- Epidiolex® NDA submission expected mid-year -

- New data in Lennox-Gastaut syndrome presented at the American Academy of Neurology -

- Conference call today at 4:30 p.m. EDT-

LONDON, May 09, 2017 (GLOBE NEWSWIRE) -- GW Pharmaceuticals plc (NASDAQ:GWPH) (GW, the Company or the Group), a biopharmaceutical company focused on discovering, developing and commercializing novel therapeutics from its proprietary cannabinoid product platform, announced financial results for the second quarter ended 31 March 2017.



“Our primary focus is on the submission of the Epidiolex NDA, which is expected in the middle of this year. Based on the efficacy and safety profile, we are confident in the prospects for an Epidiolex approval and continue to expand the commercial organization in preparation for a highly successful launch,” stated Justin Gover, GW’s Chief Executive Officer. “Beyond Epidiolex, we continue to advance a number of additional exciting clinical programs.”

OPERATIONAL HIGHLIGHTS

• Epidiolex (CBD) orphan epilepsy program in Dravet syndrome, Lennox-Gastaut Syndrome (LGS), Tuberous Sclerosis Complex (TSC) and infantile spasms (IS)

Regulatory:

-- NDA submission for both Dravet and LGS indications expected mid-2017

-- Expected EU regulatory submission in H2 2017

-- Rare pediatric disease designation conditionally granted by FDA – pre-cursor to priority review voucher

-- Orphan Designation granted by European Medicines Agency (EMA) in the treatment of LGS



-- NDA submission for both Dravet and LGS indications expected mid-2017 -- Expected EU regulatory submission in H2 2017 -- Rare pediatric disease designation conditionally granted by FDA – pre-cursor to priority review voucher -- Orphan Designation granted by European Medicines Agency (EMA) in the treatment of LGS Clinical:

-- New Phase 3 LGS data presented at the American Academy of Neurology (AAN) Annual Meeting in April 2017

-- 3 podium presentations at AAN

-- Phase 3 Dravet syndrome trial accepted for publication in high status journal with publication expected in Q2

-- Phase 3 trial in Tuberous Sclerosis Complex ongoing

-- Part A of two-part Phase 3 trial in infantile spasms underway



-- New Phase 3 LGS data presented at the American Academy of Neurology (AAN) Annual Meeting in April 2017 -- 3 podium presentations at AAN -- Phase 3 Dravet syndrome trial accepted for publication in high status journal with publication expected in Q2 -- Phase 3 trial in Tuberous Sclerosis Complex ongoing -- Part A of two-part Phase 3 trial in infantile spasms underway Management Update:

-- Scott Giacobello appointed as Chief Financial Officer

-- Adam George appointed as Managing Director – UK



-- Scott Giacobello appointed as Chief Financial Officer -- Adam George appointed as Managing Director – UK Manufacturing scale-up on track to deliver significant commercial launch inventory:

-- Pre-NDA CMC meeting held with FDA in November 2016

-- Successful UK regulatory Good Manufacturing Practice (GMP) inspection of GW manufacturing facility in December 2016. On track for FDA GMP inspection anticipated in H2 2017



-- Pre-NDA CMC meeting held with FDA in November 2016 -- Successful UK regulatory Good Manufacturing Practice (GMP) inspection of GW manufacturing facility in December 2016. On track for FDA GMP inspection anticipated in H2 2017 Expanded access program and open label extension:

-- Over 1,500 patients now exposed to Epidiolex treatment

-- 97 percent of patients who complete Phase 3 trials have entered long term extension



-- Over 1,500 patients now exposed to Epidiolex treatment -- 97 percent of patients who complete Phase 3 trials have entered long term extension Commercial:

-- U.S. commercial team build well underway and pre-launch preparations advancing well

-- EU commercial team now being established



-- U.S. commercial team build well underway and pre-launch preparations advancing well -- EU commercial team now being established Intellectual Property

-- 13 distinct patent families in prosecution relating to the use of CBD in the treatment of epilepsy; decisions expected for several patents towards end 2017 and H1 2018



• Other cannabinoid pipeline product candidates:

CBDV Phase 2 partial-onset epilepsy study in adults fully enrolled. Data expected Q4 2017

CBDV in field of autism spectrum disorders

-- Expanded access IND granted by FDA for 10 patients with autism

-- Open label study in Rett syndrome to commence Q4 2017 and Phase 2 placebo-controlled trial in planning for Q1 2018

