliance on third parties, and our ability to defend our intellectual property. We may not actually achieve the plans, intentions or expectations disclosed in our forward-looking statements, and you should not place undue reliance on our forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in the forward-looking statements we make. Additional information that could lead to material changes in our performance is contained in our filings with the U.S. Securities and Exchange Commission. The forward-looking statements in this presentation represent our views as of the date of this presentation. We anticipate that subsequent events and developments will cause our views to change. However, while we may elect to update these forward-looking statements at some point in the future, we have no current intention of doing so except to the extent required by applicable law. You should, therefore, not rely on these forward-looking statements as representing our views as of any date subsequent to the date of this presentation. Additional InformationThis presentation concerns a product that is under clinical investigation and which has not yet been approved for marketing by the U.S. Food and Drug Administration. It is currently limited by Federal law to investigational use, and no representation is made as to its safety or effectiveness for the purposes for which it is being investigated.

Safe Harbor Statements

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Menlo Investment Highlights

Serlopitant Phase 3 Development in 2 Pruritus Indications + Pipeline• Phase 3 prurigo nodularis

• Granted Breakthrough Therapy Designation by the FDA• Phase 3 psoriasis • Phase 2 chronic pruritus of unknown origin

Success in Large, Placebo-controlled Phase 2 Pruritus Trials• Hit primary endpoint in 3 of 4 large placebo-controlled Phase 2 trials• In all 4 trials, at every time point, showed improvement in pruritus vs. placebo

Large Market Opportunity in Pruritus• PN: 300-600K patients in the U.S. with no approved therapy• Psoriasis: 7.5M patients diagnosed in the U.S.; >90% experience pruritus

Cash Runway through the end of 2020• ~$122M cash as of 3/31/19

Solid IP• U.S. composition of matter to 2030, incl. extensions; methods of use to 2033

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Indication Phase 1

Phase 2

Phase3 2019 2020

Serlopitant Pipeline and Upcoming MilestonesSerlopitant is a highly selective small molecule inhibitor of NK1 Receptor, given once daily, as an oral tablet

4

Recent and Anticipated Milestones

Psoriasis

Chronic Pruritus of Unknown Origin

EOP2 Mtg

File NDA

Prurigo Nodularis Complete enrollment

2 Phase 3 trials ongoing

Targeting to initiate Phase 3 program in 2019

Phase 2 initiated in January 2019

Trial Results

Complete enrollment

Targeted initiation

-2.5

-2

-1.5

-1

-0.5

0

0 2 4 6

Atopic Dermatitis – MTI-103

Serlopitant Met Primary Endpoints in 3 of 4 Phase 2 Pruritus Trials and Demonstrated Improvement Over Placebo at Every Assessed Time Point

VAS

% C

hang

e fr

om B

asel

ine

WI-N

RS C

hang

e fr

om B

asel

ine

-2.01-2.25-2.32 p=0.11

p=0.17

Chronic Pruritus – TCP-101

Treatment Week

Treatment Week

-9mm-15mm -19mm-18mm

-25mm

-36mm

-40

-30

-20

-10

0

0 2 4 6 8

Avg

Itch

VAS

Cha

nge

from

Bas

elin

e

p=0.001

Treatment Week

Prurigo Nodularis – TCP-102

Psoriasis – MTI-109

0%5%

10%15%20%25%30%35%

0 Day 7 2 3 4 5 6 7 8

WI-N

RS 4

-poi

nt R

espo

nder

Rat

e 33%

21%

-50

-40

-30

-20

-10

0

0 1 2 3 4 5 6

N=127

*

*Primary endpoint

N=257

*

Serlopitant 0.25 mg Serlopitant 5 mgPlacebo Serlopitant 1 mg

-42.5%p=0.013

-34.1%-41.4%

-28.3%

N=203N=484

*

5

p=0.028*

Treatment Week

26%

47%

Phase 2 Pruritus Studies – Serlopitant 5mg Responder Rate

WI-NRS 4-Point Responder Analysis (Baseline to Week 8)Prurigo Nodularis – TCP-102Chronic Pruritus – TCP-101

17%21%

Atopic Dermatitis – MTI-103

21%

33%

WI-NRS 4-Point Responder Analysis (Baseline to Week 8)WI-NRS 4-Point Responder Analysis (Baseline to Week 6)Psoriasis – MTI-109

p=0.17 p=0.028*

Placebo Serlopitant 5mg

23%

46%NRS 4-Point Responder Analysis (Baseline to Week 6)

N=53 N=52 N=39 N=43

N=101 N=102N=158 N=160

p=0.011 p=0.05

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*Primary endpoint.

