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Immunomedics publishes Phase 2 cancer med trial results

July 12, 2017

Immunomedics, Inc.(NASDAQ:IMMU) (“Immunomedics” or the “Company”) today reported the publication in two prominent cancer journals of phase II clinical trial results with sacituzumab govitecan (IMMU-132) in a total of 104 patients with lung cancer, including advanced small-cell lung cancer (SCLC) and non-small-cell lung cancer (NSCLC) patients who relapsed after, or were refractory to, prior treatment with standard chemotherapy or immune checkpoint inhibitors.

In the SCLC study published online in Clinical Cancer Research, the authors1 evaluated the novel antibody-drug conjugate (ADC), sacituzumab govitecan, composed of an antibody targeting Trop-2 and carrying the active metabolite of irinotecan, SN-38. The study included 50 SCLC patients with metastatic (stage IV) disease who had a median of 2 prior therapies. Notable findings from the study include:

  • Ninety-two percent of the patients evaluated for expression of the target for sacituzumab govitecan, Trop-2, had elevated levels in their archived tumor specimens.
  • Patients given repeated treatment cycles had manageable toxicity, mostly Grade >3 neutropenia (34%), and 60% of those patients experienced tumor shrinkage from baseline CT measurements.
  • The objective response rate was 17% at the optimal dose schedule; the median duration of response and overall survival were 5.7 and 7.5 months, respectively.
  • Activity was observed in patients who were chemosensitive or chemoresistant to frontline chemotherapy, in patients who failed second-line topotecan, and in a subset who relapsed after immune checkpoint inhibitor therapy.

The article’s first author, Jhanelle Gray, M.D., of the Moffitt Cancer Center, Tampa, FL, remarked, “Topotecan, another topoisomerase-I inhibitor, is the only drug approved in the USA for SCLC patients who are responsive to frontline therapy with a platinum-containing chemotherapy. In contrast, sacituzumab govitecan showed activity in patients who were either responsive or refractive to frontline therapy, and also to those who relapsed to topotecan. A randomized, controlled trial comparing these two agents in second-line therapy, as well as sacituzumab in the frontline setting, should be undertaken.”

Dr. David M. Goldenberg, Immunomedics’ founder, commented that, “Sacituzumab govitecan represents a promising new therapeutic candidate for advanced mSCLC, a very lethal cancer with a five-year survival rate of only 6 percent.” Goldenberg continued, “Importantly, this candidate potentially could be the first new therapeutic approved for the treatment of metastatic (stage IV) small-cell lung cancer (mSCLC) in twenty years.”

In the second article published online on May 26, 2017, in the Journal of Clinical Oncology, the authors2 reported the results of the phase II, multicenter trial of 54 heavily-pretreated patients with metastatic NSCLC who received either 8 or 10 mg/kg sacituzumab govitecan on days 1 and 8 of 21-day cycles. The primary endpoints were safety and objective response rate (ORR). Progression-free survival (PFS) and overall survival (OS) were secondary endpoints. Notable findings from the study include:

  • In the response-assessable study population (N = 47), which had a median of 3 prior therapies (range, 2-7), 67% of patients showed a shrinkage from baseline CT measurements.
  • The confirmed objective response rate was 19.1%, the median response duration 6.0 months (95% CI, 4.8, 8.3), and the clinical benefit rate (CR+PR+SD>4 months) was 43%. Responses occurred with a median onset of 3.8 months, including patients who had relapsed or progressed after immune checkpoint inhibitor therapy.
  • Median intention-to-treat (ITT) PFS was 5.2 months (95% CI, 3.2, 7.1), and median ITT OS was 9.5 months (95% CI, 5.9, 16.7).
  • Grade 3 or higher adverse events included neutropenia (28%), diarrhea (7%), nausea (7%), fatigue (6%), and febrile neutropenia (4%).
  • Over 90% of 26 assessable archival tumor specimens were highly positive for Trop-2 by immunohistochemistry.

Dr. D. Ross Camidge, Director of Thoracic Oncology at the University of Colorado Cancer Center and senior author of this study, commented, “In a heavily pretreated population like this, the results with sacituzumab govitecan are quite encouraging, suggesting further trials both alone and in combination with other drugs, potentially including immunotherapy, should be strongly considered.” Camidge continued, “Non-small-cell lung cancer patients will always benefit from additional therapeutic choices, and while immunotherapy and oncogene targeted therapy have certainly revolutionized the treatment for subsets of the disease, the use of ‘smarter’ chemotherapy in the form of an effective antibody-drug conjugate such as sacituzumab govitecan may well be the next major advance we see.”

Dr. Behzad Aghazadeh, Chairman of the Board of Immunomedics, stated, “These promising results in two lung cancer indications, comprising the major cancer killers, attest to the breadth of the therapeutic potential for IMMU-132 in the treatment of metastatic solid cancers. Our principal focus is to seek accelerated approval for this ADC in patients with advanced, heavily-pretreated triple-negative breast cancer (TNBC), for which there is no approved therapy and significant patient unmet need.” Aghazadeh continued, “We have also reported that sacituzumab govitecan, in addition to TNBC, SCLC, and NSCLC, is active in patients with metastatic urothelial cancers, where we hope to update results at a future medical meeting, so we now know it is active in at least four different major solid cancers.”


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