-- Orphan Drug Designation from FDA for CBDV for the treatment of Rett syndrome

-- Expanded access IND granted by FDA for 10 patients with autism -- Open label study in Rett syndrome to commence Q4 2017 and Phase 2 placebo-controlled trial in planning for Q1 2018 -- Orphan Drug Designation from FDA for CBDV for the treatment of Rett syndrome Neonatal Hypoxic-Ischemic Encephalopathy (NHIE) intravenous CBD program

-- Phase 1 trial complete. Phase 2 protocol discussions with FDA in H2 2017

-- Orphan Drug and Fast Track Designations granted from FDA and EMA

-- Phase 1 trial complete. Phase 2 protocol discussions with FDA in H2 2017 -- Orphan Drug and Fast Track Designations granted from FDA and EMA THC:CBD for Glioma

-- Positive Phase 2 placebo-controlled data in Recurrent Glioblastoma Multiforme (GBM)

-- Abstract accepted at ASCO

-- Orphan Drug Designation from FDA and EMA

FINANCIAL HIGHLIGHTS

Cash and cash equivalents at 31 March 2017 of £306.3 million ($383.9 million) compared to £374.4 million as at 30 September 2016



Revenue for the six months ended 31 March 2017 of £3.7 million ($4.6 million) compared to £6.3 million for the six months ended 31 March 2016



Loss for the six months ended 31 March 2017 of £50.0 million ($62.6 million) compared to £34.5 million for the six months ended 31 March 2016

Solely for the convenience of the reader, the above balances have been translated into U.S. dollars at the rate on 31 March 2017 of $1.25331 to £1. These translations should not be considered representations that any such amounts have been, could have been or could be converted into U.S. dollars at that or any other exchange rate as at that or any other date.

Conference Call and Webcast Information

GW Pharmaceuticals will host a conference call and webcast to discuss the second quarter 2017 financial results today at 4:30 pm EDT. To participate in the conference call, please dial 800-860-2442 (toll free from the U.S. and Canada) or 412-858-4600 (international). Investors may also access a live audio webcast of the call via the investor relations section of the Company’s website at http://www.gwpharm.com. A replay of the call will also be available through the GW website shortly after the call and will remain available for 90 days. Replay Numbers: (toll free):1-877-481-4010, (international):1-919-882-2331. For both dial-in numbers please use conference ID # 13661781.

About GW Pharmaceuticals plc

Founded in 1998, GW is a biopharmaceutical company focused on discovering, developing and commercializing novel therapeutics from its proprietary cannabinoid product platform in a broad range of disease areas. GW is advancing an orphan drug program in the field of childhood epilepsy with a focus on Epidiolex (cannabidiol), which is in Phase 3 clinical development for the treatment of Dravet syndrome, Lennox-Gastaut syndrome, Tuberous Sclerosis Complex and Infantile Spasms. GW commercialized the world’s first plant-derived cannabinoid prescription drug, Sativex®, which is approved for the treatment of spasticity due to multiple sclerosis in 31 countries outside the United States. The Company has a deep pipeline of additional cannabinoid product candidates which includes compounds in Phase 1 and 2 trials for glioma, schizophrenia and epilepsy. For further information, please visit www.gwpharm.com.

Forward-looking statements

This news release contains forward-looking statements that reflect GW's current expectations regarding future events, including statements regarding financial performance, the timing of clinical trials, the timing and outcomes of regulatory or intellectual property decisions, the relevance of GW products commercially available and in development, the clinical benefits of Sativex and Epidiolex and the safety profile and commercial potential of Sativex and Epidiolex. Forward-looking statements involve risks and uncertainties. Actual events could differ materially from those projected herein and depend on a number of factors, including (inter alia), the success of GW’s research strategies, the applicability of the discoveries made therein, the successful and timely completion of uncertainties related to the regulatory process, and the acceptance of Sativex, Epidiolex and other products by consumer and medical professionals. A further list and description of risks and uncertainties associated with an investment in GW can be found in GW’s filings with the U.S. Securities and Exchange Commission including the most recent Form 20-F filed on 5 December 2016. Existing and prospective investors are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof. GW undertakes no obligation to update or revise the information contained in this press release, whether as a result of new information, future events or circumstances or otherwise.