23.1% 22.2%

46.2%

30.8%35.7%

29.6%

52.9%

33.3%Placebo

.25 mg

1 mg

5 mg

Post Hoc Analyses of Completed Phase 2 Studies with Serlopitant

Observed patterns in three completed Phase 2 studies in pruritus suggest the following types of patients respond better to serlopitant:• patients without inflammatory skin disease• older patients• patients with longer duration of pruritus

(1) Includes patients with a self-reported history of cutaneous lupus erythematosus, dermatitis, atopic dermatitis, contact dermatitis, dry skin, dyshidrotic eczema, eczema, asteatotic eczema, nummular eczema, hand dermatitis, keratosis pilaris, lichen planus, mechanical urticaria, neurodermatitis, photosensitivity reaction, psoriasis, rash, erythematous rash, pruritic rash, seborrheic dermatitis, stasis dermatitis, and urticaria.

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TCP-101 Post-hoc Analysis Results

N=27 N=26 N=27 N=18 N=26 N=26 N=28 N=34

Patients with a Self-reported History of Inflammatory Skin Disease (1)

Patients Without a Self-reported History ofInflammatory Skin Disease

NRS

4-p

oint

Res

pond

er R

ate

at W

eek

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Consolidated Safety Summary of Serlopitant

Evaluated in ~1,600 patients and shown to be well-tolerated, including in patients who received treatment up to one year

Most commonly reported treatment emergent adverse events across completed Phase 2 trials were:

N=670 N=1261TEAE Placebo (%) Serlopitant (%)

Urinary Tract Infection 2.5% 4.8%Nasopharyngitis 3.7% 4.8%

Diarrhea 3.4% 4.7%Headache 6.3% 4.4%

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Serlopitant for Pruritus Associated with Prurigo Nodularis

Granted Breakthrough Therapy Designation by the FDAPhase 3 Program OngoingTargeting 2020 NDA Filing

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Prurigo Nodularis

Prurigo Nodularis (PN)

A chronic intensely pruritic skin condition

Scratching leads to nodules which lead to more itch

No approved therapies in US or EU No effective treatment options

Image courtesy of Prof. Sonja Stander, University Munster

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Itch is the Primary Complaint Among 100% of PN Patients (1)

(1) Company survey of 30 physicians who treat PN patients.

0% 20% 40% 60% 80% 100%Itch

0% 20% 40% 60% 80% 100%

Sleep Pain / Burning / Bleeding Lesion / Appearance Other

Secondary Complaint

Primary Complaint

Limited Treatment Options Frustrate Patients and Physicians

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ManagementTreatmentDiagnosisLiving with PN

• Constant itch is extremely bothersome and alters lifestyle

• Majority of patients diagnosed by dermatologists

• Treatments are not always effective and may have limitations such as side effects

• “Trial and error” - topical steroids- antihistamines- intralesional injections- phototherapy - cryotherapy

• Patients resign themselves to live with it

• Severe patients may visit physician regularly (every 3-6 months)

“Yes, I had some type of relief. But, then, it started again. Every time I'd have a little bit of relief, and then it seems like another trigger…”

—PN Patient

“It can be frustrating...very limited options to treat patients with. And even the options that we have, sometimes don't help or help just a little bit. So, these patients you see on an ongoing basis.”

—Dermatologist

Attractive Commercial Opportunity in PN

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300K – 600K patients in US (1)

~185K PN patients visit physicians each year (1)

• 75% of PN patients are diagnosed by a dermatologist

On therapy 2-6 months per year (1)

$900 – $2,400 per month(2)

(1) Internal company estimates (2) Estimates based on company payer research and symptom relief analogs

• ~5K derms treat majority of PN patients

• Estimated 50 person field force could reach high-prescribing derms

• If approved, serlopitant would be 1st to market in PN

26%

47%

Placebo (N=63) VPD-737 5mg (N=64)

25%

54%

Placebo (N=63) VPD-737 5mg (N=64)

VAS – Primary Endpoint

WI-NRS - 4 Point Responder Analysis (Baseline to Week 8)Worst Itch NRS

NRS

VAS - 40mm Responder Analysis (Baseline to Week 8) Average Itch VAS

PN Phase 2 Study: Data Consistent Across Multiple Endpoints

PlaceboPlacebo Serlopitant Serlopitant

-9mm-15mm

-19mm

*

-18mm *-25mm * -36mm

-50

-40

-30

-20

-10

0

0 2 4 6 8 10

Aver

age

Itch

VAS

Chan

ge

from

Bas

elin

e (m

m)

Treatment Week

*p ≤ 0.05bars show standard error

Placebo5 mg -1.5

-1.9

-2.4

*-2.4*

-3.0* -3.7

-5

-4

-3

-2

-1

0

0 2 4 6 8 10

Aver

age

Itch

NRS

Cha

nge

from

Bas

elin

e (p

oint

s)

Treatment Week

*p ≤ 0.05bars show standard error

Placebo5 mg

13

p=0.002 p=0.05

serlopitant serlopitant

Ongoing NULARIS Phase 3 Studies in Prurigo Nodularis

Placebo

Primary endpoint

WI-NRS 4-point responder rate at

Week 10

Serlopitant 5 mg

MTI-105 (US) & MTI-106 (EU)

