UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM 8-K
CURRENT REPORT
Pursuant to Section 13 or 15(d)
of the Securities Exchange Act of 1934
Date of Report (Date of earliest event reported): April 2, 2019
PIERIS PHARMACEUTICALS, INC.
(Exact name of registrant as specified in its charter)
Nevada | 001-37471 | 30-0784346 | ||
(State or other jurisdiction of incorporation) | (Commission File Number) | (IRS Employer Identification No.) | ||
255 State Street, 9th Floor Boston, MA (Address of principal executive offices) | 02109 (Zip Code) | |||
Registrant’s telephone number, including area code: 857-246-8998
N/A
(Former name or former address, if changed since last report.)
Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:
☐ | Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) |
☐ | Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) |
☐ | Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) |
☐ | Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) |
Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (17 CFR §230.405) or Rule 12b-2 of the Securities Exchange Act of 1934 (17 CFR §240.12b-2).
Emerging growth company ý
If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐
Item 7.01: Regulation FD Disclosure.
On April 2, 2019, Pieris Pharmaceuticals, Inc. presented preclinical data regarding PRS-342 at the 2019 American Association for Cancer Research Annual Meeting. The poster is furnished as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated by reference herein.
The information set forth under this “Item 7.01. Regulation FD Disclosure,” including Exhibit 99.1 attached hereto, shall not be deemed “filed” for any purpose, and shall not be deemed incorporated by reference into any filing under the Securities Act of 1933, as amended, or the Securities Exchange Act of 1934, as amended, regardless of any general incorporation language in any such filing. except as shall be expressly set forth by specific reference in such filing.
Item 9.01 Financial Statements and Exhibits
(d) Exhibits.
SIGNATURE
Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.
PIERIS PHARMACEUTICALS, INC. | ||
Dated: April 2, 2019 | /s/ Allan Reine | |
Allan Reine | ||
Chief Financial Officer | ||
Costimulatory T-cell engagement by PRS-342, a GPC3/4-1BB bispecific molecule, leads to activation of T cells AACR Annual and tumor growth inhibition in a HCC humanized mouse model Meeting 2019 Birgit Bossenmaier, Corinna Schlosser, Rachida-Siham Bel Aiba, Eva-Maria Hansbauer, Thomas Jaquin, Christian Barthels, Janet Peper, Markus Zettl, Benjamin Weiche, Thibaut Angevin, Michelle Yegres, Reno Winter, Stefan Grüner, Christine Rothe, Shane A. Olwill Abstract # 4302 Pieris Pharmaceuticals, Inc., 255 State Street, Boston, Massachusetts Pieris Pharmaceuticals, GmbH, Lise-Meitner Strasse 30, 85354 Freising, Germany Reporter Assay PRS-342 leads to tumor-localized increase of TILs Background PRS-342 reporter cell assay Pharmacokinetic profile of PRS-342 in mice in a humanized HCC xenograft model 4-1BB (CD137) is a key costimulatory immunoreceptor and a highly promising therapeutic • PRS-342 costimulated T cells in a Jurkat Nf-kB reporter cell assay only in the • Preliminary mouse PK was performed in male CD-1 mice to compare PRS-342 with an • FFPE embedded xenograft tumor were analyzed histologically (HE) and immuno- target in cancer. To overcome toxicity and efficacy limitations of current 4-1BB-targeting presence of GPC3-positive tumor cell lines. a-GPC3 antibody. histologically (IHC) for