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Our Viral immunotherapy and Antibody-Toxin Conjugate Pipeline

Expanding Potentially Transformative Therapy Options for the Treatment of Glioblastoma Multiforme (GBM) and a Variety of Solid Tumors.


Tumor Type


Phase 1

Phase 2

Phase 3

Viral Immunotherapy


PVSRIPO monotherapy


PVSRIPO + pembrolizumab


PVSRIPO + anti-PD-1/L1

Other Solid Tumors


Antibody-Toxin Conjugate




D2C7 + atezolizumab


D2C7 + anti-CD40

Istari is progressing clinical research on multiple fronts with the powerful, versatile PVISRIPO technology. A Phase 2 clinical study in glioblastoma multiforme (GBM) began in mid-2017 and is fully enrolled. A Phase 1 clinical study in melanoma has also been completed and a Phase 2 study is planned to begin in fall 2020. Initial pre-clinical and clinical studies are also underway that indicate other solid tumor types may also be optimal targets for PVSRIPO.

Istari’s Antibody Toxin Conjugate (ATC), D2C7, is under evaluation in a dose escalation Phase 1 study. We also have ATCs for additional tumors in pre-clinical development. Using different cytotoxic agents and linkers may lead to additional pipeline therapeutics for Istari Oncology. A wide variety of tumor types can be targeted by ATCs.

Learn more about our ongoing clinical studies with PVSRIPO and ATCs.

Therapeutic Areas

Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is the most aggressive and most common malignant primary brain tumor, making up 54% of all gliomas and 16% of all primary brain tumors. Each year, more than 13,000 patients diagnosed with GBM in the United States and virtually all patients experience recurrence.

Current treatments are mainly palliative and involve a combination of surgery, radiology therapy, temozolomide and tumor treating fields (TTFs). These therapies elucidate only a modest enhancement in survival with newly diagnosed glioblastoma and virtually no benefit in recurrent tumors. GBM remains an incurable tumor with a median survival of only 16-20 months after diagnosis and treatment with current options.

These outcomes highlight the need for a new therapy to change the course of care for patients with GBM. Given the need for individualized patient treatments, we believe that there is ample opportunity to improve patient outcomes with targeted therapies. As such, Istari is pursuing recurrent GBM as a target indication with its PVSRIPO and ATC technologies.


There are estimated to be over 12,000 new and recurrent cases of advanced, unresectable melanoma diagnosed in the US each year, and around 7,000 deaths. While checkpoint inhibitors have dramatically improved the outlook for advanced melanoma patients today, most patients treated with these immunotherapies are either primary non-responders or eventually develop immuno-refractory progressive disease and require additional therapy.

Istari is investigating PVSRIPO as a potential new option alone or in combination with anti-PD-1/L1s for checkpoint-refractory advanced melanoma.

Other Potential Indications

The poliovirus receptor CD155 is expressed in virtually all solid cancers, of which PVSRIPO infects and kills the malignant cells. Pre-clinical studies indicate that additional solid tumor types may represent viable tumor targets for PVSRIPO, including breast, prostate, colorectal, lung, pancreatic, ovarian and renal cancer, among others. We plan to initiate a basket trial in new solid tumor targets in 2021.

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