The Valcyte Decision – An Analysis. Srividhya Ragavan [email protected] Feroz Ali Ali Associates. IN 207232. Patentee: F.Hoffmann-La Roche AG. The Invention . Drug: Valganciclovir Hydrochloride H ydrochloride salt of the L-valyl ester of ganciclovir
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Patentee: F.Hoffmann-La Roche AG
Drug: Valganciclovir Hydrochloride
Hydrochloride salt of the L-valyl ester of ganciclovir
L-valyl ester prodrug of ganciclovir (two diastereomers)
Diastereomers → ganciclovir (intestinal esterases)
2-(2-amino-1, 6-dihydro-6-oxo–purin-9-yl) methoxy-3-hydroxy -1-propanyl –L-valinate
Patent application: 27 July 1995
FER: 17 May 2006
Pre-grant Opposition: 12 July 2006
Grant published: 29 June 2007
Patent Expiry: 27 July 2015
Oct 2008: Pre-grant opponent files writ in Chennai
Dec 2008: Order setting aside the grant; hear opponent
Patentee → Supreme Court : hear opponent
Jan 2009: Controller dismisses pre-grant opposition
Pre-grant Opponent → Supreme Court
Challenged the decision of Controller
March 2009: SC order to combine both the SLPs
Pre-grant opponent intervene in post-grant proceeding
Five post-grant oppositions
Ranbaxy, Cipla, Bakul Pharma, Matrix, DNPP (NGO)
Sep 2008: Roche sues Cipla in Mumbai
Apr 2010: Order rejecting product patent
Ester form of a known drug
Ganciclovir known since the 1980s (US 4,355,032 )
Product claims: 1 to 9; 10 to 12 for process
Lack of Novelty
Lack of Inventive Step
Not an invention under section 3(d)
Non-compliance with section 8
EP 0375329 (‘329)
US 5043339 (‘339)
US 6083053 (‘053)
US 4355032 (‘032)
US 4957924 (‘924)
Beauchamp et al, Drugs of the Future, 1993, 18(7): 619,-628
Beauchamp et al, Antiviral Chemistry and Chemotherapy (1992), 3(3), 157-164
Anticipated by US ‘339
Held, an anticipating prior art document should name the claimed compound individually and should contain sufficient description, which would enable a person of ordinary skill in the art to arrive at the invention without further experimentation.
Neither ‘339 or ‘329 disclose or contain an enabling disclosure to carry out the claimed invention so as to render the US ’339 as anticipating the claimed invention.
Held, US ‘339 or EP ‘329 do not specifically disclose the mono-(L)-valinate ester of ganciclovir either expressly or inherently.
Although both the patents generally disclose the existence of mono esters as a part of a large class of compounds, it does not particularly disclose the compound or other property of the said compound . the information provided may be relevant but not appropriate to obtain the compound of the claimed invention.
Four Corners Rule for novelty determination:
All the elements of the claimed invention should be
found within the ambit of a single prior art reference
Counsel for patentee: but, with a 3 fold excess of the activated amino acid
Such an argument would not work for novelty purposes in the US since the
requirement is that all the elements have to be disclosed in a single prior art.
It was argued that a skilled person in the art would have been able to
accordingly appreciate the reduction
test to prove non-obviousness – not a
In the US too, a reference has to be fully enabled in order to anticipate.
Generally, to take care of the objectives of the patent system
Inventiveness has to be determined at the time of the invention (and not at the time
of evaluation of the patent)
The same principle is codified in the statute
under Title 35, §103:
“A patent may not be obtained unless…
the subject matter…would have been obvious at the
time the invention was made …
Opponents: US’924 discloses valine esters of acyclovir that exhibit more bioavailability than acyclovir. Drugs having poor absorption are converted into ester to make the drug more bioavailable when administered orally. The amino acid ester of ganciclovir, preferable D-L and DL amino acids. It also teaches bis-(l-valinate) ester of ganciclovir and example 6(b) teaches the process to get mono-(L-alaninate) ester along with bis-(L-alaninate) ester of ganciclovir in the ratio of 1:9.
US ‘032 discloses ganciclovir and pharmaceutically acceptable salts which are active against Herpes Simplex virus I and II and related virus such as cytomegalovirus, Epstein-Barr Virus and Varicella Zoster virus.
The oral form of parent drug ganciclovir has been commercially known from the US Patent ‘032. The L valine ester of acyclovir has improved bioavailability than the acyclovir after oral administration.
A skilled person in the art follows the route of L-valine ester of acyclovir, i.e., valacyclovir and apply same to ganciclovir to get valganciclovir. Valacyclovir and valganciclovir are nucleoside analogs having similar structure and used for similar treatment.
Beauchamp in 1992 and 1992 disclosed the best amino-acid ester for acyclovir. L-valyl ester was the best prodrug amongst 18 amino acid esters sysnthentised and tested as potential prodrugs. Valacycolvir, the prodrug of acyclovir is more bioavailable than acyclovir that is proved to be rapid hydrolysis in vivo than the parent compound.
Various forms of esters are prepared using hydroxyl group of the purine ring and the side chain of acyclovir with amino acids. The modifications made to the purine ring was toxic and the modifications made to the acyclic chain resulted in improved effect.
Acycolvir and ganciclovir are structurally similar and functionally similar nucleoside analog. It is obvious to a person would try for similar ester which is alresdy proved with improved effect. US ‘924 patent discloses the L-valinate ester of acyclovir and hydorcholorde sasl of the L-valinate ester. The disease targeted by the two drugs, L-valinate ester of acyclovir and ganciclovir are similar. L-valine is a chiral compound, its derivative L- valinate ester of ganciclovir inherently will be a chiral molecule, therefore (R) or (S) diastereoisomers can be expected by a skilled artisan.
