Updated Interim Results from Ongoing Phase 2a Study of Portola Pharmaceuticals’ Oral Syk/JAK Inhibitor Cerdulatinib Continues to Demonstrate Clinical Responses in Heavily Pre-Treated T-Cell Malignancies

– Early Signs of Durable Response Across Patients with Relapsed/Refractory PTCL –

– 50 Percent Complete Response Rate Observed in Patients with AITL –

– Rapid and Significant Reduction in Itching Among Patients with CTCL –

SOUTH SAN FRANCISCO, Calif., Dec. 03, 2018 (GLOBE NEWSWIRE) — Portola Pharmaceuticals, Inc.^® (Nasdaq: PTLA) today announced updated interim results from the Company’s ongoing Phase 2a study of cerdulatinib, an investigational, oral Syk/JAK inhibitor, in patients with specific subtypes of T-cell Non-Hodgkin Lymphoma, including relapsed/refractory peripheral T-cell lymphoma (PTCL); angioimmunoblastic T-cell lymphoma (AITL), a subset of PTCL; and cutaneous T-cell lymphoma (CTCL). The data will be presented today during an oral session at the 60th American Society of Hematology (ASH) Annual Meeting in San Diego (December 1-4).

As of the November 1, 2018 cut-off date, 41 PTCL patients and 27 CTCL patients were evaluable for response. The objective response rate (ORR) was 34 percent in the PTCL cohort and 26 percent in the CTCL cohort. Among the subset of patients in the PTCL cohort with AITL, the ORR was 57 percent.

PTCL Cohort Data

• Eleven of 41 patients (27 percent) achieved a complete response (CR), and three patients (7 percent) achieved a partial response (PR).
• In the subgroup of 14 patients with AITL, seven patients (50 percent) achieved a CR and one patient (7 percent) achieved a PR.
• One patient who achieved a CR went on to transplant.
• Eight responding patients have remained on drug for three to more than 12 months and five patients have had a duration of response of six months or greater. Follow-up is ongoing.

CTCL Cohort Data

• In the CTCL cohort, two patients (7 percent) achieved a CR and five patients (19 percent) achieved a PR. Responses have been seen in patients with Mycosis Fungoides and Sezary Syndrome.
• Eleven of 23 patients (48 percent) achieved a ≥ 50 percent reduction in skin lesions, based on the Modified Severity Weighted Assessment Tool (mSWAT).
• Rapid improvements in pruritus, or severe itching – a common and often serious condition associated with CTCL – have been observed, as measured by the Likert scale.
• The CTCL cohort continues to enroll and data analysis is ongoing.

Cerdulatinib has demonstrated tolerability in both PTCL and CTCL. The most common grade 3 or greater adverse events across the PTCL and CTCL cohorts with a frequency > 5 percent were lipase increase (23 percent), amylase increase (18 percent), sepsis/bacteremia (8 percent), and neutropenia, pneumonia/lung infection and diarrhea (7 percent each). These events are manageable and further accrual is ongoing.

“The ongoing Phase 2a cerdulatinib data continue to demonstrate meaningful clinical activity, with particularly compelling complete response rates among AITL patients and the potential for durable response among patients with PTCL and CTCL,” said Steven M. Horwitz, M.D., Memorial Sloan Kettering Center, and study investigator. “Like many others with T-cell malignancies, the patients in this study have failed prior therapies and are in need of additional treatment options. It is encouraging to see such a strong early signal in both disease response and quality-of-life measures, such as itching.”  

“While still early, the continuing and durable response rates in PTCL and the encouraging responses in CTCL underscore the potential of cerdulatinib to control relapsed/refractory T-cell malignancies,” said John Curnutte, M.D., Ph.D., executive vice president and head of research and development at Portola. “We will apply our learnings from this study to inform the design of a pivotal trial, and look forward to continuing discussions with the U.S. Food and Drug Administration about the potential for an accelerated approval pathway for cerdulatinib in PTCL.”

ASH Oral Session Details – Monday, December 3, 2018 at 7:15 p.m. PST

About Cerdulatinib
Cerdulatinib is an investigational oral, dual spleen tyrosine kinase (Syk) and janus kinase (JAK) inhibitor that uniquely inhibits two key cell signaling pathways implicated in certain hematologic malignancies and autoimmune diseases. There is a strong rationale for inhibiting both Syk (B-cell receptor pathway) and JAK (cytokine receptors) in B-cell malignancies where both targets have been shown to promote cancer cell growth and survival. In addition, pre-clinical data suggest an important role for Syk and JAK in PTCL tumor survival.

The U.S. Food and Drug Administration granted cerdulatinib Orphan Drug Designation for the treatment of PTCL in September 2018. 

About Portola Pharmaceuticals, Inc.
Portola Pharmaceuticals is a commercial-stage biopharmaceutical company focused on the discovery, development and commercialization of novel therapeutics that could significantly advance the fields of thrombosis and other hematologic diseases. The Company’s two FDA-approved medicines are Andexxa^® [coagulation factor Xa (recombinant), inactivated-zhzo], the first and only antidote for patients treated with rivaroxaban and apixaban when reversal of anticoagulation is needed due to life-threatening or uncontrolled bleeding, and Bevyxxa^® (betrixaban), the first and only oral, once-daily Factor Xa inhibitor for the prevention of VTE in adult patients hospitalized for an acute medical illness. The company also is advancing cerdulatinib, a Syk/JAK inhibitor for the treatment of hematologic cancers.

Forward-Looking Statements
This announcement contains forward-looking statements, including statements regarding next steps for the development of cerdulatinib, including the potential for an accelerated approval pathway in the U.S. for certain tumor subtypes. Risks that contribute to the uncertain nature of the forward-looking statements include: failure to obtain FDA agreement to an accelerated or other regulatory approval pathway, regulatory developments in the U.S. and foreign countries; our expectation that we will incur losses for the foreseeable future and will need additional funds to finance our operations; the accuracy of our estimates regarding our ability to initiate and/or complete our clinical trials and the timing and expense of these trials; the results of our clinical trials related to the efficacy and safety of our product candidates; our potential inability to manufacture our product candidates on a commercial scale in a timely or cost-efficient manner; the accuracy of our estimates regarding expenses and capital requirements; our ability to successfully build a hospital-based sales force and commercial infrastructure; our ability to obtain and maintain intellectual property protection for our product candidates; and our ability to retain key scientific or management personnel. These and other risks and uncertainties are described more fully in our most recent filings with the Securities and Exchange Commission, including our most recent quarterly report on Form 10-Q. All forward-looking statements contained in this press release speak only as of the date on which they were made. We undertake no obligation to update such statements to reflect events that occur or circumstances that exist after the date on which they were made.