GW Pharmaceuticals plc

Condensed consolidated income statement

Three months ended 31 March 2017

Three months

ended Three months

ended

Three months

ended

31 March 31 March 31 March 2017 2017 2016 $000’s £000’s £000’s Revenue 2,039 1,627 2,649 Cost of sales (861 ) (687 ) (542 ) Research and development expenditure (34,036 ) (27,157 ) (25,749 ) Sales, general and administrative expenses (11,643 ) (9,290 ) (3,242 ) Net foreign exchange (loss) / gain (4,998 ) (3,988 ) 4,488 Operating loss (49,499 ) (39,495 ) (22,396 ) Interest income 392 313 131 Interest expense (192 ) (153 ) (16 ) Loss before tax (49,299 ) (39,335 ) (22,281 ) Tax benefit 6,226 4,968 5,449 Loss for the period (43,073 ) (34,367 ) (16,832 ) Loss per share – basic and diluted (14.2c) (11.3p) (6.4p) Loss per ADS – basic and diluted(1) (170.4c) (135.6p) (76.8p) Weighted average ordinary shares outstanding (in millions) – basic and diluted 303.7 262.6 All activities relate to continuing operations. (1) Each ADS represents 12 ordinary shares

Condensed consolidated statement of comprehensive loss

For the three months ended 31 March 2017

Three months

ended

31 March

2017

£000’s Three months

ended

31 March

2016

£000’s Loss for the period (34,367 ) (16,832 ) Items that may be reclassified subsequently to profit or loss Exchange loss on retranslation of foreign operations (177 ) (46 ) Other comprehensive loss for the period (177 ) (46 ) Total comprehensive loss for the period (34,544 ) (16,878 )

GW Pharmaceuticals plc

Condensed consolidated income statement

Six months ended 31 March 2017

Six months

ended Six months

ended

Six months

ended 31 March 31 March 31 March 2017 2017 2016 $000’s £000’s £000’s Revenue 4,616 3,683 6,316 Cost of sales (1,757 ) (1,402 ) (1,229 ) Research and development expenditure (65,261 ) (52,071 ) (49,888 ) Sales, general and administrative expenses (20,020 ) (15,974 ) (6,867 ) Net foreign exchange gain 9,810 7,827 8,089 Operating loss (72,612 ) (57,937 ) (43,579 ) Interest income 734 586 194 Interest expense (305 ) (243 ) (35 ) Loss before tax (72,183 ) (57,594 ) (43,420 ) Tax benefit 9,564 7,631 8,886 Loss for the period (62,619 ) (49,963 ) (34,534 ) Loss per share – basic and diluted (20.7c) (16.5p) (13.2p) Loss per ADS – basic and diluted (1) (248.4c) (198.0p) (158.4p) Weighted average ordinary shares outstanding (in millions) – basic and diluted 303.2 262.0 All activities relate to continuing operations. (1) Each ADS represents 12 ordinary shares

Condensed consolidated statement of comprehensive loss

For the six months ended 31 March 2017

Six months

ended

31 March

2017

£000’s Six months

ended

31 March

2016

£000’s Loss for the period (49,963 ) (34,534 ) Items that may be reclassified subsequently to profit or loss Exchange gain/(loss) on retranslation of foreign operations 241 (99 ) Other comprehensive gain/(loss) for the period 241 (99 ) Total comprehensive loss for the period (49,722 ) (34,633 )

GW Pharmaceuticals plc

Condensed consolidated statement of changes in equity

Six months ended 31 March 2017

Called-up Share share premium Other Accumulated capital account reserves deficit Total £000’s £000’s £000’s £000’s £000’s Balance at 1 October 2015 261 349,275 19,189 (123,455 ) 245,270 Exercise of share options 2 623 - - 625 Share-based payment transactions - - - 3,164 3,164 Loss for the period - - - (34,534 ) (34,534 ) Deferred tax attributable to unrealized share option gains - - - 4 4 Other comprehensive loss - - (99 ) - (99 ) Balance at 31 March 2016 263 349,898 19,090 (154,821 ) 214,430 Balance at 1 October 2016 302 556,477 19,538 (177,827 ) 398,490 Exercise of share options 2 88 - - 90 Share-based payment transactions - - - 4,768 4,768 Loss for the period - - - (49,963 ) (49,963 ) Deferred tax attributable to unrealized share option gains - - - 595 595 Other comprehensive income - - 241 - 241 Balance at 31 March 2017 304 556,565 19,779 (222,427 ) 354,221

