Frequently Asked Questions

Alloplex develops SUPLEXA, an autologous (patient-derived) cell therapy with applications in cancer, autoimmunity and health span. SUPLEXA is manufactured from a patient’s peripheral blood mononuclear cells (PBMCs), which are activated and reprogrammed outside the body using our proprietary ENLYST™ (ENgineered LYmphocyte STimulator) immune cell training platform. The company is headquartered in Woburn, Massachusetts.

SUPLEXA is a population of a patient’s own immune cells that have been switched into a coordinated activated state. We expose the patient’s white blood cells to ENLYST immune cell training reagent, which is a tumor cell-derived manufacturing reagent that has been specifically engineered to display an array of immune cell activating signals. The patient’s cells respond by receiving these signals through their own naturally occurring receptors. These cells mature and proliferate into the SUPLEXA activated product cells, which are then frozen and subsequently returned to the patient by intravenous (IV) infusion.

Three things.

First, SUPLEXA cells are not genetically engineered — no viral vectors and no synthetic receptors are involved — so they retain their normal biology and can return to a resting state after acting.

Second, SUPLEXA is multicellular and multifunctional rather than built around a single target or function: individual SUPLEXA cells co-express a full range of both tumor-killing and antigen-presenting markers and can act as inflammatory or regulatory cells depending on the circumstances they encounter in vivo.

Third, SUPLEXA cells carry out a sequence of immune functions with respect to cancer that include:

• surveying a variety of tissues where they reside;
• discriminating aberrant, stressed cells from normal ones;
• killing those aberrant cells;
• scavenging the resulting cell fragments;
• recruiting other immune cells to the site; presenting antigen to them; and
• priming an antigen-specific immune response.

At its core, SUPLEXA cells are cytolytic antigen presenting cells (APC) with adaptable immune regulatory function depending on the circumstances they encounter in vivo. The APC function is HLA-restricted meaning that an exact HLA (Human Leukocyte Antigen) match is ideal. This can only be assured by using the patient’s own cells. To accommodate this approach, we developed a manufacturing protocol that substantially overcomes all prior difficulties identified for autologous cell therapy manufacturing. The net result is a robust 2- to 3-week process that yields a product with a favorable safety profile, lack of antigenicity for longer persistence and a perfect HLA match to the host.

In our assays, SUPLEXA cells kill a broad range of tumor cell lines but have no apparent effect on normal, naïve white blood cells — whether from the same patient (autologous) or a different person (allogeneic). This selectivity for tumor cells is a central feature of the platform which is based on the ability of SUPLEXA cells to discriminate aberrant, stressed cells from normal cells in the tissues where they reside. The molecular basis for this recognition is increasingly well understood. Aberrant, stressed cell types include:

• tumor cells that are metabolically deranged,
• virally infected cells whose metabolism is hijacked, and
• senescent cells that accumulate with aging, malfunction, and which are a source of significant, damaging chronic systemic inflammation.

Extensively, using complementary functional and molecular tools, including:

• Flow cytometry and in vitro cytolysis assays with cytokine analysis
• Mass cytometry (CyTOF) for high-dimensional single-cell phenotyping
• Single-cell cytokine and proteomic profiling
• NanoString and RNA-sequencing transcriptomic analysis
• T-cell receptor (TCR) repertoire sequencing
• Patient-derived xenograft and organoid models

Together, these data create a cohesive description of SUPLEXA and show the cells to be a reproducible, process-driven population of multifunctional cytotoxic, antigen-presenting effector cells. The individualized source of starting blood sample influences the exact composition but not the fundamental identity of the product which has been demonstrated to be consistent.

SUPLEXA cells are not genetically engineered; they are trained. Since no viral vectors are used, there is no possibility of tumorigenic risk from random DNA insertions. The ENLYST immune cell training platform activates through native receptors — the cells do not experience an unbalanced, supraphysiologic signaling that lacks regulation, as is the case for the introduction of synthetic chimeric antigen receptors (CARs). This not only avoids the chronic signaling responsible for clinical adverse events — such as cytokine release syndrome — but it allows SUPLEXA cells to return to a resting state after engaging and lysing a tumor cell. These features are the basis of the highly-favorable safety profile observed in a completed Phase 1 study.

ENLYST cells express an array of modified and wild-type immunomodulatory proteins that, in combination, drive a comprehensive and coordinated activation of lymphoid cells in an autologous (individualized) PBMC preparation. A generalized description is provided in an issued U.S. patent, but the precise composition of ENLYST cells remains a protected trade secret; the patent covers core features of the platform in a generalized manner.

In independently conducted patient-derived xenograft and organoid studies, SUPLEXA cells were assessed by the contract research organization as highly active. They produced dose-dependent tumor killing with strong statistical significance, outperforming tumor-infiltrating lymphocytes (TILs) and NK cells using in vitro and in vivo animal models. Administered intravenously, SUPLEXA cells were able to exit the vasculature and reach and act on tumor in vivo.

Yes. The first-in-human Phase 1 study (SUPLEXA-101) was conducted in Australia and is complete. Across the trial, SUPLEXA was administered to roughly 35 patients, over more than 220 infusions, with no treatment-related serious adverse events. Durable responses were observed — including in mismatch-repair-deficient / MSI-high colorectal cancer and clear-cell renal cell carcinoma.