T-cell infiltration. antibodies, we have developed 4-1BB Anticalin®/tumor-targeting mAb bispecifics that • PRS-342 has a typical antibody like PK profile in mice comparable to the a-GPC3 • Tumor IHC staining for human CD3, CD4 and CD8 shows a dose-dependent increase activate T cells in a tumor localized fashion. We have previously reported on the generation antibody used as building block in the bispecific PRS-342 construct. in the frequency of human tumor associated T cells (TILs) for PRS-342 vs controls, and characterization of PRS-343, a clinical-stage 4-1BB/HER2 bispecific molecule, with suggesting tumor-localized T-cell activation. regard to preclinical proof-of-concept and basic drug-like properties (1). Here, we describe PK in CD1 mice the preclinical dataset for PRS-342, a 4-1BB/GPC3 bispecific based on the Anticalin® technology. GPC3 is an oncofetal protein with high tumor selectivity and high expression in B % TIL frequency hCD3, hCD4 and hCD8 by IHC (necrotic areas are excluded) not only hepatocellular carcinomas, but also in a variety of other tumors with high medical need. Intratumoral T-cell infiltration % TILs of total tumor area - necrotic area Anticalin® therapeutics are 18 kD proteins derived from human lipocalins. We utilized phage display to generate an Anticalin® protein binding to 4-1BB with high affinity and TILs %CD3 T cells %CD4 T cells %CD8 T cells specificity. The PRS-342 bispecific construct was generated by genetic fusion of the 4-1BB- Vehicle control 0.8 0.7 0.4 specific Anticalin® protein to a humanized high affinity GPC3-targeting monoclonal antibody • PRS-342 PRS-342 0.8 µM 6.2 4.7 4.5 • a-4-1BB antibody PRS-342 13 M 4.1 3.3 3.0 with an engineered IgG4 backbone. EC50 [nM] EC50 [nM] EC50 [nM] µ • a-GPC3 antibody PRS-342 has excellent drug-like properties and can be produced with high yields. PRS-342 Hep-G2 Hep-GB NCI-N87 PRS-342 67 µM 10.7 4.9 7.3 • Isotype control -GPC3 antibody 0.8 M 1.6 1.3 0.7 was designed to be strictly dependent on tumor binding, which is necessary for clustering a-4-1BB antibody 0.94 1.39 1.77 a µ a-GPC3 antibody 13 µM 0.8 0.6 0.5 of 4-1BB, to elicit 4-1BB costimulation and T-cell activation. This was confirmed using a-GPC3 antibody - - different in vitro T-cell costimulation assays based on mixed culture of human T cells and a-4-1BB antibody 13 µM 0.8 0.7 0.2 GPC3-expressing tumor cell lines. These data further demonstrate the ability of PRS-342 PRS-342 0.38 0.78 - to bind both targets simultaneously. PRS-342 was also evaluated for activity in a PRS-342 induces 4-1BB clustering and downstream signaling in a Jurkat Nf-kB reporter cell line in humanized HepG2 mouse xenograft model, with results supporting its differentiated MoA + the presence of GPC3-positive HepG2 and Hep3B cells with low nM EC50 values. GPC3-negative NCI C TIL frequency (hCD8 ) by IHC compared to relevant benchmark controls. –N87 cell are used as control. Only the 4-1BB antibody can activate the Jurkat Nf-kB reporter cell in Concept: tumor-specific and tumor-localized the absence of GPC3 positive tumor cells. costimulatory activation of T cells PRS-342 induces 4-1BB engagement and T-cell T cell costimulation activation in a GPC3 dependent manner Tumor cell Concept of costimulatory T-cell engagement by An analysis of the pharmacokinetic properties of PRS-342 as well as of an a-GPC3 antibody was in tumor PRS-342: Within a patient´s tumor, tumor-specific performed in mice. Male CD-1 mice approximately 5 weeks of age (2 mice per timepoint) were