1. Menlo Therapeutics Inc.
March 2019
Developing Serlopitant, a Once-Daily Oral NK1 Receptor Antagonist for Pruritus

2. Safe Harbor Statements
Special Note Regarding Forward-Looking Statements This 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 Information This 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.

3. 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: K patients in the U.S. with no approved therapy
Psoriasis: 7.5M patients diagnosed in the U.S.; >90% experience pruritus
Cash Runway into Q4 2020
~$136M cash as of 12/31/18
Solid IP
U.S. composition of matter to 2030, incl. extensions; methods of use to 2033 3

4. Serlopitant Pipeline and Upcoming Milestones Serlopitant is a highly selective small molecule inhibitor of NK1 Receptor, given once daily, as an oral tablet
Indication
Phase 1
Phase 2
Phase 3
2019
2020
Anticipated Milestones
Prurigo Nodularis
Complete enrollment
File
NDA
2 Phase 3 trials ongoing
Psoriasis
EOP2 Mtg
Targeting to initiate Phase 3 program in 2019
Chronic Pruritus of Unknown Origin
Complete enrollment
Phase 2 initiated in January 2019
Trial Results
Targeted initiation 4

5. Serlopitant Met Primary Endpoints in 3 of 4 Phase 2 Pruritus Trials and Demonstrated Improvement Over Placebo at Every Assessed Time Point
Chronic Pruritus – TCP-101
Prurigo Nodularis – TCP-102
N=257
N=127
Avg Itch VAS Change from Baseline
VAS % Change from Baseline
-28.3%
-34.1%
-41.4%
-42.5%
p=0.001 *
p=0.013 *
Treatment Week
Treatment Week
Atopic Dermatitis – MTI-103
Psoriasis – MTI-109
N=484
N=203
33%
21%
WI-NRS Change from Baseline
WI-NRS 4-point Responder Rate
p=0.028 *
-2.01
-2.25 *
p=0.17
-2.32
p=0.11
Treatment Week
Treatment Week
*Primary endpoint
Placebo
Serlopitant 0.25 mg
Serlopitant 1 mg
Serlopitant 5 mg 5

6. Phase 2 Pruritus Studies – Serlopitant 5mg Responder Rate
Chronic Pruritus – TCP-101
Prurigo Nodularis – TCP-102
NRS 4-Point Responder Analysis (Baseline to Week 6)
WI-NRS 4-Point Responder Analysis (Baseline to Week 8)
p=0.011
p=0.05
N=53
N=52
N=39
N=43
Atopic Dermatitis – MTI-103
Psoriasis – MTI-109
WI-NRS 4-Point Responder Analysis (Baseline to Week 6)
WI-NRS 4-Point Responder Analysis (Baseline to Week 8)
p=0.17
p=0.028 *
N=158
N=160
N=101
N=102
Placebo
Serlopitant 5mg
*Primary endpoint. 6

7. 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=1261
TEAE
Placebo (%)
Serlopitant (%)
Urinary Tract Infection
2.5%
4.8%
Nasopharyngitis
3.7%
Diarrhea
3.4%
4.7%
Headache
6.3%
4.4%

8. Serlopitant for Pruritus Associated with Prurigo Nodularis Granted Breakthrough Therapy Designation by the FDA Phase 3 Program Ongoing Targeting 2020 NDA Filing

9. 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
Itch is the Primary Complaint Among 100% of PN Patients (1)
Primary Complaint
Secondary Complaint
Image courtesy of Prof. Sonja Stander, University Munster
(1) Company survey of 30 physicians who treat PN patients.

10. Attractive Commercial Opportunity in PN
300K – 600K patients in US (1)
~185K PN patients visit physicians each year (1)
On therapy 2-6 months
per year (1)
75% of PN patients are diagnosed by a dermatologist
~5K derms treat majority of PN patients
Estimated 50 person field force could reach high-prescribing derms
$900 – $2,400
per month(2)
(1) Internal company estimates (2) Estimates based on company payer research and symptom relief analogs

11. Limited Treatment Options Frustrate Patients and Physicians
Living with PN
Diagnosis
Treatment
Management
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)
“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
“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

12. PN Phase 2 Study: Data Consistent Across Multiple Endpoints
VAS – Primary Endpoint
NRS
serlopitant
serlopitant
VAS - 40mm Responder Analysis (Baseline to Week 8)
Average Itch VAS
WI-NRS - 4 Point Responder Analysis (Baseline to Week 8)
Worst Itch NRS
Placebo
Serlopitant
Placebo
Serlopitant
p=0.002
p=0.05

