TEM-MM-101: A Phase I/IIa Dose Escalation Study Evaluating the Safety and Activity of Autologous CD34+ Enriched Hematopoietic Progenitor Cells Genetically Modified for Human Interferon-α2 in Multiple Myeloma Patients with Early Relapse after Intensive Front Line Therapy

BACKGROUND

Multiple Myeloma (MM) is an incurable malignancy heralded by an immunosuppressive tumor microenvironment (TME). Therapeutic efforts to reprogram the TME and release innate and adaptive immunity may synergize with current anti-MM drugs, deepen responses and ultimately prolong long-term survival. We have developed an ex vivo gene therapy approach that locally delivers interferon-alpha (IFNa) into the TME through the Tie2+ myeloid progeny of transplanted gene-modified hematopoietic stem and progenitor cells (HSPCs). Preclinical studies in the immunocompetent Vk*Myc murine model as well as in the hematochimeric xenotransplantation setting demonstrate that IFNa gene therapy has anti-MM effect and may subvert the immunosuppressive MM TME, acting both on myeloma cells as well as on the immune infiltrate. Additional toxicology data, demonstrates that a mixture of genetically modified and unmodified CD34+ cells can be transplanted safely. We have therefore progressed into the clinic at Ospedale San Raffaele in Milan, Italy, with our gene therapy approach (Temferon).

METHODS

The TEM-MM-101 study recruits patients with MM in early relapse (within 18 months) after intensive front line therapy defined as triplet induction (at least 3 cycles including a proteasome inhibitor and/or immunomodulatory drug [IMID]) followed by single or double autologous stem cell transplantation, or, triplet or quadruplet induction including at least a proteasome inhibitor and an IMID, followed by consolidation/maintenance treatment.

Three cohorts of 3 patients will be included in the study. Patients will be dosed sequentially in each cohort with data review by an independent data monitoring committee before dose escalation to the next cohort.

Key eligibility criteria include achieving at least a VGPR after second line salvage therapy, age 18-70 years, ECOG <2 and Karnofsky >70%, adequate cardiac, renal, hepatic and pulmonary function, and willingness to use appropriate contraception if relevant. Important exclusion criteria include the presence of active autoimmune disease or ineligibility for autologous bone marrow transplant.

After confirmation of eligibility, patients undergo autologous peripheral blood HSPC mobilization with lenograstim and plerixafor, before undergoing apheresis. After purification, CD34+ cells undergo transduction with a third-generation, vesicular stomatitis virus-G pseudo-typed lentiviral vector driving myeloid-specific IFNa2 expression. Patients will be offered maintenance treatment from successful HSPC collection until Temferon release. A reduced intensity conditioning regimen is administered at Day -2 followed by ASCT and administration of Temferon at Day 0. Following hematological recovery, patients will be discharged from the Transplant Unit with regular outpatient follow up.

After Day +100 from Temferon infusion, patients will resume anti-myeloma consolidation/maintenance treatment according to best clinical practice, unless there is Temferon engraftment and absence of disease on Day +100 evaluations, documented by stringent complete response (sCR) according to the IMWG response criteria, imaging (PET, MRI) negativity, and bone marrow minimal residual disease < 10^-4 by multi-parameter flow cytometry, to be confirmed by next generation sequencing. If these response criteria are met on Day +100, patients may stay off maintenance treatment, as long as MRD≤10^-5 documented on bone marrow aspirates performed every 3 months, starting from the Day +180 visit.

The primary endpoints for this study are:

• Engraftment of Temferon between Day +30 and Day +100

• The proportion of patients achieving hematologic recovery by Day +30 from ASCT

• Safety of Temferon (short-term tolerability of Temferon; stable blood counts and absence of cytopenias > grade 2, unless related to myeloma progression or concomitant medications; absence of systemic IFNa toxicity; absence of Replication Competent Lentivirus; absence of hematologic malignancy that is distinct from progression of the primary neoplasm)

The study is actively recruiting patients in Italy. In parallel, a study using Temferon in patients with glioblastoma multiforme with a similar study design and approach (TEM-GBM-001) is also in progress with the first cohort fully recruited.