Information Request, Face to Face Meeting Package, April 3, 2013 - Hyqvia



FOOD AND DRUG ADMINISTRATION
CENTER FOR BIOLOGICS EVALUATION AND RESEARCH
MEMORANDUM

Date: April 3, 2013

From: Jennifer L. Reed, Ph.D.; CBER/OBRR/DH/LPD
HFM-345; 301-496-0625

To: File for BLA 125402/26

Reference: IND 13840; STN BL 125105 (Immune Globulin Intravenous (Human), 10% 
Solution; Gammagard Liquid); NDA 21-859 (hyaluronidase human injection, Hylenex)

Through: Dorothy Scott, M.D.; CBER/OBRR/DH/LPD; HFM-345; 301-827-3016

Cc: Mark Shields; CBER/OBRR/DBA; HFM-380; 301-827-6173

Subject: Information Request, Face to Face Meeting Package re: Reply to CR 
Letter and Update on Nonclinical and Clinical Studies
Product: Immune Globulin Infusion (Human), 10% with Recombinant Human 
Hyaluronidase: HYQVIA
Submission Date: March 29, 2013
Manufacturer: Baxter Healthcare Corporation, Halozyme Corp

Recommendation:
The following IR may be communicated to the Sponsor.

1) Please provide an update on clinical trial experience of rHuPH20 used as a 
permeation enhancer for chronic subcutaneous biologics treatments in other 
ongoing clinical trials. Specifically, is immunogenicity of rHuPH20 a consistent 
finding? What adverse events if any have been associated with the development of 
PH20-directed antibodies in other trials?

2) You stated that based on additional studies, you have concluded that PH20 is 
not expressed in enteric plexus or in CNS. Please submit additional information 
regarding the IHC, RT-PCR and in situ procedures you used to reach this 
conclusion. What positive controls were used to demonstrate sensitivity of these 
assays for detecting progenitor cell antigens and transcripts?

3) Your conclusion that PH20 is not expressed in CNS or enteric plexus appears 
to be based on assessments made in baseline, normal tissues obtained from 
adults. Since PH20 expression may be enhanced in progenitor cell types (Preston 
2013), use of gut tissues that have enhanced numbers of progenitors such as 
post-natal tissues (Metzger et al Gastroenterology 2009) may increase the 
sensitivity of your detection approach and help to increase confidence in your 
conclusion. We note that Preston and coworkers (2013) successfully documented 
PH20 expression in active CNS lesions of MS patients and in mice with EAE. In 
both instances oligodendrocyte precursors were more numerous than in baseline 
tissues. Please comment.

4) Please provide additional information on the studies you performed in SPAM1 
knockout mice. Since expression of Hyal1 and Hyal2 has been reported in corpus 
callosum and purified OPCs (Preston 2013), it seems possible that these might be 
able to compensate for constitutive deletion of SPAM1 during neurological 
development. Please comment. Has an EAE model been performed using mice with 
constitutive SPAM1 deletion? Have you investigated whether an inducible SPAM1 
knockout mouse is available for study?

5) Have you evaluated PH20 expression in enteric plexus and/or CNS of monkeys or 
rabbits, either at baseline or in models featuring injury and damage?

6) For your CR letter response, please submit:
  Details of Halozyme’s studies on enteric plexus samples, including details of 
  antibody preparations used (commercial sources, how patient plasma was 
  selected for IgG purification), and more details about the “specific 
  laboratory reagent” believed to be responsible for positive staining.
  Results of GLP pregnancy studies, in utero antibody exposure in rabbits study, 
  and male rabbit fertility study.
  Sensitivity testing and positive controls for tissue staining and PCR 
  detection of rHuPH20.

Background: Product Information
The proposed product is Immune Globulin Infusion (Human), 10% (IGI, 10%) with 
recombinant human hyaluronidase (rHuPH20), intended for the treatment of 
patients with primary immunodeficiency (PI) with defects in humoral immunity.