T cells are bridged with tumor cells by the • Pan T cells were coincubated with GPC3high Hep-G2, Hep-GB and MKN-45 cells and injected into a tail vein with a dose 2 mg/kg. Plasma samples from the mice were obtained at the Vehicle a-4-1BB mAb (3.9 mg/kg; 13 µM) costimulatory bispecific PRS-342 which PRS-342. timepoints of 5 min, 24 h, 168 h, and 336 h. Plots of the plasma concentration over time for the simultaneously binds the tumor target GPC3 and anti-GPC3 antibody and PRS-342 are shown. Both the antibody and the bispecific-construct show Costimulatory the immune receptor 4-1BB. The resulting • Supernatant concentrations were determined for IL-2. bispecific Tumor target typical antibody pharmacokinetics profiles. GPC3 MHC- clustering of 4-1BB -provides a local coactivatory peptide signal to the T cell, further enhancing its T-cell Hep-G2 (GPC3 positive) Clustering Hep-GB (GPC3 positive) MKN-45 (GPC3 negative) 2 5 0 0 2 5 0 0 Costimulatory T cell receptor receptor (TCR)-mediated activity and leading to 2 0 0 0 receptor tumor destruction. Toxic side effects are expected 2 0 0 0 ] ] L Tumor-specific 4-1BB L to be manageable, as PRS-342 does not induce m 1 5 0 0 m Signal 2 Signal 1 / PRS-342 leads to tumor growth inhibition in a 1 5 0 0 / g g T Cell p p [ [ clustering and activation of 4-1BB in the absence 1 0 0 0 2 2 [pg/ml] 1 0 0 0 2 - - - L L Activation I IL of target-positive cells, and healthy tissue is I humanized HCC xenograft model 5 0 0 spared by tumor costimulated T cells due to the 5 0 0 a-GPC3 mAb (3.9 mg/kg; 13 µM) PRS-342 (3.9 mg/kg; 13mM) 0 absence of a primary, TCR-mediated signal. 0 1 1 0 1 1 0 c o n c e n t r a t i o n [ n M ] c o n c e n t r a t i o n [ n M ] PRS-342 design, target binding and activity in • PRS-342 (B) FFPE Xenograft tumors taken from the in vivo study described in (A) were stained for HE (not • a-4-1BB antibody • Immunocompromised mice (NOG) engrafted with GPC3-positive tumor cells (HepG2) were injected with human PBMC and treated weekly with PRS-342 at three dose levels. shown) and for the T-cell marker CD3, CD4 and CD8. Percentage of TILs per tumor area excluding reporter and T-cell costimulation assay • a-GPC3 antibody the necrotic area were calculated for all groups (BioSiteHisto). (C) Representative pictures for CD8 • Isotype control • Control molecules were an a-GPC3 antibody (IgG4 variant) in equimolar doses, an a-4- staining of Hep-G2 tumors demonstrating significant increased TIL infiltration for PRS-342 tumors 1BB benchmark antibody in equimolar doses, and vehicle control. compared to all controls (vehicle, a-GPC3 antibody and a-4-1BB antibody). A Anti-4-1BB B PRS-342 Design C PRS-342 Design (DNA) IL-2 induced by human Pan T cells costimulated by PRS-342 in the presence of GPC3-positive Anticalin Protein (Ac) HepG2 and Hep-GB cells in a coculture assay. No PRS-342 dependent activation was observed in • PRS-342 showed dose-dependent tumor growth inhibition (TGI) comparable to a-GPC3 α-GPC3 antibody presence of GPC3-negative MKN-45 cells. IL-2 levels in the culture supernatants were measured antibody, indicating that TGI is dominated by GPC3 inhibition in this model. by an electrochemiluminescence (ECL) immunoassay. Summary PRS-342 leads to dose dependent T-cell mediated TM=74°C (DSC) PRS-342 Median tumor growth inhibition in a humanized HepG2 xenograft model KD=02.3nM (SPR) A • PRS-342 was designed to elicit 4-1BB costimulatory effects in a tumor- α-4-1BB Ac cytolysis of GPC3 expressing tumor cells localized manner. D