Study to Assess the Safety and Tolerability of Repeated Doses of an Investigational New Drug in Patients With Cancer and Cachexia.

Study to assess the safety and tolerability of repeated doses of an investigational new drug in patients with cancer and cachexia.

This 12-week open-label study will explore how PF-06946860 is tolerated, the effects of the study drug, the best dose for treatment and how participants with non-small cell lung, pancreatic or colorectal cancer and cachexia feel after receiving repeated subcutaneous dosing. During the 12-week treatment period, study drug will be administered subcutaneously every 3 weeks for a total of 5 doses. There is a 12-week follow-up period following the last dose of study drug. Additional assessments include:

* body weight measurements
* blood pressure and heart rate measurements
* Lumbar Skeletal Muscle Index (LSMI) by CT scan
* Blood samples:

  * to evaluate safety,
  * to measure the amount of the study drug in the blood,
  * to evaluate if the study drug causes an immune response,
  * to examine the effects of the study drug on levels of a specific cytokine,
  * and for exploratory samples for bio banking.
* Measure the impact of the study drug on appetite, nausea, vomiting, fatigue, physical function, and health-related quality of life with questionnaires.
* Measure the impact of study drug on physical activity using wearable digital sensors.
* To evaluate the effect of study drug on ability to complete anti-tumor treatment and survival in participants with cancer and cachexia.
* To evaluate tumor size.

Eligibility Criteria:
Inclusion Criteria:

* Documented histologic or cytologic diagnosis of advanced metastatic NSCLC, advanced/unresectable pancreatic cancer, or metastatic colorectal cancer.
* Cachexia, defined by BMI \<20 kg/m2 with involuntary weight loss of \>2% within 6 months prior to screening or Involuntary weight loss of \>5% within 6 months prior to screening irrespective of BMI or If medical record documentation is unavailable, patient's report will suffice to estimate involuntary body weight loss.;
* Will receive the following for non-small cell lung cancer:

  * a platinum + pemetrexed ± pembrolizumab or
  * a platinum + nab paclitaxel or paclitaxel ± pembrolizumab or
  * pembrolizumab alone
* Will receive the following for pancreatic cancer:

  * FOLFIRINOX or
  * Nab-Paclitaxel + Gemcitabine
  * Gemcitabine
* Will receive the following for colorectal cancer:

  * FOLFOX +/- Biologic (Bevacizumab or Cetuximab/Panitumumab) or
  * FOLFIRI +/- Biologic (Bevacizumab or Cetuximab/Panitumumab) or
  * FOLFOXIRI +/- Biologic (Bevacizumab or Cetuximab/Panitumumab) or
  * Pembrolizumab for MSI-H • Will be entering the study at the first or second cycle of their current course of anti-cancer treatment/ therapy.
* Adequate renal and liver function.
* Signed informed consent.

Exclusion Criteria:

* All other forms of cancers not specified above unless currently considered cured (\>5 years without evidence of recurrence).
* Planned radiation therapy as part of the primary anti-tumor therapy regimen. However, localized radiation therapy for symptomatic relief is permitted
* Cachexia caused by other reasons: Severe COPD requiring use of home O2, heart failure or AIDS.
* known symptomatic brain metastases requiring steroids.
* Active hepatitis B or C virus.
* Confirmed positive HIV test.
* Current active reversible causes of decreased food intake.
* Receiving tube feedings or parenteral nutrition at Screening.
* Elevated blood pressure that cannot be controlled by medications.
* Women who are pregnant or breast-feeding