GW Pharmaceuticals plc

Condensed consolidated balance sheets

As at 31 March 2017

As at

31 March As at

31 March As at

30 September 2017 2017 2016 Non-current assets $000’s £000’s £000’s Intangible assets - goodwill 6,530 5,210 5,210 Other intangible assets 1,271 1,014 629 Property, plant and equipment 50,873 40,591 38,947 Deferred tax asset 6,340 5,059 3,873 65,014 51,874 48,659 Current assets Inventories 5,819 4,643 4,248 Taxation recoverable 35,773 28,543 21,322 Trade receivables and other assets 9,069 7,236 4,556 Cash and cash equivalents 383,870 306,285 374,392 434,531 346,707 404,518 Assets held for sale 1,139 909 - Total assets 500,684 399,490 453,177 Current liabilities Trade and other payables (28,841 ) (23,013 ) (31,170 ) Current tax liabilities (192 ) (153 ) (883 ) Obligations under finance leases (287 ) (229 ) (211 ) Deferred revenue (3,056 ) (2,438 ) (2,686 ) (32,376 ) (25,833 ) (34,950 ) Non-current liabilities Trade and other payables (12,245 ) (9,770 ) (9,423 ) Obligations under finance leases (6,089 ) (4,858 ) (4,959 ) Deferred revenue (6,026 ) (4,808 ) (5,355 ) Total liabilities (56,736 ) (45,269 ) (54,687 ) Net assets 443,948 354,221 398,490 Equity Share capital 381 304 302 Share premium account 697,548 556,565 556,477 Other reserves 24,789 19,779 19,538 Accumulated deficit (278,770 ) (222,427 ) (177,827 ) Total equity 443,948 354,221 398,490

GW Pharmaceuticals plc

Condensed consolidated cash flow statements

For the six months ended 31 March 2017

Six months ended Six months ended Six months ended 31 March 31 March 31 March 2017 2017 2016 $000’s £000’s £000’s Loss for the period (62,619 ) (49,963 ) (34,534 ) Adjustments for: Interest income (734 ) (586 ) (194 ) Interest expense 305 243 35 Tax benefit (9,564 ) (7,631 ) (8,886 ) Depreciation of property, plant and equipment 2,895 2,310 1,540 Impairment of property, plant and equipment 119 95 - Reversal of impairment of property, plant and equipment (271 ) (216 ) - Amortization of intangible assets 109 87 27 Net foreign exchange gains (9,810 ) (7,827 ) (8,377 ) Increase/(decrease) in provision for inventories 59 47 (45 ) Decrease in deferred signature fees (1,031 ) (823 ) (592 ) Share-based payment charge 5,976 4,768 3,164 Loss on disposal of property, plant and equipment 707 564 - (73,859 ) (58,932 ) (47,862 ) (Increase)/decrease in inventories (554 ) (442 ) 138 Increase in trade receivables and other assets (2,089 ) (1,667 ) (498 ) (Decrease)/increase in trade and other payables and deferred revenue (5,148 ) (4,108 ) 2,740 Income taxes paid (1,038 ) (828 ) (894 ) Net cash outflow from operating activities (82,688 ) (65,977 ) (46,376 ) Investing activities Interest received 548 437 186 Purchases of property, plant and equipment (11,274 ) (8,995 ) (4,655 ) Purchases of intangible assets (536 ) (428 ) (149 ) Net cash outflow from investing activities (11,262 ) (8,986 ) (4,618 ) Financing activities Proceeds on exercise of share options 113 90 625 Expenses of new equity issue (168 ) (134 ) - Interest paid (579 ) (462 ) (35 ) Repayments of fit out funding (822 ) (656 ) - Repayment of obligations under finance leases (103 ) (82 ) (55 ) Net cash (outflow)/inflow from financing activities (1,559 ) (1,244 ) 535 Effect of foreign exchange rate changes on cash and cash equivalents 10,150 8,100 8,271 Net decrease in cash and cash equivalents (85,359 ) (68,107 ) (42,188 ) Cash and cash equivalents at beginning of the period 469,229 374,392 234,872 Cash and cash equivalents at end of the period 383,870 306,285 192,684





Enquiries: GW Pharmaceuticals plc Stephen Schultz, VP Investor Relations 401 500 6570 Sam Brown (U.S. Media Enquiries) Mike Beyer 312 961 2502