SPR Affinity • PRS-342 induced 4-1BB costimulation results in a dose-dependent T-cell killing of • PRS-342 is a 4-1BB/GPC3 bispecific genetic fusion of a high-affinity 4-1BB- ® kon koff KD GPC3 expressing tumor cells measured with an impedance based method. binding Anticalin and a high affinity a-GPC3 antibody. target name [M-1*s-1] [s-1] [nM] • No increase of T-cell mediated killing was observed with equimolar doses of anti-GPC3 • PRS-342 has excellent drug like properties and can be produced with high Fc-a-4-1BB antibody, Fc-4-1BB Anticalin fusion, anti-4-1BB-antibody and isotype control. yields. hu-4-1BB-His 3.5E+04 1.5E-04 4.1 Anticalin fusion Fc-a-4-1BB Anticalin fusion • PRS-342 has a pharmacokinetic profile comparable to classical antibodies. T c e ll k illin g H e p G 2 a-GPC3 antibody huGPC-3-His 3.6E+05 2.5E-04 0.7 • T-cell costimulation by PRS-342 leads to: 1 0 0 G C 3 3 -h Ig G 4 v 1 -L 1 -S 0 5 7 5 .0 4 J 1 0 ( H C ) 0 .0 8 n M o Nf-kB activation in a reporter cell assay. PRS-342 huGPC-3-His 4.1E+05 2.7E-04 0.7 a-GPC3 antibody G C 3 3 -h Ig G 4 v 1 - L 1 - S 0 5 7 5 .0 4 J 1 0 ( H C ) 0 .4 n M o Increased production of IL-2, a pro-inflammatory cytokine associated s i G C 3 3 - h Ig G 4 v 1 - L 1 -S 0 5 7 5 .0 4 J 1 0 ( H C ) 2 n M with anti-tumor immune response in a co-culture assay. E Binding ELISA s 5 0 y l G C 3 3 - h Ig G 4 v 1 - L 1 - S 0 5 7 5 .0 4 J 1 0 (H C ) 1 0 n M o Dose dependent cytolysis in impedance based real time killing assay. 4-1BB/anti-Anticalin-HRP GPC3/anti-human IgG-HRP GPC3/4-1BB-Bio/Extravidin-HRP c i a-GPC3 antibody f G C 3 3 - h Ig G 4 v 1 1 0 n M o TIL infiltration in tumors of a HCC xenograft in humanized mice. i PRS-342 c e h Ig G 4 - S 0 5 7 5 .0 4 J 1 0 -S 2 2 8 - F A L A 1 0 n M • The preclinical studies reported here demonstrate potent T-cell activation p 0 s that is strictly dependent on the presence of GPC3-positive tumor cells. U re lu m a b 1 0 n M % h Ig G 4 v 1 1 0 n M • GPC3-dependent activation of tumor-specific T cells is expected to result in an improved safety profile. -5 0 2 0 4 0 6 0 8 0 • Collectively our in vitro and in vivo data support the continued 4-1BB ELISA GPC3 ELISA Dual binding ELISA development of PRS-342. PRS-342 Design (A, B, C) and target binding (D, E). (D) shows binding of the Fc-a-4-1BB Anticalin tim e [h ] (A) Immunocompromised female NOG mice carrying established HepG2 xenograft tumors were fusion with a KD of 4.1 nM. The GPC3 arm binds with 0.7 nM to GPC3. On and off-rate kinetic T-cell mediated cytolysis of GPC3 expressing HepG2 tumor cells was assessed using the engrafted with 5 × 106 fresh human PBMC, followed by weekly i.p. treatment with PRS-342, a-4-1BB binding constant for a-GPC3 antibody and PRS-342 are similar. (E) ELISA data demonstrate PRS- xCELLigence RTCA HT system. Non-adherent CD8+ T cells were cocultured with HepG2 cells in benchmark antibody, a-GPC3 antibody or isotype control at 0.5 mg up to 20 mg/kg doses (i.p.) 342 binds GPC3 with comparable behavior to the a-GPC3 parental antibody. In a dual binding presence of test constructs. 4-1BB costimulation of cytotoxic T cells results in an increased (Charles River). Mice (n=15 per gr. remained on the study until spontaneous death or if ethical ELISA setting PRS-342 (4-1BB/GPC3 bispecific), is capable of binding both targets simultaneously. cytolysis of HepG2 cells which is measured over time. sacrifice was required, read out median tumor growth). References: (1) Cancer Immunol Res 2016;4(11 Suppl):Abstract nr B016.