The combination product contains one vial of rHuPH20 and one vial of IGI, 10% 
for sequential administration. Hyaluronidase pretreatment of the injection site 
is intended to allow patients to receive a monthly dose of IGI, 10%, in a single 
subcutaneous injection. To facilitate a typical adult dose of 40 g subcutaneous 
IGI, 10% in a single site, the chosen administration site would be pre-treated 
by injection of 20 ml rHuPH20 at 160 U/ml, followed by infusion of 400 ml IGI 
solution.

Hyaluronidase preparations from ovine and bovine sources have a six decades-long 
history of use as single-dose permeation enhancers in the US. Hyaluronidase 
permeation enhancers including rHuPH20 are frequently used off label to aid in 
administration of subcutaneous medications in patients with chronic disease, and 
such use is considered generally safe based on anecdotal experience. The 
proposed combination product, if approved, would be the first licensed chronic 
use of a hyaluronidase permeation enhancer in combination with a biologic 
product.

BLA 125402 CR Letter

After thorough review of BLA 125402, a discussion of remaining review issues and 
possible paths forward was held by teleconference with the Sponsor on April 5, 
2012. Advice communicated to the Sponsor included the following (also 
communicated by letter on April 11, 2012).

1) FDA has outstanding concerns about immunogenicity of rHuPH20. Toxicology data 
submitted in the BLA is insufficient to address concerns about possible 
anti-PH20 antibody effects on developing male reproductive tissue and enteric 
plexus. Long-term effects of anti-PH20 antibodies in women who may become 
pregnant and in pediatric populations have not been addressed.

a) Enteric Plexus
1) There is insufficient evidence that PH20 expressed in enteric plexus is 
cytoplasmic, or that neuronal plexus is an immune privileged site.
2) The impact of elevated levels of transplacental maternal anti-PH20 on 
neuronal development is not known.
3) The impact of PH20 directed antibodies on neuronal development and plasticity 
in childhood, as well as the effect of chronic exposure to elevated anti-PH20 
levels, is unknown.

b) Male Reproductive Tissue
1) Developmental impact of elevated levels of transplacental, maternal anti-PH20 
directed antibodies on the fetus is unknown.
2) Developmental impact of elevated levels of anti-PH20 on development of 
reproductive tissue during childhood is unknown.

2) The Sponsor should propose preclinical studies in relevant animal species 
and/or clinical studies to address these issues.

3) FDA plans to seek advice concerning what data could reasonably address these 
concerns from BPAC and welcomed the Sponsor’s participation.

In discussion with the Sponsor, FDA highlighted the importance of identifying a 
relevant animal model. Specifically, FDA was looking for models that featured 
transplacental transfer of antibodies during fetal development. Possibly 
appropriate species discussed were guinea pig and monkey. FDA additionally 
requested data on expression of PH20 in neuronal tissue, preferably in enteric 
plexus, to help rule in or out particular species for further preclinical 
toxicity studies. The Sponsor did not contact FDA again regarding these studies, 
but instead designed and carried out the studies reviewed below at risk, without 
further consultation with FDA.

Concerns with Sponsor’s Reply to Issues Raised in the CR Letter

Neuronal (Enteric Plexus) Expression of PH20
The Sponsor makes reference to several new studies performed by Halozyme to 
re-investigate detection of PH20 in enteric plexus samples, originally reported 
in the - ---(b)(4)- GLP cross reactivity study in a normal adult human tissue 
panel. Although the details of the new studies are not provided, the Sponsor 
states RT-PCR and in situ hybridization methods were performed by Halozyme. 
Additional IHC studies were also performed by Halozyme, using various 
monoclonals, and a purified antibody preparation from patients who generated 
PH20-directed antibody responses during the clinical trial. The Sponsor 
indicates that the additional methods failed to confirm expression of PH20 in 
enteric plexus.

To further assure that PH20-directed antibodies do not have a deleterious effect 
on GI health, The Sponsor performed additional analysis of GI-related adverse 
events in clinical study 160603 and 160602. The Sponsor reports no relationship 
between GI adverse events and the presence or magnitude of the PH20 antibody 
response.

The Sponsor also cites normal neuronal development in the SPAM1 knockout mouse, 
in which PH20 is constitutively deleted.