Building on the Phase 1 safety and activity data, Alloplex is prioritizing hematologic (blood) cancers, specifically acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) — areas where no validated CAR target exists and the need is high. This pivot to hematologic malignancies of the bone marrow was driven by observations in the Phase 1 clinical trial. Specifically, we learned that SUPLEXA cells have the receptors which are known to drive immune cells to the bone marrow and lymphatics. The solid-tumor activity observed in Phase 1 also supported an initial U.S. IND and Fast Track designation in MSI-high (Microsatellite Instability-High) colorectal cancer; the hematologic indications represent the program’s forward priority.

Phase 1 informed dosing for the program. Approximately 10 billion SUPLEXA cells are prepared as a cryogenically preserved cell suspension that is subsequently thawed, diluted, and administered by IV infusion. The entire course can be manufactured from a single modest (50 mL) blood draw, frozen, and administered in multiple split doses.

As with all cellular therapies, key early-phase considerations include cytokine release and tumor lysis syndrome and selecting the right patient population and dose. The Phase 1 experience — with more than 220 infusions and without any treatment-related serious adverse events — provides meaningful reassurance, as clinical trials advance.

SUPLEXA cells can act as inflammatory or regulatory cells depending on the signals they encounter in vivo. In their regulatory mode, they may help restrain inappropriate immune activity rather than amplify it, which is the basis for Alloplex’s interest in autoimmune and inflammatory disease. This is a preclinical, exploratory extension of the platform and is distinct from the clinical oncology program described above.

Senescent cells are also stressed cells that accumulate with age and are a source of chronic, damaging inflammation. They display the same stress proteins on their surface as do stressed tumor cells. Using receptors that recognize these stress proteins, SUPLEXA cells can discriminate stressed and senescent cells in addition to tumor cells from normal cells. The platform therefore has potential senolytic (senescent-cell-clearing) applications relevant to the health span field and age-related disease. This work is early but leverages well-understood immunology established over decades. This is a timely and differentiated application of the ENLYST immune cell training platform.

The autologous process is straightforward, robust and can be conducted at a low cost of goods in a 2- to 3-week process. A modest blood draw is collected from the patient. The isolated PBMCs are activated ex vivo with ENLYST cells. The ENLYST cells are then removed, leaving only SUPLEXA cells, which are washed, aliquoted, and cryopreserved for later infusion. From the patient’s perspective, this requires one blood draw and roughly a three-week window for manufacturing and quality control before the first infusion.

Coincubation of ENLYST tumor cell-derived manufacturing reagent with patient-derived PBMC is integral to the manufacturing protocol. ENLYST tumor cell-derived manufacturing reagent is treated prior to use to ensure it is non-viable. As the coincubation proceeds the ENLYST cells are further degraded into cell fragments and eliminated at the time of cell harvest, when the small fragments and soluble proteins are removed.

For the Phase 1 study conducted in Australia, the manufacturing was performed in a GMP facility in Brisbane, Australia. For future clinical studies performed in other countries, a GMP facility will have to be hired to produce the product for local patients.

SUPLEXA requires no viral vector or transduction, which keeps manufacturing simpler and supports a low cost of goods relative to engineered cell therapies. The process is robust and reproducible across individuals, and a clinical-grade standard operating procedure has been transferred to the first GMP manufacturing facility. Because the protocol transfers to standard GMP facilities, it can be deployed locally to serve patients in each region as the program expands.

The first-in-human Phase 1 study was conducted in Australia and achieved all its milestones. Alloplex has submitted a U.S. Investigational New Drug (IND) application for relapsed/refractory MSI-high colorectal cancer and has been granted FDA Fast Track Designation. Alloplex is now planning an IND application for AML/MDS, a spectrum of hematologic malignancy of myeloid cell origin.

For its targeted indications, SUPLEXA follows a standard biologics pathway — IND, clinical development, and ultimately a Biologics License Application (BLA). With supportive clinical data, the program is positioned to pursue FDA expedited routes such as Fast Track and Regenerative Medicine Advanced Therapy (RMAT) designation.

Accelerated approval is possible but depends on a clear efficacy signal in a defined patient population with high unmet need. The current focus on hematologic malignancies is intended in part to create such opportunities.

The platform was invented by Alloplex’s founder and CEO, Frank Borriello, MD, PhD, a Harvard-trained immunologist who was on staff at Brigham and Women’s Hospital before entering the pharmaceutical industry.

Alloplex pursues a combined strategy of patents and trade secret. A foundational U.S. patent covering the ENLYST platform has been issued and additional applications are pending. The IP strategy protects a significant portion of the immunomodulatory “combinatorial space” while keeping the exact composition of the ENLYST cells a trade secret. Hence, proposed Alloplex drug products are not expected to carry third-party royalty obligations.

Alloplex Biotherapeutics, Inc. is a Delaware corporation with laboratories in Woburn, Massachusetts, and a wholly owned Australian subsidiary supporting GMP manufacturing in Brisbane. The company is led by founder and CEO Frank Borriello, MD, PhD, supported by a scientific and operating team and a network of specialized external partners.

Alloplex has been privately financed to date and is actively pursuing pharmaceutical partnerships and additional financing to advance the program. Specific details and terms are discussed directly with qualified investors and partners under appropriate confidentiality.

Our peer-reviewed papers, conference posters, and presentations are listed on the Alloplex publications page.