Over 160 patients enrolled in each trial as of 5/2/19Data expected H1 2020

N~280 per trialPN of ≥6 weeks Trial 1: ~50 sites in US Trial 2: ~50 sites in

Europe•Screening pruritus ≥7 on WI-NRS

•Excludes active pruritic skin disease

2-4 week screening 10-week treatment 3-5 week follow-up

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Serlopitant for Pruritus Associated with Psoriasis

Phase 3 Targeted for 2019

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Psoriasis

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Itch is the Most FrequentPatient Complaint(2)

Psoriasis is a chronic inflammatory disease of multiple systems causing areas of thickened skin, itch and pain No cure; treatments aim to improve symptoms ~7.5M diagnosed in the U.S.(1)

25% Mod / Severe Psoriasis(3)

75% Mild Psoriasis

(1) Armstrong, Dermatol Ther 2016 (2) Quality of Life & Work Productivity Impairment among Psoriasis Patients: Findings from National Psoriasis Foundation Survey 2003–2011 (3) National Psoriasis Foundation (4) Armstrong, JAMA Derm 2013

Moderate-Severe Psoriasis(1)

• 59% not treated• 9% biologics• 13% oral systemic• 17% topicals

Mild Psoriasis(4)

• 49% not treated• 42% topicals only

Current Standard of Care Does not Target Itch for Majority of Patients

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Large Market Opportunity for Pruritus with Psoriasis

~7.5M diagnosed patients in the US (1)

74% with moderate to severe itch (2) (~5.5M)

~75% not well controlled with current therapy(2) (~4M)

On therapy 4-8 months per year (3)

$900 – $1,200 per month(3)

~100-150 person field force could target high-prescribing derms and PCPs

(1) Armstrong, Dermatol Ther 2016 (2) Company market research (3) Internal company estimates

PSORIXA Phase 2 Study in Psoriasis – Data Announced Dec. 2018

Primary endpoint

WI-NRS 4-point responder rate at Week 8

MTI-109

N=204 Plaque-type PsO for

≥6 months, ≤10% BSA Pruritus ≥ 4 weeks WI-NRS ≥ 7 w/in 24

hours of initial screening

Serlopitant 5 mg

2-4-week screening 8-week treatment 2-week follow-up

Placebo

PsO = PsoriasisClinicalTrials.gov ID: NCT03343639

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21%

33%

Psoriasis Phase 2 Study: Data Consistent Across Multiple Endpoints

19

WI-N

RS C

hang

e fr

om B

asel

ine

WI-NRS (Change From Baseline)

Primary Endpoint - WI-NRS 4-Point Responder Analysis (Baseline to Week 8)

p=0.028

11%

21%

Secondary Endpoint: WI-NRS 4-Point Responder Analysis (Baseline to Week 4)

p=0.039

-3-2.5

-2-1.5

-1-0.5

0

-2.02

-2.77

*

*Follow-up visit at Week 10. Treatment through Week 8 only. Placebo Serlopitant 5mg

0%5%

10%15%20%25%30%35%

WI-N

RS 4

-poi

nt R

espo

nder

Rat

e 33%

21% p=0.028

WI-NRS 4-Point Responder Analysis (Change from Baseline)

*

Serlopitant for Chronic Pruritus of Unknown Origin (CPUO)

Phase 2 Initiated in Q1 2019

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Chronic Pruritus of Unknown Origin – A Large and Underserved Market

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CPUO Defined as pruritus lasting 6 weeks or longer, with no identified underlying disease

• Also referred to as idiopathic pruritus or pruritus of undetermined origin • Overlaps with pruritus of the elderly / senile pruritus Large market

• 8-15%(1) of ~80M chronic pruritus patients(2)

No approved therapies in US or EU

(1) Weisshaar, 2012 (2) Lifetime prevalence. Matterne, Acta Der Venereol, 2013

In patients with severe pruritus that cannot be eliminated by identifying and treating an underlying cause…, topical therapy and lifestyle changes are unlikely to be sufficient, and systemic

therapy should be considered. Given a paucity of data from randomized trials to evaluate various therapies, therapeutic

choices are largely based on clinical experience and anecdotal reports. Sedating antihistamines are commonly used as first-line

therapy but often have only modest efficacy….

Yosipovitch. NEJM. 2013

Phase 2 Study in CPUO

Primary endpoint

WI-NRS 4-point responder rate at

Week 10

MTI-117

Data Expected mid-2020

N~200

Chronic pruritus of unknown origin ≥6 months

WI-NRS ≥7 prior to screening

Serlopitant 5 mg

2- or 4-week screening

10-week treatmentPrimary endpoint at week 10

3-week follow-up

Placebo

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Financial Information and Conclusion

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Key Financial Highlights

Quarter Ended March 31, 2019

Cash & investments ~$122M

Operating expenses Including $1M non-cash stock-based compensation

$20M

Common shares outstanding 23.7M

Forward-Looking Information

2019 Estimated operating expenses*Including ~$3M-$6M non-cash stock-based compensation

$78M-$88M

Estimated cash runway Through 2020

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*Provided 2/27/19