A person skilled in the art would combine the teachings of Beauchamp’s publications, US 032, US 339 and EP 329 and US 924 to prepare the compound in the alleged invention.
Patentee - Combining the prior art, Beauchamp’s publications with US 924, a person skilled in the art will be motivated to block all the free OH groups resulting in bi-ester.
Controller held that the nucleosides such as acyclovir, penciclovir show low aqueous solubility and low bioavailability when administered orally. To increase oral bioavailability many modifications were done to the purine ring and acyclic side chain. Conversion of acyclovir into L-valine ester of acyclovir was suggested by ‘924 patent.
The ‘329 patent discloses di-valyl amino acid ester of ganciclovir. Prior art suggests that many similar nucleosides are converted into ester of amino acids, preferably L-valine to increase oral bioavailability.
The preferred ester forming compounds suggested by ‘329 patent and ‘924 patent are aminoacids, particularly valine, more particularly, L-valine to overcome the problem of oral drug delivery.
Beauchamp suggests and motivates the involvement of stereospecific (L- vs D-) transport process using common branched chain amino acids, L-valine and L-isoleucine, particularly L-valine ester which makes the drug more bio available.
A skilled person would have been motivated to prepare mono L-valine ester of ganciclovir from the teachings of ‘329, ‘924 and the Beauchamp articles. Claim 1 and its dependant claims are not inventive.
Ex 9 of the patent does not show the improvement in oral bioavailability of the esters of ganciclovir
Comparison made between esters and HCl salt as an improvement with regard bioavailability is not scientific and results provided are not proper to meet the patentability requirement.
Since the object of the invention is to provide a prodrug of ganciclovir with improved oral bioavailability, the comparison provided in the specification to show such improvement is not scientific
Improved oral bioavailability not proved in the complete specification
Most drugs listed in the pharmacopoeias are in the salt forms, because salt forms of the drugs influences the solubility for better therapeutic effect.
Neither ‘339 nor ‘329 specifically mentioned the process for the preparation of the compound of the claimed invention.
Identification of the compound of the invention from ‘329 is obvious, but the method for the preparation of such a compound requires extensive research work.
Even though the method of hydrolyzing one of the ester group of ‘329 patent or any other steps involved in the preparation is by conventional method, it could not have been ascertained before it was produced. Process claim allowed but restricted to a single process.
New form of a known compound already disclosed in US ‘339
Ester form of a known substance should show significant enhancement in efficacy to merit a patent grant
Novartis v Union of India – efficacy means therapeutic efficacy (High Court and IPAB) – ‘Efficacy’ and ‘bio-availability’ are two different concepts.
Data provided in Ex 9 of the specification pertains to bioavailability but not therapeutic efficacy.
The compound and its pharmaceutically acceptable salts, isomers, crystalline form and composition do not fulfill the requirement of the Act.
POSITA would solve a problem by looking at
prior arts that solves different problem.
When a claimed invention implements a
predictable variation of the patent, then §103 bars it
What is the US position on this?
The “teaching away” controversy
Pfizer sued Apotex for infringing the patent on Norvasc - besylate form of amlodipine.
Norvasc is used to treat hypertension and forms of angina.
Apotex alleged that Pfizer’s earlier ‘909 patent over amlodipine anticipated the patent over amlodipine besylates – (salt form of amlodipine).
Federal Circuit agreed with Apotex on the grounds that the besylate form lacked enhanced utility from the base compound.
The Federal Circuit reiterated an established principle that salts of known compounds are deemed obvious unless there is an unexpected utility or improvement or efficacy!!
What is the US position on this?
Given this, the post-grant decision is commendable in clarifying
the constituents of the efficacy requirement
Dillon claimed tetraorthoesters
Prior art taught triorthoesters
Fed. Circuit held that a compound can be prima facie obvious if the examiner can show:
Structural similarity, or,
Suggestion or expectation that the prior art and claimed compound will have same or similar utility
The Teaching Away Controversy
In the Valcyte dispute, acyclovir and ganciclovir
seems to have demonstrated
structural similarity and similar utility.
Patent filed Form 4 declaring the status of the US Patent Application as ‘pending’ – application was abandoned on 16.06.1995 – this amounts to furnishing false information. Patentee has met the requirements under section 8 of the Patents Act.
Photocopy of prosecution history of US application was taken from the USPTO website submitted during the proceedings as evidence is not an authenticated document and hence not considered.
Amendment of statement of opposition not allowed
Since claim 1 is not inventive, making a composition of known drug with known excipients cannot be considered as an invention. Therefore Claim 9 is a mere admixture resulting only in aggregation of known properties.
Controller ordered to amend the patent to process claims restricted to a single process – within 15 days of the decision
Animal Defense Fund (Fed. Cir) (1991)
Can the procedure for post-grant be different from the revocation proceeding?
US: Re-examination is completely different from the pre-grant opposition – designed to prevent the registration of a patent
US: Re-examination procedurally completely different from the proceedings in courts - designed to achieve the exact same result
Art. 14 – equal protection – does not apply because the objective with post-grant
is administrative removal of patents as opposed to judicial removal. Administrative
procedures are meant to be less burdensome as a rule.
Should the evidence statute be implicated?
Both in the US and Europe, administrative procedures rarely implicate the evidentiary requirements.
There has to be a reason for India to do that.