13. Ongoing NULARIS Phase 3 Studies in Prurigo Nodularis
MTI-105 (US) & MTI-106 (EU)
N~280 per trial
PN 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
Primary endpoint
WI-NRS 4-point responder rate at Week 10
Serlopitant
5 mg
Placebo
2-4 week screening
10-week treatment
3-5 week follow-up
MTI-105 ~50% enrolled*
MTI-106 >50% enrolled*
Data expected H1 2020
*As of 2/22/19

14. Serlopitant for Pruritus Associated with Psoriasis Phase 3 Targeted for 2019

15. Psoriasis
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)
Itch is the Most Frequent Patient Complaint(2)
Current Standard of Care Does not Target Itch for Majority of Patients
Moderate-Severe Psoriasis(1)
59% not treated
9% biologics
13% oral systemic
17% topicals
25% Mod /
Severe Psoriasis(3)
75% Mild Psoriasis
Mild Psoriasis(4)
49% not treated
42% topicals only
(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

16. 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)
~ person field force could target high- prescribing derms and PCPs
$900 – $1,200
per month(3)
(1) Armstrong, Dermatol Ther 2016 (2) Company market research (3) Internal company estimates

17. PSORIXA Phase 2 Study in Psoriasis – Data Announced Dec. 2018
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
Primary endpoint
WI-NRS 4-point responder rate at Week 8
Serlopitant
5 mg
Placebo
2-4-week screening
8-week treatment
2-week follow-up
PsO = Psoriasis
ClinicalTrials.gov ID: NCT

18. WI-NRS 4-point Responder Rate WI-NRS Change from Baseline
Psoriasis Phase 2 Study: Data Consistent Across Multiple Endpoints
Primary Endpoint - WI-NRS 4-Point Responder Analysis (Baseline to Week 8)
WI-NRS 4-Point Responder Analysis (Change from Baseline)
33%
21%
p=0.028
WI-NRS 4-point Responder Rate
p=0.028 *
Secondary Endpoint: WI-NRS 4-Point Responder Analysis (Baseline to Week 4)
WI-NRS (Change From Baseline)
-2.02
WI-NRS Change from Baseline
-2.77
p=0.039 *
*Follow-up visit at Week 10. Treatment through Week 8 only.
Placebo
Serlopitant 5mg

19. Serlopitant for Chronic Pruritus of Unknown Origin (CPUO) Phase 2 Initiated in Q1 2019

20. Chronic Pruritus of Unknown Origin – A Large and Underserved Market
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
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
(1) Weisshaar, 2012 (2) Lifetime prevalence. Matterne, Acta Der Venereol, 2013

21. Post Hoc Analyses of Completed Phase 2 Studies with Serlopitant Support Phase 2 Study in Chronic Pruritus of Unknown Origin
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
TCP-101 Post-hoc Analysis Results
Patients Without a Self-reported History of
Inflammatory Skin Disease
Patients with a Self-reported History of
Inflammatory Skin Disease (1)
NRS 4-point Responder Rate
at Week 6
N=27
N=26
N=27
N=18
N=26
N=26
N=28
N=34
(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.

22. Primary endpoint at week 10
Phase 2 Study in CPUO
MTI-117
N~200
Chronic pruritus of unknown origin ≥6 months
WI-NRS ≥7 prior to screening
Primary endpoint
WI-NRS 4-point responder rate at Week 10
Serlopitant
5 mg
Placebo
2- or 4-week screening
10-week treatment
Primary endpoint at week 10
3-week follow-up
Data Expected mid-2020

23. Financial Information and Conclusion

24. Key Financial Highlights
Quarter Ended December 31, 2018
Cash & investments
$136M
Operating expenses
Including $1M non-cash stock-based compensation
$18M
Common shares outstanding
23M
Forward-Looking Information (Provided Feb. 27, 2019)
2019 Estimated operating expenses
Including ~$3M-$6M non-cash stock-based compensation
$78M-$88M
Estimated cash runway
Into Q4 2020

25. 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: K patients in the U.S. with no approved therapy
Psoriasis: 7.5M patients diagnosed in the U.S.; >90% experience pruritus
Cash Runway into Q4 2020
~$136M cash as of 12/31/18
Solid IP
U.S. composition of matter to 2030, incl. extensions; methods of use to 2033 25