The Sponsor concludes that the originally reported enteric plexus binding was an 
artifact associated with the “specific laboratory reagent” used in the 
---(b)(4)--- GLP tissue cross-reactivity study. The Sponsor further states that 
enteric plexus considerations are not relevant for the assessment of risk in 
patients with anti-PH20 directed antibodies, and not relevant for the selection 
of preclinical species to assess risk.

Remaining Concerns:
Emerging data (Preston et al 2011, 2012) show a role for PH20 in regulating the 
maturation of neuronal progenitor cells. Since progenitor cells are few in 
number at baseline in adult tissues, detection of PH20 at baseline in normal 
adult human enteric plexus would require a sensitive assay. The sensitivity of 
the Sponsor’s orthogonal methods for PH20 detection has not been shown. The 
Sponsor claims the PH20 detection in male reproductive tissue as a positive 
control. Male reproductive tissue demonstrates a very high level of PH20 
expression, so this positive control isn’t helpful for determining sensitivity 
of the Sponsor’s assays. It is not clear that a positive control was used to 
show the Sponsor’s assays could detect antigens or transcripts associated with 
neuronal progenitor cells. Importantly, Preston et al (2013) very recently 
demonstrated that PH20, and related hyaluronidases Hyal1 and Hyal2, are 
increased in lesioned and regenerating neuronal tissue, both in an animal model 
of EAE and in lesions of MS patients. If PH20 does have an important role in 
neuronal homeostasis, either in CNS or PNS, an injury model may be the most 
straightforward and sensitive way to show it, rather than performing assessments 
at baseline in adults, or in timed pregnancy models. Metzger et al 
(Gastroenterology 2009) and others have used GI surgical specimens from neonates 
and children to recover enteric plexi, in which precursor cell numbers were 
increased and could be outgrown in vitro. An evaluation of PH20 expression in 
those tissues and cells would be a valuable addition to this data set.

Mouse Development and Reproductive Toxicity Study (DART)
The Sponsor retrospectively studied PH20-directed antibody levels in (b)(4) mice 
administered rHuPH20, and present new data from a satellite study, investigating 
the timing of anti-PH20 antibody formation in (b)(4) female mice administered 
rHuPH20. The Sponsor states that anti-PH20 antibody levels were detectable in 
maternal plasma as early as gestation day 15, and were primarily IgG isotypes 
capable of crossing the placenta. High-titer anti-PH20 antibodies were confirmed 
in pups from gestation day 18 through adulthood. The Sponsor concludes that 
PH20-directed antibodies were present “throughout critical stages of 
neurological and reproductive development’, and revealed no ill effects on pre- 
and post-natal death, growth or development. Antibodies that bound PH20 also 
bound murine hyaluronidase 5 (Hyal5).

Remaining Concerns:
Transplacental transfer in mice during fetal development was not confirmed in 
this study. The conclusion that PH20-directed antibodies have no adverse effects 
on fetal development is not strong based on this study alone. Substantial 
development of CNS, PNS, and male reproductive tissues occurs in mouse prior to 
gestation day 15, which is the first time point that the Sponsor documents 
PH20-directed antibodies in maternal plasma.

Ongoing Toxicology Studies in Rabbit
The Sponsor chose to further investigate potential effects of anti-PH20 
antibodies on fertility and embryo-fetal development in a rabbit model. The 
Sponsor states that the rabbit was chosen as the model species because (1) 
rHuPH20 is immunogenic in rabbits; (2) anti-rHuPH20 antibodies generated in 
rabbit bind to rabbit reproductive tissue and sperm; (3) maternal antibody 
transfer is considered similar in rabbit and human; (4) fertility studies with 
good statistical power are feasible in rabbits. The Sponsor indicates that two 
GLP studies have been initiated. The full data set for these two GLP studies 
will be available in 3Q2013. An additional study of in utero antibody exposure 
in the rabbit model will be initiated shortly, and a final report is expected in 
4Q2013. The initial data set shows very strong antibody responses to rHuPH20, 
whether administered with --(b)(4)--------. TheSponsor’s initial data set 
suggests no impact of high-titer maternal PH20-directed antibodies on fertility 
or preimplantation loss. In litters collected by Caesarian section, no 
differences were observed in litter size, sex ratio in litters, fetal birth 
weight, or viceral or skeletal findings in fetuses. Initial data from the 
natural delivery phase of the rabbit studies suggest no impact of maternal PH20 
antibodies on pup survival, pup body weight, or on developmental landmarks. A 
separate study of fertility in male rabbits administered rHuPH20 (n=22) or 
control (n=22) is currently ongoing. Initial data suggest no effects of 
anti-PH20 antibodies on sperm count or motility. Mating outcomes evaluated by 
Caesarian section were similar in control and rHuPh20 groups.

