CytomX Therapeutics Clinical Programs Highlighted at American Society of Clinical Oncology ASCO20 Virtual Scientific Program - Seite 2

• Evidence of target lesion reduction was seen, principally in patients with tumors of squamous histology. (Figure 1)
  °  3 confirmed partial responses were observed in 17 response-evaluable patients treated at doses ≥2 mg/kg of CX-2029, 2 in patients with squamous non-small cell lung cancer (SqNSCLC) and 1 in a patient with head and neck squamous cell cancer (HNSCC).
  °  2 of the partial responses (both at the 3 mg/kg dose) were confirmed after the April 20^th cutoff date.

CX-2029 Waterfall Plot (Doses 2–5 mg/kg)

Figure 1 is available at https://www.globenewswire.com/NewsRoom/AttachmentNg/51129ea3-a850-4d2f ...

Safety Profile Supports Recommended Phase 2 Dose of 3 mg/kg, Every Three Weeks

• CX-2029 was generally well tolerated at doses up to 3 mg/kg.
• At doses of 0.25 – 5 mg/kg, CX-2029 circulated predominantly as the intact species (>90%).
• The most common treatment related adverse events (TRAE) were infusion related reactions, anemia, and neutropenia/leukopenia.
  °  Infusion related reactions were mostly Grade 1/2, occurred at the first dose, were not dose dependent and resolved upon initiation of supportive care.
  °  Hematologic TRAEs Grade ≥ 3 were dose dependent.   
      •  Anemia and neutropenia are commonly observed with the MMAE payload. 
      •  Anemia was managed with transfusions and supportive care.
• No CX-2029 treatment related deaths were reported and late onset Grade 3/4 TRAEs were predominately anemia and neutropenia.
• The etiology of anemia is under investigation and is likely multifactorial, including MMAE-related and CD71 expression on red blood cell precursors.
• CytomX is preparing to advance the dose of 3 mg/kg of CX-2029 administered every 3 weeks into 4 dose-expansion cohorts: HNSCC, SqNSCLC, esophageal carcinoma and diffuse large B cell lymphoma.

“Targeting CD71 with this novel approach has the potential to address areas of unmet medical need in difficult to treat tumor types, improving patient benefit,” said Melissa L. Johnson, M.D., CX-2029 principal study investigator and associate director of lung cancer research at Sarah Cannon Research Institute at Tennessee Oncology. "This first-in-human data of CX-2029 establishes the transferrin receptor as a high potential anticancer target addressable with CytomX’s Probody technology.”