Remaining Concerns:
Transplacental transfer of maternal Ig has not been studied much in rabbits. It 
is not clear that transfer of Ig to the fetus is more similar to humans than 
that observed in rodents. The conclusion that PH20-directed antibodies have no 
adverse effects on fetal development is not strong based on this study alone. 
Expression of PH20 in neuronal tissues of rabbits has not been evaluated, so it 
is unclear whether this model is useful for evaluating possible effects of 
anti-PH20 on CNS or PNS homeostasis.

Evaluation of Immunoglobulin Deposition in the 39-Week Monkey Study, Plus 
Additional Information re: ---(b)(4)--- Fertility Study in (b)(4) Monkeys
The Sponsor performed a retrospective analysis to evaluate any treatment-related 
microscopic changes in testis, epididymis, and enteric plexus tissues No 
toxicities associated with rHuPH20 directed antibodies were observed. The 
Sponsor indicates that no immune globulin deposition was detected in testis, 
epididymis, and enteric plexus tissues. The Sponsor concludes that these sites 
are immunoprivileged.

In addition, a brief report was provided by ---(b)(4)-- describing the limited 
amount of health outcomes data for 14 ----(b)(4)--- monkeys immunized with 
recombinant monkey PH20, in a regimen very similar to that described in the Deng 
et al 2002 report. The immunization regimen resulted in peak anti-PH20 titers of 
10,000 to 100,000 reciprocal endpoint, and these levels were maintained for 4 to 
5 months. Three weeks after the last injection a mating study was performed, and 
8 out of 14 immunized females conceived. This rate of conception was similar to 
the control group. Of the 8 conceptions, 7 resulted in live birth, which is 
similar to historical rates. The stillbirth demonstrated pathology consistent 
with dystocia. One female offspring of an immunized mother was reported to have 
a live vaginal birth at age 5. No unusual health concerns were reported in the 
14 immunized monkeys or their offspring.

Remaining Concerns:
Immune privilege of reproductive and neurological tissue may be reduced during 
development or in the event of a tissue injury. Expression of monkey PH20 in 
reproductive and neurological tissue during development and in adults has not 
been investigated. The -(b)(4)- retrospective information is certainly 
encouraging that PH20 directed antibodies may not pose a safety risk, but the 
data set is small and incomplete.

Additional Information on Anti-rHuPH20 Antibody in Humans
The Sponsor provides a longitudinal display of rHuPH20-directed antibody titers 
in 15 patients from clinical study 160603 and 160902. These patients 
discontinued use of rHuPH20 permeation enhancer. Since the discontinuation of 
rHuPH20 antibody titers have generally trended downward.

The Sponsor affinity-purified treatment emergent anti-PH20 antibodies and 
compared them with PH20-directed antibodies obtained from normal plasma 
donations. The Sponsor states that the antibody preparations are similar, in 
that weak tissue binding to human male reproductive tissue was observed, and no 
binding to adult human enteric plexus. The Sponsor’s completed study of 961 
normal plasma samples revealed approximately 6% of antibody samples have 
positive binding to rHuPH20. The majority of positive samples were below 1:40 
endpoint. Halozyme is increasing this data set in an ongoing study.

Remaining Concerns:
The potential safety implications of increased anti-PH20 antibodies in PID 
patients are not addressed by the data set discussed here. The Sponsor has not 
provided an update on a clinical study of 
-----------------------(b)(4)--------------------------.
 

    